GB1000500A - Hydraulic valve - Google Patents

Abstract

1,000,500. Valves. NEW YORK AIR BRAKE CO. March 23, 1964 [June 20, 1963], No. 12133/64. Heading F2V. A valve comprises a housing 11 containing a bore 14 intersected by three spaced chambers, a supply chamber 19, exhaust chamber 22 and an intermediate motor chamber 21, a valve member 26 movable in the bore 14 containing an internal passage 34 intersected by ports 39 and 41, the valve 26 having a first position in which the port 41 registers with the motor chamber 21, a second position in which the port 39 registers with the supply chamber 19 and the port 41 with the motor chamber 21, and a third position in which the port 39 registers with the motor chamber 21 and the port 41 with exhaust chamber 22, a check valve seat 42 encircling the internal passage and located between the ports 39 and 41, a check valve head 43 reciprocable in the passage 34 and co-operating with the seat 42 for controlling flow from the port 39 to the port 41, reaction surfaces on the head 43 subject to the pressure in the port 41, i.e. the annular area defined by the difference in diameter of the seat 42 and the outside diameter of the head 43, and the end wall area of the bore 47, for developing forces that urge the head 43 in both directions, the surfaces being so proportioned that the force urging the head in the opening direction does not exceed the force urging the head in the closing direction, means, e.g. a sleeve 45, defining a vent chamber within the valve member 26 which communicates with the exhaust chamber 22 at least when the valve member is in the first position, a relief passage 49 connecting the vent chamber with the port 41, and a relief valve 51 normally preventing flow from the port 41 to the vent chamber through the passage 49 but arranged to open that passage upon occurrence of a predetermined pressure in the port 41. The valve member 26 further comprises a bore 33 having a seat 42, the valve 43 not being provided, and ports 37 and 38 which can be operatively connected with further exhaust, motor and supply chambers 15, 16, 17, respectively, in the control of a double-acting piston motor 59. In the first position of the valve, shown in the drawing, the pump 55 delivers fluid from the reservoir 56 past a relief valve 25 and through the grooves 27 and 28 to the exhaust 13 and reservoir 56. Excessive load pressure in the line 58 and chamber 21 is relieved by valve 51. Rightward movement of valve 26 allows fluid to be delivered to the motor 59 through chamber 17, ports 38, 37 and chamber 16. Exhaust fluid in the chamber 21 acts on valve 43, against the action of spring 54, to pass to exhaust chamber 22. Leftward movement of valve 26 allows fluid to be delivered to motor 59 past valve 43 by overcoming the combined pressure of spring 54 and the load pressure in chamber 21 and to be exhausted through chamber 16, ports 37 and 38, and chamber 17. Specification 892,036 is referred to.