Coupler for Coupling an Attachment to a Machine

Abstract

A coupler ( 1 ) for coupling an accessory ( 5 ) to an arm of a machine is disclosed. The coupler comprises: a structure ( 6 ) having first and second jaws ( 25, 26 ); first retention means ( 21 ) for locking a first pin ( 35 ) of an accessory in said first jaw; second retention means ( 28 ), for locking a second pin ( 36 ) of the accessory in said second jaw; and actuating means ( 12, 13, 14 ) for moving said first retention means between a first position, in which it locks said first pin in said first jaw, and a second position, in which it does not lock said first pin in said first jaw. The arrangement is such that, if said first retention means is in said first position, said second retention means locks said second pin in said second jaw and, if said first retention means is in said second position, said second retention means does not lock said second pin in said second jaw. The coupler also comprises restraining means ( 22 ) for restraining movement of said first retention means from said first to said second position in the event of a failure of said actuating means.

1 . A coupler for coupling an accessory to an arm of a machine, the coupler comprising:
 a structure having first and second jaws;   first retention means, for locking a first pin of an accessory in said first jaw;   second retention means, for locking a second pin of the accessory in said second jaw;   actuating means for moving said first retention means between a first position, in which it locks said first pin in said first jaw, and a second position, in which it does not lock said first pin in said first jaw, the arrangement being such that, if said first retention means is in said first position, said second retention means locks said second pin in said second jaw and, if said first retention means is in said second position, said second retention means does not lock said second pin in said second jaw; and   restraining means for restraining movement of said first retention means from said first to said second position in the event of a failure of said actuating means.   
     
     
         2 . A coupler according to  claim 1 , wherein said actuating means comprises a hydraulic cylinder and piston arrangement. 
     
     
         3 . A coupler according to  claim 1 , wherein said restraining means comprises spring means, the actuating means acting against the action of said spring means to move said first retention means from said first position to said second position. 
     
     
         4 . A coupler according to  claim 1 , wherein said first retention means is carried by a slide which is movable by said actuating means. 
     
     
         5 . A coupler according to  claim 4 , wherein said restraining means comprises spring means, the actuating means acting against the action of said spring means to move said first retention means from said first position to said second position and wherein said spring means has one end attached to said slide and an opposite end fast with said structure. 
     
     
         6 . A coupler according to  claim 4 , wherein said slide maintains said second retention means in a position to lock said second pin in said second jaw if said first retention means is in said first position. 
     
     
         7 . A coupler according to  claim 6 , wherein, if said first retention means is in said second position, said slide does not maintain said second retention means in a position to lock said second pin in said second jaw. 
     
     
         8 . A coupler according to  claim 7 , wherein said slide has a slot into which said second retention means can move if said first retention means is in said second position. 
     
     
         9 . A coupler according to  claim 1 , wherein said second retention means comprises a pivoted member which is provided with spring urging means for urging said member away from said second pin if said first retention member is in said second position. 
     
     
         10 . A coupler according to  claim 9 , wherein said spring urging means comprises coil spring means around a pivot axis of said pivoted member. 
     
     
         11 . A coupler according to  claim 1 , wherein said first retention means comprises a hook member. 
     
     
         12 . A coupler according to  claim 1 , wherein said second pin enters said second jaw in a first direction, substantially parallel to the direction in which said first retention means moves from said first to said second position, said first pin entering said first jaw in a second direction which is substantially perpendicular to said first direction. 
     
     
         13 . A coupler according to  claim 1 , including a locking arrangement for preventing said actuating means moving said first retention means to said second position unless a longitudinal axis of the coupler is disposed in a direction for that to occur. 
     
     
         14 . A coupler according to  claim 13 , wherein said direction is a vertical direction or up to a given angle either side of the vertical in use of the coupler. 
     
     
         15 . A coupler according to  claim 14 , wherein one of said jaws faces in a direction parallel to said longitudinal axis, the locking arrangement preventing said actuating means moving said first retention means to said second position unless said one of the jaws faces upwards or faces upwards at said given angle either side of the vertical in use of the coupler. 
     
     
         16 . A coupler according  claim 13 , wherein said locking arrangement comprises a member carrying first and second movable locking devices at least one of which is in a position to prevent said actuating means moving said first retention means to said second position unless said longitudinal axis is disposed in a direction for that to occur. 
     
     
         17 . A coupler according to  claim 16 , wherein said locking devices act on said first retention means. 
     
     
         18 . A coupler according to  claim 17 , wherein said first retention means is provided with first and second chambers, at least one of said locking devices being in engagement with said first retention means via a respective one of said chambers for preventing said actuating means moving said first retention means to said second position unless said longitudinal axis is disposed in a direction for that to occur. 
     
     
         19 . A coupler according to  claim 16 , wherein said locking devices are movable under gravity. 
     
     
         20 . A coupler according to  claim 16 , wherein at least one of said locking devices is movable in a bore of said member of the locking arrangement. 
     
     
         21 . A coupler according to  claim 16 , wherein said locking devices are ball bearings.