Title of Invention

" AN OVERHOIST PROTECTION APPARATUS OF CRANE TO PROTECT SNATCH BLOCK"

Abstract

This invention relates to an overhoist protected snatch block comprising side plates having a pulley provided therebetween rotatably, a hook being secured to the bottom end of said plates, characterised in that a top plate which is fitted with the bottom surface of the manual extension at the distal end of the boom of the crane, valves are provided with the hydraulic system which releases the hydralic oil to the oil tank.

Full Text

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 Another object. of this invention is to propose an overhoist protected snatch block system which no longer has an overhead warning system. A •still another object of this invention is t o p r o p o s e a n o v e r h o i s t p r o t e c: t e d s n a t c h b 1 o c k s y s t e m and wherein the hook no longer needs a tie chain to hold the same. Yet a further object of this invention is to propose an overhoist apparatus to protect snatch block and wherein the snatch block can now take full head clearance in lift height. According to this invention there is provided an overhoist protection apparatus of crane to protect snatch block comprising side plates having a pulley provided therebetween rotatably, a hook being secured to the bottom end of said plates, characterised in that a top plate which is fitted with the bottom surface of the manual extension at the distal end of the boom of the crane, relief valve and priorty valve are provided with the hydraulic circuit which releases the hydralic oil to the oil tank. In accordance with this invention a top plate is provided on the top of the snatch block to facilitate the butting of the snatch block with the bottom side of the boom. Further means comprising a relief valve are provided with the hydraulic system to release the excess hydraulic fluid into the oil tank in order to stop the winding of the rope during lifting of the snatch block towards the boom and when the block is in contact with the boom. An overhoist protected snatch block system for use in a crane according to a preferred embodiment is herein described and illustrated in the accompanying drawins wherein!~ Fig.i shows the snatch block extended from the manual extension of the boom; Fig.2 shows the snatch block butted with the bottom portion of the manual extension of the boom; and Fig.3 shows the hydraulic circuit. Referring to the drawings particularly fig.i and fig.2 the snatch block system comprises a snatch block i consisting of side plates 2 having a pulls 3 provided therebetween rotatataly for facilitating the passing of rope 4 therethrough. A hook 5 is riveted with the snatch block 1 at the bottom end thereof. The snatch block i is moved up and down by winding and unwinding of the rope 4 with the help of a hydraulics: system provided in the crane. These features are? such known in the art and do not constitute features. Specifically, according to this invention top plate 6 is secured at the upper end of the snafu block 1 for facilitating the butting/contact (as shown in fig.2) of the snatch block with the manual extensic n 7 provided at. the distal end of the boom 8. Refere?nce is now made to fig.3 the hydraulic system as shown in fig. 3 is a conventional hydraulal system provided for the winding and unwinding of rope 4 during the operation of the crane. However according to this invention a relief valve 9 is providi in flow communication with the priority valve 1® of the hydraulic system so as to release the excess hydraulac I oil to the hydraulic oil tank 11 through the conveyiffc pipe 12 provided therewith,. During the operation of the crane when motor 13 is switched on the hydraulic oilj is pumped the lever assembly 14 provided for operation winch 15, Upon complete winding of the rope 4 the snatch block 1 is butted/comes in contact with the manual extension of the boom 8. After butting the snatch block i with the manual extension 7, the motor 13 still remain in switched-on position, but the physical rotatioh of the motor 13 is stopped but the oil is continuously fed into relief valve 9 and thus the oil pressure crosses the predetermined limit of the relief valve 9 ar»d vavle 9 is then opened and facilitate the supply of the oil to the oil tank 1.1 and the motor 13 is then ; stopped. Therefore after butting the snatch block i viith the manual extension 7 of the boom 8 the rope 4 is not further winded and thus the damage caused during the operation of the crane? is eleminated. WE CLAIM: 1. An overhoist protection apparatus of crane to protect snatch block comprising side plates (2) having a pulley (3) provided therebetween rotatably, a hook (5) being secured to the bottom end of said plates, characterised in that a top plate (6) which is fitted with the bottom surface of the manual extension (7) at the distal end of the boom (8) of the crane, relief valve (9) and priorty valve (10) are provided with the hydraulic circuit which releases the hydralic oil to the oil tank (11). 2. An overhoist protection apparatus of crane to protect snatch block substantially as herein described and illustrated.

Documents:

2262-del-1997-abstract.pdf

2262-del-1997-claims.pdf

2262-DEL-1997-Correspondence-Others-(06-01-2009).pdf

2262-del-1997-correspondence-others.pdf

2262-del-1997-correspondence-po.pdf

2262-del-1997-description (complete).pdf

2262-del-1997-drawings.pdf

2262-del-1997-form-1.pdf

2262-del-1997-form-13-(06-01-2009).pdf

2262-del-1997-form-19.pdf

2262-del-1997-form-2.pdf

2262-DEL-1997-Form-26-(06-01-2009).pdf

2262-del-1997-form-3.pdf

2262-del-1997-form-5.pdf

2262-del-1997-form-6.pdf

2262-del-1997-gpa.pdf