Quote:
Originally Posted by ksafin
Well, it wouldn't move 
By what means can I calculate a given torque at a given speed, then?
The motor is 152 rpm.
If I wanted, say, 80 rpm, could I find the percentage of total RPM (80/152) and multiply that by the stall torque to find corresponding torque at the given speed?
I'm assuming speed and torque change by the same factor, proportionally to the drop in voltage. |
Yes, Good.
Assuming constant voltage, T = -Ts/wf * w + Ts.
T = torque
w = speed (in the same units as wf)
These are both variables.
Ts = Stall Torque
wf = Free Speed
These are both constants (and linearly scale with voltage).
So, to give the last tidbit. An accepted practice is to determine the max load the lift must lift and/or hold. You'd then want to choose your gear ratio and drum diameter such that this corresponds to some percentage of stall torque. The lower the percentage, the less heat you'll make and the longer the motor will last (but the slower you'll go).
Depending on the time it needs to run, and how much it has to hold still (Versus just lift up, then down quickly) anywhere from 10%-25% are valid numbers for FRC. Be careful trusting the word of others (including me) too much on that %age though. It varies motor to motor and is a function of how much heat is made to how much heat the motor is able to dissipate from the armature.