1. The fixing screws of the power supply inlet and outlet wires of the contactor in the power distribution box of the tower crane are loose, the connection bolts of the terminal block are poorly connected, and the main contacts of the contactor are poorly connected.
2. The connection plugs of the motor rotor and stator coil are ablated.
3. The wear of brake pads of high and low speed motors exceeds the specified requirements.
4. The gear of the gearbox is broken, and the bolts of the fixed gear are loose.
5. The phase loss protector does not work.
