hi, i know the method comonly used to brake DC motors is to short the windings.

But in my application i need to pull objects to a certain height with a very simple system consisting of a mottor turning a wire around its shaft and the object is attached to the other end of the wire, i hope you see what i mean.

If i use this classical way of braking i think it wont overcome the weight of the object being pulled.

So, wouldn't i get much better bracking if i keep inversing the current in the winding (Fwd-Reverse) at a relatively high frequency? in such way that the motor doesen't have time to response or move according to any of the 2 currents, but in the same way it would be kind of being braked by a foce as strong as the one that raised it..

is this theory true?

if so, what frequency would be suitable..?

thx a lot

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Ibrahim Kamal
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It would probably have some kind of 'locking' effect, but it's highly likely to destroy the motor through over heating. I would suggest you use a worm gear from the motor, this will greatly improve it's resistance to movement from the load, even without braking - plus give you much greater torque.

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Further to Nigel's suggestion, a mechanical brake is often used too. You'll find small band type brakes inside every cassette tape recorder or in the older VCR machines. Another way is external brake shoes around a narrow drum on the shaft, this system is used on lift motors.
the mechanical brakes are solenoid activated.
Klaus