Belt tensioner for wide belt sanding machines

Claim 1

A belt tensioner for sanding machines and the like comprising in combination: A. a pair of superimposed rigid members movable towards and away from one another, one of said members having a hole therethrough; B. a piston and cylinder type fluid pressure motor connecting said superimposed members and comprising 1. a cylinder consisting of a straight piece of tube stock having a uniform wall thickness from end to end and having one end portion thereof received in the hole in said one rigid member, 2. a collar secured to said end portion of the cylinder, said collar having a flange portion projecting beyond the outer diameter of the cylinder and overlying the portion of said one rigid member bounding the hole therein and secured to said one rigid member whereby the cylinder is fixed to said one rigid member, said collar having a bore smaller in diameter than the bore of the cylinder and coaxial therewith, 3. a uniform diameter piston rod passing slidably through the bore in said collar and having an outer end portion which spans the distance between said superimposed rigid members and an inner end portion inside the cylinder, 4. means securing the outer end portion of the piston rod to the other one of said rigid members, 5. a piston fixed to the inner end portion of the piston rod and having sealing engagement with the bore of the cylinder, 6. a closure disc snugly fitted into the other end of the cylinder to close the same, 7. a pair of snap rings seated in annular grooves in the cylinder bore at opposite sides of said closure disc to secure the same in place, 8. means projecting from the side of the piston remote from the piston rod to collide with the closure disc and define the limit of retraction of the piston into the cylinder at a point spaced from the closure disc, 9. a snap ring seated in a groove encircling the piston rod and projecting radially beyond the cylindrical surface of the piston rod to collide with the portion of said collar bounding the bore therein to limit projection of the piston rod out of the cylinder, and 10. ports through the wall of the cylinder for the passage of pressure fluid into and out of the cylinder, said ports being spaced apart axially of the cylinder and so located as to be at opposite sides of the piston in all positions thereof.