Quote:
Originally Posted by 114Klaatu0x72
During Overdrive, our team decided on using a pivoting arm with one or two 80lb constant force springs, along with an underpowered gearbox, Chinese cast iron gears and "pwm cables" aka painted string, and a broken anti-back drive mechanism. It worked about once, and then the gears sheared off half their teeth, the anti-back drive pins fell out, and a cim burnt out in the manor of seconds.
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I'm curious about the gear specs and the load you put on those gears; would you mind explaining further? (Besides, I also want to know the supplier of the gears, so that I can consider avoiding them!)
Quote:
Originally Posted by cire
2003... Never use #25 chain for your drivetrain. It may seem like you will never hit that several hundred lb limit, but when you throw in missalignment and shock loading, well lets just say we went through a lot of chain that year.
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188 broke about 13 strands of ANSI #25 in 3 events that year. Of course, we didn't exactly have the best setup—small drive sprockets on very powerful transmissions,* rigid and convoluted chain guides instead of idlers, and a bit of misalignment.
On the other hand, on a different drivetrain,
ANSI #25 chain can be a perfectly reasonable choice—this year, for example, with all the high-speed driving, teams can probably expect substantially less chain load, especially if they've got room for big sprockets on their big wheels.
*Actually, as far as I know, they were the most powerful transmissions on any FIRST robot to that point; each transmission had a CIM, a Bosch drill motor and a Fisher-Price motor.