Locking device for a quick coupler

Abstract

A wedge locking element ( 10 ) for a locking device of a quick coupler A for coupling the pin P 2 of an attachment to earth working machinery. The wedge locking element ( 10 ) has a sloping wedge surface ( 13 ). Projecting from the wedge surface ( 13 ) is an engagement surface ( 12 ) with which the attachment pin P 2 can engage but not apply any substantial driving force to the wedge locking element ( 10 ) in the event of failure of a force maintaining the wedge locking element ( 10 ) in a position where the pin P 2 is retained with the coupler A. The pin engagement surface ( 12 ) lies in a plane that is substantially in line with the direction in which the locking element ( 10 ) is, in use, moved by the driving force.

1 . A quick coupler for coupling the pin of an attachment to earth working machinery, the coupler comprising a locking device comprising:
 a wedge locking element slidingly retained in the quick coupler and configured to move in a linear direction for coupling the pin of an attachment to said earth working machinery, the wedge locking element including a sloping wedge surface, wherein projecting from the wedge surface is a pin engagement surface located at and forming a distal leading part of the wedge locking element, wherein the pin engagement surface is substantially planar and lies in a plane that is substantially in line with the linear direction in which the wedge locking element and pin engagement surface are, in use, moved by a driving force, the pin engagement surface remaining in substantial alignment with said linear direction during movement of the wedge locking element, wherein the attachment pin which engages with said pin engagement surface does not apply any substantial loading to the wedge locking element in the event of failure of the driving force maintaining the wedge locking element in a position whereby the pin is wedge couped by the wedge surface to the coupler, wherein an angle between the sloping wedge surface and the pin engagement surface is obtuse.