Folding arm device for window cleaning machine

A fold-arm mechanism for gondola of cleaning device field includes fold-arm, fold-arm rotary mechanism, base arm and balance weight of fold-arm. The connection relationship is that the fold-arm is connected with the base arm through the fold-arm rotary mechanism and the balance weight of fold-arm is installed at back of the fold-arm. If the utility model's fold-arm rotates, the electromotor through the fold-arm rotary mechanism drives a rotary bearing for turning to realize rotary purpose. During the fold-arm's rotating, since it increases the balance weight of fold-arm, the fold-arm greatly drops torque of the head of the base arm and largely improves the device's stability and safety.