GB1504545A - Hydraulic reciprocating motor - Google Patents

Abstract

1504545 Hydraulic reciprocating motors INGERSOLL - RAND CO 5 Nov 1975 [18 Dec 1974] 45907/75 Heading F1A [Also in Division B4] In a hydraulic reciprocating motor for driving a rock drill breaker 12 and comprising a piston 46 having alternately pressurized surfaces 50, 52 and a shoulder 54 movable into and out of a cushion chamber 40, the resulting changes in the pressure of liquid in the cushion chamber 40 causes the reversal of a valve 56 controlling the pressurization of the surfaces 50, 52. As shown the valve 56 is a sleeve which also acts as the working cylinder for the piston 46, but in a further embodiment, Figs. 6 and 7 (not shown), the valve is a spool (100). In the position of the motor shown liquid supplied through passages 22, 26, 28 to a chamber 30 enters the sleeve 56 through ports 60 and acts on the lower surface 50. Piston 46 thus moves upwardly resulting in a pressure rise in the cushion chamber 40 due to the entry of the shoulder 54 thereinto. The cushion chamber pressure is applied to the upper end of the valve sleeve 56 through a ring of pins 62 slidable in bores in a retainer 66, the bores being in communication with the cushion chamber 40 through ports 64. When the force applied to the valve via the pins 62 exceeds the force due to the supply pressure acting on a shoulder 70 and the exhaust pressure acting on a shoulder 74, the valve is displaced downwardly. Thus the piston reverses since the ports 60 align with an annular chamber 86 connected by passages 32, 36, 38 to exhaust and the upper piston surface 52 is pressurized through ports 58 now in communication with chamber 30. The downward stroke continues until the valve returns due to the forces acting on the shoulders 70, 74 exceeding the force due to cushion chamber pressure acting on the pins 62.