JPH0210889Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention is a combine harvester that travels within a field to reap grain culms planted in the field and threshes the harvested grain culms. Therefore, the present invention relates to a cutting height adjusting device for adjusting the cutting height of grain culms according to the length of planted grain culms, the degree of lodging, field conditions, etc.

Conventional technology Conventionally, when the machine of a combine harvester is rotated around the edge of a ridge, the reaping section is raised and then manually lowered to a position where the appropriate cutting height can be obtained. The electromagnetic switching valve is moved to the lowering position, and when the reaping section is lowered to the proper position, the electromagnetic switching valve is returned to the neutral position and the reaping section is stopped. Therefore, it is necessary to operate the valve twice to lower the cutting section, and this operation is troublesome.

Therefore, a mechanical stopper is provided to stop the lowering of the reaping section, and the hydraulic cylinder for raising and lowering the reaping section is a single-acting type that uses the own weight of the reaping section to lower the reaping section. There is also a known example in which once the switching valve is operated, the reaping section is lowered until it comes into contact with the stopper and then automatically stopped. The operation only needs to be done once, but in order to change the lowering position of the reaping section, the vertical position of the above-mentioned mechanical stopper, which receives the heavy reaping section, must be changed by getting off the combine harvester. It is very troublesome to change the lowering position of the reaping part during the harvesting operation.

In this regard, the cutting height adjustment operation disclosed in Japanese Patent Application Laid-Open No. 51-91126 is equipped with a rotary switch that maintains the on state within a certain rotation angle range, and the movable contact of this rotary switch is connected to the operating lever. At the same time, a contact element that brings the movable contact into contact is provided to move in conjunction with the lowering of the reaping part, and the movable contact is operated to be displaced to a certain position by an operating lever, and the contact element is moved to a certain position. When the solenoid switching valve is moved to the lowering position by turning on the rotary switch, the contact moves in conjunction with the lowering of the reaping section, and the movable contact moves to a position corresponding to the amount of displacement operated by the operating lever. The rotary switch is turned off, the electromagnetic switching valve automatically returns to the neutral position, and the lowering of the reaping section is automatically stopped. I'm trying to get a suspension.

Therefore, according to this known example, when the switch is operated to lower the reaping section, the lowering position of the reaping section is set at the same time, and then the reaping section is automatically lowered to the set position and stopped at the same position. This makes it easy to lower the cutting section to a position where the proper cutting height can be obtained.

Problems to be Solved by the Invention However, in this known example, after the reaping section is raised at the edge of the ridge and the machine is rotated, the reaping section is adjusted each time by adjusting the amount of displacement of the movable contact using the operating lever. The lowering position, that is, the position at which the appropriate cutting height can be obtained, must be set, and the mental fatigue of the worker cannot be ignored as the operator must set the appropriate cutting height position repeatedly. . In particular, after the machine has rotated, a plurality of other operations such as engaging the reaping clutch and adjusting the rows of the reaping section are required, which increases the mental fatigue of the operator.

Therefore, this invention allows for easy control of changing the cutting height determined by the lowered position of the reaping section to an appropriate value when necessary, but it also allows for easy control of changing the cutting height to an appropriate value when necessary. It is an object of the present invention to provide a novel cutting height adjusting device for a combine harvester, which eliminates the need to set the cutting height and greatly reduces the mental fatigue of the operator.

Means for solving the problem The technical means taken by this invention to solve the problem of this invention are as follows.

That is, in the combine harvester illustrated in FIG. 1, the reaping section 2 supported by the machine body so as to be movable up and down is connected to a hydraulic cylinder 9 whose supply and discharge of hydraulic oil is switched and controlled by an electromagnetic switching valve 10 as shown in FIG. On the other hand, as shown in FIG. 3, the hydraulic cylinder 9 has its piston rod 9b end connected to the machine body and its cylinder body 9a end connected to the reaping section 2 side. It is set up in an inverted shape. Similarly, as shown in Figure 3,
A lowering stop switch 28 is provided on the cylinder body 9a, which is a member that is displaced in conjunction with the raising and lowering of the reaping section 2.
In addition, a switch operating bar 38 having an operating protrusion 38a is supported by the piston rod 9b, which is another fixed position member provided on the aircraft body, and the operating position of the lowering stop switch 28 is near the cockpit. The mowing height set lever 34 provided allows the position of the lowering stop switch 28 to be adjusted continuously by remote control. Note that the descent stop switch 28 is placed on the aircraft side, and the switch operation bar 3 is
Switch actuators corresponding to 8 may be provided on the reaping section side, and the operating position of the lowering stop switch 28 may be changed and adjusted by adjusting the position of the switch actuators.

As shown in FIG. 4, the electromagnetic switching valve 10
Solenoids 18 for raising and lowering the reaping section,
An operation control circuit is provided that includes a raise operation switch 47 and a lower operation switch 48 that selectively excite the reaping section 19 to raise or lower the reaping section 2.
8 is inserted into the circuit that connects the solenoids 18 and 19 to the power source, and when the lower operation switch 48 is turned on and the reaping section 2 is lowered (in the illustrated example, the reaping section 2 is lowered by operating the upper operation switch 47). (even when part 2 is raised) lowering stop switch 29
When the solenoid 19 is turned off, the energization to the solenoid 19 (in the illustrated example, the energization to the solenoid 18 as well) is cut off, and the electromagnetic switching valve 10 is displaced to the neutral position N shown in FIG. There is.

That is, in this invention, one member 9a that is displaced in conjunction with the raising and lowering of the reaping section 2 and another member 9b that is fixed in position provided on the machine body are supported by one member and the other member respectively. A lowering stop switch 28 and switch actuators 38, 38a are provided, and a remote control means 34 is provided to continuously change and adjust the operating position of the lowering stop switch 28 on the displacement path of the above-mentioned member 9a. During the lowering of the reaping section 2 by the switching operation of the manual switch 48, the lowering stop switch 28 is set in the operation control circuit for the electromagnetic switching valve 10 that switches and controls the supply and discharge of hydraulic oil to the hydraulic cylinder 9 for raising and lowering the reaping section. The above-mentioned problem of the invention is solved by a technical means that is incorporated so that when the lowering stop switch 28 is operated, the electromagnetic switching valve 10 is displaced to the neutral position N.

It goes without saying that the above-mentioned one member and other members are not limited to the cylinder body 9a and the piston rod 9b as shown in the figures.

Effect According to the present invention having the above configuration, the manual switch 48
When the reaping section 2 is lowered by operating the switch, the lowering stop switch 28 on the one member 9a that is displaced in conjunction with the lowering of the reaping section 2 or the switch actuators 38, 38a move on the other member 9b on the machine side. When the reaping section 2 is lowered until it reaches the switch actuators 38, 38a or the lowering stop switch 28 position, the lowering stop switch 28 is operated, and the electromagnetic switching valve 10 is automatically moved to the neutral position. As a result, the lowering of the reaping section 2 is automatically stopped.

The operating position of the lowering stop switch 28 can be changed and adjusted remotely by the remote control means 34, so that when the reaping section 2 is lowered by operating the manual switch 48, the lowering stop is automatically stopped by such changing and adjusting. The position can be changed and set steplessly.

Structure of Example Combine Harvester The illustrated example relates to an example in which this invention is implemented in a combine harvester as shown in FIG.

In this combine, while the machine is driven by a crawler 1, planted grain culms are separated by a divider 3 at the lower front end of a reaping section 2 at the front of the machine, and a grain culm lifting device 4 in the reaping section 2 separates the planted grain culms. The planted grain culm is raised, the planted grain culm is harvested at the base of the stock by the cutting blade 5, and the harvested grain culm is conveyed to the direction of the threshing section 7 by the vertical conveyance belt 6, and the harvested grain culm is conveyed to one side of the threshing section 7. The feed chain 8 is configured to transport the harvested grain culm rearward and feed the tip side of the grain culm into the threshing section 7 for threshing.

Structure of Hydraulic Circuit The above-mentioned reaping section 2 is supported so that it can be raised and lowered as usual, and the raising and lowering of the reaping section 2 is
This is carried out by a single-acting hydraulic lift cylinder 9 shown in the figure. In order to control the operation of the hydraulic lift cylinder 9, an electromagnetic switching valve 10 shown in FIG. 2 is provided.

This electromagnetic switching valve 10 includes an oil supply circuit 14 that guides the hydraulic oil at a pressure set by a pressure regulating valve 13 from an oil tank 11 by a hydraulic pump 12 toward a hydraulic lift cylinder 9, and from the hydraulic lift cylinder 9 toward an oil tank 11. The primary side is connected to an oil drain circuit 15 for discharging hydraulic oil. The electromagnetic switching valve 10
As shown in the figure, the end of the connection circuit 16 connecting the secondary side to the hydraulic lift cylinder 9 is blocked,
A neutral position N that maintains the hydraulic lift cylinder 9 in a constant expansion/contraction position and a connection circuit 16 between the oil supply circuit 14 and the above-mentioned connection circuit 16
a lifting action position U for supplying hydraulic oil to the hydraulic lift cylinder 9 and causing the cylinder 9 to extend and raise the reaping section 2; and the connection circuit 1 described above.
6 is connected to the oil feeding circuit 15 to drain oil from the hydraulic lift cylinder 9, and a lowering operation position D is provided to allow the reaping section 2 to descend under its own weight. The connection circuit 16 described above includes a check valve 17 that allows oil flow only in the direction of the hydraulic lift cylinder 9.
A slow return valve 17 formed by connecting a variable throttle a and a variable throttle 17b in parallel is inserted. The electromagnetic switching valve 10 moves from the neutral position N shown in the figure to the solenoid 18.
The energization of the solenoid 19 causes the solenoid 19 to move to the upward action position U, and the excitation of the solenoid 19 causes the solenoid 19 to move to the downward action position D.

In the illustrated case, the vertical conveyance belt 6 is of a double-acting type for changing the posture so that the position of the grain culm joining end of the conveyance belt 6 to the feed chain 8 is changed according to the length of the harvested grain culm. Vertical conveyance adjustment cylinder body 2
The same hydraulic system is used to supply hydraulic pressure to the 0. That is, as similarly shown in FIG. 2, a port is provided on the secondary side of the above-mentioned electromagnetic switching valve 10 to which the oil supply circuit 21 connected to the vertical conveyance adjustment cylinder 20 is connected, and the electromagnetic switching valve 10 The switching valve 10 is configured such that the oil supply circuit 14 is connected to the oil supply circuit 21 at the neutral position N and the downward action position D. The primary side is connected to the oil supply circuit 21 described above and another oil drain circuit 22 connected to the oil drain circuit 15, and the extension oil chamber 20a and the contraction oil chamber 20b of the vertical conveyance adjustment cylinder 20. Other electromagnetic switching valves 23 are provided, each having a secondary side connected to the two. The other electromagnetic switching valve 23 is connected to the oil supply circuit 2 as shown in the figure.
1 and the oil drain circuit 22 and block both secondary ports to maintain the vertical conveyance adjustment cylinder 20 at a constant extension/retraction position, and the oil supply circuit 2.
1 is connected to the extension oil chamber 20a, and the reduction oil chamber 20b is connected to the oil drain circuit 22, so that the vertical conveyance adjustment cylinder 20 is extended to the extension action position, and the oil supply circuit 21 is set to the extension action position described above. It is connected to the contraction oil chamber 20b of the cylinder 20, and also connects the extension oil chamber 20a to the oil drain circuit 22, thereby reducing the vertical conveyance adjustment cylinder 20. In FIG. 2, reference numeral 24 denotes a flow rate control valve consisting of a combination of a variable throttle 24a and a relief valve 24b, and is used to control the supply ratio of hydraulic oil to the vertical conveyance adjustment cylinder 20.

The hydraulic supply and discharge mechanism described above is integrated into a hydraulic unit 25, as shown in FIGS. 2 and 3, and is installed at an appropriate location on the combine harvester shown.

Cutting height adjustment mechanism As shown in Fig. 3, the end of the cylinder body 9a is placed on the side of the cutting section 2, and the end of the piston rod 9b is placed on the side of the machine body.
A mounting plate 26 is attached to the cylinder body 9a of the hydraulic lift cylinder 9 which is connected to each other and arranged in an inverted manner.
A support frame 27 is fixedly mounted through the cylinder body 9a, and two switches 28 and 29 are supported by the support frame 27 as follows.

That is, the support frame 27 includes the cylinder body 9a.
A long hole 27a is formed along each switch 2.
8, 29 have their support legs 28a, 29a inserted into the elongated holes 2.
7a, and is supported by the support frame 27 so as to be movable along the elongated hole 27a. Each switch 28,2
At the ends of the support legs 28a and 29a of 9, a mounting plate 26 is attached.
The springs 30, 31 attached to the operating cables 32, 33 are connected from one direction, and the inner wires 32a, 33a of the operating cables 32, 33 are connected from the other direction. to the set lever 34 and to the other operating cable 3.
The ends of the inner wires 33a of No. 3 are guided to the reaping section upper limit position set lever 35, respectively. Both of the set levers 34 and 35 mentioned above are provided near the operator's seat 36 (FIG. 1) in the combine harvester as shown.

As a result of the above, each of the set levers 34 and 35 described above
When the inner wires 32a, 33a are tensioned by the force of the springs 30, 31, each switch 28, 29 is lengthened by the force of the springs 30, 31 when the inner wires 32a, 33a are relaxed. By displacing each switch 28, 29 in this way, the position of the hydraulic lift cylinder 9 along the expansion/contraction direction can be adjusted.

Similarly, as shown in FIG. 3, the piston rod 9b of the hydraulic lift cylinder 9 is fixedly supported by a mounting plate 37 attached near the tip thereof.
A switch actuating bar 38 is provided parallel to the direction b, and an actuating protrusion 38a is provided at the tip of the switch actuating bar 38 to project in the direction of the switches 28 and 29. When the operating protrusion 38a reaches the position of each switch 28, 29, it pushes in the movable contact members 28b, 29b of each switch 28, 29 to turn off each switch 28, 29.

As shown in FIG. 3, a controller 39 incorporating a control circuit as described later is provided, and the switches 28 and 29 are connected to the controller 39.
Connected to 9. Similarly, as shown in FIG. 3, a manual lift lever 40 with a function to be described later is provided, and the manual lift lever 40 disposed near the cockpit 36 is also connected to the controller 39. is further connected to the electromagnetic switching valve 10 or its solenoids 18 and 19.

Operation control circuit Solenoid 1 of the electromagnetic switching valve 10 shown in Fig. 2
8, 19 and switches 28, 29 shown in FIG. 3 are incorporated into the control circuit shown in FIG. 4, which is provided in the controller 39, as follows.

That is, the solenoids 18 and 19 are each
The switch 28 is connected in parallel with the surge absorbing diodes 41 and 42, and is connected to the power supply terminal at one end and grounded at the other end, and is incorporated into the control circuit. ,19
The switch 29 is inserted into a common power circuit that connects the solenoid 1 to the power terminal.
8 to the power supply terminals. NPN transistors 43 and 44 whose emits are grounded are inserted into the ground circuits of the solenoids 18 and 19, respectively, and other NPN transistors 45 and 46 whose emits are grounded are provided on the base sides of these transistors 43 and 44, respectively. There is. Of the other transistors 45 and 46, transistor 45 has its collector connected directly to the power supply terminal, and transistor 46 has its collector connected to the power supply terminal via switch 28, respectively. Of the other transistors 45 and 46, transistor 45 has its base directly connected to the power supply terminal, and transistor 46 has its base directly connected to the power supply terminal.
The bases of the transistors 45 and 46 are respectively connected to the power supply terminals via the switch 28, and the bases of the transistors 45 and 46 are grounded via the raising operation switch 47 and the lowering operation switch 48, respectively. There is. The lift operation switch 47 and the fall operation switch 48 are turned on by the manual lift lever 40 shown in FIG.

As shown in FIG.
A cutting height sensor 50 is provided supported by 9. This cutting height sensor 50 is equipped with a sled-shaped sensor arm 50a that is supported so as to be movable up and down and slides into contact with the field surface, and also has a pair of sensors (not shown) that are operated by a switching operation by the up and down movement of this sensor arm. This sensor switch is equipped with a pair of sensor switches that detect the upper and lower limits of the appropriate cutting height range from the ground height of the cutting section 2. In FIG. 4, reference numeral 51 denotes an automatic cutting height control circuit incorporating the sensor switch described above, and this automatic cutting height control circuit 51 is connected to a power terminal via an automatic control switch 52. Also, from the automatic cutting height control circuit 51, a transistor 4 is connected.
The rising signal transmission circuit Cu connected to the base of 5
and a falling signal transfer circuit Cd connected to the base of transistor 46. Fourth
In the figure, 53 is a battery that constitutes a power source;
54 is a main switch that connects and disconnects the entire illustrated control circuit and the battery 53.

Operation The control circuit shown in FIG. 4 operates as follows.

That is, when the main switch 54 is turned on and the automatic control switch 52 is turned off during manual control, when the raise operation switch 47 is turned on, the base of the transistor 45 is grounded and no voltage signal is input from the power supply to the base, so the transistor 45 takes the off state,
For this reason, a base signal is input from the power supply side to the transistor 43 whose collector is connected to the base of the transistor 45, and the transistor 43 is turned on, thereby conducting current to the solenoid 18. is excited. Conversely, if the lowering operation switch 48 is turned on during manual control, the base of the transistor 46 is grounded and no voltage signal is input to the base from the power supply side.
is in an off state, so that the transistor 46
A base signal is input from the power supply side to a transistor 44 whose collector is connected to its base, and the transistor 44 is turned on, thereby conducting current to the solenoid 19 and energizing the solenoid 19.

When automatic control is performed by turning on both the main switch 54 and the automatic control switch 52, a cutting section rise signal, which is at a low (L) level, is output from the automatic cutting height control circuit 51 to the rise signal transmission circuit Cu. When the base of the transistor 45 is grounded by this signal, the transistor 43 is turned on and the solenoid 18 is energized as in the case of manual control, and conversely, a low voltage is transmitted from the automatic cutting height control circuit 51 to the lowering signal transmission circuit Cd. When the reaping section lowering signal of the (L) level is output and the base of the transistor 46 is grounded by this signal, the transistor 44 is turned on and the solenoid 19 is energized as in the case of manual control.

As mentioned above, when the solenoid 18 is energized, the electromagnetic switching valve 10 shown in FIG. It is moved to the working position D. Therefore, during manual control, the lift operation switch 47 is operated by the manual lift lever 40.
The reaping section 2 can be raised or lowered by selectively operating the and lowering operation switch 48, and during automatic control, the reaping section 2 is automatically raised or lowered by an output signal from the automatic control circuit 51.

In the illustrated combine harvester, the upper and lower limits of the appropriate cutting height range during automatic cutting height control are set by changing and adjusting the overall vertical position of the cutting height sensor 50. There is. On the other hand, when manually controlling the cutting height, the appropriate cutting height is set using the switch 28 described above.

That is, this switch 28 is inserted into the power supply circuit common to both solenoids 18 and 19, as described above. Therefore, during manual control of the cutting height, the hydraulic pressure is Due to the expansion and contraction of the lift cylinder 9, the operating protrusion 38a on the switch operating bar 38 reaches the switch 28 position, pushes the movable contact member 28b, and closes the switch 28.
When turned off, the solenoid 18 or 19 that had been energized until then is demagnetized, the electromagnetic switching valve 10 is returned to the neutral position N, the hydraulic lift cylinder 9 is stopped, and the reaping operation is started. The vertical movement of section 2 stops. And this switch 28
The position of the hydraulic lift cylinder 9 is as described above.
Since the cutting height can be changed and adjusted along the expansion/contraction direction using the set lever 34, the cutting height can be arbitrarily set by manual operation. When automatically controlling the cutting height, the switch 28 is pulled up to the standby position by operating the lever 34.

The switch 29 described above is used as follows. That is, since this switch 29 is inserted into the power supply circuit of the solenoid 18 for lifting the reaping section 2 as described above, the solenoid 18 is in the energized state, that is, the hydraulic lift cylinder 9 is extended and the reaping section 2 is raised. When the switch 29 is turned off while the cutting section 2 is being raised, the solenoid 18 is demagnetized and the raising of the reaping section 2 is stopped. The position of this switch 29 can be changed and adjusted by the reaping section upper limit position set lever 35 along the expansion and contraction direction of the hydraulic lift cylinder 9, as described above. Therefore, by adjusting the position of this switch 29, the upper limit position of the rise of the reaping section 2 can be freely adjusted. For this reason, for example, when raising the reaping section 2 prior to turning the machine around the edge of a ridge during harvesting work, it is set so that the minimum amount of rise that does not interfere with the turning is obtained depending on the field conditions, etc. etc. can be done.

Effects of the invention In the cutting height adjusting device of the present invention, which is configured as described above and operates as described above, when the lowering stop switch 28 is operated, the lowering of the reaping section is stopped at the position corresponding to the operating position of the lowering stop switch 28. Since the switching valve 10 is automatically stopped when the switching valve 10 automatically returns to the neutral position, in order to lower the reaping section after turning around at the edge of a ridge, simply operate the manual switch 48 and the electromagnetic switching valve 10 Since it is only necessary to displace the reaping section to the lowering position and such manual operation does not require adjustment of the amount of operation, manual lowering of the reaping section does not have to be a nuisance. do not have.

Therefore, according to this invention, it is no longer necessary to set the cutting height by controlling the lowering position of the cutting part in order to obtain the appropriate value for the cutting height each time the machine is rotated at the edge of the ridge. At the same time, since the operating position of the lowering stop switch can be adjusted remotely, it is easy to control the operating position of the lowering stop switch and adjust the cutting height when necessary. This allows you to control changes in the size.

Incidentally, instead of the single downward stop switch 28 described above, a plurality of downward stop switches are installed in the one member 9.
It is also possible to consider a structure in which a selection switch is provided on the combine operator's seat side, which is arranged in parallel along the displacement path of a, and which can selectively control one of the plurality of lowering stop switches. According to the structure, due to restrictions on the arrangement of switches, such as the need to install multiple switches to avoid interference with each other, it is necessary to maintain a certain vertical interval between the lowering stop positions of the reaping part by two adjacent lowering stop switches. Aki,
This makes it impossible to precisely change and control the lowering stop position of the reaping section. In addition, in the above structure in which a plurality of lowering stop switches are provided, when an automatic cutting height control mechanism is also provided as in the embodiment, the lowering stop switch operates for control during automatic cutting height control. In order to prevent this from becoming a hindrance, it is necessary for a prisoner to, for example, provide the selection switch with an operating position that does not select any of the lowering stop switches.

On the other hand, the present invention, which is based on a single lowering stop switch 28, eliminates the restriction on switch arrangement as described above, and therefore the operating position of the single lowering stop switch 28 can be changed steplessly. The position where the optimum cutting height can be obtained according to conditions such as the softness and hardness of the field and the degree of lodging of the planted grain culm can be selected as the automatic lowering and stopping position of the cutting section. If an automatic cutting height control mechanism is installed, the single lowering stop switch 28 should have a wide adjustment range for its operating position.
When switching from manual control to automatic control of the cutting height, the operating position of the switch 28 can be brought out of the adjustment range for changing the height of the cutting section by the automatic control by operating the remote control means 34. , does not require any modifications to the electrical control circuit for manual control.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a combine harvester equipped with an embodiment of this invention, Fig. 2 is a circuit diagram of one hydraulic circuit in the combine, Fig. 3 is a mechanical diagram of the embodiment, and Fig. 4 is a diagram of the same embodiment. FIG. 2 is a circuit diagram of an electrical control circuit. 2...Reaping section, 9...Hydraulic lift cylinder, 9
a...Cylinder body, 9b...Piston rod,
10... Solenoid switching valve, 18, 19... Solenoid, 26... Mounting plate, 27... Support frame, 27a...
...Elongated hole, 28...Switch, 28a...Support leg, 3
0...Spring, 32...Operation cable, 32a...
... Inner wire, 34 ... Cutting height set lever,
37...Mounting plate, 38...Switch operating bar, 3
8a... Operating projection, 39... Controller, 40
...Manual lift lever, 43, 44...transistor, 45, 46...transistor, 47...lift operation switch, 48...fall operation switch.

Claims (1)

[Scope of utility model registration request] A lowering stop switch and a switch actuator are supported by one member and the other member, respectively, of a member that is displaced in conjunction with the raising and lowering of the reaping section and another member that is fixed in position provided on the machine body. In addition, a remote control means is provided to continuously change and adjust the operating position of the lowering stop switch on the displacement path of the above-mentioned member, and further to switch the supply and discharge of hydraulic oil to the hydraulic cylinder for raising and lowering the reaping section. In the operation control circuit for the electromagnetic switching valve to be controlled, the lowering stop switch is installed, and when the lowering stop switch is operated while the reaping section is lowered by the switching operation of the manual switch, the electromagnetic switching valve is displaced to the neutral position. A cutting height adjustment device for a combine harvester, characterized in that it is built-in so that the cutting height can be adjusted.