A-arms are lame

[Dylan]

A-arms are OK but cant we do better??

What do we want our wheel to do and how do we want it to move?

At a given steer angle we only want one degree of freedom, up and down.

Let’s skin this cat another way!

Dylan

[Bob_Sheaves]

OK, accepting your challenge...LOL....

The single most important item in vehicle dynamics is control over the ground contact patch- all other things are secondary.

Agreed?

Best regards,

Bob Sheaves

[Jimmy8]

There is another way to do front suspension other than I beams, a arms or a 4 link if that is what you are getting at. We were going to apply it to my new Trophy Truck but decided against it. We may try it out on a pre runner before we do it on a competition vehicle, but there is another way. It hasnt ever been done before, and could revolutionize the sport. We have the idea, but I am not going to let it out in the open because we may do it in the future. Use you imagination.

Trophy Truck #15
Class 8 #8080
www.jimmybeaver.com

[FABRICATOR]

Ho hum...
Perhaps Bob, but there is the omnimissing parameter of application! Things like vehicle weight, speed requirements, terrain, and durability (just to name a few) will significantly affect overall design. Are we talking swell geometry on pavement, high speed over rough terrain, or what? Application defines what compromises are made to perfection.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[Bob_Sheaves]

Nope- reread what I said-GCP is THE SINGLE most important item-all else is lower priority, regardless of the application. In other words-you ain't going anywhere if you ain't got traction.

I was under the impression from Dylan's post that he wanted to have a discussion on designing a new suspension. This requires a starting point. If I am wrong, or ya'll don't wish my input-please tell me and I'll be quiet....LOL!


Bob

[Dylan]

Yes I agree!
But in off road conditions is the normal way we quantify the effectiveness of the contact patch (vertical to lateral load conversion, slip properties, ect.) really appropriate or should we model the tire after a farm plow disc that is displacing dirt?
On the “secondary” or maybe "primary" properties: how do we get the loads (however they are generated) at the contact patch back to the chassis with the reaction that we want throughout our ridiculous amount of travel. We have been using A-arms primarily but we never get the pivot points quite were they need to be.

??Eclipse lower “quasi” A-arm, Mercedes rear ??

Dylan

[Bob_Sheaves]

The next thing to define, now that we agree on the "ground set" boundary condition (for those not familiar- "ground set means the immovable element where traction force is applied), we need to define the starting point or "input set" boundary condition, i.e. the total mass of the vehicle. This is where you define the mass and center of gravity (obtained from a general packaging diagram with this info).

Combined with the GCP- this sets the limits of mass parameters. The input loading is applied to the CG (actually the polar moment, but we'll get into that in a bit) is reacted against the ground set through the GCP.

Best regards,

Bob

<P ID="edit"><FONT SIZE=-1>Edited by Bob_Sheaves on 04/09/02 11:47 AM (server time).</FONT></P>

[FABRICATOR]

Bob, my comments addressed a lack of specification from Dylan, and had nothing to do with your post. I don't think anyone here, especially myself, has anything but great respect for your experience and input.

As far as the "SINGLE" most important thing...it ain't going anywhere if it's broken either. It appears Dylan is talking about going fast off-road, but if it's not realistic it is of little use. My apologies if I only rebut some of your theories.

The extreme wheel travel needed, among other things, will dictate a lot about what must be used or cannot be used. The system must also put up with severe abuse. I must question dirt as an immovable element where traction force is applied. Seems that I don't agree with much today. I'll be quiet. (LOL)


<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[Bob_Sheaves]

ROFL!!! Guess we both misunderstood each other....LOL!!!

Anyway, I don't take offence so easy-you ought to know that....what I was intending was to introduce comments just like it was a real design project (I have started with less information before...LOL). Figgered that the mind excercise would be good for me. If no one objects-I'd like to use my software as the definition grows to show in 3D what the discussion is all about. Sound like a good excercise?

Btw- the dirt IS the GCP-one of the excercises will be to determine tractive effort applicable through varying coefficients of friction....

Best to you as always,

Bob

[Mike_McCluskey]

Bob, since your gonna use your software to illustrate whats discussed here why don't you guys take it one step further and create a whole new car. Get input from everybody and design the ultimate desert race car. Maybe some FABRICATOR might help get it built. The first car conceived online!

Just a thought. These are definitely some of the better discussions.

[Tyson]

I'd be down to drive the car for you all http://www.race-dezert.com/wwwthreads/images/icons/laugh.gif LOL. . .Say in MDR, well I guess we need to know what class this "Ultimate race vehicle" would run in.

Tyson
YOTAPUNK</font color=red> (http://www.geocities.com/yotapunk>)

[rdc]

See Klaus, you are finally getting a car built for you! LOL

Bob I think 3D models of what you all are talking about is an exellant idea.. And if it were possible to build the RDC online unlimited car that would be awesome! I guess we better start taking donations...

Tony
<A target="_blank" HREF=http://www.y-not-productions.com>www.y-not-productions.com</A>

[Bob_Sheaves]

OK, guys...next is a list of information needed and assumptions for this "project". I will assume everyone will contribute to this?

In no particular order:

Assumptions:

1. Class car will run:

2. Number of passengers:

3. Maximum speed desired:

4. Gross vehicle weight: (this is a "wet" weight)

5. Number of drive wheels:

6. Fuel capacity desired:

7. Tire manufacturer:
a. Size:
b. Pressure:
c. SLR (Static Loaded Radius):
d. RPM (revolutions per mile):
e. Max section width:
f. Wheel profile and size desired (JJ, JK, or whatever profile):

8. Engine desired:
a. Weight Dry:
b. HP @ "X" rpm:
c. Torque @ "X" rpm:
d. Manufacturer:
e. Model:
f. Heat rejection (in BTU/minute):

9: Transmission desired (Automatic or manual trans)
a. Torque converter ratio (if used):
b. Number of ratios and numerical ratio for each:
c. Weight dry:
d. Manufacturer:
e. Model:
f. Heat rejection (in BTU/minute):

10. Final drive/ axle type (Salisbury, Hotchkiss, IFS. IRS, etc) desired:
a. Ratio of final drive desired:
b. Ratio of hub reduction, if used:

Suspension design is not specified, as this is the purpose of this discussion- to determine a "new" design that will fulfil the stated parameters. Now is the time to add any other desired design parameters also.....

Best regards,

Bob

[Bob_Sheaves]

To get you all familiar with thinking in 3D terms, I am attaching (I hope) a JPG image of the start model. In this image, the XYZ trihedron is your reference to what is up and down, left and right. In this image, "X" points towards the rear of the car along the centerline, "Y" points to the right side of the car, and "Z" points "up". In other words, you are viewing this from above the right rear corner of the car.....

The wheelbase shown of 3048mm (120 inches) and track width of 2032mm (80 inches) is simply for reference. The plane labled *PLN1 indicates the ground contact surface in the design position (you always start from a static, fixed plane when designing a vehicle). the other planes are referencing other information we will use later.

Bob

[Chris]

No5: Four wheel drive!

[DPpatrol]

OK. Since nobody has actually proposed a new type of front suspension yet, I'll throw one out there. This design works to combine the long travel of an I beam suspension with double A arms ability to control the suspension camber curve. Each "upright" (see how my vocabulary is increasing) would be connect to two I beams creating a quaderalateral (excuse my spelling) and a radius arm to prevent rearward movement of the suspension. I attached a picture. The top diagram shows a truck with this type suspension while the bottom diagram shows just one wheel and its complimenting suspension. The dots and circles represent pivot points. The radius arms are not shown in the pics, but they are there, just in the background. So why won't this work? (since it probably won't)

jason

[tkr]

where would you attach the radius arms? wouldn't they contact each other through the travel?

Matt Nelson
Team Kwik Racing

[Bob_Sheaves]

Good idea, but it's a little ahead of the game right now-Let's get the other parameters set first, then I will put up a packaging image so the suspension design can start....We have one vote for 4x4, any more comments on this or other information?

Bob

[DPpatrol]

The radius arms would be positioned behind the spindle just like normal radius arms. Actually I think their arc would be sweep more in just the verticle plane than with normal radius arms since the wheel will would have less camber change throughout the arc than with I beams, so they shouldn't contact. If you are talking about the beams contacting, you'd have to offest them just like normal I beams are offest.

jason

[Dylan]

Bob it must be nice to be retired, you can play on the Internet all day long.
What I was trying to provoke was a brain storm session on an alternative for A-arms. But if you want to design a whole new vehicle that’s even better, as long as it doesn’t have A-arms or beams ect.
The Mercedes rear 5 link design has been used in the rear of off road vehicle “in a very rudimentary form” quite a bit but what about the front ??
Checks out the eclipse reference that I mentioned.
Hell I don’t care, let’s get really outside the box. This is a seemingly stupid idea but what about each wheel on a huge linear slider or 6-foot tall struts or huge motorcycle forks at each corner. When all the cars were swing axle they said that IRS would never work and it didn’t succeed for a couple of years but eventually they got it dialed
Dylan

[Kritter]

Assumptions:

1. Class car will run: Class one

2. Number of passengers: 1 This thing will be bullet proof!

3. Maximum speed desired:160mph (260km/hr) For the long lake beds!

4. Gross vehicle weight: 4000 lbs (1815 kg) Build em light, wind em tight.

5. Number of drive wheels: 4

6. Fuel capacity desired:85 gallons (325 liters)

7. Tire manufacturer: Animal House Designs (Inpenetrable, only need to be changed for wear)
a. Size: 37x13.50x17
b. Pressure:40 psi (275 kPa)
c. SLR (Static Loaded Radius): 17inches (432 mm)
d. RPM (revolutions per mile):593.2
e. Max section width:12 inches (305mm)
f. Wheel profile and size desired (JJ, JK, or whatever profile):??

8. Engine desired:
a. Weight Dry:375lbs (170 kg)
b. HP @ "X" rpm:780 Hp @ 10500 RPM (
c. Torque @ "X" rpm:650 ft-lbs @ 5000 RPM
d. Manufacturer: Animal House Designs
e. Model:AHD-780
f. Heat rejection (in BTU/minute): 4500 BTU/Min (78 kW) Seems Adequate. Don't want to warp the all aluminum motor!
9: Transmission desired (Automatic or manual trans) Manual
a. Torque converter ratio (if used):
b. Number of ratios and numerical ratio for each: 7spd 4.0| 3.43 | 2.75| 2.25| 1.75| 1.25| 1
c. Weight dry:175lbs (80kg)
d. Manufacturer:Animal House Designs
e. Model:AHD-7S
f. Heat rejection (in BTU/minute): 2000 BTU/Min (35 kW)

10. Final drive/ axle type (Salisbury, Hotchkiss, IFS. IRS, etc) desired:IFS and IRS
a. Ratio of final drive desired: 5.75:1


Kris

"A signature always reveals a man's character -- and sometimes even his name. "

[Dylan]

DP
Good idea. What you propose is still an A-arm though, they just cross over each other. I saw a quad with custom suspension like that once. I’ve thought about doing that also.
Keep the ideas coming
Dylan

[Kritter]

From your sketches it appears that the mounting takes place on the inner frame rails. If you look at any truck at the inner frame rails and think about mounting up some arms from there in a cris-cros fashion it would hit the undercarriage of the truck unless the truck sat really high in the air and was limited on its bump travel. It also seems that the spindle would have to be pretty small which will limit travel on an arm set up like that.I'd like to see it though becasue a friend of mine showed me that type of design a while back and I said the same thing so now I am curious to see one built even if its only scale.

Kris

"A signature always reveals a man's character -- and sometimes even his name. "

[Kritter]

"Hell I don’t care, let’s get really outside the box"

Reminds me of the text message commercial with the marketing guy gettting all crazy and saying "pair-uh-dig-um" haha

Kris

"A signature always reveals a man's character -- and sometimes even his name. "

[rdc]

I vote to run it in unlimited. We are going to have enough rules to follow just getting it to work right.

As for how many passengers? Do you you think we can build something for 1000 people? The registered # of peopla is 942 as I type this. Okay I guess that would be to big.. But I would say 4 so we can give everyone a ride in as timely manor as possible. Wow this thing better be durable!!!!

Since we are dreamong up the ultimit off road car then lets go for 4x4...

Bob I would like to see it go around 150MPH, at least for me.. :-)

Keep it light! say between 2500 and 3500#'s

I don't like getting out to pump gas so lets put a big tank in it! Oh wait that will make it heavy, damn! But anyhow I would think 40 to 60 gals should work well.

I would have to go with a chevy 350 for the motor. Tons of parts out there for a good price. We will not have make anything custom..

Auto trans

And tires I would go with 37' BFG Projects

Tony
<A target="_blank" HREF=http://www.y-not-productions.com>www.y-not-productions.com</A>

[DPpatrol]

9) Transmission desired: Lets get Dave G to make us a copy of the Herbst 4wd tranny. It looks like the bugs are just about worked out of it.

jason

[Bob_Sheaves]

Sorry Kris, I wasn't clear on what I meant by wheel profile. There are several SAE wheel contours available, depending on load and application- this also includes beadlocks.

I apologize for not being clear.....

Bob

[Bob_Sheaves]

ROFL!! Gee THANKS- I can't let my wife see your comments.....

Seriously, I figgered that just to work out the mechanics would not make too much of an impact- that is why I thougt it would be better to approach it from a "whole car" standpoint and how the parts interact. True, we aren't going to get into the really fine points (unless demand is there) but this would be a better example of what you called "thinking outside the box" (which I agree with)....now WHERE"S THE INFO ANSWERS from YOU????


LOL!!!

Best as always,

Bob

[BIG_FAT_LOSER]

reading all this makes my brain hurt...lol

<font color=red>PAT KAPKO</font color=red>
<font color=yellow>Self appointed King of ghetto fab</font color=yellow>

[Dave_G]

Bob,
Lets put a gas turbine (PT6-A) engine in this thing, make it hydrostatic drive and 4WD with hydraulic drive motors at each wheel. Then we'll incorporate some software to ........ok, I'll shut up now. ;-)

Best,
Dave

"I know it all, but I can't remember most of it..."

[MNotary]

1. Class car will run: 1

2. Number of passengers: 1

3. Maximum speed desired: 160 mph

4. Gross vehicle weight: (this is a "wet" weight) 2000

5. Number of drive wheels: 2

6. Fuel capacity desired: 25

7. Tire manufacturer:
a. Size:33 x 12
b. Pressure: 22
c. SLR (Static Loaded Radius): 14
d. RPM (revolutions per mile):
e. Max section width:
f. Wheel profile and size desired (JJ, JK, or whatever profile):

8. Engine desired:
a. Weight Dry:
b. HP @ "X" rpm: 550 7000
c. Torque @ "X" rpm: 500 4500
d. Manufacturer: Mr. Aluminum 5 valve
e. Model:
f. Heat rejection (in BTU/minute):

9: Transmission desired (Automatic or manual trans) Sequential manual
a. Torque converter ratio (if used):
b. Number of ratios and numerical ratio for each:
c. Weight dry:
d. Manufacturer:
e. Model:
f. Heat rejection (in BTU/minute):

10. Final drive/ axle type (Salisbury, Hotchkiss, IFS. IRS, etc) desired: IRS Torque sensing
a. Ratio of final drive desired:
b. Ratio of hub reduction, if used:

Hey Kris, build a RACE car not a tank.

[Bob_Sheaves]

OK guys,

Using the 37 inch tall BFG Projects, we lay in the 4 tires on the vertical centerlines thru the GCP with 0 degree camber at this time. Then we set the kingpin inclination angle we desire (KPI). A rule of thumb for low steering effort is 1/2 nominal pass car design, or roughly 6 degrees, as shown in the attachment. With the instant center shown (see next image post), we have a projected roll center 50mm BELOW the ground level.

Is this good or bad? At this point, we are not sure, because we do not have a mechanism in place to move the tire yet.

Bob

[Bob_Sheaves]

This is image #2 for the previous post, showing the instant center length (ICL) for the right front tire.

[fishd00d]

Pat I am with ya! I dont understand any of this :)

Go Big Or Go Home

[Bob_Sheaves]

Hang in there...LOL...I know it's confusing, but it will start to make more sense once more information is drawn. The next step (tomorrow, as it's after midnite here) will be to define the ground clearance and jounce (up) travel.

Best regards,

Bob

[mobben]

ok dylan. you've succeeded in getting are brains rolling keep it up!

[Greg]

I think Dave is on the right track but how 'bout electric drive from a super-effcient (powerful) turbo diesel powering a generator to servo controlled motors in each "wheel". Thereby eliminating they conventional drivline and giving complete traction controll. the biggest set back woul be weight. On second thought, maybe hydrostaric would be better. We work with a company that designs hydrostatic control valves that would easily handle 500 hp to each wheel, that part seems semi-possible.

Greg http://prerunners.com/images/assorted/rockdevil.gif

[Bob_Sheaves]

Gee Dave, you DO remember me from the days with Walter!!!

ROFLMAO!!!!


Best as always,

Bob

[Mike_McCluskey]

I second MNotary's choices. I like the lighter, quicker, more agile setup. 37" tires are just so damn large! I guess I understand why everybody runs them but how many of you have actually had to change a 37" BFG flat by yourself!? Them suckers weigh quite a bit.
Are we trying to design/build something realistic or completely off the deep end? There are a few people who haven't given any input yet, Kreg, FABRICATOR, class... anyone!

[Bob_Sheaves]

Hi Mike,

I have and I KNOW how much of a pain (literally and figuratively) that is. However, the "indestro" tire comment made me think that one of the example trade off studies for this thread would be a Central Tire Inflation System similar to what was put onto the Hummer and HEMTT trucks for the US Army and Marine Corps. These systems flow enough air to keep an 18.00x22.5 tire at 35psi with a 1.5inch hole in the sidewall. The catch is that the systems are HEAVY.....just what I wanted for this demo....LOL

Best as always,

Bob

[Motorider]

If we are going to make this thing four wheel drive, why dont we try something like what the hummers use. they have really small drive shafts and axles, because all of the downgearing is done at the wheel hubs. Sounds like a great project. And gives me something interesting to think about when I'm at work screwing around with inventor.

[MNotary]

Chenowth tried a F1 car on steroids. Just needs tuning. Maybe 35/65 weight bias? Make the front work a little and give it some control. A sprint car is 1200 lbs. 800 lbs is alot of suspension. Got to get these guys out of truck mode and into race car mode. I would like to see a 4000 lb F1 car....FIA rule 12.3.2 Minimum weight: 4000 lb. The steering racks are so light they wear out after one race.

Realistically off the deep end.

[Bob_Sheaves]

Hi all,

Final comment for the night....

One thing I want to impress upon everyone- Dylan (since he started the thread) is the "design supervisor" and should make the final configuration decisions. My "job" is to act as the design engineer and simply point out things that CAN be done, and make the "requirements" a "reality", NOT tell anyone what SHOULD or WILL be designed (unless we run into an insurmountable problem-which I doubt with all the talent here). I do not care how "off the deep end anyone goes" as long as Dylan agrees. My suggestion (only) is to make this thing as light as possible (2500lbs MAX.) AWD (instead of 4WD), 2 seat (always a backup "system") and as effecient as possible (less parts means less breakage, generally).

Best as always,

Bob

[ntsqd]

Hydrostatic tends to suffer from excessive heat generation and fluid cavitation at high speeds. May be cureable, but the cure gets large and heavy.
IC's are inefficient no matter what you do to them. Push on one really hard and you might get 35% For efficiency I'll vote for a Capstone Turbine APU (~60%), CuMH batteries, and 3 phase AC hub motors with a controler/magic box similar to AC Propulsion's designs.

As for suspension general design, just because I'm a masochist I'll vote for Morgan's sliding pillar design. That gets you GCP control, springing, steering, and damping all in one unit. The, uh, para-dig-um of efficient design...........

TS

"Teach you all I know and you're still stupid"
-- Howdy Lee

[Ryno]

Wow-

Working two jobs and staying up late really kills your brain! Dylan....what about having IFS...with a kingpin and J arm. You would use the actual axle as the lower pivot point. Kinda like a solid axle, but pivoting from either side of the pumpkin. Those of you that know me, my vote is for a small block chevy. Maybe some around a 406, or 396 small block. Nice set of heads, and a race cam, and we're pumping out easily 500 hp. For weight, don't sacrifice weight for durability and reliability. Tranny...I'could see a ZF in there, 6 spds would be kinda nice! Get that Dana 60 from Greg, and you're set!! This is like me in the candy store!!

Ryno

Build it like a Rhino, and Leave it be.

[AllwaysRcn]

"some around a 406, or 396 small block."

440cid " Rocket Block" Alluminum small block, GM Performance, 700+HP, Light!!!
Sorry off topic a little!!!!

[BradM]

You're on the right track Bob. Keep it light. I would say 3000# is an attainable target. I don't see how you could come up with a AWD system that would be durable enough to last and keep the car under 4000#. Besides, it would also require more HP to overcome the additional drive losses. My vote is for 2WD. I agree with the 2 seat concept too. I conquer with MNotary, smaller tires are lighter (maybe 35s) and less unsprung weight will allow the entire suspension to be simpler and lighter as well as more effective. Suspension travel needed will be dependent on overall size and weight but likely could get by with 20-24 inches on a smaller, lighter car. You have got to carry the fuel (60-80 gal) for long runs and that will weight it down too. Everything is a compromise but you have to consider the trade offs and the overall objective. Should look towards mid engine and 4 wheel independent to improve handling. I guess you'll have to design a suitable transaxle at the same time.

Be realistic with the ideas. It is not feasible to build a 2500# AWD unlimited car. At least not if you consider any sort of budget. Good luck.

[Dylan]

Assumptions:

1. Class car will run: 1
2. Number of passengers: 2
3. Maximum speed desired: 160mph (if were going this fast we better look at the aerodynamics)

4. Gross vehicle weight: (this is a "wet" weight)
OK I like the idea of keeping it under 2500lb but if we go with 37”BFG’s @ 150# each + hubs and brakes ect we will have 1000lb’s unsprung. And for a 2500 lb car that’s not going to work. So lets back up and define a max unsprung weight %. How about shooting for 15% with a max of 20% ??

5. Number of drive wheels: AWD would be great but up goes the unsprung weight

6. Fuel capacity desired: depends were it is. If its hanging of the ass end-10 gal. If it’s centrally located 80 gal. But watch the % change of vehicle weight full and empty

7. Tire manufacturer: ACME
a. Size: 37 x 12.50 R 20??
b. Pressure:
c. SLR (Static Loaded Radius):
d. RPM (revolutions per mile):
e. Max section width:
f. Wheel profile and size desired (JJ, JK, or whatever profile):

8. Engine desired: I like the hydrostatic or electric ideas but hub motors are heavy “ unsprung weight again”
a. Weight Dry: keep it light ~ 400lb
b. HP @ "X" rpm: 3~4 lb / hp
c. Torque @ "X" rpm: if its electric how about 1500ft*lb @ 0rpm
d. Manufacturer:
e. Model:
f. Heat rejection (in BTU/minute):

9: Transmission desired (Automatic or manual trans) (CVT???) to be determined

10. Final drive/ axle type (Salisbury, Hotchkiss, IFS. IRS, etc) desired:
a. Ratio of final drive desired:
b. Ratio of hub reduction, if used:

Suspension design is not specified, as this is the purpose of this discussion- to determine a "new" design that will fulfil the stated parameters. Now is the time to add any other desired design parameters also.....

Here is a parameter that might be worth investigating. A dimensionless # to determine the pitch resistance called CPR(center of percussion “ratio”) not to be confused with the actual center of percussion

CPR=K/(L1*L2) were K= radius of gyration and L1&L2 are distances from CG to front and rear axles

Bob: you had mentioned a kingpin inclination of 6deg. This may not be a constant value, it could change through both travel and steer angle (along with trail). Also roll center height?? Why so low and how are we going to keep it in a reasonable range through out travel of 22+”. Isn’t it also sometimes problematic when it crosses ground level. Maybe we should keep it above or below ground level @ all times. I’d also like to see front sway bars maybe blade adjustable type.
That’s enough for now I have to get back to work
Dylan

[FABRICATOR]

There's a lot of good ideas here (and some not so good). There are two things going on here that might not be compatible. Designing a "new" car is cool but starting off with the limitation of no A-arms may be a built in handicap. MAYBE. You may need to decide which is more important in order to end up with anything usable. It's up to Dylan for this thread.

Looks like you guys need a goal keeper. It can't be me (not that anyone asked) because I've been through too much of this stuff already and am too much of a realist. I nominate BradM, because he is one of the few engineers with real off-road racing experience that includes driving and fabricating.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[tkr]

The origional point of this was to come up with an alternative/improvement to a-arms. I think we need to stick with that.

Matt Nelson
Team Kwik Racing

[BradM]

I am just a casual observer who offered a few thoughts towards the design. I think Bob has already appointed Dylan for that anyhow.

[Jkrell]

Any thought to a Rotory power plant, great power to weight ratios. I seem to remember a couple of cars using them back in the mid 90's, but haven't seem much since.

Jon

[Bob_Sheaves]

OK all...now that I have had time to regret my actions....LOL....

First off, let me go over some suggestions as they apply to previous comments:

1. Hydrostatic drives. One thing that is interesting from my viewpoint is that most (not all ) of the comments centered on the hydrostatic drive system, and yet still mentioned brakes. Sorry guys, but a pure hydrostat does NOT use brakes as you may be thinking. This is actually an advantage in this application, due to the usual unsprung weight associated with the rotors, calipers, mounting bracketry, etc. The hydrostat used fluid flow restriction (yes Dave I know this is REALLY simplified) for braking effort. Drive a Bobcat 700+ series with the hydrostat drive and you will see what I mean- you release the levers from a forward position to spring back to the neutral position and you STOP (and probably almost turn the thing upside down as it pitches forward around the front hub centerline.

2. Inboard discs have been used successfully for a number of years, and with strong half shafts are no detriment to the vehicle durability (this assumes proper cooling, etc.).

3. The hydrostat WILL create a LOT of heat in use and will require a really big cooler-something on the order of 36"x48"x2 inch core (2 pass- capable of some 20K BTU/min heat rejection) that will need to be calculated later, if that is the way you all want to go.

4. Hydrostat drives are very speed limited and ineffecient when outside their proper operating range-this will require the use of a range box (of some type) to increase and decrease this range as needed for the desired 150-160mph vehicle speed.

5. Specifically to the 6 degree KPI angle used, that number was simply derived to provide a location for the center of the drive joint packaging-it may or may not change, depending on what components I use in the design.

The following posts will cover the ground clearance and travel limitations first, then the packaging of a wheel end (I think I have some live spindle info around here to use, since that was recently discussed) and drive joint.

Best as always,

Bob

[Bob_Sheaves]

G/A drawing (general arraingment) showing overall layout of right side drive- you are looking at the front of the vehicle.

[Bob_Sheaves]

G/A of unitized wheel hub and bearing assembly (live spindle discussed earlier this week).....

[Bob_Sheaves]

G/A of Double Cardan "CV" joint- used as drive input as shown. May change location with single cardan.

[Bob_Sheaves]

Projected jounce maximum travel available, assuming shown ground clearance (18"), 37" tall Project BFG's, and available joint angle in shown joints.. Not necessarily what is wanted- simply mechanical maximums on current configuration.

[Bob_Sheaves]

Rebound travel with current configuration components......

[MNotary]

6 inches of drop and 14 inches of up travel (jounce)? 20 inches total travel? With that CV seems like more would be available. Is this thing at max. towing width?

<P ID="edit"><FONT SIZE=-1>Edited by MNotary on 04/10/02 09:25 PM (server time).</FONT></P>

[scott]

Dylan, crossover A-arms..... Isn't that an I-beam .......

[rdc]

Hey Dylan, don't you think its funny when you post a suspension comment that all the self proclaimed experts emerge from, well, whatever they emerge from..anyways..the person you should be asking is Bob Lommel, he opened up that new shop in West Hollywood.....

[Bob_Sheaves]

It's at a track width of 80 inches (96 OA) but I have reserved roughly 1/2 the joint travel for the steering angle which we haven't installed yet....the parts are not optimized yet either-just pulled from some other jobs I have on the system.....One thing I'd look at is increasing the diameter of the brg races to allow the outer joint to be pulled into the wheel deeper-decreasing the 14.1 KPI angle.


Bob

[Dave_G]

Re: The hydrostat WILL create a LOT of heat in use and will require a really big cooler

Yea, but Bob..... look at the up side to this. You can swing a really big cooling fan really fast with that gas turbine. LOL !!

On another note.... It would be nice to see the weight of the front springs and shocks behind the cab and actuated by light weight control links bell cranks and swing arms. And while your at it, mount the steering box under the drivers seat as well. Are we starting to get Al Unser Jeep short course car night mares yet? ;-)

Dave

"I know it all, but I can't remember most of it..."

[Bob_Sheaves]

Thanks Dave- ya ruined my dinner....LOL...surprised you didn't bring up the Dakota bodied MJ's for MTEG, or Leslie's Class 3 (I think it was a 3? Lord I'm getting too OLD for this stuff)....

The "big fan" is good- angle the resultant thrust and guarantee that the rear always lands first, plus you didn't mention the exhaust could be used to prevent rear nerfing.....PLUS there's no seperate water cooling system on the turbine- less weight!!!


Best as always....

Bob

[Dave_G]

Re: plus you didn't mention the exhaust could be used to prevent rear nerfing

That's true. We could put an oil injection system into the last stage of the turbine and smoke'm out! ;-)


Re: or Leslie's Class 3

Ok, now you've done ruined my dinner too! LOL!!!

Best,
Dave

"I know it all, but I can't remember most of it..."

[MNotary]

Dylan, we are still early, can we get rid of 500 lbs by getting rid of the AWD? And what is the difference between AWD and 4WD.

Bob, you lost me on the larger bearing and moving the joint. And I thought we were shooting for 6 deg. king pin inclination.

[DPpatrol]

OK... Someone want to explain Hydrostatic drive and a Capstore Turbine? please...

jason

[Bob_Sheaves]

OK guys...ready or not....


In the attached image, there are 2 views of the wheel end assembly-on the left is the newer optimized design, on the right- the same view of the older design. This optimized design's KPI has been modified to the desired 6 degrees and appears to be the best that can be done with a single or double cardan joint transmitting the power from the hydrostatic dirve motor (not shown yet). A rzeppa joint possibly could be installed here in the future, depending on wheel cut desired. At the present, we have gained a total of 2.375 inches in wheel travel (assuming the same joint angles as before) due to the repositioning of the ujoint inside the inner wheel bearing......

Additionally, you can see the new beadlock wheel in place. This is designed as a spun titanium piece with a projected mass of 7.86kg (17.3 lbs)......



<P ID="edit"><FONT SIZE=-1>Edited by Bob_Sheaves on 04/11/02 07:40 PM (server time).</FONT></P>

[Bob_Sheaves]

In this second picture, you can see the new GA of the assembly.... Any questions so far? (Yes, I know the wheel studs need shortened... LOL)

A suggestion- tomorrow I plan on "installing" the hydrostatic drive motor and hydrostatic steering ram for packaging purposes and making any changes ya'll come up with tonight. You should all start thinking about the layout of the front suspension you want to see designed. As a "help" you might look at hte Morgan trunnion design mentioned earlier, a late 60's to early 80's AMC Ambassador, Javelin, AMX, or Matador for the AMC style trunnion design, and start sketching what you want for next monday night.

Answers to current questions:

For DPpatrol: A hydrostatic drive is a system that uses fluid for it's power transferring capabilities. There is no mechanical connection (like a transmission) to couple the engine and drive wheels. This eliminates a bunch of weight, at the expense of the heat generated. (VERY simplified version- do you have any specific questions?). The turbine engine was a joke between Dave and I, perhaps better left from this board or thread-sorry.

For MNotary: The hydrostat drive will weigh less overall (including the fluid and cooler required) than a mechanical drive system. The issues of a hydrostat (other than what has been mentioned) are all related to leaks and fracture of tubine (the working pressure wil be between 3000 and 6000 psi). The difference between AWD and 4WD (in simple terms) is that 4WD is usually where the front and rear propshafts are either locked together or not functional (i.e. 2WD). AWD generally uses a coupling of some type (torque proportioning or even an open diff, or an overrunning clutch in the case of the Chrysler Minivans). The 6 degree was the target, but the components I had on hand did not allow that- hence the component re-design today to make a package that would work.

Bob

<P ID="edit"><FONT SIZE=-1>Edited by Bob_Sheaves on 04/11/02 08:00 PM (server time).</FONT></P>

[rdc]

Re: I don't see how you could come up with an AWD system that would be durable enough to last and keep the car under 4000#.

The ex-Nick Baldwin AWD Class 1 car 3600 lbs.
New AWD TT ----Even less!
Both use slightly modified stock Transfer Cases.

A properly designed AWD car takes advantage of the fact that all the loads will be shared by the front and rear drives and the structure of the vehicle can be adjusted accordingly. The Herbst AWD TT is basically a rear wheel drive vehicle with a front drive added, that's why it's so heavy.

Re: And what is the difference between AWD and 4WD.
When somebody comes up with a definition that everyone can agree on let me know. Currently the SAE standards committee is trying to come up one but, to no surprise, nobody can agree! Generally, the three terms, Part Time, Full Time and On Demand cover just about all the systems out there. Personally I use 4WD when I talk about a Part Time System and AWD for Full Time and On Demand Systems.

Dennis

[MNotary]

Bob, quit holding out on us. How is king pin inclination affected by the joint position? OK,... I see, KPI is not what I thought it is. Moving the joint out allows a longer axle and reduces joint angle (just like out board hubs).... What don't I see???

Millens' CORR 4 truck had the wheel offset all the way out, like your new GA. Same stuff is going on I imagine.

Like you said, no tech guy is going to let those wheel studs pass. Well, maybe.....

[Dave_G]

Bob,
I'm already one step ahead of you here. I've already made the hubs and drive spindles from your engineering data. Have a look! I made them from 300M and heat treated them to Rc54. I finish machined the bearing journals, bores and seal diameters with ceramic tooling in my CNC lathe after heat treat. I have only one question here.....what is your address so I can send you the invoice. LMFAO!!!

hehe...

Best,
Dave

"I know it all, but I can't remember most of it..."

[Dave_G]

Bob, another view ......


Dave

"I know it all, but I can't remember most of it..."

[Dave_G]

Ok, one more and I'm done...... ;-)


Dave

"I know it all, but I can't remember most of it..."

[Bob_Sheaves]

Hi MNotary....

Actually, it's reversed...the joint location is affected by the KPI- you understand it in theory....just remember I am "fudging" a bit because we do not have any ball joints, trunnions, or kingpins in place yet. My experience tells me approximately what will be required for packaging the components, based on the various designs I have done in the past. Doesn't mean I am smarter-just means I have broken more parts than most...LOL!! It will all become clear once the basic geometry is finished. I wanted to take this slow so that no one got left behind and had the opportunity to ask any question- as I have said before- the only stupid question is the one unasked. Who knows....I may get an offer to write out of all this....ROFLMAO!!

Seriously, just stick with us...it'll come clear soon.

Best as always,

Bob

[Bob_Sheaves]

No problem Dave...I'll just add it to Dylan's bill for my time.....ROFLMAO!!!

Seriously, nice work. Got a question tho'.....why RC56? My gut says that might be too hard and will brinnell under shock loading????? If I had to guess, I would have guessed closer to RC48-52. Anyway-nice job....

BTW- Note to the private emailer that didn't want to be named....I have always held to the belief that "If you want to run with the big dogs, you have to learn to pee on tall trees" (famous old saying from GM), or in other words, you never know your limits untill you try-don't let ANYONE, no matter WHO they are, tell you that you are stupid. Asking questions is what makes you smarter- not dumber. I'm living proof of that- just ask Dave.....LOL!! In my experience, if it can be screwed up- I can do it. I just try not to make the same mistake twice.


Best as always to all....


Bob

[Dave_G]

RE: why RC56? My gut says that might be too hard and will brinnell under shock loading????? If I had to guess, I would have guessed closer to RC48-52. Anyway-nice job....


Bob,
They are Rc54 not Rc56. If they were 4340 I would keep them between 48 to 52 but the 300M works very well at 54 if they are double tempered at 525 degrees F minimum. We've done that for many years with very great success on racing parts. You just have to be VERY careful with the processing to prevent hydrogen embrittlement and stress risers when going that hard. Nice big radi in all the corners etc.. where ever you can.... If I could get 300 Maraging big enough I would have used that except it's really hard to find over 3 inches in diameter.

RE: you never know your limits untill you try

Exactly. That's what keeps life interesting. Those that are not willing to adventure into new things and push themselves a little might as well go live in a closet !

Best,
Dave

"I know it all, but I can't remember most of it..."

[Donahoe]

Pretty stuff Dave.

NEVER LIFT!!!!!

[FABRICATOR]

Hi Bob,
I have some questions if you would.
1) Why a double cardon joint? These are rare at best on final drives and effectively increase angles by shortening the axle.
2) Are you going for maximum practical travel? If so, you have a long way to go with a 96" overall width.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[Dave_G]

Bob,
By the way, pay no attention to that long thread on the drive spindle....I tried my best to talk the customer out of doing that but he was insistent on having it. Oh well, I know when to shut my mouth, bite my lip, take the money and make what the customer wants. ;-)

Best,
Dave

"I know it all, but I can't remember most of it..."

[Bob_Sheaves]

OOPS...sorry- that's what 18 hours of looking at a tube will do to ya....

BTW- I figured that the customer wanted that long lead thread section....LOL ! Gotta love it- customers are money in the bank.

Best as always,

Bob

[Bob_Sheaves]

Responses to Fabricator:

1. The double (and single) cardan joints will allow me to demonstrate the differences in design and application to critical speed of the shafts when compared with a rzeppa once the "linkage" is in place.

2. Remember I am reserving 1/2 the total joint travel at this time for steering geometry. The total travel will be revised once we have "linkage" to move the wheel asm. up and down.

Best as always,

Bob

[Bob_Sheaves]

latest pictures....

rear inside view of assembly....

[Bob_Sheaves]

front outside view of assembly....

[Bob_Sheaves]

front inside view of assembly....

[Bob_Sheaves]

latest GA of components, ready for suspension members.....

[Bob_Sheaves]

Finally, a closeup of the unitized hub and bearing, knuckle, and wheel assembly....

[FABRICATOR]

Very impressive Bob. If you print any of this stuff it comes out very similar to a real blue print, blue background and all. Pardon me if I missed something (I often do the first time around...)

I don't want to get left behind either so I have a few more questions:
1) Why a conventional wheel instead of the offset type typically used on FWD or AWD?
2) Why that wide tapered bearing set up?
3) Why save 1/2 of the CV angle for steering?

Notes re. questions:
1) Offset wheels have proven themselves to be very strong and light (Macpherson TT and dozens of others).

2) I see you have enlarged the bearings and brought the CV into one of them. I assume this was to bring the CV joint farther into the wheel.

The point I am getting at is that an offset wheel allows the entire hub and CV to reside farther into the wheel and away from the chassis. This along with using the big factory double row ball bearings (no, these have little in common with any industrial bearing), as found in several 1+ ton trucks these days (and some TTs and others). It will also bring the CV farther into the wheel and away from the chassis, almost on par to that of the expensive "outboard CVs". This translates into less angle on the CVs and whatever suspension members you may use and therefore more available travel. I realize that I am stuck on A-arm philosophy but this still applies to at least the shaft taking power to the wheel.

3) Steering angle is not added to suspension angle on a 1 to 1 ratio. 40 degrees of suspension angle during 40 degrees of turning does not add up to 80 degrees on the CV. Hmmm

I hate to see us forge ahead, like so many race teams do, and ignore a lot of technology that is right in front of all of us. Are we building it the best we can?




<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[Bob_Sheaves]

Hi Fabricator,

If you do not mind, I'll paste in your note and answer inline.....

"Very impressive Bob. If you print any of this stuff it comes out very similar to a real blue print, blue background and all. Pardon me if I missed something (I often do the first time around...)"

Thanks-you haven't missed anyrhing yet....

"I don't want to get left behind either so I have a few more questions:
1) Why a conventional wheel instead of the offset type typically used on FWD or AWD?"

I have some tooling at the fab shop for some spun titanium wheels my guys built for a military project that I was able to use here. That is also why the funny looking beadlock- it's a mil-spec one. I eliminated some of the details simply for expediency's sake.

"2) Why that wide tapered bearing set up?"

One of the most common failures (in durability) of the unitized bearing pack is from offset loading (meaning one or both sets of rollers on one side of the load center of the tire). I am currently consulting with an axle manufacturer here in Detroit on just this problem. By spacing the bearings such that one is on each side of the load centerline- longevity is improved over 3 times in both fatigue and impact (especially with the larger diameter inner bearing shown, even though it is closer to the centerline than the outer). BTW- this is a production piece for an axle coming out in a couple years.

"3) Why save 1/2 of the CV angle for steering?"

Personal preference, because I want to do some playing with the uniballs. I want to get 88 degrees of total wheel steer (at the jounce and rebound limits) to counteract the long (120") wheelbase's detmimental effect on manoeuverability. In order to do this (and gain the manoeuverability back) requires bunches of joint angle. BTW- what is shown is still the single cardan joints at the wheel end-I won't do the replacement untill we get a geometry of the suspension in place so it can be cycled from jounce to rebound.

"Notes re. questions:
1) Offset wheels have proven themselves to be very strong and light (Macpherson TT and dozens of others)."

Agreed, I would do it that way, but it was simpler for me to pull in the design I had that was existing and adapt it to the unitized bearing pack.

"2) I see you have enlarged the bearings and brought the CV into one of them. I assume this was to bring the CV joint farther into the wheel."

Yes and no- yes that is what I did, but shown is still a single cardan joint.

"The point I am getting at is that an offset wheel allows the entire hub and CV to reside farther into the wheel and away from the chassis. This along with using the big factory double row ball bearings (no, these have little in common with any industrial bearing), as found in several 1 ton trucks these days (and some TTs and others). It will also bring the CV farther into the wheel and away from the chassis, almost on par to that of the expensive "outboard CVs". This translates into less angle on the CVs and whatever suspension members you may use and therefore more available travel. I realize that I am stuck on A-arm philosophy but this still applies to at least the shaft taking power to the wheel."

Agreed on all points. This design could (at it's current state) go either way with the shown uniballs.


"3) Steering angle is not added to suspension angle on a 1 to 1 ratio. 40 degrees of suspension angle during 40 degrees of turning does not add up to 80 degrees on the CV. Hmmm"

See above on the large travel I want to have (with 100 percent ackermann effect, if possible, to lessen tire wear).

"I hate to see us forge ahead, like so many race teams do, and ignore a lot of technology that is right in front of all of us. Are we building it the best we can?"

No, there are still some tricks used today and in the past that no one has brought up yet and need to be considered before the suspension goes in (even preliminarilly). BUT it's up to Dylan to accept and give the direction to go.....

Final comment...Come on guys....let's think (no matter what you say or ask- no one will think you are crazy- I hold THAT position alone.....LOL). I have given several hints about what is missing and needed to be considered....what are ya'll's thought?

Best regards as always,

Bob

[heavy8]

Ever seen the fire control system on the M1 tank? It uses a gyroscope to stabilize the massive gun. It remains almost perfectly stable while the tanks plows through the rough. Is it to far fetched to run a floating cab area cage that is stabalized by this type of system. It could be done with pitch and yaw or just yaw control. It could also be set up to lean on sharp turn for better wieght transfer. Since it looks like the car will already have a hydro pressure source, it might be possible. Mabye some day...

[Bob_Sheaves]

To all:

If you have some ideas and do not have one or access to one to email you sketches, you can fax them to me a 1-781-240-6339. This is an efax account and they will arrive to me as an email for convenience.

Best regards.

Bob



<P ID="edit"><FONT SIZE=-1>Edited by Bob_Sheaves on 04/12/02 11:17 PM (server time).</FONT></P>

[Bob_Sheaves]

I have seen both the FCS on the M1 and the IFCS/I on the M1A1 with the 120mm smoothbore. The idea is sound, but packaging might be an issue inside the wheel rim for the syspension. I am NOT saying it cannot be done, but it would require some thinking. If you only used a "yaw" axis and a single leading arm, I think it might be able to be fit into the system.

For the central cage-yes, but weight could be an issue.

Any comments from others?

Best regards,

Bob

[FABRICATOR]

Very good Bob, just want you to know we're still awake out here. Are you waiting for ideas to pour in???
Just a few:
1) single stand alone strut (jet fighter style)
2) dual strut (straddle or inboard)
3) large Macpherson strut
4) single trailing arm
5) single trailing arm with radius arms
6) pair of trailing arms (VW)
7) trailing LCA with non-trailing UCA
8) leading LCA with trailing UCA
9) trailing rods with triple or quadruple radius rods (Indy rear, etc.)
10) solid axle
11) straight LCA w/strut (still an "A"?)
12) articulated solid axle
13) twin I beam
14) triple or quad I beam
15) articulated LCA having two modes of movement (uh oh!)
16) typical parallelogram setup but with for and aft rigidity inboard (within the chassis)
17) guided control arms that mimic movement of longer arms (sshhh!)
18) C, H, J, L, T, U, or Y arms

Need more?

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[Bob_Sheaves]

OK, I'll put up a suggestion also....

Think of this....more parts equals (statistically) more failures. Take a tube to provide a solid connection between knuckle pivot points...

Think of this....what does a skid plate on the front do?

Think of this....compression struts for "X"-axis loading.....

Think of this... how does a voided bushing allow relative motion in 1 axis, but not it's normal axis?

Think of this...how does a hinge control motion?

Think of this...Morgan trunnions....


More later.....

Best as always,

Bob

(BTW- Fabricator, you are on the right track with a couple ideas you posted)

[Bob_Sheaves]

While we are talking steering angle....

You can see in the attachment that the 40mm dia ball joints I initially installed will not give me the needed travel. They bind up around 34 degrees of steer angle (measured down the KPI) The new joints need to be 51.69mm in diameter.....

Bob

[Bob_Sheaves]

....and you can see the installation a little better here....along with the spanner type locking rings for ball retention....

[DPpatrol]

Bob, what program are you using to make all these drawings? Also back to hydrostatic drive, how much frictional power loss is there through a hydrostatic drive in comparison to a mechanical drive? Are there any vehicles which use hydrostatic drive?

jason

[Bob_Sheaves]

Hi Jason,

The program is CATIA....I am not really making drawings , as you mean the term, but showing planar images of 3D data. In a real world situation, I would (once the design is complete) create NC cutter paths on the 3D geometry for manufacture, program bar feeders to machine parts, etc. That is one of the reasons the program is so expensive, that is to say, it is a CAM (Computer Aided Manufacturing) and NOT a CAD (Computer Aided Design) program (it irratates me that IBM markets CATIA as a simple CAD program when it's far more than that).

To make drawings is simply a matter of AUXVIEW2/UPDATE (specific CATIA funtion calls) and then plotting the information out at whatever scale you want. Working in 3D space is just like machining real parts (think of CATIA as a "window" on a 5axis mill and machine shop) in that I can "machine" the solids just like real metal and the geometry has mass properties, inertia, movement, etc.....you are not "drawing" anything, but actually manufacturing the parts-without wasting material if you make a mistake or want to change something. Interferences, dynamics, etc. can all be analysed with the program.

On you questions on the hydrostatic drive system, the losses are similar to a mechanical system, BUT the losses are almost totally HEAT related in output. There are many vehicles that use hydrostatic drive and steering systems around the world. There are not more due to the "status quo" in automotive design in the US. In Japan, for example, it is very common to see road mobile cranes driving down the freeway at 60-80KPH- steered, driven, AND braked solely through hydraulics. The single biggest problem (after heat generation) is leakage. There has not been a hydraulic system made to date that does not leak somewhere.

If you'd like, I can dig up some URL's on hydrostatic drives and equipment (construction, military vehicles, etc.)

Best as always,

Bob

[DPpatrol]

Bob,

Thanks for the answers. I would appreciate it if you could find those urls. How acurate is the dynamic analysis capability of that program? Is it the status quo program for design engineers? It seems quite impressive.

jason

[MNotary]

Dave does Apex (sp) ring a bell for CVs'?

[fishd00d]

I just wanted to be the 100th reply to this post that I have not understood one word about :)

Go Big Or Go Home

[MNotary]

If you can make a red RX-7 go over a jump on your signature....this should be cake.

Bob, give us a couple of clues on the direction you are going. I looks like the hub is set up for A-arms of some sort. But you say you have something else in mind.

They put A-arms on F1 cars because there is no better design? Maybe A-arms aren't that lame???

[Bob_Sheaves]

OK....one BIG clue- 1956 Maserati "Birdcage"...look up some photos of the rolling chassis and the rear end/suspension configuration (DeDion type).

Best as always,

Bob

PS- I agree on the jumping RX7...I have NO idea how that was done!!!!!!

[Bob_Sheaves]

or a second clue....Look at the rear suspension configuration on an AWD Chrysler/Dodge/Plymouth minivan.....(DeDion type again, but different in the details).

[Bob_Sheaves]

final clue- preliminary beam configuration.....see pix.

[Bob_Sheaves]

Hi Jason,

One good reference is the Parker-Hannifin web site "http://www.parker.com/mobilesystems/index.html#". This is their mobile products group and you can find lots of data sheets, calcs, and system requirements here.

http://www.silvatechfluidpower.com/defence.htm contains info on a retrofit kit for the M113 APC drive system (an Allison transaxle) with a pure hydrostatic system,

http://www.tacom.army.mil/tardec/vetronics/demoIIIpage.html is an autonomus (meaning- NO DRIVER!!!!) demonstrator built by TAACOM here in Michigan.

http://www.tawd.com/products.html is an aftermarket refitter of hydrostatic systems to Unimog U1400 (and other) model trucks.

http://www.tracyequipment.com/raptoruv.htm is a smaller scale hydrostatic vehicle currently in military use as well as commercial use.

Best as always,

Bob

[FABRICATOR]

Well Bob...unless you think it is the ultimate, perfect suspension, you might as well throw it out there.

The most widely used and famous hydrostaticly driven vehicle around is the Bob Cat loader/excavator. That's the one at most smaller construction sites and nearly all swimming pool digs. Home Depot even rents them out. Most of them have a single left and right "motor" with a chain connecting each to that side's pair of wheels. They turn by either by running one side and stopping the other or if you're in a tight spot or hurry, one side goes forward while the other is in reverse. The motors and chains are inside the big belly tub on the bottom of the vehicle. That keeps things clean and small leaks aren't a big deal. They also have a big cooler for the fluid. Very successful, very reliable, very torquey, very slow and very, very heavy.

There used to be a motorcycle that was hyrostaticaly driven. It was a neat setup. The motor handled the speed fairly well and acted as a very effective brake. It basically replaced the rear hub/brake/sprocket/chain assembly. Don't know what happened to them...

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[vwguy]

i rememberr a long time ago a magazine article on a 2 wheel drive dirt bike that was powered by hydraulics it seemed to haul butt in the photos. i guess you could try to look that up if some of you wanted info on that stuff

how ironic is it that most people slow down for speed bumps yet almost all of us here im sure pin it

[mxjeremy]

yeah, that article is from an old dirt rider of mine. I'll try to find it. I remember that they took a picture of the front tire at launch, and you could see roost from the front tire. That was awesome. I'm sure that weight was the major factor as to why no one has adopted the 2x2 motorcycle. But imagine how it would climb hills. late.

[DPpatrol]

Ok. If hydrostatic drive creates loads a heat, (more than mechanical drive) wouldn't it be less effiecent of a design when compared to a mechanical drive, since all that heat that is created is in fact energy that was converted into heat which could have been used to drive the wheels? More heat=more transfer of useable drive energy into wasted energy?

jason

[Bob_Sheaves]

Hi Fabricator-

Nope this ain't the be-all and end-all, but it's a good start....LOL!

1st image-Layout front , top (plan), and right side....

[Bob_Sheaves]

next one- close up GA....

[Bob_Sheaves]

next up- plan view...(top view)....

[Bob_Sheaves]

Finally, travel from front-showing 27inches from jounce to rebound. This is also with 0 track change, 0 scrub, 0 toe change, 0 camber change, and 0 caster change.......per the requirements set out originally......

[MNotary]

Scrub...steering scrub? How about side scrub thru the travel. (The contact patch moves in and out.) It has to have some..?? Looks cool. 27 inches...

[Bob_Sheaves]

nope to both....close one eye and look REALLY close- think 1908 Model T...

Bob

[FABRICATOR]

Clever Bob. There may be too many zeros in that system... How about the rest of the car???

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[MNotary]

Ouch... hit my head on the screen. I guess I need to see more.

[Bob_Sheaves]

Maybe these will help...

1st, inside of right side front front...

[Bob_Sheaves]

2nd, left side view, showing the leaf spring behind the axle tube...

[Bob_Sheaves]

left side upright (without knuckle and uniballs), tube, and voided bushing/mount...

[Bob_Sheaves]

Finally, a closeup of the voided bushings. In this illustration, you can see "through" the empty "voids" in the rubber. This is how a voided bushing works-by limiting the motion in one direction (where there is rubber "blocks" tying the shell and bolt carrier together) and allowing motion in the normal axis (at right angles to "blocks").

[MNotary]

I like it. How far back will the wishbone go. I was locked in on upper A-arm. You had said leave but I thought you hadn't added that. That will go 27 inches??? Durability?

[Bob_Sheaves]

The travel is artifically limited to 27 inches right now- there MAY be a couple more that can be squeezed out of the design, but the total vehicle will need to be finished to do that. The 2 areas of durability questions I have right now are:

1. The composite leaf spring. Carbon fiber is durable, but needs rock and impact protection. Possible a Kevlar or Spectra wrap will do the job- I need to think more on this.

2. The voided bushing travel limits- Right now I have a temporary durometer of 87 assigned to the parts- this may need to be increased for durability, but if so- size will need to change to preserve the travel extents.

NOTE TO DYLAN: You have been awfully quiet....any comments???

NOTE TO KLAUS, et al:I hope this thread is not causing you problems with it's size. I can easily see it increasing by 4 fold before it is complete.... Please let me know if it is a problem....


Best as always,

Bob

[klaus]

Our server and bandwidth limits are way beyond what you guys can post..... ;-)

So please no holding back.

[MNotary]

Why do I see two voided bushings in this view. I thought one voided bushing per side for some sort of front to rear track bar.

[Bob_Sheaves]

There is only one per side-the image is from the left side, below so you could see both of them....BTW- the arm is 1608.94mm in length from bushing centerline to frame mounting centerline.



<P ID="edit"><FONT SIZE=-1>Edited by Bob_Sheaves on 04/18/02 02:16 PM (server time).</FONT></P>

[jcorsico]

I'm having a hard time picturing how the suspension cycles. What exaclty is moving? Is the bar that connects both wheels togeather solid, or an I interpreting the drawings incorrectly? I might be way off here.

An animiation would be great, but that's probably time consuming to come up with.

Jon

[motoxscott]

I've been following these posts and have only one thing to say......

Bob you da man !!!

I'm pretty familar with photoshop and illustrator, but what you're drafting is awesome.

Thanks for putting the time into this.

-Scott

[Bob_Sheaves]

Hi Jon,

If you re-read my reply above....Check out a Ford Model T front suspension-that is the basis of this design. I have added the drive ends to the knuckles and uprights (like a DeDion suspension), converted the kingpin to uniballs (really BIG uniballs...LOL), and added secondary struts (the shocks, not shown yet) to restrain the motion extents....

This system meets the original requirements- that is to say, 1 degree of freedom-straight vertical travel, with no fore and aft motion, common in most designs, with a minimum of parts.

Best as always,

Bob

[Bob_Sheaves]

Hi Scott,

Thanks for the kind words, but this isn't rocket science. Remember, I am not drawing anything-mathematically, this design exists just as if the parts were on the floor in front of you......

The thing to remember is that this is what guys like Jerry, Kreg, and others all do for a living. I just happen to be able to do the same job in a different manner than what they do- not necessarily better, just different (plus I've been doing this kind of thing for 28 years....LOL...it get's OLD after a while). Be sure to tell those guys you appreciate them also-they are the ones making a living building your kits for ya'll.....I'm just a good ol' boy from back up the holler......

Best as always,

Bob

[partybarge_pilot]

OK, so what we have hear is a strait axle with slightly better ground clearance at the center on drop. The GC of IFS on bump and a whole lot of axle plunge! You could put some soliniod valves and O-rings on them and use them as air pumps for a run flat system!!!

Now for the hydro motors. The largest gerotor motor bucher hydraulics makes will take a max of 4570PSI, turns 920 rpm, requires .55 gallon per rev. and delivers 2726 FTLB of torque.

This gives you a top speed (37 inch tire no wheel spin) of about 106mph, requiring 506 gpm X (4 wheel drive)=2024 GPM!

Torque versus normal gear reduction tranny 400 FTLB (mild est) X 3.21(first gear)x 5.2 ( rear end)=6676.8 FTLB / # drive wheels. 2= 3338.4 4=16692 per wheel. Your OK on torque production on 4 wheels but you have no gear reduction to the motor which is why bob cats are so slow. Speed or torque, one or the other, Take your pick.

4500 psi at 506 GPM needs a very large heavy walled pipe! Don't forget you have to filter all that as well.

Not trying to be a downer but I've already been the hydro route.

[Bob_Sheaves]

No problem, you are just getting a bit ahead of things...have you looked at Parker's stuff.....4000psi rated motor-2250rpm double ended with a clutch...nevermind, I'll explain when it goes in....LOL!
8br>Anyway, a couple more illustrations with the struts in place...top view from left side....

Best as always,

Bob

[Bob_Sheaves]

frontal view.....

[jeff]

Regarding the composite spring material... as long as the wrap of kevlar didn't affect how the "spring" acted it should be more than enough resistant to rocks and other debris. I haven't ever used it in an application that supported a vehicles weight or been subjected to harsh cycles that an off-road racing vehicle would see... but I've seen composite "feet" for artificial limbs cycle in the millions and millions with almost zero loss of its spring like quality. The abrasion resistance is awesome too... if you could make sure the spring acted how it needs to with the Kevlar it should withstand whatever you throw at it. I've read some stuff about incorporating more of this kind of material into tires - good grip and they last (almost) forever. I've played with this stuff and just love trying to wear it out and damage it. I wonder how much weight could be saved using a composite belly pan (if this vehicle will incorporate one) over aluminum. Composite exhaust can be routed closer to the passenger compartment too if routing ever becomes a pain. Come up with a mold and you could build composite arms or spindles. If anyone wants to do some low run composite stuff I have access to some pretty nice machines - same machines that build/mold composite bike frames... they are ridiculously simple to operate and are embarassingly goof proof.

Aloha

[drtdevil93]

leaf springs, huh?

i think a conventional, well built leaf spring could conceivably work very well. since there is no load other than the weight on the spring, it could last a very long time.

erik

[Flea]

It kind on resembles corvettes old IRS a little but.

looks awesome keep up the great work!

GOD BLESS AMERICA! and hopefully my poor truck too.

[ntsqd]

See, I knew we'd get back around to Morgan's Sliding Pilar (as they call it) design. Specifically I was thinking of a design inverted from the way Morgan employs the design, but......

TS

"Teach you all I know and you're still stupid"
-- Howdy Lee

[mxjeremy]

I found the article about the 2x2 dirtbike.

[mxjeremy]

page 2

[Bob_Sheaves]

Couple more detailed pix....

I have spent a few hours cleaning up the basic design to get some accurate weights of components......

[Bob_Sheaves]

next one...

[Bob_Sheaves]

3rd one...

[Bob_Sheaves]

4th one...

[Bob_Sheaves]

final one....

[Bob_Sheaves]

If there are no more questions on the basic layout I have shown, the next post will cover the gradability of the vehicle to size the hydraulic motors and to determine if a range box is required......

Best regards,

Bob

[partybarge_pilot]

Hi Bob,
With a 2250 rpm motor It's going to need some kind of gear reduction. Power = PSI X effective piston area at the pump. Smaller pump more speed same fluid rec. Clutch? Por que? I looks as if your going to mount the motor in the center like a normal differintial. Why not use 2 single output motors on opposing sides with the axels clocked slightly for clearance of each other? This would greatly reduce CV angles and reduce axle plunge. Also eases mounting to the frame as it's closer to the outside mebers and spreading the load around.

[DPpatrol]

Bob, what does the severed bushing, which is attached to nothing now, attach to?

jason

[farmboy]

Bob, i think i read all the posts and maybe i missed it but, what's the name of the computer program your using to do this? i am really impressed by all this. any engineering i've done was all trial and error.

the faster you go the smoother it is

[Kritter]

CATIA is the software

Kris

"A signature always reveals a man's character -- and sometimes even his name. "

[Bob_Sheaves]

Jason,

I am not sure what you are referring to...severed bushing??? Do you mean voided bushing? If so, I have put some parts in "NOSHOW" which is, as the name implies, a way of "removing" parts without erasing them to visually clean up the parts illustration. In this case, I placed the leading link into NOSHOW.

Best as always,

Bob

[Bob_Sheaves]

Kris is correct. CATIA is an acronym for "Computer Aided Three dimentional Interactive Application" hence C-A-T-I-A.....this is the same program that Chrysler, Mercedes, Honda, Ferrari, Boeing, Toyota, Freightliner, Maserati, Husquavarna(SP?), Volvo, Black and Decker, Mitsubishi, and others all use to develop their products.

Best as always,

Bob

[Bob_Sheaves]

In response to several email requests, I am posting this under one heading.....

WHY I USE CATIA

CATIA is, in my opinion, the most versatile design and manufacturing program available on the market today. Dassault Systems (the writers of the program) and IBM have parlayed the capabilities of CATIA into the most used CAD/CAE/CAM system in the world, with over 25,000 seats installed.

While I was with GM in the early 80's, I was trained on the corporate system, CGS, and CADAM originally. Prior to that, I was a "board rat", working on vellum, mylar, and the worse thing anyone ever created, gold on aluminum panels (yep this is what it sounds like- 24K gold pencil "lead", drawing on white laquered aluminum panels 4 feet wide x 20 feet long). In 1984, when I was with GM/Military Vehicles Operations, working on the CUCV (military Blazers and pickups) and FMTV/FHTV programs, I got my first exposure to CATIA and it's 3D capabilities for kinematic body simulation (since I was working on repowers and suspension design, I had to manually draw the motion of the kinematic bodies to determine interferences, fittings, routings, etc.).

Fast forwarding to the late 80's when I was with AMC then Chrysler, I was the Sr Suspension Designer responsible for the Dodge BR 4x4's (which were introduced in 1994). I designed all the 4x4 suspensions for the full line of vehicles in CATIA, using the kinematic functionality to cut the design time down from approximately 8 weeks per design, to just over a week for each design.

When I left Chrysler in 1992 and formed my own consulting business, all the customer base I worked with used CATIA at the direction of Boeing and Chrysler. For this reason, I had to invest a TON of money into unix workstations and multiple seats (module licences) of various configurations of CATIA. Since then, CATIA has paid for itself in job turnaround time and manufacturing turnaround time several times over. Now, since I am supposed to be "retired", I only have 1 seat of all CATIA modules that costs me (you all had better be sitting down for this)......

$12,850 per MONTH!!!!

THAT is why I do not recommend, as some of you have asked, for an individual to purchase a CATIA licence. It is far cheaper for my customers to share the cost and my time by purchasing blocks of "time" to have me do the needed work for them. In addition, I run CATIA v4.2.4 on the unix boxes. To use CATIA v5 (the PC version) I'd have to give up a lot of the functionality I have now (the version of PATRAN and NASTRAN- Finite element analysis programs- I have is workstation only, DADS- dynamic analysis program- will not run on a PC, etc.) which I am not willing to do. At some point, v5 will replace v4, but not till they pry v4 from my cold dead fingers (to use a much overworked phrase).

If you are serious about paying $800-$1500.00 per month for a seat of v5, IBM has a promotion going on now where you can obtain a free 30 day licence of v5 for the PC (it requires a special configuration, so a $29.99 eBay special PC ain't gonna cut it) to try it out. If you are interested in more info, see:

http://www-3.ibm.com/solutions/plm/d45/na/

Best regards,

Bob

[Bob_Sheaves]

Now ...back to the show....LOL

The first thing we need to calculate (now that we have a basic suspension and driveline design for the hydrostatic system is to determine the wheelspeed required to obtain the required top speed for the vehicle.

Taking the previously supplied numbers:

1. 37" tall BFG "Project tire" the specs are:
a. Static loaded radius of 17"
b. Revolutions per mile is 593.2

2. Required vehicle top speed, over flat hard terrain, is 160 mph.

3. Proposed gross wehicle weight: 2500 lbs.

To find the wheel speed, convert the MPH into miles per minute, i.e.:

160/60=2.666666666=2.67miles per minute

Now, to find wheel speed required, take the tire revolution per mile figure and multiply it times the number of miles per minute, i.e.:

593.2*2.67= 1583.844 revolutions per minute of each of the 4 wheels.

The next step is to calculate the required wheel torque to move the vehicle at this speed.....in the next post.

[farmboy]

wow, thanks for that link Bob, i've messed around with a program called turbo cad and one called rhinocerous that was about $1000, but had no idea how drastic of a price difference CATIA was, but looking at your attachments i see why. i ordered that free trial but without training probably won't get to far. thanks though and i can't wait to see how this project turns out.

the faster you go the smoother it is

[Bob_Sheaves]

Hi Farmboy,

The help files that come with v5 are all in HTML format and context sensitive/interactive with v5. You should not have many problems understanding it, if you have used TurboCAD to any large degree. v5 of CATIA was originally a program called "SolidWORKS" which Dassault Systemes bought and retitled....LOL...that's why I have a hard time dealing with v5-it was not developed from v4 and doesn't work in the same manner as v4.

As a side issue, if there was enough interest (and credit rating....LOL) I could set up 4 or 5 machines in southern CA/AZ/NV and run training classes on utilizing v5. Something to think about.....contact me privately if you are interested. You could do your own designs and then take the plots of the components to a fab shop to have built. These machines could be setup in various ways so time could be rented on them for those in the business also.

Best as always,

Bob

[JoeB]

Bob,

Just curious what your opinion on SDRC IDEAS is? I'm pretty sure many companies are using this program now.

JoeB

[Kritter]

I like it, but I find Solid Works and it's plug ins much more user friendly.

Kris

<A target="_blank" HREF=http://www.dmsrace.com>www.dmsrace.com</A>

[Bob_Sheaves]

Hi JoeB,

Ford is currently in the process of changing over from SDRC to CATIA, due to several issues of system integration that SDRC was unable to accomplish as they originally stated.

Personally, SDRC is, in my opinion, far easier to use than CATIA v4, but has serious shortcomings in a CAE/CAM environment. EDS (which owns UG also-used by GM) has purchased SDRC and is in the middle of combining the UG and SDRC systems in an attempt to compete with Dassault's CATIA v5 package.

Best regards,


Bob

[jcorsico]

Where does Pro Engineer fit into this mix?

[Kritter]

At the under $3000 range of software. I have toyed with it and do not prefer it at all. At recent job fairs only 2 of the several comapnies I spoke with want PRO-E. Most want SW or IDEAS and few of the stoneagers want autocad.

Kris

<A target="_blank" HREF=http://www.dmsrace.com>www.dmsrace.com</A>

[partybarge_pilot]

Autocad, Ha thats nothin! I still have Cadkey! Not that I use it. Lets see the machine shop cad progression went autocad, cadkey, pro-e, solid works.... SW is like starting over from scratch almost. The concept of drawing is totally deferent. You start with a solid block and cut away to get your final shape. The previous method was creating points to get lines to make planes/surfaces to make solids. Lots of room for errors in the old method that just can't be replicated in SW due to the deferent drawing approach.

[Bob_Sheaves]

Hi guys,

ProEngineer is not a bad program for one thing-making solids....everything else is done through either conversion of the dataset, or through a piece of 3rd party software. Not really conducive to the way I work. However, that is not to say it's bad-Harley Davidson uses it exclusively.

The modeling method described for SolidWORKS (CATIA v5) is an example of why I like that approach. You are not "drawing" anything, you are actually "machining" your parts. With the NC package, you can go directly to cutter paths and cut your part, NO DRAWINGS or the headaches of interpretation by the machinist. The downside is that you had better understand the machining processes, cutting speeds, material properties, and tooling, or all you are going to have is a bunch of broken tooling and scrap stock material.

Best regards,

Bob

[jcorsico]

Pro Engineer for under $3000? A standard package is $19,995 according to PTC's web site and that doesn't include any of the finite element analysis tools. If you add all the FEA stuff the price balloons to $54,975.

I used Pro-E for some stuff in college. I also used IDEAS. In general I liked Pro-E more, but I have to admit my experience is very limited.

I was more curious what Pro-E did differently compared to these other programs - meaning is it less capable than CATIA, or SolidWorks, or what does it do better/worse, etc.

I'm not familiar with all the different packages well enough to determine which packages compete against each other. They all will help you design a part, but one may be geared much more towards manufacturing, while another is geared towards design, while another is designed to work in collaborative environments where you have 100's of people all working on the same total design at once.

Thanks.

Jon

[MNotary]

If you were to roll it back (angle the struts back) to give it some front to rear movement in the travel will it mess up the bump steer, scrub.... It seems like a good idea to take some of the forward momentum out of the suspension in compression. I think you kind of pushed the vertical only early. Don't you like these design change charges that get added on.

[Donahoe]

Wow This thread has gotten way too long and way too tech.... All I want to know is how much will it waight and can I crash it when your done?

NEVER LIFT!!!!!

[Bob_Sheaves]

Actually, the vertical travel was an original design requirement by Dylan-I am not saying I agree or disagree. Either way, with the hydrostatic steering, there is no affect on any of the parameters you mentioned because the linkage design is all tied to the main axle DeDion beam, where the reaction cylinder is mounted. I will post pix tomorrow-when I get some time.

Best regards as always,

Bob

[Bob_Sheaves]

Heck Kreg, we haven't even gotten to the hard part yet...LOL!!! The weight right now hasen't been calculated, but I will try to get to it soon. As far as doing what you do best....I am sure it will withstand that treatment once...but if ya kept going, I wouldn't hazard a guess how many more times you could do it....

ROFLMAO!!


Best as always,

Bob

[Bob_Sheaves]

OK...showtime......

#1 of 7...

[Bob_Sheaves]

#2 of 7....

[Bob_Sheaves]

#3 of 7....

[Bob_Sheaves]

#4 of 7...

[Bob_Sheaves]

#5 of 7...

[Bob_Sheaves]

#6 of 7...

[Bob_Sheaves]

#7 of 7...

[Bob_Sheaves]

and an extra one for good measure....

[Bob_Sheaves]

#8 is a right side view of the assembled front suspension, so you can get a sense of location and scale of the components.

#7 is a front view of the right side, showing the GA and the 1207.79mm strut span.

#6 is a front view of the GA, showing the ROLL CENTER HEIGHT of 640.34mm, the static Ground Clearance of 299.41mm.

#5 is a plan view of the GA, showing the leaf spring, the struts, the DeDion tube, and the spring plate on the left side.

#4 is a plan view of the GA, showing the tie rod, the hydrostatic steering cylinder, the struts, the DeDion tube, and the spring plate on the right side.

#3 is a plan view colored illustration of the front suspension assembly.

#2 is a left rear isometric colored illustration of the assembly.

#1 is a left front isometric illustration of the assembly. Note that the inner joints on the half-shafts are NOT shown, the attachment link for the hydrostatic slave cylinder to the tie rod is NOT shown, nor is the frame attachment bushing and pivot for the lower strut frame assembly.


Weights (preliminary) total (including tires) , but NOT including hydrostatic DRIVE motors, totals 164.4kg approximately (361.72lbs), of which, approximately 100kg (220lbs) is unsprung weight.

Best regards,

Bob

[MNotary]

The king pin inclination wouldn't affect the steering geometry if it was "rolled". Dylan, I would "pay" for this design change if I was you. What is the weight of those tires?

[FABRICATOR]

Hi Bob,
Is this thing going to have in-board-brakes or did I miss something? Anything outboard may create a huge DeDeon/carbon-fiber pretzel (LOL)

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[Bob_Sheaves]

ROFLMAO...yep..and no salt to make it go down easier either.....

Seriously, no conventional braking at all, but rather hydrostatic braking and automatic torque biasing. I am working on the detailed motor and clutch design right now and will take a day or two (maybe more ) to finish due to "real" (means paying) work.

Best as always,

Bob

[Dylan]

Wow!
You guys have really been going off on this one!
I’ve been moving my house and changing jobs for the last couple of weeks and haven’t had the time to check out race desert at all.
Sorry I slacked off on this thread. It will probably be another week before I can get around to reading the last 3 weeks of posts.
Keep up the good work
Dylan

[Bob_Sheaves]

Well, time for the front drivetrain install preview....3 pics this time.

Number 1....

[Bob_Sheaves]

Number 2....

[Bob_Sheaves]

Number 3...

[Bob_Sheaves]

What you are seeing here is the traction drive system, less the hydrostatic motor (s). This configuration allows one motor to drive both front half shafts through a "differential" clutch mechanism (the funny rod sticking up out of the case is the lockup lever shaft), OR allow 2 motors to be used in parallel, locking them together when needed (stuck, extra traction needed, etc.).

As you can also see, there is some rework needed on the DeDion tube and the hydrostatic steering cylinder mounting to allow full travel past the gearbox/differential.

Sometimes you get the bear, sometimes the bear gets you........oh well. This is a good example of why you should use a true CAD system when designing something out of the ordinary. Things tend to happen at ijordinate times and it's a lot cheeper to fix electrons than it is to cut new metal.

Best as always,

Bob

[tkr]

Bob -
Can you explain exactly what a DeDion tube is? I've been staring at your pics for hours and can't quite seem to figure this whole thing out. It looks to me likes it not much differenti that ne I front I beam on my 57 Chevy P/U, only its using one spring instead of two. Am I missing something?

Matt Nelson
Team Kwik Racing

[Bob_Sheaves]

Hi Matt,

You have hit the nail on the head, so to speak. it is exactly the same function as your front axle (or similar to a sprint car, or the old favorite, the Model T). The difference is that this system (properly called a DeDion suspension) uses a frame mounted drive system to provide power to the wheels. In a DeDion system, the halfshafts are used to transmit power only and not used as control arms as on a Corvette 1st generation IRS. The main "new thing" here is that a true DeDion uses the springs (note the plural) to control it's motion. In this case, the A-frame (not shown in these pics-see last set of 8) and the vertically mounted struts provide the single axis of motion, that is straight up and down-the axle does not roll fore and aft,so caster does not change throughout the full 27" of travel.

The idea of this design is really a combination of a DeDion (for power transmission) and a 1908 Model T Ford front geometry (for springing).See:

http://www.bath.ac.uk/~en8khw/sustype.htm

...for a description of an unmodified DeDion, using coil springs, instead of the transverse leaf I show. You will also see a lateral sliding joint in the axle I have deleted for control purposes.
Best as always...

Bob

[tkr]

Thanks Bob, I understand more now. I do have another question, and please forgive my ignorace as I have absolutely no background in engineering or suspension. Without a lateral sliding joint and/or an upper locating arm, wouldn't there be a lot of camber change throughout the travel?

Matt Nelson
Team Kwik Racing

[Bob_Sheaves]

Hi again,

Practically speaking, no, because the angles of caster and camber are relative to the ground contact patch. No matter what gyrations the ground goes through, the relative camber and caster angles (with this design) always maintain the static travel measurements. Please note however that I am not commenting on the overall design as to my personal preferences. This is a "job" for Dylan and it's up to him to "approve" of design direction....

Best as always,

Bob

[Bob_Sheaves]

New pix of the "completed" drive system.....

1st one .... you are looking at an illustration from above and the left side, looking forward and down on the installed hydrostatic drive system....

[Bob_Sheaves]

2nd one....low view from the left front showing the drive and the recontoured DeDion tube....

[Bob_Sheaves]

3rd one...Closeup of the left hand aux. hydrostatic drive motor and drive mounting....

[Bob_Sheaves]

4th one....GA plan (top) view showing relocated hydrostatic steering cylinder......

[Bob_Sheaves]

final one tonite-front GA view showing drive system and recontoured DeDion tube.

[FABRICATOR]

Hi Bob,
One thing being shown here is that when you are designing or even building something that is not based on previous examples, you end up re-designing and upgrading as you go along. A lot of builders are afraid to jump into this and always end up with trailing edge technology. The downside is that it will take a bit longer to finish. The more you think outside the bubble, the more possibilities you will see. It is also difficult to think of everything ahead of time if you haven't done the same thing before.

Even though, in my opinion, A-arms on the front end are one of the very few things on an off-road race vehicle that are not lame (a new thread?), I applaud your efforts to design something basically from scratch that actually could work.

<font color=orange>The best ideas are the ones that look obvious to the casual observer.</font color=orange>

[Bob_Sheaves]

You have picked out the most important (unstated) point of this entire excercise- that is, a suspensions design engineer must think about the end results he/she wants to achieve, NOT about what everyone else is doing. Just copying another's design can and will turn around and bite you, because you do not have all the exact same parameters driving each vehicle. True all vehicles in a given class must meet the same basic specifications, but things like driver's weight, location of components, amount of fuel carried, etc. all conspire against a direct copy of another car. This is assuming you want to win and not be an also-ran or a wannabe.

Guys like Kreg, Russ, Dave and others have all spent years doing this sort of thing and have developed a set of parameters that works for their own configurations. For example, I'd lay dollars to doughnuts that if you measured and evaluated cars of the same class, all built by each of the previously mentioned people, each car would have it's own unique "signature" in that it's handling over the same course would be totally different from one another. This is where it is important to allow for the driver of that car-after all, he/she is the one that is dependent on the design engineer giving him something that is comfortable, durabile, and repeatable. BUT (and this is a BIG "but"), no 2 driver's will drive in the exact same manner. Hence, the design engineer must be able to "translate" the driver's input into usable modifications and adjustments of the vehicle to improve its usefullness. Note that I did NOT say "competitiveness", that is solely up to the driver. It is the responsibility of the design engineer to give the driver the tools he thinks he needs to win.

Best to you as always....

Bob

[Donahoe]

Well Bob that is true. Every fabricator builds cars to what they think is the right set of values for off-road. Adjustability is the key in my cars. If you look at the Skunk pics of the truggy I built for Helm it is completely Changable. Like Anti dive is ajustable, rear 4-link bite, Roll centers. I find that steering akramen means very little in an off road truck yet Nestor at Newline thinks it plays a big part. I guess most of it goes down to testing and what works for you and your driver. Taking Road racing rules and tranlating them to off-road trucks dosnt really work becuse of the scrub we get with dirt. So tire scrub, akramen, and contact patch play less effect in the dirt. Were in my opinion Anti- dive, castor gain, center of gravity, and roll center do play a big part. In mexico you want lots of anti-dive, in Barstow you dont. Soo there are lots of veriables that play in off-road. Thats why the trucks Racing in our sport are by far the grooviest race vehicals built.

NEVER LIFT!!!!!

[DRIVE Jon]

OK...so i stumbled on this thread. It was way before my time. The pages stopped at 20...looks like lots of pages were deleted.

Does anybody know what happened with all this stuff. Cool thread!

[FABRICATOR]

Bob was a gentlemen always. I like the bottom of this page...:)

http://www.race-dezert.com/forum/showthread.php?t=2292&page=18

[DRIVE Jon]

Is Bob no longer with us? Seems like a really cool and obviously very bright guy....nice on top of that...must have been from Uranus or something....oh he's from Detroit...that explains why he is so nice;) Detroit...Uranus.....I'll take Uranus!

Did any one build it?