Belt tensioner, part therefor and methods of making the same

摘要

A tensioner for a power transmission belt that is adapted to be operated in an endless path and a method of making the same are provided, the tensioner comprising a piston and cylinder unit having a cylinder member and a piston member disposed in the cylinder member, the cylinder member having a tapering chamber defining a substantially straight line tapering internal peripheral side wall of the cylinder member that extends substantially from one end thereof and to the other end thereof and carrying a rolling diaphragm for rolling against the tapering side wall throughout substantially the entire normal tensioning range of movement of the belt engaging unit of the tensioner relative to the support unit of the tensioner whereby the relative movement between the members changes the effective area of the rolling diaphragm and, thus, the tensioning force on the belt engaging unit in a substantially linear manner throughout the normal tensioning range of movement of the belt engaging unit relative to the support unit, the diaphragm having its outer periphery secured to the cylinder member intermediate the opposed ends thereof whereby the tapering chamber extends from the opposed sides of the diaphragm.