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Why is the crane not allowed to diagonally lifting or pulling?
- Jan 09, 2019 -

No matter overhead bridge crane, Jib crane, gantry crane,electric chain hoist or wire rope hoist , even manual chain hoist . To warranty the safety during lifting or material handling . Customers are not allowed to diagonally slant . What the reason for this prohibition ?

1. Inclined lifting may cause overload .

Suppose that the object with weight Q is lifted from the ground and lifted vertically. If the rope tension S is equal to Q or slightly larger than Q, the weight can leave the ground.

However, if it is diagonally pulled, the wire rope will be at an angle to the vertical line of the ground. According to the mechanics principle, the tensile force S acting on the wire rope can be decomposed into a force P that causes the object to move vertically upward and a force F that moves horizontally. To lift the object from the ground, P must be at least equal to Q. At the same time, F increases as the angle increases. That is to say, the larger the angle at the time of slanting, the greater force that wire rope receives when lifting the same heavy object. Therefore, if a heavy object is fully loaded when lifting vertically, the slanting crane or hoist is inevitably overloaded, even wire rope might be broken .

2. Inclined crane produces inertial force, which put people in dangerous working condition .

The horizontal component force F generated during the slanting is also affected by the friction force before the weight is removed from the ground. At the moment of leaving the ground, the object will be swung to the vertical center, which may cause an accident with the hanging person, surrounding workers or other objects.

In short, if diagonally slanting , it will not only cause the overload to break the wire rope, but also cause the heavy object to sway and collide with objects and personnel, causing personal and equipment accidents. So customers have to follow the crane and hoist operation instructions strictly, operate or maintain the crane and hoisting equipment in correct way , improve efficiency and lower

potential risks .