GB581062A - Improvements in or relating to bearings - Google Patents

Abstract

581,062. Bearings. AUTOMOTIVE PRODUCTS CO., Ltd., and FOSTER, S. Oct. 6, 1944, No. 19238. [Class 12 (i)] A bearing in which a bearing member of substantially cylindrical operative surface cooperates with an axially slidable shaft or a rotary shaft is formed with a pressure recess fed with pressure fluid and with a relief recess open to a discharge passage, the two recesses being arranged in circumferential alignment separated by an area (or land) on which the shaft rests when there is no pressure fluid but from which the shaft is moved slightly when pressure fluid is supplied, the land then acting as a throttle to cause different pressures in the pressure recess and relief recess whereby the radial load on the shaft is taken up by the fluid pressure in the pressure recess. The invention is applicable to oleo-pneumatic telescopic struts of aircraft undercarriages to prevent jamming by side thrust. As shown in Figs. 1 and 2, a tubular housing 13 has mounted therein a bearing member 12 which supports the slidable or rotary shaft 10 by pressure fluid admitted to a pressure recess 25 on the inner periphery of the bearing member 12, the fluid passing to a relief recess 26 through the throttling clearance below ribs 27, 28 which separate the pressure recess from the relief recess so that different pressures are set up in the two recesses whereby the radial load on the shaft, acting in the direction 11, is taken up by the fluid pressure in the pressure recess 25. The pressure fluid is admitted from an inlet connection 20 through an external groove 18 on the bearing member 12 and ports 30 leading to the pressure recess; the groove 18 is enclosed by the tubular housing 13. The relief recess communicates with a drainage connection 21 in a similar manner through ports and an enclosed external groove 19. To maintain the shaft centralized the relief recess 26 is provided with a rib 29, but this has openings therethrough to allow free communication so that no throttling effect is set up at this point. The shaft is automatically maintained in position with load variation since any slight change in clearance at the ribs 27, 28 causes a stabilizing change in the pressure conditions. The bearing member shown in developed view in Fig. 5 has an internal land 36 of rectangular shape located within the pressure recess 35 to take the weight of the shaft when the pressure fluid is not in operation. The pressure recess 35 is bounded by a rectangular throttling land 37 and the relief recess 26 is circumferentially continuous by reason of connecting grooves 38 provided adjacent to the axial ends of the rectangular land 37. Fig. 7 shows the application to an oleo-pneumatic strut comprising a piston plunger 46 working in an oil cylinder 45, the piston having an internal piston 48 below which air is confined. The piston plunger 46 has a head 51 with a restricted passage therethrough by which oil can pass from upper space 52 to a space 50 within the piston plunger and to the annular surrounding space 62. The lower portion of the cylinder as shown at the right hand side of Fig. 7 is formed with two pressure recesses 25b, 25c to take side thrust in the direction of arrows 83, 84 and with a relief recess 26a. When the piston plunger 46 is forced upwards pressure is set up in the upper oil space 52, and this passes by a non-return valve 59 to pipe 60 communicating with two control valves 71, 72 and passes thence by pipes 79, 80, respectively, to the pressure recesses 25b, 25c. With side thrust in the direction of arrow 83 the clearance at rib 28a will be larger than at rib 27a, so that the pressure in pressure recess 25c will be lower than that in pressure recess 25b, and accordingly the pressure in pipe 80, space 77 of control valve 72, and pipe 82 will be less than the pressure in the corresponding pipe 79, space 77 of control valve 71, and pipe 81. The plunger 74 of control valve 72 will accordingly be closed by the higher pressure applied through pipe 81, so that pressure to the pipe 80 and pressure recess 25c will be cut off. The drainage from relief recess 26a passes by pipe 65 and non- return valve 67 to the annular surround space 62 of the oil cylinder 45. Similar actions arise if the piston plunger 46 is moved downwards, the oil pressure then being developed in the space 62 and passing by non-return valve 64 to the pipe 60, while the drainage passes by non-return valve 66 to the upper oil space 52. According to the Provisional Specification the bearing member 12 may be tiltably supported in the housing 13 with rubber sealing rings at the middle and ends.