Patent GB-805061-A (GB)
Title: Power operating and control system for tractors
IPC: A01B63/111
Filed: 1955-03-22
Abstract: 805,061. Tractor power lift mechanisms. MASSEY - HARRIS - FERGUSON, Inc. March 22, 1955 [March 23, 1954], No. 8252/55. Class 79(1) [Also in Groups XXIX and XXXII] In a hydraulic power lift control system having position control and draft control both applicable to the control valve, the draft control has motion transmitting means under the control of a driver-actuated controller moveable to a selected position and an automatic draft responsive component, and the position control comprises a driver-actuated controller independent of the draft controller, a follow up device moved by, and in unison with, the hitch linkage, and motion transmitting means under the control of the controller and follow up device, both motion transmitting means including valve actuators each capable of moving the control valve in the raise direction through one way connections. General. An implement 17 is carried on a tractor by a three-link system consisting of two lower draft links 15, pivoted at 20 to the tractor, and a control link 16, Fig. 1, connected by a pin 21 to a control plunger 22 and to a U-shaped rocker 25 pivoted between a pair of jaws 26b of an extension 26a of cover plate 26. The draft links 15 are raised by ram 36, 37 through rod 38, arm 39, rock shaft 40 and arms 41, 42, Fig. 2, by the admission of fluid to the ram from pump 45, exhaust of fluid from the ram lowers the links 15. A valve V, operated by lever 85 pivoted to a fixed rod 87, controls the flow of fluid, e.g. oil, to and from the ram. Operation of valve V. Fig. 8. The valve V, situated in a bore 57 in the pump housing, comprises a hollow tubular plunger 55, having an interior partition with a square cross-section opening and being slidable through bearing rings 63, 65 which define a high pressure chamber 62 sealed by elastic rings 70, a third ring 64 floats transaxially within an outer ring 68; the nose of the plunger 55 being tapered so that it can enter and oentre the ring 64. Spacing sleeves 66 and 67 interposed between the rings 64, 63 and 63, 65 do not contact the plunger 55, the valve being held assembled by a plate 69, the inner ring 65 abutting a shoulder 60 in bore 57. To exhaust fluid from the cylinder 36 the lever 85 moves clockwise to permit the spring 77 acting on rod 78, 79, to move the plunger 55 rearwards so that fluid can pass to the sump via passage 49, ports 72 to high pressure chamber 62, ports 74 and passage 58a; for rapid lowering the plunger is moved to permit the fluid to also pass through the wide ports 75 in the plunger. To supply fluid to the pump 45 which is driven from the tractor's engine, the lever 85 is turned counterclockwise to move plunger 55 forwards against spring 77 until ports 73 pass ring 64 to admit fluid through ports 71 in sleeve 66 to the pump intake 47; from the pump 45 it passes through passage 48 to ram 36, 37. To hold the links 15 in any desired position the valve plunger 55 is returned to a neutral position where uninterrupted portions of its surface extend between the rings 63, 65 and 63, 64. A stop ring 76 on plunger 55 coacts with rings 63 and 65 to limit the movement of the plunger 55. The heads 82 and 80 or rods 81 and 79 respectively are of circular cross-section to permit flow of fluid past them and through the square cross-section passage in the plunger partition. The head 78 of rod 79 is of square crosssection, the corners sliding in grooves in cylinder 89 which houses spring 77, clearances between the edges of head 78 and the cylinder permit a restricted flow of fluid during movement to create a dashpot effect. The cylinder 89 is rotatably mounted at 91 and 92 in the pump body and is concentric with valve bore 57, an arm 95 (Fig. 9) embracing cylinder 89 is connected to a rod 97 having a ring portion encircling an eccentric 98 on pump shaft 99, so that as the pump shaft rotates the cylinder 89 oscillates and this movement is transmitted by rod 79 to valve plunger 55 to ensure smooth and easy sliding of the plunger. A spring-loaded safety valve 45a is supplied 'on pump 45. Position control. Fig. 10. Movement of hand lever 100, guided on quadrant 104 and 'fixed to shaft 101, to the "lower" position causes a roller 107, on arm 106 fixed to shaft 101, to abut the jaw 109 of a lever 110, pivoted at 111 to lever 112, to.,raise the rear end of lever 110 to allow its cam edge 115 to ride rearwards over a roller 116 carried by a rocker 117. This moves lever 112 counterclockwise and its lower end, in a slot 111<SP>1</SP>, moves away from the upper end of lever 85 to permit the spring 77 to move the valve plunger 55 to the lowering position. A follow up device in the form of cam 120 on shaft 40 moves in unison with links 15, 41, 42 to contact a roller 119 on rocker 117 and move the rocker 117 and levers 110, 112 and 85 to return the valve to the neutral position as the links 15 reach the position set by lever 100. Raising the lever 100 to the "raise" position causes lever 110 to move forward and operate lever 112 and 85 to move the plunger 55 to the raise position; the cam 120 moves to allow the plunger to return to a neutral position when the links have reached the desired position. If lever 100 is raised too quickly a spring 127, on a sliding rod 125 to which the pivot 113 of Lever 112 is attached permits the lever 112 to move forward and as the links are raised the rod 125 returns to its normal position. A knurled nut 105 on a bolt can be adjusted in a slot in quadrant 104 to set a position for lever 100. The lever 100 has control of raising and lowering above a certain soil level whereas the draft control and depth setter (see below) takes full control below this level. Depth setter. Fig. 7. A driver actuated depth setter 141 comprises a hand lever 141b secured to shaft 140 and guided by a quadrant 142 slotted at 144, and a finger piece 141a integral with a slide 141c having two lugs 141d, (Fig. 7a, not shown) to engage in slot 144; a nut 143 on a bolt extending through slot 144 may be tightened to secure the slide 141c in any selected position. A bolt 141f maintains frictional relationship between the quadrant 142, slide 141c and lever 141b. In use the nut 143 is loosened and finger piece 141a and lever 141b are moved to a position corresponding to a working depth required, the nut 143 is tightened so that for short time adjustment the lever 141b may be moved and returned to register with finger piece 141a for the previous setting. The connection between the depth setter 141 and the valve V through shaft 140, Toller 139, lever 135, pivot 135a and levers 136 and 85 is similar to that of the position control. With lever 100 in the raise position the depth setter 141 on moving to the "raise" position takes over control of valve V since the lower end of lever 136 has a greater permissible movement than lever 112, Fig. 3 (not shown). Draft control. Figs. 2 and 7. The rocker 25 to which link 16 is pivoted carries a yoke 27 with a screw threaded portion in which a plunger 22 is secured by a locking pin 22a the head 22b of plunger 22 has a flange 22c which is slidable in a cup 28. A control spring 29 surrounds plunger 22 and is seated against a lip of cup 28 and against a collar 30 screw threaded into plate 26a, a rubber saling ring 32 is fixed between the collar 30 and yoke 27. A rocker 130 pivoted at 118, to one side of rocker 117, is connected to a push rod 131 by pin 132, journalled to pin 132 is a roller 133 adapted to ride over a cam 134 on lever 135 to force the lever 135 forwards. The rod 131 is urged, through levers 85, 136 and 135, by spring 77 into contact with the plunger head 22b so that as the plunger 22 moves the rod 131 follows to move the rocker 130 whose roller 133 moves the lever 135 forward to operate the valve plunger 55 through levers 136 and 85. The lever 136 is mounted on a slidable rod 145 which acts similarly to rod 125 above. If link 16 is in compression, due to excess draft, the plunger 22 moves forward to compress the spring 29 and also push rod 131 to act on lever 135 and so move' the plunger 55 to the raise position. With link 16 in tension the cup 28 and plunger 22 slide rearwards to compress spring 29 and so allow rod to move rearwards and the valve plunger 55 to move to the lower positiion. Prevention of overcontrolling by a draft implement. The lever 100 is moved downwards from the full lowering position in Fig. 5 to overcome the overcontrolling of a heavy draft implement, in doing so the connection between the cam 120 and valve actuating linkage is broken and the hooklike end 121 of lever 110 engages eccentric 122 on lever 112 to lock the levers 110 and 112 together hence they will turn clockwise about fulcrum 113 to move plunger 55 towards the raise position. Overload release mechanism. On hitting an obstruction with an implement the draft load exceeds that set by depth setter 141 and causes the plunger 22 to move forward and through levers 135, 136 and 85 to move the plunger 55 to the limit of the raise position in which case the ports 73 are beyond the central ring 63 to permit exhaustion of fluid from the ram to lower the links 15, the support of the implement by ram 36, 37 is removed and the sudden relief of weight from the tractor causes rear wheel spin and reduces the tractive force and the possibility of damage. Operation of auxiliary apparatus. A supply line to an auxiliary hydraulic apparatus may be connected to pipe 48 across passage 51a in cover plate 26 below a removable plate 50, the plate 50 may be replaced by plates having valves and passages for connection to auxiliaries. With lever 100 in the "lower position" the depth setting lever 141 is moved to "raise" position and then either fluid goes first to ram 36, 37 and then to the auxiliary or vice versa depending on whether the links 15 carry a greater load than the auxiliary. Description is given in the Specification of the ord