Tensioning device with a single securing ring

A tensioning device comprising a tensioner housing, a tensioning piston that is guided displaceably in a piston bore of the tensioner housing and has a piston skirt, a transport securing device for fastening the tensioning piston in the tensioner housing, an adjustment device for incrementally adjusting and limiting the working range of the tensioning piston, and an end position securing device for loss-proof arrangement of the tensioning piston in the piston bore,

• wherein the transport securing device, the adjustment device and the end position securing device jointly comprise a single securing ring for fastening the tensioning piston in the tensioner housing, for incrementally adjusting and limiting the working range of the tensioning piston and for loss-proof arrangement of the tensioning piston in the piston bore,
• the adjustment device comprises an adjusting profile formed on the piston skirt of the tensioning piston and having a first plurality of grooves, on which the securing ring is arranged in operation for adjusting the working area of the tensioning piston, and comprises an adjusting groove formed in the piston bore, the adjusting profile being arranged on the distal end of the tensioning piston, and
• the transport securing device has a transport securing profile formed on the piston skirt of the tensioning piston, in which the securing ring is arranged in a transport securing device position, and has a transport securing groove at the tensioning-side end of the piston bore, and
• wherein the piston skirt at the tensioning-side end of the tensioning piston is configured as a smooth profile-free guide region, wherein the smooth profile-free guide region extends between the tensioning-side end of the tensioning piston and the adjusting profile formed on the piston skirt over at least 35% of the axial length of the tensioning piston, and
• the piston bore at the tensioning-side end of the tensioner housing is configured as a smooth profile-free bore region, wherein the smooth profile-free bore region extends between the transport securing groove at the tensioning-side end of the piston bore and the adjusting groove, the distance between the tensioning-side opening of the piston bore in the tensioner housing and the adjusting groove formed in the piston bore over at least 25% of the axial length of the tensioning piston, wherein guiding of the smooth profile-free guide region of the tensioning piston along the smooth profile-free bore region of the tensioner housing allows low-friction guidance of the tensioning piston in the cylinder bore and ensures that the adjusting profile formed on the piston skirt of the tensioning piston is protected by the tensioner housing over most of the operating conditions.