[Name of the Document] Specification
[Title of the Invention] “Lever Operating Arrangement for Tractor”
[Technical Field]
[0001]
The present invention relates to a lever operating arrangement for a tractor including an oil pressure position lever movable between a lift arm operating range for operating a lift arm of the tractor and an oil pressure supplying range for supplying an oil pressure of a hydraulic cylinder to the outside, and a restricting member for restricting movement of the oil pressure position lever from the lift arm operating range to the oil pressure supplying range.

[Background Art]
[0002]
As an example of the conventional lever operating arrangement of the above-noted type, there is known an arrangement including a lever guide for guiding an oil pressure position lever and a bolt-fixed restricting member for restricting movement of the oil pressure position lever to the vicinity of the border (the upper limit position of the lift arm operating range) between a lift arm operating range and an oil pressure supplying range that are provided in a guide slot of the lever guide.
[0003]
With the above-described lever operating arrangement, by moving the oil pressure position lever up/down in the guide slot of the lever guide within the lift arm operating range, lifting up/down operations of the left arm can be effected. And, with this lever operating arrangement, the oil pressure takeoff operation of the hydraulic cylinder becomes possible by first removing the restricting member by rotating the fixing bolt and then manually moving the oil position lever from the lift arm operating range to the oil pressure supplying range (see JP2006-129776A).
[0004]
Further, as another type of lever operating arrangement for a tractor, there is known an arrangement including a spring member provided in the vicinity of the border between the lift arm operating range and the oil pressure supplying range. With this different type of lever operating arrangement, if the oil pressure position lever is manually moved to the oil pressure supplying range and then the operator's hand is released there from, due to the elastic of the spring member, the oil pressure position lever is returned automatically to the lift arm operating range.

[Summary of the Invention]
[Problem to be Solved by Invention]
[0005]
In the case of the lever operating arrangement disclosed in the JP2006-129776A described above, there is the need to remove the restricting member. So, there is a risk of the operator's forgetting to attains the restricting member again after completion of the takeoff operation of the oil pressure or losing the restricting member Yet, absent the restriction by the restricting member, the lever will be moved to the oil pressure supply range unnecessarily, so that there are such risks as loss of power, rise of oil temperature, breakdown of the hydraulic components, etc.
In the case of the latter type of lever operating arrangement, when a worker is to operate the oil pressure position lever to the oil pressure supplying range, the worker needs to operate the oil position lever to the oil pressure supplying range against the elastic resilience of the ring member. That is, the worker needs to exert a greater amount of force when operating the oil pressure position lever in the oil pressure supplying range. Therefore, this further type of lever operating arrangement suffers poor operating performance of the oil pressure lever in the oil pressure supplying range.
[0006]
The object of the present invention is to provide a lever operating arrangement which is free fort)m the troublesome reattachment of the restricting member or the accidental loss of this member and which also allows easy and smooth movement of the oil pressure position lever between the lift arm operating range and the oil pressure supplying range.

[Means to Solve Problem]
[0007]
A lever operating arrangement for a tractor, according to the present invention, comprises an oil pressure position lever movable between a lift arm operating range for operating a lift arm of the tractor and an oil pressure supplying range for supplying an oil pressures of a hydraulic cylinder to the outside; and a restricting member for restricting movement of the oil pressure position lever from the lift arm operating range to the oil pressure supplying range!
wherein the restricting member can be manually switched over from a locking state for restricting the movement of the oil pressure position lever from the lift arm operating range to the oil pressure supplying range and a non-locking state for not restricting the movement of the oil pressure position lever from the lift arm operating range to the oil pressure supplying range; and
wherein the restricting member is automatically switched over to the locking state if the restricting member is manually operated first to the non-locking state to move the oil pressure position lever to the oil pressure supplying range and thereafter the oil pressure position lever is moved to the lift arm operating resurge.
[0008]
With the above-described construction, in order to take off an oil pressure, the restricting member will be manually switched over to the non-locking state first and then the oil pressure position lever will be moved fixed the lift arm operating range to the oil pressure supplying range. Therefore, there is no need to take the trouble of removing the restricting member for switching over to the non-locking state! thus, there is no trouble of reattachment of the restricting member or no risk of accidental loss of the restricting member.
Further, with this construction, when the pressure position lever is moved back to the lift arm operating range after completion of oil pressure takeoff the restricting member is automatically switched over to the locking state. Therefore, there does not occur the worker's forgetting to return the restricting member to the locking state.
Moreover, with this construction, there is no need to provide the oil pressure position lever with any urging means such as the spring member described above Therefore, the oil pressure position lever can be easily and smoothly moved between the lift arm, operating range and the oil pressure supplying range. So, the construction provides good operating performance also.
[0009]
In the above-described construction, preferably, the arrangement further comprises a spring member for switching over the restricting member from the non-locking state to the locking state, and when the oil pressure position lever is located in the oil pressure supplying range, the restricting member minder the non-locking state comes into abutment against a lateral face of the oil position lever from a direction perpendicular to the moving direction of the oil pressure position lever and presses the lateral face of the oil pressure position lever under the urging force of the spring member.
[0010]
With the above-described construction, the oil pressure position lever is maintained in the oil pressure supplying range by the pressing force from the restricting member. Therefore, the takeoff operation of oil pressure from the hydraulic cylinder can be carried out in a reliable manner. With this construction, when the oil pressure position lever is moved from the oil pressure supplying range to the lift arm operating range, the oil pressure position lever is moved with its lateral face being kept in contact with the restricting member. Therefore, a frictional force is generated between this oil pressure position lever and the restricting member. However, this frictional force does not provide so much resistance as to hinder time movement of the oil pressure position lever.
[0011]
In the above-described construction, preferably, separately from the locking state and the non-locking state, there is furnisher provided an intermediate state for maintaining the restricting member at a position not restricting the movement of the oil pressure position lever to the oil pressure supplying range, but being free from abutment against the lateral &ice of the oil pressure position lever, against the urging force of the spring member, and
wherein if the oil pressure position lever is moved fixed the lift arm operating range to the oil pressure supplying range with the restricting member being set to the intermediate state, the restricting member is switched over from the intermediate state to the non-locking state.
[0012]
With the above-described construction, when effecting an oil pressure takeoff operation from the hydraulic cylinder, the worker can set the restricting member to the intermediate state End then operate the oil pressure position lever to the oil pressure supplying range. Therefore, the worker does not need to operate the restricting member and the oil pressure position lever at one time. Hence, the operability may be further improved.

[Brief Description of the Drawings]
[0013]
[Fig. l] an overall side view of a tractor,
[Fig. 2] a side view of a dump trailer connected to the tractor,
[Fig. 3] a plane view showing the coupling portion between the tractor and the dump trailer,
[Fig. 4] a diagram showing a hydraulic circuit for position control,
[Fig. 5] (a) a side view, (b) a front view in vertical section, and (c) a plane view, of a lever operating arrangement when a restricting member is under a locking state,
[Fig. 6] (a) a side view, (b) a front view in vertical section, and (c) a plane view, of the lever operating arrangement when the restricting member is under an intermediate state,
[Fig. 7] (a) a side view, (b) a front view in vertical section, and (c) a plane view, of the lever operating arrangement when the restricting member is minder a non-locking state,
[Fig. 8] (a) a side view, (b) a front view in vertical section, and (a) a plane view, of a lever operating arrangement when the restricting member is under the locking state,
[Fig. 9] a perspective view of the lever operating arrangement, and
[Fig. 10] a plane view of a lever operating arrangement according to a further embodiment.
[Mode of Embodying the Invention] [0014]
Next, an embodiment of the present invention will be described with reference to Fig. 1-9.
[General Construction of Tractor]
With reference to Figs. 1-3, there will be described a tractor having a lever operating arrangement relating to the present invention.
As shown in Pig. 1-3, this tractor induces steer able front wheels 1 and rear wheels 2 as propelling wheels. And, an engine 3 is mounted on a front portion of the body of this tractor and on the rear portion of the vehicle body, there are mounted a three-point link mechanism 4 for allowing coupling of an implement such as a rotary plow and a pair of right and left lift arms 5 for driving the three-point hunk mechanism 4 up/down. Further, a driver's seat 6 is between the right and left rear wheels 2 of the tractor.
[0015]
Fig. 4 shows a hydra circuit for hydraulically driving the lift arms 5. The lift arms 5 are driven by a single-action type hydraulic cylinder 7. When a pressure oil is supplied from a pump 31 driven by the engine 3 to the hydraulic cylinder 7, the hydraulic cylinder 7 is expanded to lift up the lift arms 5. When the oil is discharged from the hydraulic cylinder 7, the hydraulic (under 7 is contracted to allow the lift arms 5 to gravity-fall due to the weights thereof. The hydraulic cylinder 7 is operated and controlled by a position control valve 8.
[0016]
The position control valve 8 includes a main spool 11, a lowering valve 12, a relief valve 13, a check valve 36, a pilot-operation type check valve 34, etc. The hydrauhc cylinder 7 is connected to a cylinder port 14 of the position control valve 8 via a -speed adjusting valve 15. Between the hydraulic cylinder 7 and the falling-speed adjusting valve 15, a relief valve 35 is connected. A dump cylinder 10 is provided for lifting up/down a load deck 29 of a dump trailer 23. This dump cylinder 10 is removable connected to an oil pressure takeoff portion 16 provided between the hydrauhc cylinder 7 and felling-speed adjusting valve 15.
[0017]
A balance hunk 17 is privately connected, via its coupling point 17a provided midway in the right/left direction thereof, to an end of the main spool 11. To opposed ends of this balance 17, there are engaged a position adjusting arm 18a extended from a position adjusting shaft 18 and a feedback arm 19a extended from a feedback shaft 19. And, the position adjusting shaft 18 and the oil pressure position lever 20 disposed on the right side of the driver's seat 6 to be pivotal in the front/back direction are mechanically coupled with each other via a coupling link 32. The feedback shaft 19 and the lift arms 5 are mechanically coupled with each other via a feedback 33.
[0018]
The position control valve 8 having the above-described construction operates as follows when the dump cylinder 10 is not connected thereto. The condition shown in Fig. 4 is a neutral state where the oil pressure position lever 20 is maintained at an operational position in a lift arm operating range A. Under this neutral state, the main spool 11 is maintained at a neutral

position UN and the lowering valve 12 is maintained at a path closing position, so that the pilot pressure of the check valve 34 to the closing side is absent. Under this neutral state, the pressure oil from the pump 31 is discharged via the check valve 34 and the flow of the pressure oil from the hydraulic cylinder 7 is stopped by the check valve 36 and the path closing position of the lowering valve 12. [0019]
If the oil pressure position lever 20 is operated from the neutral state shown in Fig. 4 to an up U (elevating) side, in association with this operation, the adjusting arm 18a is pivoted counterclockwise in Fig. 4 around the position adjusting shaft 18. And, the balance link 17 is pivoted downward in the figure about its point of engagement with the feedback arm 19a, whereby a coupling point 17a is moved downward in the figure. With this downward movement of the coupling point 17a in the figure, the main spool 11 too is moved downward in the figure. Therefore, with the lowering valve 12 being maintained at the path closing position, the main spool 11 is switched over to an UP position IIU. And, the check valve 34 is maintained under the closed state due to the pilot pressure of a pilot oil passage 37 and also the relief valve 13 is maintained under the closed state due to the pilot pressure of a pilot oil passage 38. And, as the pressure oil is supplied fixed the cylinder port 14 to the hydraulic cylinder 7, the lift arms 5 are elevated.
[0020]
In association with the elevation of the limb arms 5, this displacement of the lift arms 5 is transmitted via the feedback link 33 to the feedback shaft 19, so that the feedback arm 19a is pivoted counter-clockwise in . 4 aroid the feedback shaft 19. And, the balance link 17 is pivoted upward in the figure about its point of engagement with the adjusting arm 18a, whereby the coupling point 17a is moved upward in the figure. With this upward movement of the coupling point 17a in the figure, the main spool 11 too is moved upward in the figure. And, as the main spool 11 is moved upward in the figure to be switched over to the neutral position UN, the upward movement of the lift arms 5 is stopped.
[0021]
Further, if the oil pressure position lever 20 is operated fixed the neutral state shown in Fig. 4 to a down D (lowering) side, in association with this operation, the adjusting arm 18a is pivoted clockwise in Fig. 4 around the position adjusting shaft 18. And, the balance link 17 is pivoted upward in the figure about its point of engagement with the feedback arm 19a, whereby the coupling point
17a is moved upward in the figure. With this upward movement of the coupling point 17a in the figure, the main spool 11 too is moved upward in the figure to be switched over to a DOWN position IID, and also the lowering valve 12 is pushed upward in the figure by a branching portion 11a extending fix)m the main spool 11, to be switched over to a path opening position. As a result, the cylinder port 14 becomes communicated to the tank via the lowering valve 12, thus allowing oil discharge from the hydrauhc cylinder 7. As a result, the lift arms 5 are allowed to fall due to the weights of their own.
[0022]
In association with the lowering of the lift arms 5, this displacement of the lift arms 5 is transmitted via the feedback link 33 to the feedback shaft 19, so that the feedback arm 19a is pivoted clockwise in Fig. 4 around the feedback shaft 19. And, the balance link 17 is pivoted downward in the figure about its point of engagement with the adjusting arm 18a, whereby the coupling point 17a is moved downward in the figure. With this downward movement of the coupling point 17a in the figure, the main spool 11 too is moved downward in the figure to be switched over to the neutral position UN, and the lowering valve 12 is switched over to the path closing position, whereby the lowering movement of the lift arms 5 is stopped.
[0023]
That is to say, when the oil pressure position lever 20 is operated within a lift arm operating range A of a lever guide 21, the lift arms 5 are moved up/down to the height corresponding to the position of the oil pressure position lever 20 and then automatically stopped. Incidentally, when the oil pressure position lever 20 is operated to its upper limit position, the lift arms 5 will be moved to a position slightly lower than the mechanical upper limit of the lift arms 5 per se. Further, when the oil pressure position lever 20 is operated to the lowermost position, the feedback operation associated with a lowering displacement of the lift arms 5 is rendered inactive or uninvolved, so that the main spool 11 will not be returned to the neutral position UN, but will be maintained at the DOWN position IID. That is, under the condition of the oil pressure position lever 20 being operated and set to the lowermost position, there is provided a state where the lift arms 5 can be lowered by the weights of their own to the mechanical lower limit, i.e. the so-called, floating state.
[0024]
Further, by moving the oil pressure position lever 20 to an oil pressure supposing range B in the lever guide 21, the oil pressure of the hydraulic cylinder 7 can be taken off to be supplied to an external implement such as the dump trailer 23, etc.
[0025]
[Lever Operating Arrangement]
As shown in Fig. 9, the lever operating arrangement includes the oil pressure position lever 20, the lever guide 21 and a restricting member 24.
[0026]
As shown in Fig. 9, a guide slot 22 elongate in the front/belt direction is formed in the lever guide 21 disposed on the right side of the driver's seat 6. As shown in Fig. 5 (a) through Fig. 8 (a), in the guide slot 22, there are provided the lift arm operating range A for operating the lift arms 5 of the tractor and the oil prestige supplying range B for supplying an oil pressure of the hydraulic pincer 7 to the outside.
[0027]
The oil pressure position lever 20 extends through the guide slot 22 and at its pivot point P, there is provided a friction maintaining mechanism 25 utilizing a plate spring. With this construction, the oil pressure position lever 20 is movable between the lift arm operating range A and the oil pressure supplying range B and can be maintained at a desired position within these ranges.
[0028]
As shown in Fig. 9, the restricting member 24 is formed by welding and integrating two roomed bar members bent in L-shape and having differing lengths, and combined together in the F-shape. Thus, the restricting member 24 includes a short shaft portion 24a, a long shaft portion 24b and a grip portion 24c.
[0029]
The short shaft portion 24a of the restricting member 24 extends through two opposed side walls 26a, 26a of a bracket 26 having a U-shaped cross section and fixedly welded to the lower face of an upper portion of the lever guide 21. With this construction, the restricting member 24 is pivotally connected to the bracket 26 to be pivotally collapsible in the front/back direction about an axis X of its short shaft portion 24a. Incidentally, on the outer periphery of the short shaft portion 24a of the restricting member 24, there is provided a spring member 27 to be disposed on the inner side of the bracket 26. The restricting member 24 is attached to the bracket 26 such that the member 24 can be automatically moved to the right direction of the vehicle body (the direction from the right side to the left side in Fig. 5 (b)) due to the elastic resilience of the spring member 27.
[0030]
At an upper left side portion of the lever guide 21, there is provided an L-shaped cutout 28 consisting of a deep portion 28a, a shallow portion 28b and an accurate guide portion 28c.
[0031]
Under the condition where the dump cylinder 10 is not connected, in order for a worker to effect a lifting operation of the lift arms 5, the worker will need first to set the oil pressure position lever 20 immovable fix)m the lift arm operating range A to the oil pressure supplying range B (that is, restricting the movement of the oil pressure position lever 20 from the lift arm operating range A to the oil pressure supplying range B).
[0032]
To the above end, as shown in Fig. 5, the short shaft portion 24a of the restricting member 24 will be set in the vicinity of the border C (vicinity of the upper Omit position of the lift arm operating range A) between the lift arm operating range A and the oil pressure supplying range B, so that the short shaft portion 24a will project into the pivotal path of the oil pressure position lever 20.
[0033]
In the above condition, as shown in Fig. 5 (c), the short shaft portion 24a of the restricting member 24 extends perpendicular to the guide slot 22 of the lever guide 21 as seen in its plane view. And, as the grip portion 24c of the restricting member 24 is disposed at the deep portion 28a of the cutout 28, the long shaft portion 24b of the restricting member 24 is disposed rearward of the short shaft portion 24a as seen in the plane view. The state of the restricting member 24 under the above condition will be referred to as a "locking state", hereinafter.
[0034]
When the restricting member 24 is minder the locking state, even if the worker attempts to move the oil pressure position lever 20 from the lift arm operating range A to the oil pressure supplying range B, the oil pressure position lever 20 cannot be moved more upward than the above-described border vicinity C, since the oil pressure position lever 20 will come into abutment against the short shaft portion 24a of the restricting member 24 at this border vicinity C. That is, when the restricting member 24 is under the locking state, the worker can move the oil pressure position lever 20 within the lift arm operating range A, but cannot move it to the pressure supplying range B.
[0035]
On the other hand, when the worker desires to take off the oil pressure of the hydride cylinder 7 to supply this oil pressure to the external implement such as the dumping trailer 23, etc., as shown in Fig. 6, first, the worker will grip the grip portion 24c of the restricting member 24 and it toward the vehicle right/left center side (the right side in Fig. 6 (b)) against the elastic resilience of the spring member 27, thus moving the restricting member 24. Thereafter, the worker will keep pulling the grip portion 24c and privately collapse it rearward about the axis X of the short shaft portion 24a, thereby to place the grip portion 24c to the shallow portion 28b of the cutout 28. The state of the restricting member 24 under this condition wile be referred to as an "intermediate state", hereinafter. [0036]
Under the intermediate state, the restricting member 24 does not check or restrict movement of the oil pressure position lever 20 to the oil pressure supplying range B and also the restricting member 24 is maintained at a position free from the abutment against the lateral face of the oil pressure position lever 20, against the spring member 27. Namely, as shown in Figs. 6 (b), (c), the short shaft portion 24a of the restricting member 24 will be moved away from the pivotal path of the oil pressure position lever 20 and the long shaft portion 24b of the restricting member 24 is placed slightly forwardly of the short shaft portion 24a as seen in the plane view to project into the pivotal path of the oil pressure position lever 20.
[0037]
Next, as shown in Fig. 7, when the worker moves the oil pressure position lever 20 to the oil pressure supplying range B, the long shaft portion 24b of the restricting member 24 will be pushed rearward by the oil pressure position lever 20. Then, the restricting member 24 will be pivotally collapsed forwardly about the axis X of its short shaft portion 24a and the grip portion 24c will be removed from the shallow portion 28b of the cutout 28. As a result, the short shaft portion 24a of the restricting member 24 will be moved to the right side of the vehicle (the direction from the right side to the left side in Fig 7 (b)), due to the elastic resilience of the spring member 27 and then come into abutment against the left side face of the oil pressure position lever 20, from the direction perpendicular to the moving direction of the oil pressure position lever 20, that is, the direction perpendicular to the guide slot 22 of the lever guide 21 as seen in the plane view.
Namely, the short shaft portion 24a of the restricting member 24 will press the left side face of the oil pressure position lever 20, due to the elastic resilience of the spring member 27.
[0038]
The state of the restricting member 24 under the above condition will be referred as to as a "non-locking state", hereinafter. Under this un-locking state, the restricting member 24 does not restrict the movement of the oil pressure position lever 20 from the lift arm operating range A to the oil pressure supplied range B. Therefore, the worker now can take off the oil pressure of the hydraulic cylinder 7 by moving the of pressure position lever 20 to the oil pressure supplying range B. In this oil pressure supplying range B, the feedback link 33 is not activated, so that the oil pressure can be supposed continuously. With this, the dump cylinder 10 is expanded to lift up the load deck 29 of the dump trailer 23.
[0039]
Incidentally, in the case of moving the oil pressure position lever 20 from the lift arm operating range A to the oil pressure supplying range B, if the oil pressure position lever 20 is placed in the lift arm operating range A, the lift arms 5 to which the implement is not connected will move upward to reach the upper limit position as described above. Whereas, as the dump cylinder 10 is subjected to the load of the load deck 29, actually, the dump cylinder 10 will not be activated and the load deck 29 will not be lifted up.
[0040]
And, in the case of lowering or stopping movement of the load deck 29 of the damp trailer 23, as shown in Fig. 8, when the oil pressure position lever 20 is moved to the lift arm operating range A, the abutment of the short shaft portion 24a of the restricting member 24 against the left side face of the oil pressure position lever 20 is released.
[0041]
In case the oil pressure position lever 20 has been operated from the oil pressure supplying range B to the lift arm operating range A, if the pressure of the oil pres8iu:e takeoff portion 16 is relatively high, as the lift arms 5 to which the implement is not connected is now located at the upper limit position, the main spool 11 will not be switched over to the neutral position UN. As a result, the dump cylinder 10 will be contracted continuously, so the load deck 29 will be lowered continuously. Then, if the figuring-speed adjusting valve 15 is operated to allow the hydraulic cylinder 7 also to be contracted in association with the contracting movement of the dump cylinder 10, the feedback link 33 will now become operative in the lift arm operating range A. As a result, the contacting movement of the dump cylinder 10 will be stopped at the position corresponding to the operated position of the oil pressure position lever 20, so the lowering movement of the load deck 29 too will be stopped.
[0042]
In the course of the movement of the oil pressure position lever 20 from the oil pressure supplying range B to the lift arm operating range A, the oil pressure position lever 20 is moved with the short shaft portion 24a of the restricting member 24 being in kept in abutment against the lateral face of the lever. Therefore, a frictional force is generated between the oil pressure position lever 20 and the short shaft portion 24a of the restricting member 24, but this frictional force is not so significant as to hinder the movement of the oil pressure position lever 20.
[0043]
And, the short shaft portion 24a of the restricting member 24 will be moved to the right direction (the direction from the right side to the left side in Fig. 5 (b)) of the vehicle body due to the elastic resilience of the spring member 27 to be automatically switched over to the locking state. In the course of this, the short shaft portion 24a of the restricting member 24 will become perpendicular to the guide slot 22 of the lever guide 21 as seen in the plane view, in the border vicinity C (adjacent the upper limit position of the lift arm operating range A) between the lift arm operating range A and the oil pressure supplying range B, thus projecting into the pivotal path of the oil pressure position lever 20 and the grip portion 24c of the restricting member 24 will extend into the deep portion 28a via the accurate guide portion 28c of the cutout 28.
With the above-described construction, as the restricting member 24 is configured to be automatically switched over firm the non-locking state to the locking state, the worker does not need to worry about forgetting to return the restricting member 24 to the locking state.
[0044]
[Further Embodiments]
[l] As shown in Fig. 10, the restricting member 24 in the foregoing embodiment can be comprised of a bar-hike member having a tapered face 24d at its leading end, a spring member 27, and an U-shaped bracket 26. That is, in this construction, as shown in Fig. 10 (a), when the oil pressure position lever 20 is located in the lift arm operating range A, the restricting member 24 projects into the pivotal path of the oil pressure position lever 20, thus providing the locking state.
And, as shown in Fig. 10 (b), if the worker has moved the oil pressure position lever 20 to the oil pressure supplying range B with keeping the restricting member 24 pulled away from the pivotal path of the oil pressure position lever 20 and then attempts to move the oil pressure position lever 20 again to the lift arm operating range A as shown in Fig. 10 (c), the oil pressure position lever 20 will come into abutment against the tapered face 24d of the restricting member 24.
With the above, the restricting member 24 will be pushed up away from the pivotal path of the oil pressure position lever 20, so the worker can now move the oil pressure position lever 20 to the lift arm operating range A. And, when the worker moves the oil pressure position lever 20 to the lift arm operating range A, the restricting member 24 will be moved by the elastic resilience of the spring member 27, thus being automatically switched over again to the locking state as shown in Fig. 10 (a).

[Industrial Applicability]
[0045]
The present invention is useful for a tractor which effects switchover between a lift arm operation and an oil pressure takeoff operation from a hydraulic cylinder.
[Description of Reference Marks]
[0046]
5 lift arms
7 hydride cylinder
20 oil pressure position lever
24 restricting member
27 spring member
A lift arm operating range
B oil pressure supplying range

[Name of the Document] Claims
[claim 1] A lever operating arrangement for a tractor, comprising:
an oil pressure position lever (20) movable between a lift arm operating range (A) for operating a lift arm (5) of the tractor and an oil pressure supplying range (B) for supplying an oil pressure of a hydraulic cylinder (7) to the outside; and a restricting member (24) for restricting movement of the oil pressure position lever (20) from the lift arm operating range (A) to the oil pressure supplying range (B); wherein the restricting member (24) can be manually switched over from a locking state for restricting the movement of the oil pressure position lever (20) from the lift arm operating range (A) to the oil pressure supplying range (B) and a non-locking state for not restricting the movement of the oil pressure position lever (20) from the lift arm operating range (A) to the oil pressure supplying range (B); and wherein the restricting member (24) is automatically switched over to the locking state if the restricting member (24) is manually operated first to the non-locking state to move the oil pressure position lever (20) to the oil pressure supplying range (B) and thereafter the oil pressure position lever (20) is moved to the lift arm operating range (A).
[claim 2] The lever operating arrangement for a tractor according to
claim 1, further comprising a spring member (27) for switching over the restricting member (24) from the non-locking state to the locking state, and wherein when the oil pressure position lever (20) is located in the oil pressure supplying range (B), the restricting member (24) under the non-ladling state comes into abutment against a lateral face of the oil pressure position lever (20) from a direction perpendicular to the moving direction of the oil pressure position lever (20) and presses the lateral face of the oil pressure position lever (20) under the urging force of the spring member (27).
[claim 3] The lever operating arrangement for a tractor according to claim 2, wherein separately from the locking state and the non-locking state, there is further provided an intermediate state for maintaining the restricting member (24) at a position not restricting the movement of the oil pressure position lever (20) to the oil pressure supplying range, but being free from abutment against the lateral face of the oil pressure position lever (20), against the urging force of the spring member (27), and wherein if the oil pressure position lever (20) is moved from the lift arm operating range (A) to the oil pressure supplying range (B) with the restricting member (24) being set to the intermediate state, the restricting member (24) is switched over from the intermediate state to the non locking state.