I thought I’d share a few pictures of a prototype I recently made that will find itself on the second generation of our bot, coming soon. (rebuild after December 9th) It’s a double differential transmission, using custom differentials. I decided to use these because the normal differentials are weak. By the time I put them on the final version, they will be even more fortified
Anyway, the differential casings will be driven by one motor each. (this may change) The outputs will go to a few wheels on the bot: one to drive wheels and the other to strafe wheels. A second transmission will be installed on the other side of the robot to allow for full steering and strafing, while only using 4 motors.
In the attachments, the first image is the whole system. (One side) The second is a closeup of the differential. Found here is a video of the full range of motion of the system, but being backdriven. (I am turning the output shafts. The turning differentials are what will be hooked up to the motors)
Ouch… Do you remember your gearing? If this is a problem… I may gear the inputs 7:3 for speed and outputs 3:7 for torque. This should reduce torque on the whole system, but add a bit more friction. (not sure on that)
I remember I had the same problem last year when I put a beveled gearbox straight out of the motors before gearing it up for speed. They also cracked.
Hey that’s pretty cool! Are you going to use pneumatics to switch between using the differentials to power the tank drive wheels versus the strafe wheels? We had a similar setup on one of our early season bots but instead of switching output to strafe, we transferred power to a winch to help climb.
Ended up taking up too much space and added too much weight so we scrapped the bot design and its variations though.
No need for pneumatics. This transmission doesn’t even need them. In fact, I can verify this; our current drivetrain is working great with the transmission installed.
For an out-of-date animation, look here:
