Van Door backdrive limit

[NoodleKnight]

I've searched, but if there is an existing thread that answers the question, please point me in the right direction.

anyways, with all this talk about van door back drivability, does anyone know how much torque it takes to get the van door to back drive?

Thanks,
-Jonathan

[ahecht]

I don't have the number offhand, but it might be a fun experiment to rig up a lever arm and a scale and measure it yourself.

[gburlison]

I haven't seen any exact figures. Last year we used one for a winch it would backdrive. Using some rough calculations ( from my rough memory of our winch diameter) the motor would see about 30 ft-lb and it would backdrive. This year we have it in part of our arm and it sees about 9 ft-lb and does not seem to backdrive. I know this is a big range, but I do not remember seeing anyone post measured values. Perhaps you could attach a one foot arm to the motor and measure how much force it takes to backdrive it. If you do this, please post it so that we know.

[Andy A.]

What ever value you (or someone else comes up with), don't design around it. As the worm and gear wear in, they are going to become a little sloppy, and this could change the nature of the backdrive.

For what it's worth, with a pair of vicegrips on the output shaft, I can just drive the motor with my hands. Figure a 6 inch leaver arm and all the force a 20 year old guy can muster with his right arm. Once I get it moving, the force needed goes way down.

Maybe I'll bring a torque wrench with me tomarrow and see if I can rig something up quickly on an old motor.

-Andy A.