In recent years, electric hoists have become increasingly used on lifting machines. Therefore, the installation and use quantity of electric hoists is increasing continuously. However, in production, the number of electric hoist failures is also increasing, which not only affects the normal operation of production but will cause major accidents in serious cases. So, how to reduce or avoid accidents? Combining our company manufacturing and installation experience, the cause of some common failures of electric hoists are analyzed in detail.
1. Before using a new or reassembled electric hoist for the first time, it should be run empty several times. However, before the installation is complete, it is strictly forbidden to turn on the power for trial operation.
2. Before normal use, a static load test should be conducted for 10 minutes at a height of about 100mm above the ground with a rated load of 125%. After the test, check if everything is normal.
3. The dynamic load test involves repeatedly lifting and moving the load with the rated load in both directions. After the test, check if the mechanical transmission parts, electrical parts, and connection parts are normal and reliable.
4. It is strictly forbidden to use the hoist in conditions that are not allowed or beyond the rated load and the maximum number of times the circuit can be closed per hour (120 times).
5. During installation, adjustment, and maintenance, it is strictly necessary to check if the limit switches are flexible and reliable. When the hook reaches the upper limit position, the distance between the hook shell and the drum shell must be more than 50mm (120mm for 10t, 16t, and 20t). When the hook reaches the lower limit position, the effective safety loop must be more than 2 loops.
6. It is not allowed to press both buttons that make the hoist move in opposite directions at the same time.
7. After completing work, the power supply circuit breaker must be turned off to cut off the power supply.
8. The hoist should be operated by a designated person who fully understands the safe operation procedures. Lifting and lowering should be done in a straight line.
9. Regular inspections must be conducted by specialized personnel during use to detect and resolve any issues promptly. Detailed records should be kept.
10. When adjusting the brake's downward slippage, it should be ensured that the downward slippage S is no more than V/100 (V is the stable lifting distance within one minute under the rated load).
11. The hoist must be kept adequately lubricated during use and the lubricant should be clean without impurities or dirt.
12. Steel wire ropes should be lubricated with a hard bristle brush or wooden block, and it is strictly forbidden to lubricate the working steel wire rope directly with hands.
13. When the electric hoist is not in use, it is not allowed to leave a heavy load suspended in the air to prevent permanent deformation of parts.
14. If a fault is found during use, the main power supply should be immediately cut off.
15. Special attention should be paid to the condition of wearable parts during use.
16. For 10-20 ton hoists, there may be an automatic power-off phenomenon after prolonged continuous operation, which is the motor's overheating protection function. In this case, the hoist can be lowered, and after some time, the motor can be cooled down and continue to work.
Please also note the following points after familiarizing yourself with the operating instructions: one Please memorize the instructions and markings on the manual before operating.
Please adjust the upper and lower limit stop blocks before lifting objects.
Please confirm the reliability of the brake before using it.
Do not operate if you notice any of the following abnormalities in the wire rope before using it:
a. Bending, deformation, corrosion, etc.
b. Exceeding the specified requirement for wire rope fracture, with high wear.
Please use a 500V megaohm meter to check the insulation resistance of the motor and control box before use, and the cold resistance should be greater than 5MΩ to be used.
Please do not lift objects that exceed the rated load capacity, which is marked on the hook of the crane.
It is strictly prohibited to ride on the lifted object, and the electric hoist should not be used as an elevator hoist to carry people.
There must be no one below the lifted object.
The object and hook must not be lifted in a swinging state.
Please move the hoist to the center of the lifted object and lift it straight up, not at an angle.
The limit switch is not allowed to be used repeatedly as a trip switch. twelve Do not lift objects that are connected to the ground.
Please do not over-jerk the operation. fourteen Do not pull other objects with the flashlight cord beforehand.
Always disconnect the power supply before conducting maintenance checks.
Maintenance checks must be conducted in the unloaded state.
Please confirm that the wedge is securely installed before use.
