Torque Help

[Lord of Yetis]

Hi I'm a FRC team member of team 3506, and we are having a problem with calculating the torque required for a two speed Andymark transmission, An Adobe document with our calculation results should be attached, we are having trouble finding the torque output needed for 3 and 4: 4" diameter wheels per side with two sides having wheels, and 3: 6" diameter wheels per side with two sides having wheels

[Lord of Yetis]

The calculations use a maximum rpm efficiency of 4614 and a maximum torque efficiency of 90 in-oz

[dtengineering]

There has been a lot of writing and calculating done on predicting drive train performance with different gear ratios in the FRC environment.

Rather than writing a lot about it here, I'll give you a link to my current favorite "white paper" on the topic

http://www.chiefdelphi.com/media/papers/2750?

You'll find a write up explaining some of the factors that go into drivetrain modelling and a spreadsheet that will help you play with different gear ratios and motor combinations for getting from point A to point B as quickly as possible.

There are simpler spreadsheets available, and it takes a bit of playing with this one to figure out how it all works... particularly if you haven't done much drivetrain modelling, but the write up attached to it... particularly the last page, is excellent.

Short rule, though... for 6" wheels my favorite single-speed reduction has been 14:1. As the paper points out in most FRC applications accelleration is more important than peak speed.

Jason