GB725288A - Improvements in or relating to hydraulic control valves - Google Patents

Abstract

725,288. Valves. INTERNATIONAL HARVESTER CO. OF GREAT BRITAIN, Ltd. Jan. 16, 1953, No. 1343/53. Class 135. A hydraulic control valve for the selective operation of two or more hydraulic motors or groups of motors comprises a valve body 1 with a cylindrical bore 4 ports in the wall of which lead to the separate motors or groups of motors, and a valve plunger 11 in the bore, adapted on angular movement about its axis to selectively control ports for the operation of one or more of the motors and on axial movement between two extreme positions to control the flow of hydraulic fluid to and from the said ports and through a by-pass passage for effecting movement of the selected motor or motors in either direction under power, for hydraulically locking the same in adjusted position and for permitting a " floating " movement of the selector motor or motors under gravity. The valve is particularly applicable to the control of the front and rear implements of an agricultural tractor. As shown, the bore 4 has two radial ports 30, 31 spaced at 90 degrees leading to two different motors and axially spaced therefrom two similar ports 32, 33 leading to the opposite sides of the respective motors. The bore is also formed with a pressure chamber 2 having an inlet 54, Fig. 3, and communicates at its ends with relief chambers 3, 6. The plunger 11 has two lands 12, 13 separated by flat portions 14. The plunger has an axial passage 15 from which open by-pass ports 16 and also relief ports 17, 18, 19. The four relief ports 19 are in the same plane as and separated 45 degrees from the two opposed relief ports 17. The plunger 11 is connected by a pin 61 to a spindle 20 operated by a lever 22. The lever is connected by a link 24 to a ring 27 rotatably mounted on gland assembly 8 and held thereon by a plate 29. A clamping device 63 holds the ring 27 in any selected position. The plunger is biased to a neutral position, Fig. 3, by springs 49, 51, the spring 49 acting through a plate 50 loosely mounted on the spindle 20 and adapted to engage the top of a grooved member 34. The plate 50 engages a fixed shoulder 62 when the plunger descends below the neutral position so that the spring 49 is no longer effective on the plunger. The member 34 has three grooves 35, 36, 37 adapted to co-operate with a transverse detent pin 38 mounted between the arms 42 of a bracket member 39 pivoted at 40 and pressed towards the member 34 by a spring 41. The pin 38 engages a groove 36 in the neutral position and is released from either of the grooves 35, 37 in the end positions of the motor or motors by pressure in the chamber 2 displacing the cap 44 of a spring-loaded relief valve 46. The cap 44 raises a pin 43 connecting the arms of the bracket 39. A non-return valve 53 permits fluid to pass from the relief chamber 6 to the pressure chamber 2 when an implement is being lowered with the pump stopped. The port 30 is connected to an opposite port 56 by passages 57, 58, Fig. 2, so as to balance the radial pressure on the valve. A similar arrangement is provided for the port 31. The pressures on the lower land 13 are balanced by a groove 60 when the ports 32, 33 are cut off from the chambers 2 and 6. The ports 31, 33 communicate with the motor of the front implement and the ports 30, 32 with that of the back implement. Pressure is supplied to the ports 30, 31 to raise the implements and to ports 32, 33 to lower them under power. The flats 14 are such that both ports 30, 31 or 32, 33 may be supplied simultaneously. The ports 19 permit the ports 30, 31 to be connected to exhaust at the same time. In the lifting position, Fig. 1, the pin 38 engages the groove 35 and the bypass ports 16 are cut off from the chamber 2. In the neutral position, Fig. 3, the ports 16 are open to the chamber 2 and the ports 30, 31, 32, 33 are all closed. In the " floating " position, the ports 16 are partly obturated and in the position for lowering under power, the ports 16 are closed or almost closed and the detent pin 38 is clear of the grooved member 34.