Work vehicles

Abstract

The objective is to provide a work vehicle with minimal changes from the existing component configuration when modifying the front axle tread. [Solution] In a work vehicle comprising an axle housing 41 providing an axle 44 for driving the steering wheels 10, a final case 42 providing a wheel axle 42b connecting the steering wheels 10, and an intermediate case 43 having a kingpin 45 and connecting the axle housing 41 and the final case 42, a stopper 50 is provided on the axle housing 41 to restrict the range of motion of the final case 42 to rotate around the kingpin 45. Furthermore, a support plate 52 is fixed to the axle housing 41B, and the stopper 50 is provided on the support plate 52, and the stopper 50 has an end face portion 50a that can contact the outer end face portion 46a of a projection 46 formed on the intermediate case 43.

Description

Technical Field

[0001] This invention relates to a work vehicle such as an agricultural tractor, a ride-on mower, or an aerial work platform.

Background Art

[0002] In a work vehicle with a variable tread width, the cut-off angle stopper is arranged at a position away from the rotation center of the front wheels and has a function of restricting the rotation of the front wheels that are steered along with the operation of the steering wheel. And the cut-off angle stopper is configured to adjust the mounting position of the mounting member by providing a plurality of adjustment holes on the base side of the mounting member, or to adjust by providing a plurality of adjustment holes on the tip side of the mounting member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0004] According to the configuration of Patent Document 1, since the range of the front wheel cut-off angle can be adjusted by providing a plurality of adjustment holes, there is an effect that a suitable cut-off angle can be selected corresponding to the tread width, but the configuration is complicated.

[0005] An object of this invention is to provide a work vehicle with fewer changes from the existing component configuration in the tread change of the front axle.

Means for Solving the Problems

[0006] To solve the above problems and achieve the objective, the invention described in claim 1 provides a work vehicle comprising an axle housing 41 providing an axle 44 for driving a steering wheel 10, a final case 42 providing a wheel axle 42b connecting the steering wheel 10, and an intermediate case 43 having a kingpin 45 and connecting the axle housing 41 and the final case 42, wherein the axle housing 41 is provided with a stopper 50 that restricts the range of motion of the final case 42 to rotate around the kingpin 45.

[0007] The invention described in claim 2 is the invention described in claim 1, wherein a support plate 52 is fixed to the axle housing 41B, the stopper 50 is provided on the support plate 52, and the stopper 50 has an end face portion 50a that can contact the outer end face portion 46a of the projection 46 formed on the intermediate case 43.

[0008] The invention described in claim 3 is the invention described in claim 2, wherein the projection 46 has an upper end surface portion 46u and a lower end surface portion 46d, and the support plate 52 side has an upper restricting portion 52u that can contact the upper end surface portion 46u and a lower restricting portion 52d that can contact the lower end surface portion 46d. [Effects of the Invention]

[0009] According to the invention described in claim 1, the axle housing 41 is provided with a stopper 50 that restricts the range of motion of rotation around the kingpin 45 of the final case 42, so no special configuration is required for the intermediate case 43 and the final case 42. Therefore, when configuring the axle housing 41 with different left and right lengths to create different tread specifications, the intermediate case 43 and the final case 42 can be shared.

[0010] According to the invention described in claim 2, in addition to the effects described in claim 1, when the final case 42 comes into contact with the stopper 50, it is possible to prevent the stopper 50 from shifting inward toward the machine body.

[0011] According to the invention described in claim 3, in addition to the effects described in claim 2, vertical displacement can be prevented when the projection 47 of the final case 42 comes into contact with the stopper 50. [Brief explanation of the drawing]

[0012] [Figure 1] Overall side view of a tractor according to an embodiment of the present invention [Figure 2] Tractor rear view diagram [Figure 3] Horizontal cross-sectional view of the rear axle case showing the tread adjustment device. [Figure 4] Schematic diagram showing the control mechanism of the tread adjustment device. [Figure 5] Cross-section of the front axle case [Figure 6] Partial perspective view of the front axle [Figure 7] A perspective view of a portion of the front axle with a stopper attached. [Figure 8] (A) Front view of a portion of the front axle with a stopper attached, (B) Top view thereof [Figure 9] Enlarged plan view of the stopper [Modes for carrying out the invention]

[0013] The present invention will now be specifically described with reference to an embodiment of a tread adjustment device equipped on an agricultural tractor as shown in the drawings.

[0014] First, as shown in Figures 1 and 2, the tractor 5 has an engine 7 mounted in the front bonnet 6, and a clutch housing housing the main clutch and a transmission case 8 housing a gear-type transmission are integrally connected to the rear of the engine 7. Then, tread-adjustable rear axle cases 9 are provided on both the left and right sides of the transmission case 8, and wheels 2, 2 are axled and mounted on the ends of the cases 9 on both the left and right sides.

[0015] Below the engine 7, a front axle case is provided so as to be rollable around the front and rear axis, and front wheels 10 are provided on both side ends thereof so as to be steerable.

[0016] The driver's seat 11 is provided inside a cabin 12 mounted on the vehicle body, and a meter panel 13, a steering wheel 14, and various operation levers are centrally arranged in the front. Also, various setting devices such as a tread adjustment set switch 15 and a tread width setting dial 16, which will be described later, are provided near the levers, and these setting signals are output to a controller 17, which is a control unit below the driver's seat 11.

[0017] In FIG. 1, a cylinder case 18 with a hydraulic cylinder for lifting the working machine is provided at the upper rear part of the transmission case 8. The lift arm 19 is configured to rotate up and down by extending and retracting the piston of the hydraulic cylinder in the cylinder case 18, and to lift and lower a rear rotary tiller 20 connected thereto.

[0018] Next, the tread adjustment device will be described.

[0019] First, in FIG. 3, drive shafts 26, 26 extending from a rear wheel differential mechanism 25 arranged in the center to both left and right sides transmit running power to left and right transmission cylinder shafts 29, 29 via brake devices 27, 27 and reduction devices 28, 28, respectively. On the other hand, the left and right wheels 2, 2 are each axially mounted on wheel shafts 30, 30, and further, the wheel shafts 30, 30 are supported by wheel support cases 31, 31 by bearings.

[0020] As shown in Figure 3, the wheel shafts 30, 30 are spline-fitted to the transmission shafts 29, 29 on the vehicle 1 side so that the wheels 2, 2 at their ends (outer) can extend and retract freely from side to side, allowing the driving power from the rear wheel differential mechanism 25 to be transmitted to the wheels 2, 2. The hydraulic cylinders 3, 3 for tread adjustment have a cylinder rod 33 fixed to the housing case 34 (on the inner transmission shaft 29 side) and are installed between the transmission shafts 29, 29 and the wheel support cases 31, 31. They consist of a left cylinder chamber 3L and a right cylinder chamber 3R, and the tread can be adjusted by the extension and retraction of the two chambers 3L and 3R.

[0021] In Figure 3, the hydraulic cylinders 3,3 are shown in a retracted state on the left and in an extended state on the right.

[0022] In this case, as shown in Figure 3, the left and right hydraulic valves 4,4 are connected by pipes 35, 35 to the oil tank T (pump P) and the two chambers 3L, 3R on the hydraulic cylinder 3,3 sides, respectively. Oil is supplied and discharged from the left pipe 35 to the left cylinder chamber 3L, and from the right pipe 35 to the right cylinder chamber 3R, and these valves are configured to expand and contract.

[0023] In Figures 3 and 4, reference numeral 36, 36 denotes stroke sensors, which measure the extension and retraction stroke of the hydraulic cylinders 3, 3 and output the result to the controller 17. Reference numeral 37 denotes an input shaft rotation sensor, which detects the rotation of the wheels 2, 2.

[0024] The tread adjustment device configured as described above is controlled by the controller 17 shown in Figure 4. The tread width to be adjusted is set in advance using the tread width setting dial 16, and then the tread adjustment set switch 15 is turned ON.

[0025] As described above, the tread adjustment device configured in this way first sets the tread width to be adjusted by operating the tread width setting dial 16. Next, when the operator turns on the tread adjustment set switch 15, the controller 17 checks the detection information from the rotation sensor 37 and, only if the wheels 2,2 are rotating, outputs a control signal to control and switch the hydraulic valves 4,4 to perform tread adjustment. Then, the hydraulic cylinders 3,3 are supplied with hydraulic fluid via the hydraulic valves 4,4 and move the wheels 2,2 to the set position.

[0026] Then, once the set tread adjustment is complete, the controller 17 outputs a control signal to perform a zoom output in the opposite direction to the zoom output described above, thereby controlling the hydraulic valves 4,4 and causing the hydraulic cylinders 3,3 to zoom.

[0027] Next, the configuration for adjusting the tread of the front axle 40, which supports the front wheels 10 as steering wheels, will be described.

[0028] In Figure 5, the front axle 40 consists of a central axle housing 41 mounted on an axle bracket so as to be able to swing from side to side, a final case 42 that supports the front wheels 10, and an intermediate case 43 that connects the axle housing 41 and the final case 42. The axle housing 41 is equipped with a differential mechanism (not shown) that transmits the input power to the left and right front axles 44, 44, and the intermediate case 43 has an input shaft 43a and a bevel gear group 43b that are coaxial with the front axles 44. The final case 42 has a final reduction gear mechanism 42a and a wheel axle 42b and is configured to rotate around a kingpin 45 relative to the intermediate case 43. The intermediate case 43 has a spline shaft 43c that connects the front axles 44 and the input shaft 43a, and is flange-connected to the axle housing 41 to form an integrated structure.

[0029] Furthermore, by rotating the steering handle 14, the left and right front wheels 10, 10 can be steered around the kingpin 45 via the steering cylinder means, tie rods 48, knuckle arms 49, etc.

[0030] In adjusting the tread of the front axle 40, there is a configuration in which an extended cylindrical portion extending from the intermediate case 43 is inserted in an overlapping state through the left and right cylindrical portions of the axle housing 41, and the intermediate case 43 is moved in and out in the front axle axis direction to adjust the tread (Japanese Patent Application Publication No. 2009-6960). However, this requires a guide case and adjustment fixing device, which complicates the configuration.

[0031] As an alternative configuration, as shown in Figure 5, multiple axle housings 41A and 41B with different left and right width dimensions are prepared in advance by varying the lengths of the left and right cylindrical portions of the axle housing 41, thereby changing the tread width. In Figure 5, the width of axle housing 41B is shorter than the standard width shown for axle housing 41A. The lengths of the front axles 44A and 44B are also set according to the axle housings 41A and 41B.

[0032] Therefore, since the tread change is determined by the difference in the width dimensions of the axle housings 41A and 41B, the sub-assemblies of the final case 42 and the intermediate case 43 connecting it can be shared.

[0033] As described above, the final case 42 is configured to be rotatable around the kingpin 45 on the upper part of the intermediate case 43. A rotation restricting mechanism is provided to restrict the range of motion of this final case 42.

[0034] In other words, in the case of the standard width axle housing 41A specification, as shown in Figure 6, protrusions 46 and 47 are provided on the intermediate case 43 and the final case 42 at positions where they can come into contact with each other, serving as a rotation restricting means to restrict the range of motion of the final case 42.

[0035] On the other hand, when using the axle housing 41B specification, which is shorter than the standard width, a stopper 50 is added to create a rotation restricting means with a narrow range of motion. As shown in Figure 7, a base 51 is formed on the axle housing 41B, and a support plate 52 is bolted to this base 51. The stopper 50 is provided at the bent end of this support plate 52. An auxiliary plate portion 52a is provided on this support plate 52 along the bent end.

[0036] The stopper 50 of the support plate 52 has an end face portion 50a that can contact the outer end face portion 46a formed on the projection 46 of the intermediate case 43. The projection 46 has an upper end face portion 46u and a lower end face portion 46d, and the auxiliary plate portion 52a of the support plate 52 has an upper restricting portion 52u that can contact the upper end face portion 46u and a lower restricting portion 52d that can contact the lower end face portion 46d.

[0037] Therefore, when the projection 47 of the final case 42 comes into contact with the stopper 50, vertical displacement can be prevented. However, the rotation of the final case 42 is restricted by the presence of the stopper 50, thus narrowing the range of motion of the final case 42.

[0038] Furthermore, the projection 46 has an outer end face portion 46a, and the stopper 50 has an end face portion 50a that contacts the outer end face portion 46a of the projection 46. Combined with the fact that the contact surface 50b of the stopper 50 that contacts the final case 42 faces outward, this prevents the stopper 50 from shifting inward when the final case 42 contacts the stopper 50. [Explanation of Symbols]

[0039] 10 Steering Wheel 41 Axle Housing 41B Axle Housing 42 Final Case 42b Wheel axle 43 Intermediate Case 44 axles 45 Kingpin 46 Protrusion 46a Lateral end face 46u Upper face 46d lower face 50 ストッパ 50a End face 52 supports プレート 52u Upper Regulation Department 52d Lower Regulation Department

Claims

1. A work vehicle comprising an axle housing (41) having an axle (44) that drives a steering wheel (10), a final case (42) having a wheel axle (42b) that connects the steering wheel (10), and an intermediate case (43) having a kingpin (45) that connects the axle housing (41) and the final case (42), characterized in that the axle housing (41) is provided with a stopper (50) that restricts the range of motion of the final case (42) to rotate around the kingpin (45).

2. A work vehicle according to claim 1, wherein a support plate (52) is fixed to the axle housing (41B), the support plate (52) is provided with the stopper (50), and the stopper (50) has an end face portion (50a) that is in contact with the outer end face portion (46a) of a projection (46) formed on the intermediate case (43).

3. The work vehicle according to claim 2, wherein the projection (46) has an upper end surface portion (46u) and a lower end surface portion (46d), and the support plate (52) has an upper restricting portion (52u) that can contact the upper end surface portion (46u) and a lower restricting portion (52d) that can contact the lower end surface portion (46d).

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