Supporting 40lbs Arm with Motor?

[TheKeeg]

Originally Posted by nrogals

Hello Everyone,

Our team is looking to put a long rage shooter and acquisition unit on a single arm. Both units will weigh about 20lbs. The torque on the motor will be near 70-80 foot pounds.

Can a Mini CIM and a multiple stage gear box hold the arm up via friction in the gear box. If not, is there a method for running the motor with a certain voltage pattern such that it holds the arm and will not pull a sufficient amount of power away from the drive train.(Electric Break)

If not, at last resort, does anyone have any suggestions to apply a mechanical break to the motor shaft.

Thanks!!!!!

Well to answer your question...yes you can have the motors on brake where it switches directions rapidly so that you cannot back drive. I don't really know your situation, but I know window motors have an internal locking mechanism (to stop thiefs).
We have a RS-775 12 attached to a 1:100 reduction and we mounted a sprocket on the end of our winch. There is then a pin that inserts in the teeth/grooves of the sprocket when we want the motor to brake (not back drive). The 775 will also be on brake when the winch lock in engaged.