GB953315A - Self-adjusting packing gland structure for a fluid actuated piston and cylinder assembly - Google Patents

Abstract

953,315. Packings. G. H. TREVOR. April 27, 1960 [April 28, 1959], No. 3000/59. Heading F2B. A gland structure for a reciprocating shaft 5, Fig. 1, is provided with a gland ring 7 which, together with a bearing bush 6, is mounted in a chamber 1A in surrounding relation to the shaft, the gland ring having such an outside diameter as to allow lateral movement in the chamber and therefore self-adjustment of the ring in accordance with wear of the bush, flat upper and lower surfaces and an annular groove 18 in its upper surface receiving a fluid-energized packing ring 16 for sealing engagement with the opposed end face of the chamber (when the gland ring is above the bearing bush) or the opposed end face of the bearing bush (when the gland ring is below the bearing bush). The gland is shown applied to the reciprocating piston 5 of a fluid pressure motor formed with cylinder ends 1, 2, either or both of which is fitted with the gland structure where the piston-rod 5 passes through them and is there guided by the bushing 6 which is a press-fit in a bore 1A in the corresponding cylinder end 1. In the example shown, the gland ring 7 is disposed between the bushing 6 and an end cover cap 23 with radial clearance 8 in the chamber 1A to allow lateral movement of the ring as the inclination of the shaft 5 in the bush 6 varies with wear of the latter. The ring 7 may either slidably engage the plane end faces of the bushing 6 and end cover cap 23 or it may be urged into sealing contact with the cover cap 23 by a coil spring 11, Fig. 3, or plate spring 12, Fig. 4. The sealing ring 16 in the groove 18 may be of U-shape and arranged so that pressure fluid reaching it via channels 14 in the periphery of the bushing 6 and the space 8 around the ring 7 increases the sealing effect of the ring 16. This effect may be facilitated by providing channels in the upper surface of the ring 7 to permit free flow of fluid to the ring 16. The modified gland ring shown in Fig. 3, in addition to being urged against the end cover by a spring 11, has three recesses housing sealing rings 20 engaging the piston-rod 5, two of which are vented at 21 to prevent pressure lock. The further modified ring shown in Fig. 4 is formed of two parts 37, 38 and houses either the usual split-ring packing or V-shaped packing elements which are compressed by a spring. In yet another modification, the gland ring 7 is positioned below the bushing 6 and held in place at its lower end by a retaining ring having lugs engaging in grooves in the gland structure. In the case of hydraulic motors using hydraulic fluid, channels 19, Fig. 1, connected between the channels 14 and piston-rod 5 provide for support movement of the fluid as the latter reciprocates to generate turbulence in the fluid disposed in the clearance 8 and between the ring 7 and end cap 23 to prevent this fluid drying out.