GB1202947A - Hydraulic shearing machine - Google Patents

Abstract

1,202,947. Shearing. HILL & GILBERT (HYDRAULIC DIVISION) Ltd. 1 May, 1969 [2 May, 1968], No. 20752/68. Heading B3W. An hydraulic shear in which the hydraulic fluid supply to the hydraulic cylinder and piston assembly 17 which moves shear jaw 18 about pivot 19 is controlled by an electrical solenoidoperated distribution valve 16 which is actuated by press-button control to interrupt the travel of the shear jaw 18. Solenoids (21) and (22) (Fig. 2, not shown) act on respective ends of the valve to cause the jaw 18 to be moved downwards and upwards respectively. When neither solenoid is actuated a spring-centred spool (not shown) urges the valve to a neutral condition in which oil is returned to the storage tank 13 and the jaw remains in the position it had reached before its travel was interrupted. If the arrangement is such that the operator must continually press the relevant button to keep the jaw moving a limit switch 30 actuated by the jaw 18 or a part movable therewith is provided for preventing the operator moving the jaw 18 too far in the downward direction. For automatic operation a further press button 25 is provided which brings limit switches 27, 28 into circuit to de-energize solenoids (22) and (21) and energize solenoids (21) and (22) respectively. The limit switches 27, 28 are actuated by the jaw 18 or a part movable therewith at the limits of its upward and downward movement respectively. The automatic control can be overidden during downward travel and reversed by the operator pressing button 29 which causes solenoid 21 to be de-energized and solenoid 22 to be energized. When the jaw operates limit switch 27 automatic working will start again. The stroke of the jaw 18 is variable by moving the switches 27, 28. Alternatively the speed of the stroke may be varied, while the stroke remains the same, by varying the supply of fuel to an engine driving a pump 12 moving oil from the tank 13 to valve 16.