This invention relates to an overhoist protection apparatus of crane to protect snatch block.
In the known construction of booms provided with a crane, a snatch block is provided at the distal end of the boom, and the snatch block consists of a bracket to support a hook. The snatch block is raised or lowered through a rope system actuated by a winch at the proximal end of said boom. An overhoist warning system is provided with the winch of boom so as to protect the pully provided at the distal end of the boom from the damage and when the bracket carrying the hook is raised towards the head or distal end of the boom. The overhoist protection system comprises a mechanically operated warning switch provided at the exterior end of the winch such that upon hitting said end by snatch block it gives the alarm provided in the operators cabin.
The main disadvantage associated with the prior art is that the switch becomes inoperable after a little use of the crane in the field due to dust, moisture etc. and thus during the operation of the crane snatch block but the exterior end of the boom and causes damage to
it.
Another disadvantage is that some time the rope is broken due to excess winding of the rope even after the complete lifting of the snatch block towards the boom.
Yet another disadvantage is that no means are provided for facilitating the butting of the snatch
block with the boom and thus the snatch block is kept, hanging which means causes damage during movement of the
crane due to dan tiling of snatch block.
Still another disadvantage is that a tie rope is required to hold the snatch block.
T h e re fo re, an o bj ec t of t hi