Any Gear Driven Drivetrains?

[NetKev92]

Are any teams running gear-drive aft of the engine? I'm looking for sources and information on gear-driven systems and gear sizing.

So far it looks like chain is dominant, and I suspect that gear drive may be more trouble and weight than it's worth.

[NetKev92]

Are any teams running gear-drive aft of the engine? I'm looking for sources and information on gear-driven systems and gear sizing.

So far it looks like chain is dominant, and I suspect that gear drive may be more trouble and weight than it's worth.

[Steve Yao]

I believe SVSU was running a gear train for 2005...

[Jersey Tom]

If you're running a gear-drive system, you better have a really good reason for it.

I take simplicity over almost anything.

[Greg 08]

Are you running a stock bike motor or something else that might not have a trans and clutch? If you are running f4i/r6/gsxr then the gear is almost definitely more trouble since you can buy stock sprockets that fit. Unless of course you are mounting your engine backwards, then it may be necessary. Also keep in mind you will need either excellent alignment, some bolt on set up to your block, or another supported flexible coupling. I have done some preliminary research and it seemed like too much trouble and weight.

Another possibility is you are running some sort of integrated rear transmission that includes your suspension points like lee stohr's dsrs. Then you have some serious design work, and a really high bling factor. Has been done though, I have seen pictures of it. I didn't take them, so I don't know if they thought it worth it, but it is a serious weight, machining time, design time, and complexity commitment.

If you have facilities like tom, then maybe it is worth it....

Greg
Michigan Tech FSAE

[Storbeck]

SVSU had it in 05, and I think Adelaide (probably spelled that wrong) had it on at least one car. It would be nice to do gear drive for packaging reasons, makes the back of the chassis much simpler so that kind of offsets the added complexity of the gearcase, I'm not sure if it's really worth it though.

A few teams use a differential out of an atv and mount the motor sideways, another good posibility.

For what it's worth, the Stohr DSR uses a chain. There was a car that had a somewhat similiar really cool machined aluminum integrated rear end deal a few years back that I think was gear drive.

[murpia]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Storbeck:
For what it's worth, the Stohr DSR uses a chain. </div></BLOCKQUOTE>

http://sports.racer.net/images/chassis/stohr/drivetrain.jpg

Ian

[terra_dactile]

hi all,
in 2004 Detroit i remember a team from europe (di studi?) that had their own cone type CVT that was in the place of the structural rear transmission,they also had a tripple cylinder engine i think, Triumph if im not mistaken.

In 2005 formula student, TUG Technical university of GRAZ had a beautiful casted transmission that incorperated the suspension pick up points and housed the differnetial, it seems like they still had a chain to get from the engine to the diff, but the rear of their car looked great.

Oh yeah and if course we can not forget the team from Washington who had a carbon fiber gear box with their custom engine.

Jude Berthault
ETS Formula SAE 2003-Current
Steering and Brake System Leader

[drivetrainUW-Platt]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by terra_dactile:
hi all,
in 2004 Detroit i remember a team from europe (di studi?) that had their own cone type CVT that was in the place of the structural rear transmission,they also had a tripple cylinder engine i think, Triumph if im not mistaken.

In 2005 formula student, TUG Technical university of GRAZ had a beautiful casted transmission that incorperated the suspension pick up points and housed the differnetial, it seems like they still had a chain to get from the engine to the diff, but the rear of their car looked great.

Oh yeah and if course we can not forget the team from Washington who had a carbon fiber gear box with their custom engine.

Jude Berthault
ETS Formula SAE 2003-Current
Steering and Brake System Leader </div></BLOCKQUOTE>

Mahle 3 cylinder, tons of work with the transmission and very heavy.

[Lacy Lodmell]

I know in 2003 (and 2002 I think) University of Utah did a gear drive. They used a CBR600F?, removed the side covers, and CNC'd plates that bolted to the left and right sides of the engine. The left side plate housed the gear drive. The suspension mounted to both plates. I've got a couple of pictures, but am not smart enough to post them, so if you want pics I can e-mail them.

[NetKev92]

I have a standard bike engine, but it's a bit bigger than the typical FSAE unit. It's a '99 Yamaha YZF-R1 motor. Packaging and possible reverse options down the road are my main interests. If I had the cash on hand, I'd buy the Quiafe CD Axle Unit for Chain-Driven Cars.

http://www.quaifeamerica.com/Motorcycle/cycle.htm?main=cyclecars.htm

Getting the reduction ratio that I want with chain drive only will require going to a smaller drive sprocket on the engine end too if I want to keep any ground clearance with the driven sprocket. I need at least 4.5 to 1 reduction to keep the final drive sane. With a 16 tooth stock drive sprocket, I'm estimating a 14" driven sprocket diameter.

Nice link on that Stohr unit. That's farther than I'm gonna take things, but it's nice looking work and a good reference for ideas. It looks like it mounts to the rear of the motor similar to what I planned.

Anybody know about the Lewis Formula? Barth Revision? I calculated the acceptable gear loading based on pages 610-613 of the Rush Gear Catalog. Using a coarse-tooth helical gearset of hardened steel, it suggests the setup can only take 30 horsepower. If I nix the Barth revision, the straight Lewis equation suggests that the gear's structural limit is 110 hp in sixth gear or 210 hp in first gear (a torque limit so hp is different at different rpm).

Any other sources? If I could get an eyeball on the gears in the Stohr setup or others, I could make a sanity check on the gear sizes I'm looking at. If it doesn't start looking a little more secure though, chain drive it'll be.

[Matt Herset]

Here at the University of Idaho, we have choosen to design and make a custom drive train. Some of our reasoning for doing was that with a chain drive, our distance from the transmission output was 13", with the configuration of our gear drive we have reduced that distance to 7". I doing this we moved the driver and engine further back in the frame, give us a better weight disturbution over previous years. The there is a couple draw back to it, first, is that gear drive is not light, second, it wasn't cheap to build. http://seniordesign.engr.uidaho.edu/2005_2006/fsae05_06/CAR%20PAGE/Differential%20Housing.jpg

[Matt Herset]

Here is a small video of U of I's gear drive, in mid assembly.
http://seniordesign.engr.uidaho.edu/2005_2006/fsae05_06/Gear%20Drive.AVI

[RiNaZ]

Did anybody see that team from germany that was using the Mahle 3 cylinder with CVT last year? I missed last year FSAE, so not really sure if they come up with a better car.

[Hotlips]

We are using both, chain to a final drive unit and gear reduction in the unit, so the rear sprocket is small. Internal reduction is 3.15:1 Hopefully the bits will be running at FSAE Australasia in december.

[EliseS2]

Purdue ran a gear drive in 2003. The rear structure was an aluninum box that also contained the gear drive.

[NetKev92]

Great links. Those gears in the U of I gearbox carry some meat. They look two inches wide, about the same tooth size and width as the crown gear out of my Miata. I guess there's no way around physics.

How easy is it to get a smaller size drive sprocket and who would I call/look-up? I could really use a 10 tooth drive rather than the 16 tooth stock. There's got to be a practical minimum size.

[Matt Herset]

Yeah, our gears are a little on the thick side, but the damn thing is bullet proof. We have looked into some ways to lighten the gears up and or make thinner gears, but at this time we aren't going to spend the money on those options
at this time. This gear drive was the first production run and we are working on the next generation of gear drives.

[Cement Legs]

[QUOTE]Originally posted by Matt Herset:
Here is a small video of U of I's gear drive, in mid assembly.....
QUOTE]

Looks awesome. I bet a lot of time went into that production. Wouldnt spur gear be cheaper and more efficient. Not to mention the really cool sound they make http://fsae.com/groupee_common/emoticons/icon_biggrin.gif.

[Geoffct]

University of Michigan Dearborn 2002 car had one. A 600F2 was machined to add a mount near the output shaft. I will reinforce the downsides, weight, cost and time.

[RonBurgundy01]

I am doing my thesis this year on a gear drive for a formula SAE car.

My initial reasons are:
-Shorten the rear end of the car substantially
-Stronger than a chain/sprocket
-Less adjustabilty on a regular basis
-It's clean! Nothing worse than wrecking a sweet paint job with chain lube!

Downsides i've found:
-Heavy
-Not Cheap to manufacture
-Harder to fix (non stock components)
-Few other smaller ones

I was thinking of 3 possible designs.
1)Stand alone gearbox running into a seperate diff housing (that's just stupid)
2)Fully enclosed gearbox incorperating diff housing (probably what i'll use)
3) Same as (2) but intergrating suspension and other components into housing (maybe after the initial design/testing/breaking/swearing/fixing has happened!!)

I was simply going to mount the housing using existing mounts on the motor ie around the sprocket and un-used engine mounts

As for spur gears...ever flogged a mini cooper in reverse? LOUD AND ANNOYING!!!! A helical gear with a 20 degree helix angle gives very good efficiency, low noise and not too much axial thrust loading on bearings.

If anyone has more pictures of a geardrive on an SAE car please post them coz i'd love to get a few more idea's on how it's been done.

Cheers

Matt

[Paterson]

Adelaide ran a gear drive in 2004 and 2005 but we are changing back to a chain for 2006. Too much trouble accounting for shock loading and keeping the size of the gears down to an acceptable weight target. The gear drive was fine in 2005 for an event distance however we were well aware of the limited life span beyond this distance in the car.

The system consisted of a 3 shaft arrangement, with a duel compound gear in the middle, custom gear connected to the CBR600 output shaft and custom gear mounted on a modified torsen differential.


I will post pictures if i can find any good ones.

[Sam Zimmerman]

If you look at the U of I gear drive casing, it is remarkably light, even if the gears are not. If anybody would like to read some very cool research on optimization of structures, that gear casing was a very nice master's thesis. You can get it through inter-library loan, I'm sure.

They have been testing for quite a while now with no problems that I have heard of. As for the, "you'd better have a really good reason for it" comment, is learning a good reason? A gear school put on by UTS for one student, an optimization conference for another student, a master's thesis, and one junior working his ass off learning, applying, and optimizing a very complex gear design program lead to quite a bit of knowledge around our corner of the university. Add in the benefits that Matt mentioned plus the sex appeal and apparently that was a "really good reason" for the folks involved. This wasn't something that I was really involved with, but the pious attitudes that come forth when other people venture out to do something a bit different from the norm gets under my skin. This competition should be looked at as an educational experience first, not simply a taxpayer subsidized racing event for students. http://fsae.com/groupee_common/emoticons/icon_mad.gif

Now that I am off my soapbox, there was some cost/weight analysis that made the gears wider than you would expect, but I will let the Vandals Racing team dazzle the judges with that boring stuff. Stop by and check out the gear case, though. It is cool.

[Matt Herset]

I know that we have been running that gear drive for almost a full year now, and the only problem we have had is a little leaking of seals, We haven't had any trouble with our drive train, which in the the past has been an issue.

Its been a big thing at the U of I to push the extent of our abilities in Engineering and Manufacturing. If you become complacent with what you know do, what are you learning. Is FSAE not a learing program? Lets try to learn something new and push our selves to find something that intresting and challeging.

Now that I am off of my soap box, which seems to be a common thing for the U of I people, thanks for you interest in our gear drive and come see it out in Detroit in 15 days.

[RonBurgundy01]

Matt,

I just checked out the video on a previous thread you put up. Firstly the drivetrain looks awesome, very nicely done and as Sam said the housing has been really well optimized to reduce weight. Top work!

I was curious while watching the video as to how you have sealed the torsen though. It looks like the secondary casing you have yet to bolt on in the video does not actually encase the diff. Is this just an optical illusion? Surely the diff either has a seperate housing or the secondary casing does actually seal around the torsen...am i correct?

Also, how is the casing integrated into the rear chassis? Does it mount off the engine mounts?

In any case, its a sweet looking unit http://fsae.com/groupee_common/emoticons/icon_wink.gif

Cheers

Matt Ferrier

[Matt Herset]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by RonBurgundy01:
Matt,

I just checked out the video on a previous thread you put up. Firstly the drivetrain looks awesome, very nicely done and as Sam said the housing has been really well optimized to reduce weight. Top work!

I was curious while watching the video as to how you have sealed the torsen though. It looks like the secondary casing you have yet to bolt on in the video does not actually encase the diff. Is this just an optical illusion? Surely the diff either has a seperate housing or the secondary casing does actually seal around the torsen...am i correct?

Also, how is the casing integrated into the rear chassis? Does it mount off the engine mounts?

In any case, its a sweet looking unit http://fsae.com/groupee_common/emoticons/icon_wink.gif

Cheers

Matt Ferrier </div></BLOCKQUOTE>

Matt,

You would be correct to assume that there is a third part to the casing to seal the torsen. I beleive at the time that the video was being shot, the third case was being machined.

As for mounting the whole assembly to the car, we are using two of the engine mounts and the output spline. If you have any questions or want to see more photos, pleas email me or stop by our trailer in Detroit.