Abstract: A tensioner for a traction drive includes a cylinder arranged in a housing at a distance to a housing wall to thereby define an interior space which contains hydraulic fluid. A piston is received in the cylinder for back-and-forth movement and bounds a pressure chamber containing hydraulic fluid. The piston has a cylinder-distal end which is operatively connected to a spring-biased tension roller supported on a traction member. Formed between the piston and the cylinder is a leakage gap, and a reservoir for hydraulic fluid is provided in an area of the leakage gap to prevent ingress of air into the pressure chamber, when the traction drive is at a rest.

Abstract: A tensioner for a traction drive includes a cylinder arranged in a housing at a distance to a housing wall to thereby define an interior space which contains hydraulic fluid. A piston is received in the cylinder for back-and-forth movement and bounds a pressure chamber containing hydraulic fluid. The piston has a cylinder-distal end which is operatively connected to a spring-biased tension roller supported on a traction member. Formed between the piston and the cylinder is a leakage gap, and a reservoir for hydraulic fluid is provided in an area of the leakage gap to prevent ingress of air into the pressure chamber, when the traction drive is at a rest.

Abstract: A hydraulic tensioner for a traction drive is provided having a spring-loaded piston (8) guided for longitudinal motion in a cylinder (6), in which tensioner, a piston motion causes an exchange of volume between a high pressure chamber (9) arranged in the cylinder (8) and a hollow space (4) which is partly filled with hydraulic medium, and, depending on a direction of motion of the piston (8), said exchange of volume can take place through a one-way valve (15), the tensioner further comprising a bellows seal (18) which is arranged between the piston (8) or the piston housing (10) at one end, and the outer housing (2) at a second end and follows the longitudinal motion of the piston (8) while bearing under pre-stress against the outer housing (2) and against the radially inward stepped piston housing (10).

Abstract: Concentrated sulphuric acid aqueous solutions, stably clear through the time, are obtained starting from diluted sulphuric acid aqueous solutions containing Mg and possibly other impurities such as Fe, Al, Cr, V and Mn, by evaporation concentration. The process is characterized in that, before filtering, the slurry obtained by evaporation concentration, is cooled down to 10.degree.-25.degree. C. and maintained at this temperature for not less than 12 hours.