Patent GB-1196210-A (GB)
Title: Hydraulic Lifting Equipment for Combine Harvesters
IPC: A01D41/14
Filed: 1968-12-30
Abstract: 1,196,210. Hydraulic suspension of combine harvester table. ROBERT BOSCH G.m.b.H. 30 Dec., 1968 [28 Dec., 1967], No. 61604/68. Heading A1F. Hydraulic equipment for raising and lowering a combine harvester cutting table 36 comprses a hydraulic jack 31; a service line 32 thereto, control apparatus 6 governing pressure fluid supply from a pump 1 to the line 32 for raising the table and discharge to drain for lowering it; and regulating means for the control apparatus, including a coupling member 79 for regulating the control apparatus, according to the table height, a member 64 of length dependent on the lifting jack pressure for regulating according to such pressure, and a manual adjusting lever 58. A control apparatus housing 5 has a bore 7 with fluid inlet 4 and return 9 passages, a further passage 30 leading to the service line 32 through a non-return valve 37. A passage 40-44 normally closed by a spring loaded valve 50 connects the service line 32 to a chamber 13 drained 14 to a reservoir 2. A pilot control slide 15 having a stop 54 is urged by a spring 27 against a wedge 55 and contains a further spring urged slide 20 formed with an axial bore 23 and transverse bores 25, The inlet 4 leads into an annular groove 28 around the bore 7 adjacent transverse bores 29 in a hollow end 19 of the slide 15 and in the "neutral" position of Fig. 1, fluid may flow both through bores 17 in an annularly recessed region 16 of the slide 15 and through the bores 25, 29 to the chamber 13. Pressure in the line 32 assisted by an accumlator 38 maintains the level of the table 36 by action on a lifting piston 34, the table being pivotable about an axis 80 on a harvester chassis 33. Regulation. The wedge 55 is backed by a lever 60 having a stop 61, and may be pushed in or out between the stops 54, 61 by a hand lever, the spring 27 maintaining contact between these members. The lever 60 is rigid on a shaft 59 further rigid with a coupling lever 62, from which depends the pressure-dependent link 64 supported by a tension spring 68. The link 64 comprises a piston 65 movable in a cylinder 76 under the opposing stresses due to a control line 78 and a compression spring 73, a lug 74 in a slot 75 limiting the range of adjustment. At the lower end of the cylinder member a coupling arm 79 rigid with the upper end of the table 36 is pivoted. Operation. When the cutting table 36 is following the ground its weight is carried jointly by the piston 34 and the ground surface, and on striking a surface rise the table 36 pivots upwardly, retracting the piston 34 and lowering the pressure in its co-operating cylinder 31, the lines 32, 78 and hence in the cylinder 76. The spring 73 then shortens the link 64, pivoting the lever 62 downwards and displacing the slide 15 inwards, opening the bore at 18 of the slide 15 to an outlet chamber 8 via the recess 16, while isolating the recess 16 from the inlet 4. The slide 20 is then urged inwards, insolating drainage via the chamber 13 from the inlet 4, so that fluid enters the service line 32 round the groove 28 and through the passage 30. The pistons 34, 65 are thus acted upon, and the rise of the piston 65 leads to clockwise turning of the lever 60 and return of the slide 15 to its former neutral position, the pressure buildup in the line 32 being retained by the valve 37, and the piston 34 hence bearing an additional proportion of the weight of the table 36 to raise it over the surface rise. An analogous reverse process occurs when a ground surface depression is encountered. Adjustment of the lever 58 and hence the wedge 55 enables a range of fluid pressure to be applied to the piston 34, and at high pressure ranges the piston 34 can support the entire weight of the table 36 at chosen elevations above the ground. In an alternative embodiment, Fig. 3, the coupling arm 79 is replaced by a table position transmitting linkage comprising a cam 87, coupled by a pivoted rod to an arm 92 rigid with the table 36 and a pivoted lever 105 bearing a cam follower 83 and connected to the link 64. Further a pair of feeler skids 93 may be provided to maintain the table 36 automatically at a preset height. If either skid is raised e.g. by a rise in the ground a guide part 99 or 100 is pushed upwards by a Bowden cable connector 95 or 96, and acts on a stop 103 or 104 on the lever 105 to pivot the lever and thus act on the member 64 to operate the hydraulic mechanism. Similarly, if both skids 93 enter a depression the guides 99, 100 are lowered pivoting the lever 105. A further alternative table position transmitting linkage including feeler skid means may be used, Fig. 4 (not shown), and electrical switching circuits may be employed for transmitting the control parameters to the control slide 15, Figs. 5-6 (not shown).