Patent GB-1017284-A (GB)
Title: Improvements in or relating to devices for controlling a servo-action mechanism as a function of two magnitudes, notably for raising tractor-hauled equipments or the like
IPC: A01B63/111
Filed: 1963-05-09
Abstract: 1,017,284. Fluid-pressure servomotor systems. D. FAURE. May 9, 1963 [May 25, 1962], No. 18410/63. Heading G3P. A hydraulic servopiston 37, Fig. 4 (not shown), for actuating the lifting gear of a tractor-mounted plough or other implement is controlled by valve apparatus 36 having mechanical connections whereby the depth of the implement can be determined by either a manually controlled positional system or means responsive to the drag on the implement. The valve apparatus is shown in the implementlowering condition in which a rotary element 40 is positioned so that a chamber 51 behind a spring- loaded valve 46 is vented to sump 12 to allow pressure fluid from the pump 13 to pass through a port 45<SP>1</SP> to sump, and so that a cam on the rotary element holds open a valve 47 to vent the servocylinder to sump through a passage 45 and port 45<SP>1</SP>. In the neutral condition of the valve apparatus the element 40 is turned such that its cam allows the valve 47 to close, and in the implementraising condition the element 40 is in a position in which the chamber 51 is pressurized to hold the valve 46 closed whereby pump pressure is enabled to open the valve 47. The rotary element 40 is actuated by an arm 42 of which a pin 43 is coupled by an articulated link 81, Fig. 16 (not shown), to an arm 39 through which the servopiston actuates the lifting gear. Also coacting with the pin 43 is a slotted hole in an articulated link 92 which is pivoted at 91 to a floating lever 87 connected at one end to a crank 59a actuated by a hand lever 20 and at the other end to linkage 89, 105, 30<SP>1</SP> connected to spring-loaded mechanism (not shown) responsive to the drag of the implement. When the link 92 is pressed downwardly against a spring 101 by a cam (not shown) actuated by a second hand lever the pin 43 lies in a horizontal portion 99 of the slotted hole in the link 92 and is thus not operatively connected thereto. Also coacting with the pin 43 is a second articulated link (not shown) similar to 92 and connected to this link is a second floating lever (not shown) connected to the crank 59a and to the arm 39. A second cam actuated by the second hand lever controls the engagement of the slotted hole of the second articulated link with the pin 43, and the arrangement is such that operation of the second hand lever brings into engagement with the pin 43 a vertical portion 100 of the slotted hole of either of the articulated links whereby operatively to connect that link with the pin 43 and determine control of the servopiston by the position of the hand lever 20 or by the drag on the implement. During operation with drag control the position of the lever 20 determines the value of the drag. The link 81 interconnecting the lever 42 and arm 39, limits the raising stroke of the servopiston, adjustable by a screw 85, but is normally bent about its articulation point 84 so as to be inoperative. In a modification, the link 92 and the second, similar link are not articulated and have notches for engagement with the pin 43.