Safety device for quick-fit attachments used for fitting a tool to the end of the arm of a hydraulic excavator

Abstract

Safety device for quick-fit attachments comprising two parts ( 1 ) and ( 2 ), of which one ( 1 ) is borne by the arm of the digger while the other ( 2 ) is secured to the tool (for example a dipper), said first part having a cradle ( 3 ) formed by a pair of hooks, able to grasp hold of a shaft ( 4 ) belonging to the second part in order to raise the tool and allow the first part to pivot so that the two parts can be pressed against one another to allow for locking, characterized in that each part of the attachment has a member ( 7 ) able to collaborate with a member ( 8 ) of the other part if the weight of the tool being picked up does not exceed the capacity of the digger, collaboration being impossible when such is not the case, so that the first part is unable to be pressed against the second and locking is prevented.

1 . Safety device for quick-fit attachments, comprising two parts ( 1 ) and ( 2 ), of which one ( 1 ) is borne by the arm of the machine while the other ( 2 ) is secured to the tool (for example a dipper), the said first part having a cradle ( 3 ) formed by a pair of hooks which is capable of catching hold of a shaft ( 4 ) belonging to the second part in order to raise the tool and allow the first part to pivot in order to press the two parts against one another to allow locking, characterised in that each part of the attachment has a member ( 7  or  9 ) which is capable of cooperating with a member ( 8  or  10 ) belonging to the other part if the weight of the tool, when loaded, does not exceed the capacity of the machine, said cooperation being impossible if this is not the case, so as to resist the pressing of the first part onto the second and to prevent locking. 
     
     
         2 . Device according to  claim 1 , characterised in that, according to one mode of embodiment, one of the members is constituted by a finger ( 7 ) which is capable of penetrating into a slot ( 8 ) in the other part, safety being ensured by judiciously dimensioning the slot and finger according to the size of the machine and of the tool in such a way that the finger belonging to a small machine cannot penetrate into the slot belonging to a tool whose weight, when loaded, exceeds the capabilities of the said machine. 
     
     
         3 . Device according to  claim 1 , characterised in that one of the members is constituted by a projecting part ( 9 ) which is capable of penetrating into a recess ( 10 ) in the other part, safety being ensured by judiciously positioning the edge ( 9   a ) of the said projection in relation to the edge ( 10   a ) of the said recess in such a way that the projection belonging to a small machine cannot penetrate into the recess belonging to a tool whose weight, when loaded, exceeds the capabilities of the said machine.