2) The rope should be in the middle of the hook. The rope in the edge of hook is very dangerous, which can cause the rope to slide and result in the accident when lifting. The lifting strength is maximum when the rope in the middle of the hook. 3) Hanging up the heavy with single rope is prohibited. Use two or more ropes wound on the heavy symmetrically when hanging up. Use the single rope to lift may cause the heavy rotate when hanging up, which will cause the rope rotate in counterclockwise or slide from the original position and result in the accident. 4) The angle of rope should not be too larger.
The bearing force on each rope will increase with the angle when hanging up with several ropes. The illustration below describes the allowable variation of bearing force on each rope when hanging up with two ropes. The allowable vertical lifting forces on each rope are all 9.8 kN (1000 kg). When hanging up the heavy vertically with two ropes, the two ropes can hang up the load of 19.6 kN (2000 kg). The weight variation is 9.8 kN (1000 kg) when the angle of two ropes is of 120°. On the other hand, if lift the load of 19.6 kN (2000 kg) and the angle of two ropes is of 150° and lift the same load, the load variation of the two ropes is 39.2 kN (4000 kg). 20-7