Hydraulic jacks

Hydraulic jack with incorporated end-of-stroke damping device in which the piston is provided with at least one first damping component presenting a male element cooperating, at one of the ends of stroke, with a second damping component constituted by a ring floatingly mounted within a seating provided in the jack cylinder, said seating making possible radial wobbling of said ring, while the inner surface of said ring defines with the outer surface of said male element an annular clearance of variable section for the throttling of the hydraulic fluid, which hydraulic fluid, in the course of end-of-stroke damping, leaks from an annular chamber of variable volume, or damping chamber, delimited, in the axial direction, by an annular radial surface of said ring and by the opposed annular radial surface of the first component, said seating also making possible limited axial wobbling of said ring;

• said ring being hollowed out by through-going passages for re-supply of said damping chamber, said passages being hollowed out substantially parallel to the axis of the jack;
• and, in the damping condition, said passages are obturated, as a result of axial displacement of the ring, so as to isolate the damping chamber and render same independent of the remainder of the capacity of the jack, while, on return of the piston in the opposite direction after damping, said passages are freed so as to put the damping chamber into communication with the remainder of the capacity of the jack with the object of re-supplying said chamber with hydraulic fluid.