Thread: 12.75:1 enough?
View Single Post
  #2   Spotlight this post!  
Unread 12-01-2009, 11:38
Jared Russell's Avatar
Jared Russell Jared Russell is offline
Taking a year (mostly) off
FRC #0254 (The Cheesy Poofs), FRC #0341 (Miss Daisy)
Team Role: Engineer
  
Join Date: Nov 2002
Rookie Year: 2001
Location: San Francisco, CA
Posts: 3,078
Jared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond reputeJared Russell has a reputation beyond repute
Re: 12.75:1 enough?
The maximum frictional force is not 150lbs + 40lbs. The trailer wheels are not powered and so don't add to your maximum tractive force. The tongue weight, however, will help you - let's call it 10 lbs (probably an overestimate). So your downforce is 160lbs.

This means that the maximum tractive force (with 0.2 CoF) is .2*160lbs = 32 lbf.

Max torque = 32lbf * 3in = 96 lbf*in

Torque needed/torque provided = 96/8.5 = 11.3

And realistically the CoF is 0.1 or below, so I think direct drive off the ToughBoxes provides more than enough torque (with 1 motor per side).