Hoist Safety Device Test
G. Anti-falling Test
G1. General Explanation of Falling Test
All the newly installed hoists shall conduct falling test of cage with rated load. And then, the falling test should be conducted at least once every three months. During the falling test, people are not allowed to stay in the cage. The operator could conduct the falling test only after confirming every part of the hoist is fault free.
Speed control part of safety device has effective sealing, the moving speed should not be adjusted without authorization.
G2. Procedures of Falling Test
1. Load the cage evenly to the rated load weight;
2. Switch off the power; put the falling test control box on the ground out of enclosure; plug the plug of controlling box into the special falling test socket in the electric control box and fasten; sort out the cable to avoid breakage during the movement of the cage;
3. Switch on main power; run the cage upwards for 10 m by the controlling box on the ground;
4. Pressing “falling” button, then, the electromagnetic coil of motor brake is electrified to release brake. The cage would fall freely. When it reaches to the action speed, the safety device would brake and stop the cage on the mast stably. The braking distance shall be 0.3~1.2m (it refers to the distance from the action of anti-falling safety device to the totally stop of the cage. For VFD products, the braking distance will be increased along with the increasing of lift speed)
5. The cage shall not act when try to start the cage upward, because at this time, the micro-switch of safety device has cut off the controlling circuit of driving motor. If the cage reacts, the operator shall re-adjust the micro-switch
▲If the cage is not stopped by the safety device when the bottom of the cage is about 3m above the ground, the “falling” button must be released at once to make the motor brake resume to work for braking, to avoid bottom collision.
▲If the anti-falling safety device fails to brake the cage as per the requirements, the falling test plug should be pulled out from the special falling test socket in the electric control box, and the cage should be lowered down to the ground. After that, the operator shall analyze the reason of failure, and remove the failure. If necessary, send the safety device to the manufacturer for calibration before test again.
Danger of brake failure: it is prohibited to carry people in the cage during “falling” test.
G3. Reset of Anti-falling Safety Device
Once the anti-falling safety device makes action after the failing test or during the daily operation, the anti-falling safety device shall be reset. If it acts in usual operation, the operator must investigate the cause of action and take relevant measures. Before reset of anti-falling safety device, it is prohibited to operate the hoist.
G3.1 Inspection before Reset of Anti-falling Safety Device
Except falling test, before reset, the operator must investigate the underlying cause of the action of anti-falling safety device and inspect the content as follows:
1. Whether the magnetic brake of the motor works normally or not;
2. Whether the transmission and coupling of speed reducer work normally or not;
3. Whether the guide rollers and back wheel of cage work normally or not;
4. Whether the gear teeth are complete or not;
5. Whether the micro-switch in the anti-falling safety device works normally or not;
6. Before reset, the operator shall do trial upward running of the cage. Normally, the cage can't be started.
G3.2 Reset Procedures of Anti-falling Safety Device
1. Disassemble screw 1 and cover 2, and take off screw 3; rotate the copper nut 7 outward by special wrench 5 and rocker 4 till the end of pin 6 parallel to the plane of the end of anti-falling safety device housing (at this time, the circuit of safety switch is connected).
2. Assemble screw 3 and cover 2.
3. After switch on main power, the operator must operate the cage upward for more than 200mm to separate centrifugal block from the friction drum and make it resume to normal operation state.
4. Carry on trial operation.