Patent ID: 8002108

Claim:
A tensioning mechanism for a circulating element, comprising: a main body; a first chamber is formed in the main body; a piston in the first chamber, which piston can be displaced within the first chamber by a pressurized fluid; a piston rod connected to, and driven by the piston; a support, the main body being securely mounted on the support; a head piece secured to the piston rod and which can be moved by the piston rod into contact with the circulating element; a lock mechanism in the main body and separate from the first chamber in which the piston is displaceable, the lock mechanism being usable to lock the piston rod in a selected position, which lock mechanism is controllable using pressurized fluid; at least one second chamber, in the main body and separate from the first chamber in which the piston is displaceable, the lock mechanism being positioned in the second chamber which is pressurizable with the pressurized fluid to control the lock mechanism for releasably locking the piston rod in a selected position; an opening, in the main body and through which the piston rod passes, wherein the second chamber is arranged on a first side of the opening; and an abutment which is securely attached to the main body, a second side of the opening, which is opposite the first side of the opening, is being formed by the abutment.