Drive train and gearboxes

[artdutra04]

Originally Posted by lukevanoort

You don't actually need four sprockets on the tranny to make a 4WD. We had a 4WD last year that was so effective, the first time we lost a pushing match was at nats by a tank treaded robot. (can't remember who) We mounted the tranny in the center of the bot than ran one chain around it and the two wheels, than had idlers (literally HDPE blocks) that performed double duty as tensioners and gave us enough contact on the tranny to avoid slippage.

Although using a single loop of chain to power a four-wheel-drive robot may seem like a good idea (especially in the weight department), just remeber that "stuff" happens. At some point, that chain may break. If this said chain broke, your robot will basically be a paper weight for the remainder of the match. However, if you were to use two chains from the transmission - with one going to each wheel - you could still have at least one powered wheel if the chain broke. Thus, your robot could still "limp" through the rest of the match and try to score as much as possible. Redundancy is always a nice feature to have.