GB1182973A - Control Apparatus for the Powered-Lifter Installation of an Agricultural Tractor. - Google Patents

Abstract

1,182,973. Change speed control. KLOCKNER-HUMBOLDT-DEUTZ A.G. 7 July, 1967 [21 July, 1966], No. 31487/67. Heading F2D. [Also in Division A1] In a tractor power lift mechanism (see Division A1) control signals dependent on the speed of the tractor are derived from a governor 85 in the automatic gear-box of the tractor. The output shaft 19 is driven by the tractor engine via a torque converter 3 and gear-box 9 of the intermeshed planet type providing three forward ratios and one reverse. For gear I a clutch 10 is engaged to drive a sun-wheel 14 which transmits drive through planet wheels 16, 17 and a ring gear 18. The planet carrier 20 is held from reverse rotating by a one-way brake 21, which has a parallel two-way brake 22 for use in B setting of a manual selector valve 77. For gear II clutch 10 is engaged and brakes 24, 26 operate to hold shaft 13 stationary so that the planet carrier 20 is free and the ring gear 18 is driven with increased speed. For gear III both clutches 10, 11 are engaged to lock shaft 12 in rotation with shaft 13. For reverse clutch 11 is engaged and brake 22 operates to hold the planet carrier 20 stationary. Clutch and brake control circuit.-Pump 57 supplies pressure fluid to chambers 65, 66 of a main pressure valve 67 from whence fluid flows to a selector valve 77, a blocking valve 75 and a control throttle pressure valve 78. The selector valve has a park position P an automatic position A for freewheel operation, an automatic position B for engine braking, a neutral and reverse position. In both positions A and B of the selector valve pressure fluid is directed to conduit 80 to operate clutch 10 and is also directed to valve 84 controlling the change between gears I and II and to the governor 85 which produces a pressure in the conduit 86 in dependence on the tractor speed. This latter pressure is applied to cylinder 89 of valve 84 and also to cylinder 87 of valve 88 controlling the change between gears II and III. The difference in diameter of control pistons 94, 93 of these valves allows valve 88 to remain in its neutral position whilst valve 84 operates to change gear. On increase in speed the governor 85 increases the pressure in conduit 86 to cause valve 88 to change to gear III. In positions B and R of the selector valve pressure fluid is supplied via conduit 76a to conduit 120 feeding the control throttle pressure valve 78 whereby fluid is supplied to the converter pressure valve 128 to shift piston 127 to close the passage to sump at 129. Fluid is thus supplied via conduit 118 to move piston 69 of the main pressure valve 67 to connect the supply branch 63 to the converter 3 to couple the engine to the shaft 7. It is stated that, since the converter pressure is automatically adjusted by the valves 78 and 128 in dependence on the driving torque of the engine, the converter characteristic is adapted automatically to the attached load.