Thread: Is this a real tortion spring?
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Unread 26-01-2008, 20:03
Matt H. Matt H. is offline
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Re: Is this a real tortion spring?
Torsion springs produce torque so pounds per rotation is not a unit which can be applied to them. What the unit on McMaster car is referring to is the maximum torque when the spring is fully wound. It should have a linear decay from that point.

So for a 180 degree spring with 40in lbs of torque it would have 20in-lbs at 90 degrees and 0 in-lbs at 0 degrees.

I'm not sure if you know this so I also give a brief explanation of torque.
Essentially 1 ft-lb can support 1 lb on a one ft radius. so a 40 in-lb spring would be able to just barely support a 40lb load at 1 in from the point of rotation.

To figure out how much torque you need to produce a given speed you will have to used rotational physics equations such as torque=rotational acceleration*moment of inertia.
Last edited by Matt H. : 27-01-2008 at 00:05. Reason: A mistyped number which might have caused great confusion