pic: Experimental VP drive gearbox

[pilleya]

Originally Posted by bkahl

Are you sure that the VP will hold up with 2 CIMs powering it?

The load ratings sheet for VPs shows very different charts for a 775 motor and a CIM motor, let alone 2. While this design may hold up okay for a 775pro or 2, I think this may put the VP out of spec with 2 CIM motors driving it.

I would be pretty cautious about 1 CIM going into a VP, let alone 2. Especially in a dynamic loading situation like a drivetrain.

The reason the VP load rating charts are very different is that the 775pro has a free speed of around 18730rpm and produces 0.71 N.m of torque at stall. The CIM on the over hand has a free speed of around 5330rpm and can produce 2.41 N.m of torque at stall.

The 775pro needs a greater reduction (3 or 4:1) in order to match the speed and torque of the CIM. This is the reason why with a CIM 64:1 is the maximum ratio for safe operation, and with a 775pro a 210:1 is the max.

A major benefit of having a gearbox based around a VP is its ability to be highly versatile. It enables you to fine tune the robots FPS easily. Meaning that you can find the perfect gearing for getting over that obstacle or moving to that point as fast as possible. A gearbox like this could be really good for drivetrain prototyping and testing, as it would enable quick tuning of gear ratios, the results of the testing could then be used to determine the required reduction of the conventional spur gear gearbox.