JP4907575B2 - Tillage equipment - Google Patents

Description

  The present invention relates to a tilling device in which a rear cover that covers the rear of a tilling portion is biased in a grounding direction by a gas spring.

Conventionally, a plurality of tilling claws are attached to a nail shaft having a left and right axis, and a plowing portion is provided on the lower side of the machine frame for cultivating soil with the tilling nail by rotating the nail shaft around the left and right axes. The rear cover is provided with a rear cover that covers the rear of the tillage part, and the rear cover is inclined to move downward as it goes rearward in a work posture for leveling the soil cultivated by the tillage part, and its front upper end side is a machine. It is supported on the frame side so as to be pivotable around the axis in the left-right direction and can swing up and down. In this working position, the rear cover is attached to the lower side to ground the rear lower end side of the rear cover. There is a tillage device in which a gas spring is provided over the machine frame side and the rear cover side. (See Patent Document 1).
Japanese Patent Laid-Open No. 10-14315

In the tillage device, for example, when cleaning / inspecting the tillage part, the rear cover is lifted upward from the working position. In such a case, the rear cover is lowered to the rear cover. If an urging force that urges to the side is acting, a large lifting force is required, resulting in heavy labor. In some cases, it is desired to work in a state where no ground pressure is applied to the rear cover.
However, in the conventional tillage device, one end of the gas spring is pivotally supported via a pin on a bracket provided on the machine frame side, and the other end of the gas spring is provided on a bracket provided on the rear cover side. It is pivotally supported via a pin, and it is difficult to easily change between when the urging force of the gas spring is desired to be applied to the rear cover and when it is not desired to be effective.

  Therefore, in view of the above problems, the present invention provides a tillage device that can be easily changed between a case where the urging force of the gas spring is desired to be applied to a rear cover and a case where it is not desired to be effective. Objective.

The technical means taken by the present invention in order to solve the technical problem includes a rear cover that covers the rear side of the tillage portion provided on the lower side of the machine frame, and the rear cover is moved up and down on the machine frame side. In the cultivator provided with a gas spring that supports the movably and urges the rear cover downward over the machine frame side and the rear cover side,
One end side of the gas spring is pivotally supported by a spring support provided on either the machine frame side or the rear cover side, and an operation lever is provided on a lever support provided on the other side of the machine frame side or the rear cover side. The operation of the operation lever is switched so that the gas spring is switched between a biased state where the biasing force of the gas spring acts on the rear cover and a free state where the biasing force of the gas spring does not act on the rear cover. The operation lever is pivotally supported at the other end of the gas spring.

Further, the operation lever is rotatably supported on the lever support portion, and the operation lever is rotated from a state in which the gas spring is in an energized state, whereby the pivot point on the other end side of the gas spring is set to the gas spring. It is preferable that the gas spring be in a free state by crossing a deadline passing through the pivot point on one end side and the pivot point of the operation lever.
In addition, when the gas spring is in a biased state when the operation lever is detachably engaged with an engagement portion provided on the lever support side, the operation lever is rotated. It is preferable to provide a self-removal restrictor that restricts movement.

Moreover, it is good to be able to change the pivot position of the gas spring with respect to the operation lever and / or the spring support.
Further, it is preferable to provide a lowering device that biases the rear cover in the grounding direction by a biasing force of a coil spring that is fitted over a lowering rod provided over the machine frame side and the rear cover side.
In addition, the rear cover is inclined so as to move downward as it goes backward in the work posture for leveling the soil cultivated by the tillage part, and the front upper end side is rotatable about the left and right axis about the machine frame side. The gas spring is supported so that the front pivot point of the gas spring is located above the front side of the rear cover pivot, and the gas spring extends rearward when the rear cover is in the working position. Is good.

  According to the present invention, the switching operation of the operation lever switches the biasing state where the biasing force of the gas spring acts on the rear cover and the free state where the biasing force of the gas spring does not act on the rear cover. In contrast, it is possible to easily change between when the urging force of the gas spring is desired to be applied and when it is not desired to be applied.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 2, reference numeral 1 denotes a cultivator that is detachably attached to a rear portion of a vehicle such as a tractor via a connecting device such as a three-point link mechanism and that can be lifted and lowered so as to cultivate while moving the field.
The tillage device 1 mainly includes a machine frame 2 connected to a three-point link mechanism, a tiller unit 3 provided on the lower side of the machine frame 2, and a tiller cover 4 that covers the tiller unit 3. Yes.
The machine frame 2 has support arms 6 projecting from the gear case 5 at the center in the left-right direction on both the left and right sides, and the upper part of the transmission case 7 is attached to the outer end side of the left support arm 6 and An upper portion of a side frame (not shown) is attached to the end side to form a rear portal structure.

The lower side of a top mast 8 projecting upward from the gear case 5 is fixed to the left and right sides of the gear case 5 of the machine frame 2, and an upper bracket 9 projecting obliquely upward and forward is attached to the top mast 8. On the upper end side of the upper bracket 9, there is provided an upper connecting pin 10 with which an upper engaging portion of a connecting frame provided on the rear end side of the three-point link mechanism is engaged from below. A lower bracket 11 is fixed to each support arm 6, and each lower bracket 11 is provided with a lower connecting pin 12 to which a connecting device below the connecting frame is connected.
The upper connection pin 10 is directly connected to the work machine side connection part of the top link of the three-point link mechanism, and the lower connection pin 12 is directly connected to the work machine side connection part of the lower link of the three-point link mechanism. It may be what you did.

The lower link is connected via a lift rod to a lift arm that is moved up and down by a hydraulic device provided at the rear of the tractor. The tiller 1 is swung up and down by swinging the lower link up and down by the hydraulic device. It can be moved up and down.
The hydraulic device is composed of a single-acting hydraulic cylinder, and the tiller 1 is raised by hydraulic pressure and lowered by its own weight.
The left and right lower brackets 11 are pivotally supported at the front end side of a support frame 13 projecting rearward from the machine frame 2, and a gauge ring 14 is attached to the rear end side of the support frame 13. A height adjusting device 15 that adjusts the height of the gauge wheel 14 by swinging the support frame 13 up and down is provided between the middle part 13 and the top mast 8.

The tillage unit 3 includes a claw shaft 16 that is rotatably mounted around a shaft center in the left-right direction between the transmission case 7 and the lower portion of the side frame, and a plurality of tilling claws 17 attached to the claw shaft 16 in the left-right direction. And.
The gear case 5 of the machine frame 2 is provided with a PIC shaft 18 that projects power from the PTO shaft of the tractor via the transmission shaft so as to protrude forward, and is input from the PIC shaft 18 to the power transmission mechanism in the gear case 5. The transmitted power is transmitted to the claw shaft 16 through the transmission shaft in the left support arm 6 and the power transmission mechanism in the transmission case 7, and the claw shaft 16 is configured to be rotationally driven in the direction of arrow A in FIG. ing.

The tillage cover 4 includes an upper cover 19 that covers the top of the tillage unit 3, a rear cover 20 that covers the rear of the tillage unit 3, and left and right side covers 21 that cover the left and right sides of the tillage unit 3. .
Each of the left and right side covers 21 has a front cover part 22 that covers the upper side of the tillage part 3 and a rear cover part 20 that covers the side part between the tillage part 3 and the rear cover 20. The part 22 is divided into upper and lower parts.
The upper front cover portion 22 is fixed to the inner side of the transmission case 7 and the side frame in the left-right direction, and the lower front cover portion is fixed to the upper front cover portion.

The upper cover 19 is disposed between the upper front cover portions 22, and the left and right end portions are fixed to the upper front cover portion 22.
As shown in FIGS. 1 and 2, the rear cover 20 is inclined so that the rear lower end side touches the field and the soil cultivated by the cultivating unit 3 is leveled so that the rear cover 20 moves downward as it goes rearward. The pivot portion 24 provided on the front upper end side is pivotally supported on the pivot shaft 25 supported on the rear end side of the upper cover 19 so as to be rotatable about the left and right axis, and the rear portion The cover 20 is supported by the upper cover 19 (machine frame 2 side) so as to be able to swing up and down so that the rear side can move up and down.

The rear cover 20 may be provided with a detachable leveling cover on the lower end side thereafter.
The tilling device 1 of the present embodiment is a retracting device shown in FIGS. 1 to 7 as urging means for urging the rear cover 20 in the grounding direction in order to level the soil leveled by the rear cover 20. 26 and a gas spring 27.
The abutment device 26 and the gas spring 27 are arranged on the upper side of the rear cover 20 and are juxtaposed in the left-right direction, and are distributed from the center in the left-right direction of the machine frame 2 to the left and right. (One set of urging means is provided by one lowering device 26 and one gas spring 27).

In this embodiment, the gas spring 27 is disposed on the outer side in the left-right direction of the lowering device 26 and below the lowering device 26.
The lowering device 26, as shown in FIGS. 1 and 5, is a lowering rod 28 formed of a pipe provided over the machine frame 2 side and the rear cover 20 side, and is fitted onto the lowering rod 28. And a coil spring 29 for urging the rear cover 20.
The lower rod 28 is disposed above the rear cover 20 and is disposed so as to extend rearward in a state where the rear cover 20 is in the working posture, and the front end side thereof is the rear upper surface side of the upper cover 19. A bracket 30 (referred to as a machine frame side bracket) standing on the end side is pivotally supported, and a rear side of the lowering rod 28 is inserted through a holder 32, and the holder 32 is an upper surface of the rear cover 20. It is provided on a bracket 31 (this is referred to as a rear cover side bracket) erected on the center side in the front-rear direction of the (rear surface).

The machine frame side bracket 30 may be fixed to the support arm 6 as long as it is provided on the machine frame 2 or a member fixed to the machine frame 2.
As shown in FIG. 3, the machine frame side bracket 30 is formed in an open U-shape rearward from the left and right side walls 30a and the front wall 30b connecting the front end sides of the left and right side walls 30a. The front end side of the lowering rod 28 is inserted in the upper part between the side walls 30a, and the front end side of the lowering rod 28 is pivotally attached to the left and right side walls 30a via a pivot 33 so as to be rotatable around a horizontal axis. Thus, the lowering rod 28 can swing up and down around the pivot 33.

As shown in FIG. 3, the rear cover side bracket 31 has a pair of left and right side plates 31a connected in the middle in the vertical direction, and the holder 32 is disposed above the left and right side plates 31a. The shaft portions 34 provided on both the left and right sides are pivoted to the rear cover side bracket 31 by being fitted to support holes 35 formed in the left and right side plates 31a so as to be rotatable around the axis in the left-right direction. It is supported freely.
Further, the holder 32 is formed with an insertion hole 36 extending in a direction perpendicular to the axis of the support hole 35 (shaft portion 34) from the front surface to the rear surface, and the lower rod 28 is inserted through the insertion hole 36. The holder 32 and the lowering rod 28 are relatively movable in the axial direction of the lowering rod 28.

The coil spring 29 is disposed on the front side of the holder 32, and a spring receiving member 37 is provided on the front side of the coil spring 29.
The spring receiving member 37 includes a key 39 that is engaged with a locking groove 38 formed on the surface side of the lower rod 28, and a spring member that urges the key 39 to engage with the locking groove 38. 40, and by engaging the key 39 with the locking groove 38, the spring receiving member 37 is positioned with respect to the lowering rod 28.
Further, a large number of locking grooves 38 are formed at intervals in the axial direction of the lower rod 28, and the key 39 is spring-loaded by rotating the spring receiving member 37 around the axis of the lower rod 28. The key 39 can be detached from the locking groove 38 against the urging force of the spring member 40 and engaged with another locking groove 38 against the urging force of the receiving member 37. By combining them, the position of the spring receiving member 37 with respect to the lowering rod 28 can be changed (the spring receiving member 37 can be positioned at a plurality of positions in the axial direction of the lowering rod 28).

When the rear cover 20 is in the working posture, the coil spring 29 is compressed between the spring receiving member 37 and the holder 32, so that a biasing force that biases the rear cover 20 downward acts on the rear cover 20. . Further, the biasing force on the rear cover 20 can be changed by changing the position of the spring receiving member 37 in a state where the coil spring 29 is compressed between the spring receiving member 37 and the holder 32.
The biasing force of the coil spring 29 is applied to the rear cover by engaging the spring receiving member 37 with the locking groove 38 at the front end or by disengaging the key 39 of the spring receiving member 37 with the locking groove 38. 20 is set to a free state.

A rear end side of the lower rod 28 is provided with a contact 41 that abuts against the rear surface side of the holder 32 to restrict the downward swing of the rear cover 20.
The holder 32 is provided with a lock pin (not shown) that is inserted into a lock hole 42 formed in the lowering rod 28 and restricts relative movement between the holder 32 and the lowering rod 28. A switching lever 43 that switches the position of the lock pin between a lock position for inserting the lock pin into the lock hole 42 and a non-lock position for removing the lock pin from the lock hole 42 is provided.

The switching lever 43 is provided on the upper end side of the holder 32 so as to be rotatable about the axis in the left-right direction. As shown in FIG. When the switch lever 43 is raised, the lock pin can be inserted into the lock hole 42 by the biasing force of the spring.
Further, when the rear cover 20 is in the working posture, the lock pin is in a position disengaged rearward from the lock hole 42. When the switching lever 43 is raised when the lock pin is in this position, the lock pin is moved by the biasing force of the spring. When the rear cover 20 is lifted upward from the working posture, the holder 32 moves to the front side relative to the lower rod 28, and the lock pin is locked to the lock hole. 42, the lock pin is automatically inserted into the lock hole 42 by the biasing force of the spring to restrict the relative movement between the lower rod 28 and the holder 32, and the rear cover 20 is lifted upward from the working posture. It is configured to be held in a different position.

As shown in FIG. 4, the gas spring 27 has a tube 46, a piston 47 provided in the tube 46 so as to be axially movable, and a piston rod 48 that moves integrally with the piston 47, The inside of the tube 46 is divided into a rod-side chamber 46A and a bottom-side chamber 46B by a piston 47, and the rod-side chamber 46A and the bottom-side chamber 46B in the tube 46 communicate with each other by an orifice 49 formed in the piston 47. The tube 46 is filled with compressed gas.
Since the rod-side pressure receiving surface of the piston 47 has a smaller area for receiving the compressed gas sealed in the tube 46 than the bottom-side pressure receiving surface, the piston rod 48 always repels in the extending direction by the difference in the pressure receiving area. I have power.

The gas spring 27 may have another structure (for example, oil in the tube 46), and the piston rod 48 is urged in the extending direction by the compressed gas. That's fine.
Ball joints 53 and 54 (joint members) having fixtures 51 and 52 are provided on the bottom side of the tube 46 of the gas spring 27 and the tip side of the piston rod 48.
One end side (front end side) of the gas spring 27 is pivotally connected to a spring support portion 56 provided on the lower side of the pivot 33 of the machine frame side bracket 30 so as to be rotatable about the left and right axis. The end side (rear end side) is pivotally connected to an operation lever 57 provided on the rear cover side bracket 31 so as to be rotatable about a left-right axis.

In the present embodiment, the spring support portion 56 is configured by a plate material bent in a U-shape and is fixed to the side wall 30a on the outer side in the left-right direction of the machine frame side bracket 30. 27, the fixture 51 of the ball joint 53 on the bottom side of the tube 46 is fixedly attached.
The operation lever 57 is attached to a lever support portion 58 formed of a plate whose base end side is fixed to the side plate 31a on the outer side in the left and right direction of the rear cover side bracket 31 so as to be rotatable around the axis in the left and right direction. The fixing member 52 of the ball joint 54 at the tip of the piston rod 48 of the gas spring 27 is fixedly attached to the middle of the operation lever 57.

A cylindrical member 59 is fixed to the base end side of the operation lever 57 and an insertion hole 60 communicating with the cylindrical member 59 is formed. A pin 61 is fixed to the lever support portion 58 so as to protrude in the left-right direction. The cylindrical member 59 is fitted on the pin 61 so as to be rotatable around the axis, and the pin 61 is protruded from the insertion hole 60 and a retaining member 62 is attached to the distal end side of the pin 61, thereby operating the lever 57. Is supported by the lever support 58 in a freely rotatable manner.
The spring support portion 56 may be provided on the rear cover side bracket 31 and the lever support portion 58 may be provided on the machine frame side bracket 30. Further, the ball joint 54 at the tip of the piston rod 48 may be fixedly attached to the spring support 56 and the ball joint 53 on the bottom side of the tube 46 may be fixedly attached to the operation lever 57.

The operation lever 57 is curved in a circular arc shape, and the ball joint 54 on the front end side of the piston rod 48 is pivotally connected to the middle portion of the operation lever 57.
Further, the gas spring 27 is disposed on the upper side of the rear cover 20 (above the pivotal support 24) when the rear cover 20 is in the working posture, and the pivot point X (the ball joint 53 on the front side of the gas spring 27). Of the rear cover 20 is positioned above the front side of the rotation support shaft 25 of the rear cover 20, and when the rear cover 20 is in the working posture, the gas spring 27 extends toward the rear side (an inclined state close to horizontal). (Or a substantially horizontal state), and the gas spring 27 is arranged in parallel with the rear cover in the vertical direction.

  When the rear cover 20 is in the working posture, the pivot point Y on the other end side of the gas spring 27 (the pivot center of the ball joint 54) is the pivot point X on one end side of the gas spring 27 and the operation lever 57. When the operation lever 57 is positioned below the deadline L (dead point) passing through the rotation fulcrum Z (the rotation center of the operation lever 57), the operation lever 57 is attached in a direction to swing downward. The operation lever 57 is energized and its downward rotation is restricted by a stopper 63 provided on the rear cover side bracket 31. In this state (biased state), the biasing force of the gas spring 27 is Acts to swing the rear cover 20 downward (in the grounding direction) via the operation lever 57, the stopper 63 and the rear cover side bracket 31.

Further, as shown in FIG. 4, the operating lever 57 is operated to rotate upward from the operating position W where the urging force of the gas spring 27 acts so as to swing the rear cover 20 downward. When the pivot point Y on the other end side of the rod 27 is located above the deadline L beyond the deadline L, the urging force of the gas spring 27 acts in the direction of rotating the operation lever 57 to the rear side. The spring 27 is in a fully extended state, and is in a free state in which the urging force of the gas spring 27 does not act on the rear cover 20.
Therefore, when the operating lever 57 is turned (switched), the biasing force of the gas spring 27 acts on the rear cover 20 and the free state where the biasing force of the gas spring 27 does not act on the rear cover 20. The state of the gas spring 27 can be easily switched.

As shown in FIG. 6, in the biased state, the biasing force of the gas spring 27 acts in the direction of swinging the rear cover 20 downward over the entire range of the vertical swing of the rear cover 20, and FIG. As shown in FIG. 5, in the free state, the urging force of the gas spring 27 does not act on the rear cover 20 in the entire range of the vertical swing of the rear cover 20.
In the embodiment, the gas spring 27 is biased and the urging force of the lowering device 26 is not applied to the rear cover 20 so that the rear cover 20 is urged in the grounding direction only by the urging force of the gas spring 27. In addition, the gas spring 27 is in a free state and the urging force of the lowering device 26 is applied to the rear cover 20 to urge the rear cover 20 in the grounding direction only by the urging force of the lowering device 26. In addition, the urging force of the gas spring 27 and the lowering device 26 may be applied to the rear cover 20 or may not be applied together.

Further, when the rear cover 20 is urged only by the lowering device 26, the difference in the urging force of the lowering device 26 is large depending on the vertical position of the rear cover 20, the operating range of the urging force is narrow, and depending on the vertical position of the rear cover 20. However, if the rear cover 20 is biased only by the biasing force of the gas spring 27, the biasing force with respect to the rear cover 20 is made substantially uniform. In addition, it is possible to increase the operating range in which the rear cover can be urged without adjusting the urging force.
Further, in the gas spring 27, when the gas spring 27 is contracted, the pressure inside the tube 46 is increased by the piston rod intrusion integral. However, in this embodiment, the gas spring 27 is in a horizontal state when the rear cover 20 is in the working posture. Therefore, even if the rear cover 20 swings up and down in the working posture, the length of the gas spring 27 does not change so much and the urging force of the gas spring 27 does not change so much. Yes.

  Further, some tractors are provided with a tilling device that controls the tilling depth by raising and lowering the tilling device 1 based on the vertical swing amount of the rear cover 20. In this case, when the rear cover 20 is pushed up by the soil plowed by the tillage unit 3 or stones in the field, the gas is applied so as to give an opposite resistance against the compression of the coil spring 29 of the lowering device 26. By acting on the spring 27, the compression of the coil spring 29 can be slowed, and when the rear cover 20 returns (lowers), the resistance against the return (restoration) of the coil spring 29 of the lowering device 26 is opposite. The return of the coil spring 29 can be delayed by applying the gas spring 27 so as to provide the above.

As a result, when the rear cover 20 moves up due to the pressure of the soil, stones, or the like, the gas spring 27 suppresses the speed and amplitude of the rear cover 20 from moving upward by the action of the gas spring 27, and the rear cover 20 moves down. When moving, the gas spring 27 functions to suppress the downward movement speed and amplitude of the rear cover 20 to attenuate the vertical movement of the rear cover 20 and to suppress the number of continuous swings of the rear cover 20. it can.
That is, compared with the case where the rear cover 20 is urged only by the lowering device 26, when the lowering device 26 and the gas spring 27 are used together, the vertical swing motion of the rear cover 20 is slowed down during plowing. In the case where the vertical movement of the rear cover 20 is detected and plowing depth control is performed, an excessive response is prevented and good plowing depth control can be performed.

FIG. 8 and FIG. 9 show another embodiment. In this embodiment, the lever support portion 58 that supports the operation lever 57 is restricted from rotating downward by the operation lever 57. The stopper 63 is integrally formed (the stopper 63 may be formed separately and fixed to the lever support portion 58).
FIG. 8 shows a state where the rear cover 20 is at the lower limit position of the swing range.
Further, in the embodiment shown in FIGS. 8 and 9, the gas spring 27 is engaged with the operation lever 57 detachably with a stopper 63 (engagement portion) provided on the lever support portion 58. A self-removal restricting tool 64 that restricts the rotation (upward rotation) of the operation lever 57 so that the gas spring 27 is in a free state when is in an urging state is provided.

The self-removal restricting tool 64 is made of an elastic wire such as piano wire or spring steel, and is formed by bending one wire in a folded shape. The wire is placed on one end side and the other end side of the wire. Shaft portions 65 formed by bending inward in the direction are provided, and these shaft portions 65 are formed to have left and right axial cores and to be misaligned with each other.
The self-removal restricting tool 64 is provided so as to sandwich the operation lever 57, and one shaft portion 65 is inserted into one locking hole 66 of a pair of locking holes 66 formed in the operating lever 57, and the other The other shaft 65 is inserted through the locking hole 66.

The shaft portion 65 is provided on one end side in the length direction of the self-removing restriction tool 64, and the other end side in the length direction of the self-removal restriction tool 64 is a U-shaped knob portion 67.
Further, a hook-shaped restricting portion 68 is bent between the shaft portion 65 and the knob portion 67 of the self-removing restricting tool 64, and the urging force of the operating lever 57 and the gas spring 27 is applied to the rear cover 20. With the operating position W acting on the lever, the restricting portion 68 engages with the stopper 63 provided on the lever supporting portion 58 from the lower side, so that the operating lever 57 moves upward about the rotation fulcrum Z. The rotation is restricted.

In this self-removal restricting tool 64, the pair of shaft portions 65 are misaligned with each other. Therefore, the self-removing restricting device 64 is elastically deformed by rotating around the shaft portion 65. Yes, when the self-removal restricting tool 64 is rotated in the direction indicated by the arrow M in FIG. Is set to be pressed against the stopper 63 from above, and in this state, the restricting portion 68 is positioned at a position where it can be engaged with the lower side of the stopper 63.
Further, when the self-removal restricting tool 64 is rotated in the direction indicated by the arrow N in FIG. 8 when the operation lever 57 is at the operating position W, the direction in which the self-removing restricting tool 64 is rotated by an elastic restoring force from the middle. The self-removal restricting tool 64 is held in a state in which it is switched so as to act in the direction indicated by the arrow N and the restriction of the upward rotation of the operation lever 57 by the self-removal restricting tool 64 is released. it can.

The gas spring 27 can be brought into a free state by rotating the operation lever 57 upward from the operating position W in a state where the rotation restriction of the operation lever 57 by the self-removal restricting tool 64 is released.
10 and 11 show another embodiment, and an attachment hole 69 for attaching the ball joints 53 and 54 at the end of the gas spring 27 to the spring support portion 56 and the operation lever 57 is shown. , 70 (in this embodiment, four each, but two, three, or five or more may be provided), and the pivotal support position of the end of the gas spring 27 can be changed. Thus, the urging force with respect to the rear cover 20 of the gas spring 27 can be changed.

  Note that a plurality of attachment holes 69 and 70 may be formed only in the operation lever 57 or only in the spring support portion 56.

It is a side view of the urging means of the rear cover. It is a side view of a tillage device. It is sectional drawing which looked at the attachment part of the left gas spring from the lower side. It is a side view of the attachment part of a gas spring. It is side surface partial sectional drawing of a bouncing apparatus. It is a side view which shows the state which changed the back cover up and down in the state which applied the urging | biasing force of the gas spring. It is a side view which shows the state which changed the back cover up and down in the state which does not apply the urging | biasing force of a gas spring. It is a side view which shows other embodiment. (A) is the figure which looked at the embodiment which concerns on FIG. 8 from the lower side, (b) is B arrow figure of FIG. 8, (c) is C arrow figure of FIG. It is a side view which shows another embodiment. It is the figure which looked at the embodiment which concerns on FIG. 8 from the lower side.

Explanation of symbols

2 Machine frame 3 Tillage part 20 Rear cover 26 Retraction device 27 Gas spring 28 Retraction rod 29 Coil spring 56 Spring support part 57 Operation lever 58 Lever support part 63 Engagement part 64 Self-removal restricting tool 69 Installation hole 70 Installation hole L Dead Line X A pivot point on one end of the gas spring Y A pivot point on the other end of the gas spring Z A pivot point for the operating lever

Claims (6)

A rear cover (20) that covers the rear side of the tillage part (3) provided on the lower side of the machine frame (2) is provided, and the rear cover (20) is supported on the machine frame (2) side so as to be swingable up and down. In addition, in the tilling device provided with the gas spring (27) for urging the rear cover (20) downward over the machine frame (2) side and the rear cover (20) side,
One end side of the gas spring (27) is pivotally supported by a spring support (56) provided on either the machine frame (2) side or the rear cover (20) side, and the machine frame (2) side or the rear cover. An operating lever (57) is provided on the lever support (58) provided on the other side of the (20) side, and the urging force of the gas spring (27) is changed by the switching operation of the operating lever (57). The gas spring (27) is switched to the gas spring (27) so that the gas spring (27) is switched to a free state where the biasing force acting on the gas spring (27) does not act on the rear cover (20). A tilling device characterized by pivotally supporting the other end of (27).   The operation lever (57) is rotatably supported by the lever support portion (58), and the operation lever (57) is rotated from a state in which the gas spring (27) is biased, whereby a gas spring ( The pivot point (Y) on the other end side of 27) exceeds the deadline (L) passing through the pivot point (X) on one end side of the gas spring (27) and the pivot point (Z) of the operating lever (57). The tillage device according to claim 1, wherein the gas spring (27) is configured to be in a free state.   When the gas spring (27) is in a biased state by being detachably engaged with the operating lever (57) by an engaging portion (63) provided on the lever support portion (58) side, the gas spring ( The tilling device according to claim 2, further comprising a self-removal restricting tool (64) for restricting the rotation of the operation lever (57) so that the lever 27 is in a free state.   The tilling device according to claim 1, 2 or 3, characterized in that the pivoting position of the gas spring (27) relative to the operating lever (57) and / or the spring support (56) can be changed.   A bullet that urges the rear cover (20) in the grounding direction by the urging force of a coil spring (29) fitted over the lower rod (28) provided over the machine frame (2) side and the rear cover (20) side. The tilling device according to any one of claims 1 to 4, further comprising a lower device (26).   The rear cover (20) is inclined so as to move downward as it goes rearward in the work posture for leveling the soil cultivated by the tiller part (3), and the front upper end side is a horizontal axis on the machine frame (2) side. A pivot point (X) on the front side of the gas spring (27) is positioned above the front side of the pivot shaft (25) of the rear cover (20), and the gas spring (27) is The tilling device according to any one of claims 1 to 5, wherein when the rear cover (20) is in a working posture, the tiller device extends toward the rear side.

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