| 摘要 |
707,962. Piston and piston rod packing. BOULTON PAUL AIRCRAFT, Ltd., and DOE. A. Nov. 7, 1950 [Nov. 7. 1949], No. 28416/49. Classes 122(1) and 122(5) In an hydraulic jack, suitable for external operation in the event of failure of the liquid pressure, the piston 8 and the piston rod 7 are sealed by composite packing rings comprising rubber elements 18 and 4 bonded in alternate relation to metal elements 12, 13, 17 and 2, 3 respectively and exposed to the pressure of the liquid so that the rubber elements are deformed into sealing contact with the cylinder 1 and the piston rod 7 respectively. but in the absence of liquid pressure the packing rings are a clearance fit in or on the cylinder and the piston rod. The packing rings for the piston rod are bonded by means of one of the rubber elements 4 to the cylinder end walls 6 and the piston packing rings are carried at each end of the piston between a recess 11 in the piston and a retaining plate 14 having holes 16 therein to permit access of liquid pressure to the back of the rings. The retaining plates may be formed integral with or secured to bosses movable in liquid-tight manner in bores formed in the piston faces so that the liquid pressure on the plates is unsupported to the extent of the sectional area of such bosses and acts to compress the packing rings axially and thereby radially expand the rubber elements into contact with the cylinder wall. Specification 655,522 is referred to. |
