Belt vs. roller chain drive

[Fender]

This is dredging up an old topic, but I wanted to update this thread on what I decided to do. I kept the chain drive, but replaced the chain from the motor to the first jackshaft with an acetal plastic chain, and also used plastic sprockets. In addition, I reworked the jackshaft so I could easily tension the chains. Here are two photos. What I did was to attach a 1/2" diameter X 2" long shaft to a piece of 1/4" steel plate about 2"X4". Then, I screwed two sprockets together with #8-32 shcs, and inserted an oilite bronze bushing into them. The sprockets free-wheel on the 1/2" shaft. With this arrangement, the jackshaft can be moved up, down or to the side to tension the two chains precisely. The grey bars in the photo hold the 1/4" plate firmly against the housing, but allow the jackshaft to be moved to tension the chains.
With this arrangement, the drive is much smoother and quieter. According to the specs, the acetal chain is rated up to 4000 feet/minute, which is close to what I need. (The steel chain is rated for much lower speeds.) Altogether I am much happier with this arrangement.

[Fender]

One other thing I have noticed. The motor and controller do seem to be doing regenerative braking. At least, the ammeter is "going negative" when I run downhill! (Maybe not a rigorous definition of regenerative braking )

[highiron999]

Here is a mfg that uses only cog belt drives to a shaft and the shaft to ear boxes:http://kamilionlocomotive.com/

He could answer questions about this type of drive system. John Sweeny is his name at 810-797-5575 in Michigan 10 to 4 EST.

Leonard Evans/highiron999

[Bill Shields]

Dan:

Just be aware that timing belts, at speeds like that, are not totally silent either.

I don't think that you will find the noise objectionable, but it will probably be more than you expect.

I used one on my Bridgeport CNC primary drive and it whines quite a lot at 3000 RPM and above....but still better than a chain.

Just be careful about dirt buildup in the sprocket area, It gets in and typically cannot get out, gets compressed in the 'valleys' and before you know it, you have a really TIGHT belt and possible shaft problems if you are not using a spring loaded tensioner - which would be tough if you plan on running in reverse at all.

[Fender]

Bill,
With the loco hood on, I really can't hear the chain drive anymore, so that's as much as I had hoped for. The point about the spring loading is well taken. I made provisions for that, but decided instead to fix the position of the jackshaft once the chain tension was set. I can revert to using spring tension if I start breaking the plastic chain, which should be the weak link (literally).