A railway vehicle parking brake that can provide the appropriate tension to the braking system using a motor, a brake chain drum interconnected to the motor to take up or release a brake chain, a load arm deflects in response to tension in the brake chain, and a switch that is closed by the load arm when it deflects. A movable sheave interconnects the brake chain and the load arm and is positioned between the brake chain drum and a fixed sheave over which the brake chain is looped. A control method considers the position of the first switch to determine whether to the motor off when applying the brakes and the amount of current being drawn by the motor to determine whether to the motor off because of a system failure.