GB1448841A - Joint assemblies - Google Patents

Abstract

1448841 Pipe couplings; valves CATERPILLAR TRACTOR CO 24 Aug 1973 [25 Aug 1972] 40238/73 Headings F2G and F2V [Also in Divisions E1 and B8] In a clamshell bucket assembly (Fig. 2) of a hydraulic excavating machine, a joint assembly 24 includes a tubular member 50 (Fig. 7) having a longitudinal bore 52, a lateral passage 60 through the body of the member 50, a longitudinal shaft 40 disposed within the bore 52 with part of its outer surface in slidable contact with the inner surface of the member 50, the shaft 40 being rotatable about its longitudinal axis within the member 50, a passage 66 in the shaft body, and an annular passage 68 defined between the inner surface of the member 50 and the outer surface of the shaft 40 and providing continuous communication between the passage 60 and the passage 66 irrespective of the position of rotation of the shaft 40 relative to the member 50. The member 50 is disposed in a frame 38 which allows the member 50 a degree of longitudinal movement although rotary movement is limited by a pair of external longitudinal ears on the member 50 engaging an internal rib defined by the frame 38. The entire weight of the shaft 40 is supported by the frame 38 at an annular shoulder 48. A second lateral passage 62 in the member 50 communicates with a second passage 64 in the shaft 40 by means of an annular passage 70. The passages 64, 66 convey fluid to a hydraulic cylinder 26 to operate the jaws 86, 88 of a bucket 28. Valve means 164 (Figs. 7, 8) are fixed to the head end of the cylinder 26 and contain a valve spool 168 which is biased in the position shown (Fig. 8) by means of a spring 180. In this position fluid pressure in passage 64 is transferred to a pipe 172 and thence to the rod end of cylinder 26, thus raising piston rod 114 and closing the jaws 86, 88. To open the jaws, fluid pressure is applied to passage 66 and thence to the head end of the cylinder 26. This pressure is sufficient to shift the valve spool 168 to the right (in Fig. 8) by means of passage 182 and chamber 181, to allow fluid expelled from the rod end of cylinder 26 to flow into passages 172, 176, 178 and thence the head end of cylinder 26. Thus the pressure in the latter is increased to speed opening of the bucket. Extended portions of the jaws 86, 88 comprise stop members 200, 202 having end portions with flat surfaces 204, 206, these surfaces contacting each other across the full flat surface of each to limit opening movement of the jaws. Powered rotation of the bucket assembly may be effected by means of a hydraulic motor 222 (Fig. 7) which drives a chain 224 and thence a sprocket 46 secured to shaft 40. Fluid pressure is applied to passages 60, 62 in the tubular member 50 by means of hoses 132, 130 coupled as described in Specification 1,448,842. The bucket assembly is fitted with a cushioned stop 210 to limit pivoting as described in Specification 1,448,843.