Patent ID: 7186195

Claim:
A tensioner ( 1 ) for endless driving elements, comprising: a tensioning piston ( 3 ) provided with locking means ( 8 , 9 ); and a locking piston ( 4 ) which is adapted to move between an arresting position engaged with said locking means ( 8 , 9 ) to arrest the movement of said tensioning piston ( 3 ) and a release position disengaged from said locking means ( 8 , 9 ) to release the movement of said tensioning piston ( 3 ), the locking piston ( 4 ) having an operating section ( 15 ) causing the locking piston ( 4 ) to move to the arresting position and to the release position, and a locking area ( 30 , 33 ) used for engagement with the locking means ( 8 , 9 ) of the tensioning piston ( 3 ) and arranged separately from the operating section ( 15 ), the locking area ( 30 , 33 ) of the locking piston ( 4 ) being designed such that a hydraulic force balance is caused wherein the locking area is provided in the form of a locking opening ( 30 ) in a locking plunger ( 16 ) which extends away from the operating section ( 15 ), and at least a portion of the locking means ( 8 , 9 ) of the tensioning piston ( 3 ) extending through the locking opening ( 30 ).