Patent ID: 8287490

Claim:
In combination with a needle-less single-use injector with a housing ( 10 ) comprising at least one press rod ( 21 ), a cylinder/piston unit ( 100 ), a piston actuating plunger ( 60 ) having a collar surface ( 75 ), a triggering unit ( 80 ) and a pre-tensioned spring energy store ( 50 ), the triggering unit ( 80 ) initially interlocking the pre-tensioned spring energy store ( 50 ) by means of the at least one press rod ( 21 ), the at least one press rod ( 21 ) is slidably moveable and is displaceable, on triggering, by means of the spring energy store ( 50 ) and the piston actuating plunger ( 60 ), along at least one triggering element ( 82 ) of the triggering unit ( 80 ) and, the triggering unit ( 82 ) having an inner wall ( 59 ), the at least one press rod ( 21 ) having an abutment surface ( 24 ) in slidable contacting and displaceable relationship on triggering with the inner wall ( 59 ) to form a mutually facing pairing and a support surface ( 23 ) in slidable temporary contacting relationship on triggering with the collar surface ( 75 ) to form a mutually facing pairing, after triggering of the triggering unit ( 80 ), the spring energy store ( 50 ) displacing the at least one press rod ( 21 ) and actuating the cylinder/piston unit ( 100 ) by means of the piston actuating plunger ( 60 ), the improvement which comprises: when loaded by the pre-tensioned spring energy store ( 50 ), the pairing of the mutually facing inner wall ( 59 ) of the triggering element ( 82 ) and the abutment surface ( 24 ) of the at least one press rod ( 21 ) is provided, with at least in certain regions, a higher coefficient of sliding friction than the pairing of the mutually facing collar surface ( 75 ) of the piston actuating plunger ( 60 ) and the support surface ( 23 ) of the at least one press rod ( 21 ).