chain drive vs belt drive vs gear drive

[ae86drifter]

i'm going to be in charge of the drivetrain for the 04-05 formula team. in the past, we have driven the car through chain and sprocket. people have mentioned chaning this design to belt drive or gear drive. i could not really find a good enough justification for a different design since the chain drive design has never failed on the car before.
i was just wondering if there are any advantages of changing designs and the pros and cons.
thanks

[MikeWaggoner at UW]

Chain advantages:
Efficient
Easy to change ratios
Don't have to dissassemble drivetrain to replace chain

Belt advantages:
I've heard there's a slight efficiency improvement over chain, can't name a source though
Lighter chain/belt guard

Gear advantages:
Tighter packaging
Lower maintenance
No chain guard

I think chains are the best solution.

[Daves]

Because of their mechanical interlock, chains can function under a large range of tensions. For example, when a motorcycle's rear wheel moves up or down relative to the engine, the chain get tighter or looser but still functions. On an FSAE car the differential and engine are usually fixed relative to each other while driving, but when adjusting the chain tension, there is a great range of allowable adjustment. Also, chains are length-adjustable, so you can buy a standard chain and remove links to make it work.

Gears allow for little adjustment, but I did see at least one university use them this year.

Belts work only under a small range of tension and their lengths are not adjustable.

[jm1495]

chain... belt.... gears...
Yeah we've tried them all. Strickly gear drive last year, really really hard to seal. Gear drive/ belt drive this year. the belts never lasted under any circumstances. We also destroyed a set of gears. Ended up having to go to a chain drive 4 days before competition. Just my 2 cents

[Colin]

when we've looked at using belts a big problem is not being able to break them for installation
around the rear chassis

[clausen]

Hi,

Our gear final drive is part of the reason we were able to shorten our overall package by 600mm this year.

It's going to be a nice little unit, but pretty expensive to make.

[Kevin Hayward]

Paul,

It'll be intersting to see a gear drive in this years competition.

I do know that last year if our rear sprockets were any closer it would have been a gear drive instead of a chain. I only say this as we were able to get a very short package by going to the minimum centre to centre distance we could on a chain drive.

I have a question though Paul:

Are you going to work with more rear weight bias or go to a smaller wheelbase as a result of the shortened drive configuration?

Kev

[clausen]

Hi Kev,

Both. We do have a shorter wheelbase (nearly on the minimum), but we should be getting the cog further back as well, which I'm happy about.

[ae86drifter]

hey paul,
even though you compacted the whole package, did you also add weight. the gears would have to be in a casing in order for the gears to be lubricated, right? the fluid, casing, and three gears should be more weight than two sprockets and a chain.

[Sam Zimmerman]

As it stands now, we are planning on showing up next year with a gear drive. We are still trying to work out the details but it looks like we are close to having the gears sized appropriately. Attempting to come up with a realistic life-cycle for the gears is proving to be a pain in the butt, though.

[clausen]

Hi AE86drifter,

To be honest we arent too sure of the weight difference, but in our case it shouldnt be too drastic. The final drive and diff is all enclosed in an aluminium casing, which is strucural and replaces a fair bit of chassis, we are making our own torsen diff body out of aluminium (VS last years cast iron or steel one), and the gears are all quite small and lightweight, so hopefully we shouldnt be too far off the mark. I dont think we will be matching Delft for weight though http://fsae.com/groupee_common/emoticons/icon_smile.gif