Safety lifting system for a mechanical excavator

Abstract

The present invention provides a lifting system for an excavator, comprising a movable linkage (e.g. a chain), an actuator adapted to be coupled to the linkage for displacement of the linkage thereof, an abutment member configured to limit the displacement of the linkage and a retaining assembly arranged to releasably retain a hook attached to the linkage. The actuator is operable to reversibly displace the linkage between a first position in which the hook is free from the assembly and a second position in which the hook is retained by the assembly. As a result, the linkage may be safely stowed to avoid harm or injury to an operative associated with the lifting system.

1 . A lifting system for an excavator, the system comprising:
 a movable linkage;   an actuator adapted to be coupled to the linkage for displacement of the linkage thereof;   an abutment member configured to limit the displacement of the linkage; and   a retaining assembly arranged to releasably retain a hook attached to the linkage,   wherein the actuator is operable to reversibly displace the linkage between a first position in which the hook is free from the assembly and a second position in which the hook is retained by the assembly.   
     
     
         2 . The lifting system of  claim 1 , wherein the retaining assembly comprises an automatic gripping mechanism for retaining the hook. 
     
     
         3 . The lifting system of  claim 2 , wherein the gripping mechanism comprises a pair of pivotable surfaces biased towards each other in order to grip the hook. 
     
     
         4 . The lifting system of  claim 3 , wherein the pivotable surfaces are in the form of a pair of spring-loaded paddles. 
     
     
         5 . The lifting system of  claim 2 , wherein the retaining assembly further comprises a hook ejection mechanism. 
     
     
         6 . The lifting system of  claim 5 , wherein the hook ejection mechanism comprises a biased plate including an aperture to enable the linkage to pass therethrough. 
     
     
         7 . The lifting system of  claim 6 , wherein the biased plate is spring-loaded. 
     
     
         8 . The lifting system of  claim 6 , wherein the aperture has a tapered edge to receive a reciprocally shaped neck of the hook. 
     
     
         9 . The lifting system of  claim 1 , wherein the abutment member is in the form of a piston block housing. 
     
     
         10 . The lifting system of  claim 9 , wherein the piston block housing comprises a bore to enable the linkage to pass therethrough. 
     
     
         11 . The lifting system of  claim 1 , further comprising an engaging member coupled to an end portion of the actuator, the engaging member being configured to engage with the abutment member when the hook is free from the assembly. 
     
     
         12 . The lifting system of  claim 11 , wherein the engaging member is in the form of a piston ram block. 
     
     
         13 . The lifting system of  claim 12 , wherein the abutment member comprises an abutment surface to inhibit movement of the piston ram block. 
     
     
         14 . The lifting system of  claim 11 , further comprising at least one guide rail for guiding the displacement of the engaging member. 
     
     
         15 . The lifting system of  claim 14 , wherein the engaging member comprises at least one laterally extending pin adapted to engage with the guide rail. 
     
     
         16 . The lifting system of  claim 1 , wherein the actuator is a hydraulic ram. 
     
     
         17 . An excavator comprising a lifting system according to  claim 1 .