During normal operation, continuous current keeps the brakes in a non-braking state. This current is interrupted by a separate electrical device. If the brake coil is powered by a DC power supply, a separate contactor should be installed in the DC circuit to interrupt the DC current.
When the lift motor has a function similar to the generator, the electrical device that controls the brake cannot be powered by the drive motor. When the brake open circuit is turned on, the brake should act within 0.3 s. The brake should act by a compression spring. The spring is compressed and its stress should not be greater than 80% of the shear stress.
When it is working properly, the brake should be given a continuous liquid or pneumatic pressure in a non-braking state. The brakes should be designed so that the non-human drop of the gondola is not allowed. The brake must not be open unless the motor provides the torque to hold the gondola.
The manual hoisting mechanism shall be designed to lift or lower the load by the crank or handle force; it shall have measures to prevent uncontrolled movement or lowering. When the force applied to the end of the crank reaches 625 N, the mechanical conditions provided by the gear reduction system and the hand crank are not allowed to increase the working load by more than 2.5 times; when the working load is raised, the force applied to the end of the crank should not More than 250N.
When the force applied to the end of the handle reaches 1000 N, the mechanical conditions provided by the gear reduction system and the handle do not allow for an increase of more than 2.5 times the working load. When the window cleaner lifts the working load, the force applied to the end of the handle should be no more than 400N.