Patent ID: 7686717

Claim:
A tensioner for a traction drive, comprising: a housing defining a longitudinal axis and having a housing wall; a cylinder arranged in the housing at a distance to the housing wall to thereby define an interior space in surrounding relationship to the cylinder and at least partially containing hydraulic fluid; a piston received in the cylinder for movement in direction of the longitudinal axis and bounding a pressure chamber containing hydraulic fluid, said piston having a cylinder-distal end which is operatively connected to a spring-biased tension roller supported on a traction member; a leakage gap formed between the piston and the cylinder; a reservoir provided in an area of the leakage gap and containing hydraulic fluid to prevent ingress of air into the pressure chamber, when the traction drive is at a rest; and a one-way valve disposed between the pressure chamber and the interior space, wherein hydraulic fluid is able to flow from the interior space into the pressure chamber via the one-way valve, when the piston moves in one direction, and is able to escape from the pressure chamber via the leakage gap, when the piston moves in another direction.