In the first, the pressure is applied by a handle or treadle, and is removed by a spring or weight; this is called " braking on."
While braking, spragging, or chocking wheels 15 627 6.
In the second, or " braking off " method, the brake is automatically applied by a spring or weight, and is released either mechanically or, in the case of electric cranes, by the pull of a solenoid or magnet which is energized by the current passing through the motor.
