GB682037A - Hydraulic crane - Google Patents

Abstract

682,037. Load-handling apparatus. SUNDIN, E. O. Nov. 2, 1950. No. 26760/50. Addition to 654,418. Classes 78 (ii), 78 (iii) and 78 (iv). In a hydraulic lifting jack according to the parent Specification, a control valve for the supply of fluid to the lifting cylinder and the two cylinders for swinging the lever 4<SP>1</SP> of the jack consists of a body which is rotatable and axially displaceable in a housing and is coupled to a control lever by means of a control rod, the control lever being mounted for pivotal adjustment in two vertical planes at right angles to each other. The valve body consists of a sleeve 27 which is secured by a pin 30 to the control rod 13. A control lever 18 is pivoted at 20 to each end of the rod 13 and has an extension which is connected by a link 16 to a collar 14 rotatable on the housing 1. The sleeve 27 consists of a thick portion divided by a peripheral groove 31, and a thin.portion, of the same external diameter so as to leave an annular space 55 between the sleeve and rod 13. An axial passage 26 in rod 13 connects space 55 with the space to the left of the sleeve. An axial passage 28 is also cut in the thick portion of the sleeve. The thin portion of the sleeve is perforated as set out below. A pin 29 in the rod 13 works in an opening 10 in the right of the housing which is sealed off from the valve proper. In operation lever 18 is moved to place pin 29 in one of the recesses c, d, e or f, or between the upper row of recesses and the lower recess f. In the latter or neutral position oil from a pump flows through a conduit 13<SP>1</SP> to inlet 24, through ports 3 and an opening in the thin sleeve portion, along space 55, through port 8 and back to the pump via conduit 38. In each of position c, d and e the space 55 is eut off from the opening 3. In position d fluid flows through groove 31, port 4, a non-return valve 32, and conduit 34 to the cylinder 1<SP>1</SP> thus raising lever 4<SP>1</SP>. In positions c and e fluid flows through port 2 along passage 28, and through groove 31 to one or other of the ports 5 which are connected by conduits 35, 36 to the swinging cylinders 14<SP>1</SP>. As the piston 14<SP>11</SP> of one cylinder 14<SP>1</SP> is extended the other piston 14<SP>11</SP> retracts and fluid passes through the other port 5 and either directly through a hole in the thin sleeve portion, or through axial passage 26, to the space 55 and hence back to the pump. In position f the oil from the pump is again by-passed through port 3, space 55 and port 8, and, in addition, fluid is allowed to escape from cylinder 1<SP>1</SP> via conduit 34, a pressure reducing valve 40, conduit 37, port 6, and a hole in the thin sleeve portion, so lowering lever 41.