The powerless lowering device of the roof rail type window cleaning machine has:
1. All hoisting mechanisms of the window cleaning machine should have a manual lowering device, which can be controlled to fall within a reasonable time when the power source of the crane is invalid. The operator should have easy access to the unit on the roof or on the gondola.
2. The manual lowering device should be automatically resettable, and the minimum descent speed is 20% of the rated running speed of the hoisting mechanism.
3. In order to control the falling speed, the centrifugal speed limiter with controllable speed should be designed to reduce the power, so that the controllable falling speed of the window cleaning machine is lower than the trigger speed of the backup device, otherwise the backup device will trigger.
4. Two independently driven hoisting mechanisms mounted on the suspension device ensure that the longitudinal inclination angle of the gondolas should not exceed 14° under any circumstances when there is no power drop.
5. The design of the non-power drop device should be designed to prevent any part of the fuselage from restricting the operation of its device (such as solid handwheels, electronic interlocks, and power interruption when cranks are used).
6. The backup device should remain effective during the process of no-power drop of the window cleaner.