Patent GB-1204158-A (GB)
Title: Improvements in or relating to hydraulic actuating devices, e.g. for tractor-mounted harvesters
IPC: A01D34/24
Filed: 1967-10-06
Abstract: 1,204,158. Tractor-mounted harvesters. ROBERT BOSCH G.m.b.H. 6 Oct., 1967 [28 Oct., 1966], No. 45715/67. Heading A1F. A hydraulic actuating device comprises a first control device 45 for controlling a hydraulic motor and a second control device for controlling a hydraulic lifting cylinder (34) (not shown) the second device comprising of a flow regulating valve 9 and throttle 17 so that the quantity of hydraulic fluid delivered by a pump 1 is regulated to a constant minimum to the cylinder 34 whilst the residual fluid passes to the motor (50), (not shown. The motor 50 drives reciprocating cutter blades and is connected in series with the lifting cylinder 34 for raising and lowering the cutter bar. Fig. 2 shows a section through the primary control in which the slide 45 may be set in two longitudinal positions: as shown, connecting the motor with fluid supply, and a displacement to the right (corresponding to the dotted position of hand lever 77) blocking the fluid to the motor. In both of these positions the slide may be rotated to one of three positions to effect lift, neutral and lowering of the lift cylinder (not shown) each position being defined by engaging pin 73 locating in engaging disc 70 under the force of spring 74, said disc rotating with the slide. The two longitudinal positions are defined by an end 63 of spring-catch 62 engaging in annular grooves 65. Fig 3 is a section taken behind that of Fig. 2 through the nuts 15 and 27. It shows the control member 8 of a flow regulating valve 9. The section IV-IV of Fig. 3 is shown in Fig. 4. Slide 45 in the common enlargement 55 (see Fig. 2) carries a projection 56 that engages the control member 8. Operation Hydraulic fluid passes from inlet pipe 3, chamber 6, past throttle notches 11, pipe 42 and into chamber 44. When the slide is in the longitudinal position shown in Fig 2, 44 connects to 47 which in turn connects to the motor. If the slide is displaced to the right, 44 disconnects from 47 and connects to 52 that leads by way of pipe 83 to control devices 81, 82 (not shown). Furthermore, 54 connects 47 to 55. Fluid is thus blocked to the motor. Fig. 4 shows the neutral position of the flow regulating valve 9. The fluid enters pipe 3 into chamber 6, pipe 16 and is throttled at 17. It is disconnected from the lift cylinder 34 because cross bore 36 does not connect pipe 31 to enlargement 14. When the slide 45 is turned anticlockwise (Fig. 4) the bevel 39 allows fluid to escape from the lift cylinder 34 to outlet 30. When the slide is turned clockwise, the cross bore 36 connects pipe 31 to supply. As soon as the lift cylinder is full, the increase in pressure opens the relief valve 20 connecting the supply to return pipe 28 and outlet 30.  If through increasing resistance from the harvester side the lifting process is delayed so that the lifting speed drops, the pressure in the control chamber 14 rises whereupon flow regulating slide 8 is pressed downwards throttling the motor fluid at 11 and increasing the lift cylinder fluid at 36 so that the harvester continues to be lifted at the same speed. Conversely too great a lifting rate will be counteracted by a decrease in flow of fluid in pipe 31. The flow regulating valve 9 together with the throttle orifice 17 is designed so that it regulates the quantity of fluid delivered to the lift cylinder to a constant minimum. By means of a pressure limiting valve located in actuator 82 (not shown) the fluid delivered by the pump is set to a maximum pressure.