A device forming a coupler including a coupler, or quick-release fastener for attachment to a construction machine, such as a mechanical shovel; a connection device for attachment to a tool, such as a bucket; coupling means to couple the quick-release fastener to the connection device; and locking means to lock the coupling; the connection device including at least one trunnion and preferably two trunnions parallel with one another, the coupler including a base body defining a rear receiving cavity for at least one of the trunnions, characterised in that the coupler includes a lever mounted to pivot between a closed position holding one of the trunnions in the rear receiving cavity and an open position in which it does not hold the trunnion, the locking means being arranged to block or prevent rotation of the lever in the closed position.

A device forming a coupler including a coupler, or quick-release fastener, and a connection device; the connection device including at least one, preferably two, trunnions, front and back respectively; the coupler including a base body from which, on a front side, at least one hook originates having a region forming a rod and a region forming a hook head extending upwards from the region forming a rod to form, with the base body, at least one receiving cavity for the trunnion or trunnions, having an opening at the top extending between the base body and the region forming the respective head of the respective hook. When the trunnion or trunnions in the receiving cavity comes into contact with the region forming a rod, the region forming a head extends upwards beyond the centre of the circular section of the trunnion.

A device forming a coupler includes a coupler, or quick-release fastener, for attachment to a construction machine, such as a mechanical shovel; a connection device for attachment to a tool, such as a bucket; coupling means to couple the quick-release fastener to the connection device; and locking means to lock the coupling. The connection device includes at least one trunnion and preferably two trunnions parallel with one another, the coupler including a bottom body defining a rear receiving cavity for at least one of the trunnions, characterised in that the coupler includes a lever mounted to pivot between a closed position holding one of the trunnions in the rear receiving cavity and an open position in which it does not hold the trunnion, the locking means being arranged to block or prevent rotation of the lever in the closed position.

A wedge locking element (10) for a locking device of a quick coupler A for coupling the pin P2 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 P2 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 P2 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.