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Do the Math
O.K., here is an example:
I will use the 2 window motors, but the math works with any motor.
Tmaxp is the torque at max useable power (power just under breaker limit)
Wmaxp is the speed at the above condition
Dw is the diameter of the winch spool
Vlift is the lift velocity
Fr is the lifting force required
For our case:
Tmaxp = 4.6N-m
Wmaxp = 46 RPM
Fr = 130 lbs
We will not be using any gear ratio, just direct drive off the window motors
Equation #1: 2*Tmaxp = Fr * Dw/2 (the 2 on the torque side is due to the 2 motors)
Equation #1: Dw = 2*2*Tmaxp/Fr
Equation #1: Dw = 0.032 meters [32mm] (remember to convert lbs to Newtons)
Equation #2: Vlift = Wmaxp * Dw/2
Equation #2: Vlift = 46RPM * (2*Pi/60)rad/s * 32mm/2
Equation #2: Vlift ~ 77.1 mm/s [3.03 inches/s]
So we have a winch that can lift 130 lbs @ 3 inches/sec.
This winch could lift 1 foot in 4 seconds or 2 feet in 8 seconds.
I hope this helps.
-Paul
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