Quote:
Originally Posted by MICHAELABICK
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We designed our 2011 and 2012 gearboxes to accept more motors.
Our 2011 robot was CAD'd to accept a FP/550 through 2-stage Banebot planetary (driving the 28-tooth high gear on the intermediate cluster shaft via a larger spur gear), we later found (no surprise) we didn't have the weight. We later designed a lighter system with 775 motors (before the case short issue was well-known) into CIM-u-lators, where the extra motor would be directly across the gearbox from an existing CIM. We would have welded two CIM pinions together into a pinion/coupler for the two motors, but we didn't feel like we needed the extra power by CMP, we didn't have the weight before CMP. We had very little choice in gear ratios since we were running super shifters direct drive to 6" wheels, any gear changing would require us to machine gears, something we cannot do well.
Our 2012 robot was designed to hold a CIM-u-lator on an intermediate plate in the gearbox, we CAD'ed it with clearance for two 550's (making 8 drive motors in CAD). We assembled the gearboxes with a single 550 (plus the two CIMs), and removed the extra 550's due to weight concerns. We were able to re-gear the robot appropriately since we used a chain final drive, although we still didn't gear low enough.
We do not have definitive data showing anything about the third motor. The math says it should be good, we've been going purely on that.
As for a power take-off, your goal is essentially to have two or more clutches: One engages the motor to each load. A single dog from Andymark acts as two clutches - In one position one gear is engaged and the other is not, in the other the reverse happens (it exists in neutral with neither engaged for a short time during a shift, if you play with it you can get it there manually).
In the case of 254's 2010 robot, they had two dogs which could engage two separate outputs in three different ways each, plus a one-way ratchet. The lower dog engaged the drive into either motors via low gear, motors via high gear, or neutral. The upper dog engaged the arm into either the motors, neutral, or locked (a fixed plate with dog-face). Something like that would likely be the simplest way to design a PTO in FIRST. I would have to look at their design again to tell you anything else about it.