Patent ID: 7374153

Claim:
A dual braking device for a power winch, said device comprising a first braking device installed in a reduction box and a second braking device disposed at a force output portion of the rotating shaft of a motor, said first braking device carrying out principal braking while said second braking device functioning to quickly stop said rotating shaft of said motor, said rotating shaft of said motor inserted through a motor holder, said motor holder firmly connected with a combining base positioned at the outer side of a rope drum holder, said rotating shaft of said motor mounted thereon with a transmitting sleeve, said transmitting sleeve fitted thereon with a braking lining received in said motor holder, an electromagnetic induction coil received in the interior of said combining base and a magnetic conduction member positioned between said braking lining and said electromagnetic induction coil, said magnetic conduction member pushed by an elastic member in said combining base to move and contact with said braking lining, said magnetic conduction member moved away from said braking lining when it is magnetically attracted by said electromagnetic induction coil, said rotating shaft of said motor having its outer end secured with a spindle, said spindle inserted into said reduction device to actuate the follow-up components in said reduction box to rotate, said electromagnetic induction coil producing magnetic force to attract said magnetic conduction member to move inward and compress said elastic member when the power winch makes electrical connection for retracting or releasing steel ropes, a gap formed between said braking lining and said magnetic conduction member as well as said motor holder, said braking lining unable to perform braking even though said braking lining is rotated together with said rotating shaft and said transmitting sleeve, said induction coil unable to produce magnetic force when said power winch is electrically disconnected, said magnetic conduction member actuated by the recovering elastic force of said elastic member to move away from said electromagnetic induction coil and contact with said braking lining so that no gap is formed between said braking lining and said magnetic conduction member as well as said motor holder, said braking lining able to carry out braking to quickly stop both said rotating shaft of said motor and said spindle.