View Single Post
  #11   Spotlight this post!  
Unread 10-01-2002, 21:18
Joe Johnson's Avatar Unsung FIRST Hero
Joe Johnson Joe Johnson is offline
Engineer at Medrobotics
AKA: Dr. Joe
FRC #0088 (TJ2)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1996
Location: Raynham, MA
Posts: 2,629
Joe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond repute
We have ahd this conversation before.

I will say it again: there is no magic in having 2 motors that are different inputting to the same gear.

The bottom line is that the speeds are required to be in some ratio that is fixed by the gearing. Assuming the same voltage to the motors, the motors then simply act like the SUM of the two motors.

The speeds are equal (or geared to a ratio) the torque out is like the sum of each motor at that speed.

One of the things that you have to keep in mind is that the speed torque curves are a line that extends into negative values.

If the speed of one motor is faster than the other can provide at the voltage provided, then it is providing negative torque -- that is, it is slowing down the other motor.

As to one motor burning up the other, this can happen if the speed are SO different that the driver motor is doing a lot of extra work to drive the other motor. In this case, the driven motor can also get hot because it is generating a lot of current that might be going back into the battery or it might be going to generate heat (more probable).

Joe J.