Notes on the operation of overhead cranes

Overhead cranes play important roles in modern industries. The application of overhead cranes brings mechanicalization and automaticalization to production process. Manual labors are thus reduced and efficiency is enhanced. There are the following notes in the application of overhead cranes. 

1. The trolley must be in normal status. Safety devices should also be carefully examined in order to make sure the brake, sound and light, signal and interlocking devices are running properly and of quick response.

2. Operators must be concentrated in their works. The trolleys should be tested without cargos before the cargo is lifted. Once the cargo is found not properly bounded when it is lifted 100 - 150mms over ground, it should be rebounded. Signal bell should be rung before the trolley is initiated. The lifted cargos should not fly over people. Repairation, examination, oil supplication and cleansing of devices are banned when the trolley is running. The trolley must be stoped if any fault is found.

3. After the work is finished, the trolley should be set at the stop line, the lifting hook should be cleared and fully lifted. All controllers and joysticks shall be set as zero; power supply shall be cut off; driving cab shall be locked.

4. Overhead cranes must be equipped with sensitive and reliable safety devices. These safety devices generally consist of bumpers, limits (both stroke limit and height limit), load limit as well as wind-proofing rail tongs, etc.

5. Electriferous shells of cranes should connect to ground, in case of electric shocks. Rails for the trolley should be welded to ground if they are not welded to girder. Step-down transformer should also be equipped with ground lead from its low voltage end. 

   

   Under the following cases, overhead cranes are not allowed to work:

   ①No commander or wrong signal

   ②Trolley devices fault or safety device fault

   ③Overload or uncertain weight

   ④People standing on or below the cargo; or when lifting people with hook

   ⑤Dim environment causing blurred vision

   ⑥Sharp edges on the cargo; or when the cargo is not vertically lifted without safety precautions.