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Cable brake
Posted: Mon Nov 23, 2009 8:54 pm
by The Sky Dart
Input: An object slides upward on a metal cable. Let say 3...5 mm. Object mass is 0.5...2 kg. Speed - 30....200 m/s
Needed: A brake system that will decelerate the object on the top of the cable (1...2 meters) and won't allow it to drop back dawn. Otherwise it should create minimum resistance to the upward movement.
Any suggestions
Re: Cable brake
Posted: Tue Nov 24, 2009 5:33 am
by rockets-in-brighton
The Sky Dart wrote:Input: An object slides upward on a metal cable. Let say 3...5 mm. Object mass is 0.5...2 kg. Speed - 30....200 m/s
Needed: A brake system that will decelerate the object on the top of the cable (1...2 meters) and won't allow it to drop back dawn. Otherwise it should create minimum resistance to the upward movement.
Any suggestions
I'd go for a passive system, variable friction. Thicken or roughen the cable starting where you want the deceleration to begin and increasing towards the top end. What you use would depend on what you have got for a sleeve on the cable, which obviously can't be too tight-fitting. You could try: painting layers of PVA glue or similar over the last 2 m, thicker at the top than the bottom; wrapping tape around the cable, more layers as you go up.
I also thought about magnetic eddy currents (aluminum foil wrapper on the sleeve and strong rare earth magnets arranged around the cable, or vice versa) but you want it to stop - so have to contrive a one-way 'valve' on the cable to stop the load slipping back down, a flap of plastic could do that.
Good luck, report results.