fig1 shows a prior art cutter table connected to the conveyor channel , as seen from the harvester thresher , i . e . in the direction of motion , together with the circuit diagram of the control according to the invention , the operating cylinder and the oscillation measuring and switching device . fig2 shows the switching positions of a cross switch for the oscillation device , and fig3 shows the switching positions for the height control of the cutter table . the cutter table or an adapter portion 2 to be assigned to the cutter table , is sluingly supported , at 3 , on the conveyor channel or on an adapter portion 1 assigned to the conveyor channel . for simplicity sake , the terms conveyor channel and cutter table will in the following be used only although in many cases a two - piece adapter is mounted between these two elements . a double - acting operating cylinder 4 is pivoted , at 5 , to conveyor channel 1 and , at 6 , to cutter table 2 . if piston 7 is in the middle of its stroke to be traversed in the cylinder , cutter table 2 is in parallel to conveyor channel 1 . if piston rod 8 is projected beyond the middle position of the piston , the cutter table is lowered on the left side as seen in the direction of motion ; if it is retracted beyond the middle position of the piston , the table bends to the right side , in each case swinging around point of rotation 3 . supposing that the table has a higher weight on the left side relative to its point of rotation 3 , because of the drive aggregates , than on the right side , such higher weight will be compensated for by spring 9 supported , on one end , on a flange 10 of operation cylinder 4 and , on the other end , on a flange 11 on piston rod 8 of operation cylinder 4 . the spring , corresponding to the greater weight , is biased on one cutter table side . this bias is adjusted by threaded bolt 12 on a threaded range of piston rod 8 in acccordance with the weight difference relative to point of rotation 3 . such adjustment is at its optimum if the cutter table has its parallel position relative to the conveyor channel , it the pressure spaces of operation cylinder 4 are pressureless or , as will be described lateron , are in floating position . between conveyor channel 1 and cutter table 2 , furtheron , switching device 13 is provided which can emit switching pulses if the table is not in parallel position relative to the conveyor channel . if the table swings to the left , resiliently designed traction means 14 pulls switching lever 15 beyond its point of rotation 16 upward thus closing switch 17 . if the table swings to the right , that is if it bends on the right side as seen in the direction of motion , spring 18 pulls switching lever 15 downward and switch 19 is actuated . the hydraulic control comprises three - position valve 20 and two - position valve 21 which is normally in the shut - off position as shown . the control switch is provided as a cross switch as in accordance with fig2 . for a better view , the electric control leads were not shown since with a view to modern sps controls and other electronic switching means a plurality of possibilities are available to generate the switching pulses and their connection with one another . in the following , only the individual control circuits for the hydraulic control will be explained . control switch 2 according to fig2 comprises switch positions l for left descend , r for right descend , s for floating position and p for parallel position . if l is switched on , part 30 becomes active on valve 20 . the pressure space of operating cylinder 4 receives , on the piston rod side , pressure medium via duct 31 , and via duct 32 , pressure medium is released from the pressure space on the piston side . the table swings to the left , that is it descends on the left side . if the control switch is switched to r , part 33 of valve 20 is actuated and the table swings to the right , that is it descends on the right side . if the control switch is set to s , part 34 of valve 21 becomes active and connects the two ducts 31 and 32 with the tank . both pressure spaces of operation cylinder 4 become pressureless and the cutter table can freely oscillate into both directions about its point of rotation 3 . if the control switch is set to p , valve 21 is , firstly , switched again into the shut - off position and , secondly , switching position 13 is activated . depending on the oscillation position , the latter emits corresponding switching pulses to valve 20 and the operation cylinder 4 fixes itself in the middle position and hence cutter table 2 is fixed in parallel position relative to conveyor channel 1 . control command p can also be used for switch - over to sensor control . the sensor control referred to including scanners or contact strips or other distance - measuring sensors under or at the cutter table trough have been known and are not , therefore , shown in detail in the drawing . if a prior art cutter table height control device is installed on the harvester thresher , a cross switch according to fig3 has been provided for it . in this connection , a command combination for height and oscillation control is suggested . if the control switch according to fig3 is switched to a = automatic , which means that the cutter table is guided with a residual weight in ground contact , command s = floating position , coupled to a , is also emitted . valve 21 is switched to part 34 . on command l = position ( fig3 ), the table is guided at a determined height above ground , i . e . not in ground contact . by this command , the oscillation device is also switched to sensor control . if command h = lift is switched , the command for the oscillation device for parallel positioning of cutter table 2 relative to conveyor channel 1 is simultaneously issued . such a combination makes the operation of the machine much easier for the operator . in the drawing , the point of rotation of cutter table 2 has been provided below conveyor channel 1 , at about the middle thereof , at 3 . it is self - evident that the point of rotation can also be provided above the conveyor channel , about at 40 . it is also possible , by a special bearing via rollers or a capstan , to provide the point of rotation in the middle of the conveyor channel ( at about 41 ). if the table is heavier on the right than on the left , operation cylinder 4 may also be provided on the right side of the conveyor channel . the provision of the operation cylinder is also possible above or under the conveyor channel . switching device 13 for automatic positioning is also conceivable at all places where the angle of inclination between conveyor channel and cutter table relative to each other can be used for switching purposes . switching device 13 , for the rest , constitutes only an exemplified embodiment . it may be realized by means of potentiometers , cam switches and various other switching elements . the plurality of possibilities , such as capacitance switches , switching elements integrated within the operating cylinder , and optical measuring and switching elements have been known to those versed in the art and need not be explained in detail . in the embodiment according to the invention as shown in fig4 it is assumed that the cutter table is hearer , at a , relative to the point of rotation ( 40 ) and that lift cylinder ( 41 ) for the cutter table is under hydraulic pressure . on side a of cutter table ( 42 ), balancing cylinder ( 43 ) is pivoted which is supported at the other end on the , not - shown , conveyor channel . assigned to the balance cylinder , pressure reservoir ( 44 ) is connected in the hydraulic system . a shut - off valve ( 45 ) which can both electrically and manually be actuated is provided in duct ( 46 ) between lift cylinder ( 41 ) and balance cylinder ( 43 ). also on the cutter table , at b , double - acting hydraulic cylinder ( 47 ) is pivoted which , on the other end , is also pivoted to the conveyor channel , not shown . it is assumed that pressure reservoir ( 41 ) is pressureless on the hydraulic side , and shut - off valve ( 45 ) is closed and operation cylinder ( 47 ) is switched to floating position . because of the greater weight , at a , cutter table ( 42 ) has pitched on this side . in order to provide for the balance of the table , shut - off valve ( 45 ) is opened . from lift cylinder ( 41 ), pressure medium flows into balance cylinder ( 43 ) and into pressure reservoir ( 44 ) connected with it . the balance cylinder balances the different weight between a and b of the cutter table , and as soon as the table is in the horizontal position , shut - off valve ( 45 ) is closed . hydraulic reservoir ( 44 ) is so dimensioned that the complete desired oscillation path of cutter table ( 42 ) can be performed with a very flat spring characteristic . by means of corresponding controls as described in german patent application no . p 41 27 189 . 0 and shown in fig1 and 3 , the cutter table may be adjusted , via the operation cylinder , in any position contrary to the free oscillation .
a control for a structural assembly oscillatingly supported around a swivel axis on a base unit in a harvesting machine and including a cutter table inclinably supported about an axis of rotation relative to a conveyor channel , has an hydraulic operation cylinder . the inclination of the cutter table relative to the conveyor channel is effected by the hydraulic operation cylinder pivoted at one end to the conveyor channel and at the other to the cutter table . an hydraulically loaded relief cylinder , the pressure medium of which is cushioned by a pressure reservoir , is installed with one end to the conveyor channel and with the other end to the cutter table so as to balance a position of the cutter table relative to its point of rotation by the force of the relief cylinder .