(A) a unit of a double-beam bridge crane 10 t, its power indicator light, steering linkage Taiwan indicator light, but it can not start. The maintenance personnel to the scene, it was discovered from the cab to go to Taiwan's security door is not closed. When maintenance personnel will be safe after the doors are closed, the crane is still working properly, this is a false failure. Safety of the crane, the hatch door on the driver's cab doors and access doors on both a door switch, when the crane driver or maintenance personnel to carry out maintenance on the crane, you must open the hatch door to play

Heavy machine go on stage, or open the access door to the crane rail beam, then open the door electrical switch normally closed contacts disconnect the electrical box main contactor release, thereby cutting off the crane power, so the crane can not be started. This protection also makes the car on bridge maintenance personnel from the threat of slip line electrified, also prevents others injured starter car maintenance personnel. Visible safety gate switch protection is necessary.

(2) a 10 t double girder overhead crane power supply is normal, the safety door is closed intact, but can not start. The maintenance staff on-site inspection and found lifting the control cam is not well back to zero, ie, the zero mark, although the cam position at zero, but zero protection without touching the contacts. Because this is a crane used for many years, its contacts stretch weakened, sometimes contacts do not generate false on failure. Will be replaced with a new contact, do not start the problem is resolved. From the cam controller structure known, and only the control handle is placed in zero position, lifting, trolley and carts controller zero contacts before closing. And in any other working position (i.e. non-zero position) when both in the open position. Therefore, when any one control handle is not zero (or zero position contact is not closed), the crane can not be switched on the main circuit, the crane can not start. This prevents the handle due to some reason does not return to zero, working position in the case of re-starting, the operation of the generating mechanism sudden dangerous incidents. This is the crane zero protection.

(3) a 10 t double girder bridge crane, the power, security doors and joystick positions are normal, but can not press the start push-button starter. Maintenance personnel to inspect, forced on the main contactor start operating normally. However, when you press the stop button does not disconnect the contactor, and

Press the start button when the contactor has disconnected. Press the stop button, main contactor starter normal, indicating the start button and stop button reversed. This is made clear by the maintenance staff did not cause false failures.

(4) a 10 t double girder bridge crane, lifting capacity decreased, only lift 5 t much weight. After several repair electrical parts are considered to be caused by aging. But check the electrical part, from the power supply to the controller into the household, diameter size standard; each contactor intact; cam controller main contacts also intact; Main hook resistor wiring is correct, wiring good; Main hook Electrical wiring is correct, the rotor brushes good motor rotation sound normal, the fault is not in the electrical part. After checking the mechanical parts, they found the main hook wire rope wear large, open car rack fixed pulley cover, see the rope pulley not have been out on the pulley shaft and found a gap in the pulley rim. For a new pulley, and replaced with a new rope, hanging 10t heavy normal test results.

This failure phenomenon, a general overhaul more experience in the electrical parts, such as diameter is not enough, bad contact the main contacts, resistor wiring is wrong, and this will result in lower lifting capacity, so many are in the electrical part of the overhaul to proceed, but this fake fault is fixed pulley shield obscured, making maintenance a detour. This also shows that lifting equipment is mechatronic, electrical parts and mechanical parts are inseparable, as long as careful examination, comprehensive observation, some fake fault is able to recognize.