JP7475132B2 - Power take-off device for work equipment - Google Patents

Description

The present invention relates to a power take-off device for a work machine.

2. Description of the Related Art Some power take-off devices for working machines are capable of varying the power of an input shaft to four different rotational speeds and taking it out through a power take-off shaft.
An example of a power take-off device for this type of work machine is shown in Patent Document 1. The device shown in Patent Document 1 is provided with a transmission shaft as an input shaft, and a holder as an output shaft interlocked with the power take-off shaft (PTO shaft). Four gears are fixed to the transmission shaft, four idling gears are loosely fitted in the holder so as to mesh with the four gears, and a linking pin is provided for selectively interlocking the four idling gears with the holder. In other words, the power of the transmission shaft is changed by the four gear trains into power with four different rotational speeds, and is transmitted to the holder, and then from the holder to the power take-off shaft.

Japanese Patent Publication No. 58-43624

Conventionally, four gear trains are arranged in a direction along the axis of the output shaft, which makes the size of the gear shift mechanism larger in the direction along the axis of the output shaft.

The present invention provides a power take-off device for a work machine that can change the power of the input shaft to four different rotational speeds and take it off through a power take-off shaft, while keeping the size of the gear transmission mechanism small in the direction along the axis of the output shaft.

The present invention relates to
A power take-off device for a work machine including an input shaft, an output shaft to which power of the input shaft is transmitted, a power take-off shaft operatively connected to the output shaft for taking power of the output shaft and outputting it to a driven device, and a gear transmission mechanism for changing the speed of the power of the input shaft to power having four different rotational speeds and transmitting it to the output shaft, wherein the gear transmission mechanism includes a first input shaft gear supported rotatably relative to the input shaft and a first output shaft gear supported rotatably relative to the output shaft, the first input shaft gear being operatively connected to the input shaft and the first output shaft gear being operatively connected to the output shaft, thereby transmitting the power of the input shaft to the output shaft at a first speed transmission ratio, a second input shaft gear supported rotatably relative to the input shaft and a second output shaft gear supported rotatably relative to the output shaft, the second input shaft gear being operatively connected to the input shaft, and the second output shaft gear being operatively connected to the output shaft. a second gear train that transmits the power of the input shaft to the output shaft at a second speed transmission ratio different from the first speed transmission ratio; and an intermediate transmission shaft that is interlocked with the first output shaft gear via a first intermediate transmission gear mechanism having a first intermediate speed transmission ratio and is interlocked with the second output shaft gear via a second intermediate transmission gear mechanism having a second intermediate speed transmission ratio different from the first intermediate speed transmission ratio. the output shaft is disposed between the input shaft and the intermediate transmission shaft, the output shaft and the power take-off shaft are disposed on the same axis, the gear shift mechanism is disposed in the internal space between a transmission case and a gear case attached to a rear wall portion of the transmission case, and the first gear train is located forward of the rear wall portion .

According to this configuration, when the first output shaft gear is interlocked with the input shaft by operation of the first operating unit, and when the first output shaft gear is interlocked with the output shaft by operation of the second operating unit, the power of the input shaft is transmitted to the output shaft via the first gear train and from the output shaft to the power take-off shaft. When the first output shaft gear is interlocked with the input shaft by operation of the first operating unit, and when the second output shaft gear is interlocked with the output shaft by operation of the second operating unit, the power of the input shaft is transmitted to the output shaft via the first gear train, the first intermediate transmission gear mechanism, the first intermediate transmission shaft, the second intermediate transmission gear mechanism, and the second output shaft gear, and from the output shaft to the power take-off shaft. When the second output shaft gear is interlocked with the input shaft by operation of the first operating unit, and when the second output shaft gear is interlocked with the output shaft by operation of the second operating unit, the power of the input shaft is transmitted to the output shaft via the second gear train and from the output shaft to the power take-off shaft. When the second output shaft gear is interlocked with the input shaft by operating the first operating unit, and the first output shaft gear is interlocked with the output shaft by operating the second operating unit, the power of the input shaft is transmitted to the output shaft via the second gear train, the second intermediate transmission gear mechanism, the first intermediate transmission shaft, the first intermediate transmission gear mechanism, and the first output shaft gear, and then transmitted from the output shaft to the power take-off shaft, so that the power of the input shaft can be changed to four different rotational speeds and taken out by the power take-off shaft.

The gears of the first gear train and the gears of the first intermediate transmission gear mechanism can be arranged in a line along a straight line passing through the axis of the input shaft and the axis of the output shaft, and the gears of the second gear train and the gears of the second intermediate transmission gear mechanism can be arranged in a line along a straight line passing through the axis of the input shaft and the axis of the output shaft. In other words, since there are only two gear trains arranged in the direction along the axis of the output shaft, the size of the gear transmission mechanism in the direction along the axis of the output shaft can be made smaller than before.

In the present invention,
It is preferable that, when viewed in the fore-aft direction of the aircraft, the input shaft, the output shaft and the intermediate transmission shaft are positioned on a straight line in a direction along the up-down direction of the aircraft.

With this configuration, the input shaft, output shaft, and intermediate transmission shaft overlap when viewed from above, making it possible to reduce the size of the gear transmission mechanism in the direction intersecting the axis of the input shaft.

In the present invention,
It is preferable that the first gear train has only the first input shaft gear and the first output shaft gear in meshing state, and the second gear train has only the second input shaft gear and the second output shaft gear in meshing state.

With this configuration, the first and second gear trains can be simply constructed with just two shafts, an input shaft and an output shaft.

In the present invention,
It is preferable that the first relay transmission gear mechanism is a first relay transmission gear supported on the relay transmission shaft so as not to rotate relative to the first output shaft gear when meshed with the first output shaft gear, and the second relay transmission gear mechanism is a second relay transmission gear supported on the relay transmission shaft so as not to rotate relative to the second output shaft gear when meshed with the second output shaft gear.

With this configuration, the structure of the first relay transmission gear mechanism can be a simple structure that only includes a first relay transmission gear, and the structure of the second relay transmission gear mechanism can be a simple structure that only includes a second relay transmission gear.

In the present invention,
It is preferable that the first output shaft gear and the second output shaft gear are supported on the output shaft via a tapered roller bearing.

According to this configuration, in the case of a speed change stage in which the first input shaft gear is operatively connected to the input shaft and the second output shaft gear is operatively connected to the output shaft, the first output shaft gear is supported by the output shaft while rotating relative to the output shaft to which the driving load of the power take-off shaft is applied, but since it is supported via a tapered roller bearing, the first output shaft gear rotates smoothly and power is transmitted smoothly. In the case of a speed change stage in which the second input shaft gear is operatively connected to the input shaft and the first output shaft gear is operatively connected to the output shaft, the second output shaft gear is supported by the output shaft while rotating relative to the output shaft to which the driving load of the power take-off shaft is applied, but since it is supported via a tapered roller bearing, the second output shaft gear rotates smoothly and power is transmitted smoothly.
In the present invention, it is preferable that the output shaft is operatively connected to the power take-off shaft by spline engagement between a rear portion of the output shaft and a front portion of the power take-off shaft.

FIG. 2 is a left side view showing the entire tractor. FIG. FIG. 2 is a longitudinal sectional side view of a power take-off device. FIG. 2 is a diagram showing a power take-off device. FIG. 4 is a right side view showing the gear shift operating unit. FIG. 4 is a rear view showing the gear shift operating section. FIG. 4 is a cross-sectional view showing a drive section for the rear wheels.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In the following description, with regard to the running body of a tractor (an example of a "work machine"), the direction of arrow F shown in Figure 1 is referred to as the "forward direction of the body," the direction of arrow B is referred to as the "rearward direction of the body," the direction of arrow U is referred to as the "upward direction of the body," the direction of arrow D is referred to as the "downward direction of the body," the direction toward the front of the page is referred to as the "leftward direction of the body," and the direction toward the back of the page is referred to as the "rightward direction of the body."

[Overall configuration of the tractor]
As shown in FIG. 1, the tractor includes a traveling body 3 equipped with a pair of left and right front wheels 1 that can be steered and driven, and a pair of left and right rear wheels 2 that can be driven. A prime mover 5 having an engine 4 is formed at the front of the traveling body 3. A driver's seat 6 and a driver's section 8 having a steering wheel 7 for steering the front wheels 1 are formed at the rear of the traveling body 3. The driver's section 8 is provided with a cabin 9 that covers the riding space. At the rear of the traveling body 3, a link mechanism 10 that connects various working devices (not shown) such as a rotary tilling device so that they can be raised and lowered, and a power take-off device 40 that takes power from the engine 4 through a power take-off shaft 41 and outputs it toward the connected working device (drive target device) are provided. The body frame of the traveling body 3 is composed of the engine 4, a transmission case 11 whose front part is connected to the rear of the engine 4 and supports the rear wheels 2, and a front wheel support frame 12 that is connected to the lower part of the engine 4 and supports the front wheels 1.

[Power transmission configuration]
The power of the engine 4 is transmitted to the front wheels 1, the rear wheels 2, and the power take-off shaft 41 based on the power transmission structure shown in FIG.

That is, the power of the engine output shaft 4a of the engine 4 is transmitted to the transmission input shaft 11a of the transmission case 11. The power of the transmission input shaft 11a is input to the forward/reverse switching device 13 and converted into forward power and reverse power. The converted forward power and reverse power are input to the main transmission device 14 capable of eight speed changes and are main-shifted, and the main-shifted power is input to the creep transmission device 15 capable of two speed changes. The output of the creep transmission device 15 is input to the auxiliary transmission device 16 capable of three speed changes and is auxiliary-shifted. The auxiliary-shifted power is input to the rear wheel differential mechanism 17 and transmitted from the left and right output shafts 17a of the rear wheel differential mechanism 17 to the left and right rear wheels 2. The power from the auxiliary transmission device 16 is transmitted to the front wheel transmission device 20 via the input shaft 17b of the rear wheel differential mechanism 17, transmitted from the front wheel transmission device 20 to the front wheel differential mechanism 21, and transmitted from the front wheel differential mechanism 21 to the left and right front wheels 1. The front wheel transmission 20 is configured to be switchable between a disengaged state, a constant speed transmission state, and an increased speed transmission state. When the front wheel transmission 20 is switched to the disengaged state, it cuts off the output to the front wheel differential mechanism 21, and the tractor is in a two-wheel drive state in which only the rear wheels 2 of the front wheels 1 and rear wheels 2 are driven. When the front wheel transmission 20 is switched to the constant speed transmission state, it outputs the power from the input shaft 17b to the front wheel differential mechanism 21 in a constant speed state, and the tractor is in a four-wheel drive state in which the front wheels 1 and rear wheels 2 are driven in a state in which the average peripheral speed of the left and right front wheels 1 and the average peripheral speed of the left and right rear wheels 2 are approximately equal. When the front wheel transmission 20 is switched to the increased speed transmission state, it increases the speed of the power from the input shaft 17b and outputs it to the front wheel differential mechanism 21, and the tractor is in a four-wheel drive state in which the front wheels 1 and rear wheels 2 are driven in a state in which the average peripheral speed of the left and right front wheels 1 is faster than the average peripheral speed of the left and right rear wheels 2.

The power of the transmission input shaft 11a is transmitted to the working clutch 24 via the front rotating shaft 22, the front end of which is connected to the rear end of the transmission input shaft 11a, and the rear rotating shaft 23, the front end of which is connected to the rear end of the front rotating shaft 22, and then from the working clutch 24 to the power take-off device 40.

[Configuration of power take-off device]
The power take-off device 40 is provided at the rear of the traveling vehicle body 3 as shown in Fig. 1. The power take-off device 40 includes a power take-off case 42 formed at the rear of the transmission case 11 as shown in Fig. 3. The power take-off case 42 is composed of the transmission case 11 and a gear case 42a detachably attached to the rear wall portion 11b of the transmission case 11 in a state where the gear case 42a closes an opening formed in the rear wall portion 11b. A power take-off shaft 41 protrudes rearward from a vertical middle portion of the gear case 42a. In Fig. 3, the power take-off shaft 41 is covered by a cover 41a that is detachable from the gear case 42a.

As shown in Figures 3 and 4, an input shaft 43 is provided in the upper part of the internal space S of the power take-off case 42, extending in the fore-and-aft direction of the vehicle body. The input shaft 43 is rotatably supported by the gear case 42a and a support wall portion 44 located in front of the gear case 42a. The support wall portion 44 is connected to the gear case 42a via connecting rod portions (not shown) that extend rearward from multiple points on the periphery of the support wall portion 44, and is supported by the gear case 42a. The front portion of the input shaft 43 is interlockingly connected to the output member 24a of the working clutch 24. The power of the transmission input shaft 11a, i.e., the power of the engine 4, is transmitted to the input shaft 43.

An output shaft 45 is provided below the input shaft 43 and extends in the longitudinal direction of the vehicle body parallel to the input shaft 43. The output shaft 45 is rotatably supported by the gear case 42a and the support wall portion 44. The output shaft 45 is interlockingly connected to the power take-off shaft 41 by spline engagement between the rear portion of the output shaft 45 and the front portion of the power take-off shaft 41. The power of the output shaft 45 can be taken off by the power take-off shaft 41.

A first gear train 46 is provided between the front of the input shaft 43 and the front of the output shaft 45. The first gear train 46 has only two gears: a first input shaft gear 46A supported on the input shaft 43 so as to be rotatable relative to the input shaft 43, and a first output shaft gear 46B supported on the output shaft 45 so as to be rotatable relative to the input shaft 43 while meshing with the first input shaft gear 46A. A second gear train 47 is provided between the input shaft 43 and the output shaft 45 behind the first gear train 46. The second gear train 47 has only two gears: a second input shaft gear 47A supported on the input shaft 43 so as to be rotatable relative to the input shaft 43, and a second output shaft gear 47B supported on the output shaft 45 so as to be rotatable relative to the output shaft 45 while meshing with the second input shaft gear 47A. The first output shaft gear 46B is supported on the output shaft 45 via a tapered roller bearing 48 interposed between the boss of the first output shaft gear 46B and the output shaft 45. The second output shaft gear 47B is supported on the output shaft 45 via a tapered roller bearing 48 interposed between the boss of the second output shaft gear 47B and the output shaft 45. The tapered roller bearing 48 of the first output shaft gear 46B and the tapered roller bearing 48 of the second output shaft gear 47B have two rows of rollers facing outward.

The outer diameter of the second input shaft gear 47A is larger than the outer diameter of the first input shaft gear 46A. The outer diameter of the first output shaft gear 46B is larger than the outer diameter of the first input shaft gear 46A. The outer diameter of the second output shaft gear 47B is larger than the outer diameter of the second input shaft gear 47A. The outer diameter of the second output shaft gear 47B is smaller than the outer diameter of the first output shaft gear 46B. The first speed transmission ratio Z1 of the first gear train 46 and the second speed transmission ratio Z2 of the second gear train 47 are different.

As shown in Figures 3 and 4, an input shaft sleeve 50 is supported on the input shaft 43 between the first input shaft gear 46A and the second input shaft gear 47A so as to be non-rotatable and slidable. When the input shaft sleeve 50 is slid toward the first input shaft gear, it engages with a locking portion 46c formed on the side of the first input shaft gear 46A to interlock and connect the first input shaft gear 46A to the input shaft 43. When the input shaft sleeve 50 is slid toward the second input shaft gear, it engages with a locking portion 47c formed on the side of the second input shaft gear 47A to interlock and connect the second input shaft gear 47A to the input shaft 43.

3, 5, and 6, a first operating unit 53 that selectively links the first input shaft gear 46A and the second input shaft gear 47A to the input shaft 43 is constituted by a first shift fork 51 that engages with the input shaft sleeve 50, a first speed change arm 52 that is swingably mounted on the outside of the power take-off case 42, and the like. The first shift fork 51 and the first speed change arm 52 are linked together via a slide shaft 54 that slides the first shift fork 51, a swing arm 55 whose free end engages with the slide shaft 54, and a rotating support shaft 56 that swingably supports the swing arm 55 and the first speed change arm 52.

In the first operating part 53, the first speed change arm 52 is swung around the axis of the rotating shaft 56 as a swing fulcrum, whereby the first shift fork 51 is slid in a direction along the axis of the input shaft 43, and the first shift fork 51 engages the input shaft sleeve 50 with the first input shaft gear 46A to interlock and connect the first input shaft gear 46A to the input shaft 43, or the first shift fork 51 engages the input shaft sleeve 50 with the second input shaft gear 47A to interlock and connect the second input shaft gear 47A to the input shaft 43.

As shown in Figures 3 and 4, an output shaft sleeve 60 is supported on the output shaft 45 between the first output shaft gear 46B and the second output shaft gear 47B so as to be slidable and non-rotatable relative to the output shaft 45. When the output shaft sleeve 60 is slid toward the first output shaft gear, it engages with a locking portion 46d formed on the side of the first output shaft gear 46B to interlock and connect the first output shaft gear 46B to the output shaft 45. When the output shaft sleeve 60 is slid toward the second output shaft gear, it engages with a locking portion 47d formed on the side of the second output shaft gear 47B to interlock and connect the second output shaft gear 47B to the output shaft 45.

3, 5, and 6, a second operating section 63 that selectively links the first output shaft gear 46B and the second output shaft gear 47B to the output shaft 45 is constituted by a second shift fork 61 that engages with the output shaft sleeve 60, and a second speed change arm 62 that is swingably mounted on the outside of the power take-off case 42. The second shift fork 61 and the second speed change arm 62 are linked together via a slide shaft 64 that slides the second shift fork 61, a swing arm 65 whose free end engages with the slide shaft 64, and a rotating support shaft 66 that swingably supports the swing arm 65 and the second speed change arm 62.

In the second operating section 63, the second speed change arm 62 is swung around the axis of the rotating shaft 66 as a swing fulcrum, whereby the second shift fork 61 is slid in a direction along the axis of the output shaft 45, and the second shift fork 61 engages the output shaft sleeve 59 with the first output shaft gear 46B to interlock and connect the first output shaft gear 46B to the output shaft 45, or the second shift fork 61 engages the output shaft sleeve 60 with the second output shaft gear 47B to interlock and connect the second output shaft gear 47B to the output shaft 45.

The first operating unit 53 and the second operating unit 63 are operated by a single speed change operating device 67 linked to the first speed change arm 52 and the second speed change arm 62, as shown in FIG. 5. That is, the speed change operating device 67 is configured to be switchable between a state in which it is linked to the first speed change arm 52 and allows the first speed change arm 52 to be swung, and a state in which it is linked to the second speed change arm 62 and allows the second speed change arm 62 to be swung.

3 and 4, an intermediate transmission shaft 70 is provided below the output shaft 45 and extends in the vehicle body longitudinal direction parallel to the output shaft 45. The intermediate transmission shaft 70 is rotatably supported by the gear case 42a and the support wall portion 44. As shown in FIG. 6, when viewed in the vehicle body longitudinal direction, the input shaft 43, the output shaft 45, and the intermediate transmission shaft 70 are positioned on a straight line in the direction along the vehicle body vertical direction. As shown in FIG. 3 and 4, the intermediate transmission shaft 70 is interlocked with the first output shaft gear 46B by a first intermediate transmission gear mechanism 71 provided in the front part of the intermediate transmission shaft 70, and is interlocked with the second output shaft gear 47B by a second intermediate transmission gear mechanism 72 provided in the rear part of the intermediate transmission shaft 70. The first gear train 46 and the first intermediate transmission gear mechanism 71 are arranged in a line on the vehicle body side, which is aligned on a straight line passing through the axis of the input shaft 43, the axis of the output shaft 45, and the axis of the intermediate transmission shaft 70 in the vertical direction of the vehicle body. The second gear train 47 and the second intermediate transmission gear mechanism 72 are arranged in a line on the vehicle body side, which is aligned on a straight line passing through the axis of the input shaft 43, the axis of the output shaft 45, and the axis of the intermediate transmission shaft 70 in the vertical direction of the vehicle body. The first intermediate transmission gear mechanism 71 is composed of a first intermediate transmission gear 71 that is supported by the intermediate transmission shaft 70 in a state where it cannot rotate relatively while meshing with the first output shaft gear 46B. The second intermediate transmission gear mechanism 72 is composed of a second intermediate transmission gear 72 that is supported by the intermediate transmission shaft 70 in a state where it cannot rotate relatively while meshing with the second output shaft gear 47B.

The outer diameter of the first relay transmission gear 71 is smaller than the outer diameter of the first output shaft gear 46B. The outer diameter of the second relay transmission gear 72 is smaller than the outer diameter of the second output shaft gear 47B. The outer diameter of the second relay transmission gear 72 is larger than the outer diameter of the first relay transmission gear 71. The first relay speed transmission ratio Y1 of the first relay transmission gear mechanism 71 and the second relay speed transmission ratio Y2 of the second relay transmission gear mechanism 72 are different.

The first gear train 46, the second gear train 47, the input shaft sleeve 50, the output shaft sleeve 60, the intermediate transmission shaft 70, the first intermediate transmission gear mechanism 71, and the second intermediate transmission gear mechanism 72 constitute a gear transmission mechanism M that changes the power of the input shaft 43 into a variable power with four different rotational speeds and transmits it to the output shaft 45. In the power take-off device 40, the first input shaft gear 46A and the second input shaft gear 47A are selectively linked to the input shaft 43 by the first operating unit 53, and the first output shaft gear 46B and the second output shaft gear 47B are selectively linked to the output shaft 45 by the second operating unit 63, so that the gear transmission mechanism M is switched between the first speed change state, the second speed change state, the third speed change state, and the fourth speed change state, and the rotational speed of the power take-off shaft 41 is changed to four speeds.

That is, when the first input shaft gear 46A is interlocked with the input shaft 43 by operating the input shaft sleeve 50 with the first operating unit 53, and the first output shaft gear 46B is interlocked with the output shaft 45 by operating the output shaft sleeve 60 with the second operating unit 63, the gear transmission mechanism M enters the first speed change state. The gear transmission mechanism M in the first speed change state transmits the power of the input shaft 43 to the output shaft 45 via the first gear train 46, and the power take-off shaft 41 is driven at the rotational speed set by the first speed change state.

When the second input shaft gear 47A is interlocked with the input shaft 43 by operating the input shaft sleeve 50 with the first operating unit 53, and the second output shaft gear 47B is interlocked with the output shaft 45 by operating the output shaft sleeve 60 with the second operating unit 63, the gear transmission mechanism M enters the second speed change state. In the second speed change state, the gear transmission mechanism M transmits the power of the input shaft 43 to the output shaft 45 via the second gear train 47, and the power take-off shaft 41 is driven at the rotational speed set by the second speed change state.

When the first input shaft gear 46A is interlocked with the input shaft 43 by operating the input shaft sleeve 50 with the first operating unit 53, and the second output shaft gear 47B is interlocked with the output shaft 45 by operating the output shaft sleeve 60 with the second operating unit 63, the gear transmission mechanism M enters the third speed change state. The gear transmission mechanism M in the third speed change state transmits the power of the input shaft 43 to the output shaft 45 via the first gear train 46, the first relay transmission gear mechanism 71, the relay transmission shaft 70, the second relay transmission gear mechanism 72, and the second output shaft gear 47B, and the power take-off shaft 41 is driven at a rotation speed set by the third speed change state. At this time, the first output shaft gear 46B is supported by the output shaft 45 while rotating relative to the output shaft 45 to which the driving load of the power take-off shaft 41 is applied, but since it is supported via the tapered roller bearing 48, it transmits power while rotating smoothly.

When the second input shaft gear 47A is interlocked with the input shaft 43 by operating the input shaft sleeve 50 by the first operating unit 53, and the first output shaft gear 46B is interlocked with the output shaft 45 by operating the output shaft sleeve 60 by the second operating unit 63, the gear transmission mechanism M enters the fourth speed change state. The gear transmission mechanism M in the fourth speed change state transmits the power of the input shaft 43 to the output shaft 45 via the second gear train 47, the second relay transmission gear mechanism 72, the relay transmission shaft 70, the first relay transmission gear mechanism 71, and the first output shaft gear 46B, and the power take-off shaft 41 is driven at a rotation speed set by the fourth speed change state. At this time, the second output shaft gear 47B is supported by the output shaft 45 while rotating relative to the output shaft 45 to which the driving load of the power take-off shaft 41 is applied, but since it is supported via the tapered roller bearing 48, it transmits power while rotating smoothly.

[Rear wheel drive structure]
7, a brake case portion 75 is provided on the side of the transmission case 11, and an axle case 76 extends laterally outwardly of the vehicle body from the brake case portion 75. A reduction case portion 77 is provided at the base of the axle case 76.

A rear wheel differential mechanism 17 is provided inside the transmission case 11. An output shaft 17a of the rear wheel differential mechanism 17 extends from the side gear 79 to the inside of the reduction case portion 77. A rear wheel axle 80 is rotatably supported inside the axle case 76, positioned on the outer side of the rear wheel differential mechanism 29 laterally of the vehicle body. The output shaft 17a and the rear wheel axle 80 are provided so as to be positioned on the same axis. A locking device 82 that enables differential lock of the rear wheel differential mechanism 29 is provided between the side gear 79 and the differential case 81.

Inside the reduction case 77, a planetary reduction mechanism 83 is provided across the output shaft 17a and the rear wheel axle 80. The planetary reduction mechanism 83 has a sun gear 83a driven by the output shaft 17a, an internal gear 83b supported by the reduction case 77, and multiple planetary gears 83c aligned in the circumferential direction of the sun gear 83a. A carrier 83d supporting the multiple planetary gears 83c is connected to the rear wheel axle 80. A stopper 83e that prevents the carrier 83d from coming off the rear wheel axle 80 is attached to the rear wheel axle 80 with a bolt 84.

In the rear wheel differential mechanism 17, the power of the input shaft 17b is transmitted to the output shaft 17a via the differential case 81 and the side gear 79. The power of the output shaft 17a is reduced by the planetary reduction mechanism 83 and transmitted to the rear wheel axle 80, driving the rear wheel axle 80, which in turn drives the rear wheels 2.

A brake 85 is provided inside the brake case section 75. The brake 85 has a plurality of friction plates 86 that are engaged with a portion of the output shaft 17a between the differential case 81 of the rear wheel differential mechanism 17 and the planetary reduction mechanism 83, and a friction plate 88 that is engaged with a support section 87 provided on the brake case section 75. A friction plate receiving section 89 that receives the friction plates 86 and 88 is provided on the side where the planetary reduction mechanism 83 is located relative to the friction plates 86 and 88. The friction plate receiving section 89 is fixed to the brake case section 75. A hydraulic piston 90 is provided on the side opposite the side where the friction plate receiving section 89 is located relative to the friction plates 86 and 88.

As shown in FIG. 7, the output shaft 17a is supported by a support member 91 between the differential case 81 and the planetary reduction mechanism 83. The support member 91 is configured to engage with the output shaft 17a so as to be immovable relative to the output shaft 17a in a direction along the axis of the output shaft 17a.

Specifically, as shown in FIG. 7, the support member 91 is attached to the output shaft 17a at a position between the friction plate 86 that engages with the output shaft 17a and the planetary reduction mechanism 83. The support member 91 is composed of a bearing that includes an inner ring 91a fitted to the outside of the output shaft 17a, an outer ring 91b that fits inside an assembly hole formed in the friction plate receiving portion 89, and a rolling element 91c interposed between the inner ring 91a and the outer ring 91b. The support member 91 engages with the output shaft 17a so as not to move relative to it due to friction between the inner ring 91a and the output shaft 17a. The support member 91 is supported by the friction plate receiving portion 89 and is thereby supported by the brake case portion 75.

When hydraulic pressure is supplied to the hydraulic piston 90, the brake 85 is in the ON state and brakes the rear wheels 2, and when the supply of hydraulic pressure to the hydraulic piston 90 is released, the brake is in the OFF state and the brakes on the rear wheels 2 are released.

In other words, when the hydraulic piston 90 is supplied with operating oil pressure, the hydraulic piston 90 is pressed toward the friction plate 86 by the operating oil pressure, and the friction plate 86 and the friction plate 88 are pressed in a direction along the axis of the output shaft 17a by the hydraulic piston 90 and pressed against the friction plate receiving portion 89, and the friction braking force generated by the friction plate 86 and the friction plate 88 is applied to the rear wheel axle 80 via the output shaft 17a and the planetary reduction mechanism 83.

When the supply of operating hydraulic pressure to the hydraulic piston 90 is released, the hydraulic piston 90 is released from pressing against the friction plate 86, the friction plates 86 and 88 are released from pressure contact with the friction plate receiving portion 89, and the friction braking force generated by the friction plates 86 and 88 is released.

For example, when the brake 85 is operated to the ON state, the support member 91 prevents the output shaft 17a from moving against the friction plate 86, and after the brake 85 is returned to the OFF state, the friction plate 86 of the output shaft 17a and the friction plate 88 of the support portion 87 remain in contact with each other, preventing rotational resistance from being applied to the output shaft 78.

[Another embodiment]
(1) In the above embodiment, the first gear train 46 and the second gear train 47 each have only two gears, but they may each have three or more gears. Also, although the first intermediate power transmission gear mechanism 71 and the second intermediate power transmission gear mechanism 72 each have only one gear, they may each have two or more gears.

(2) In the above embodiment, the input shaft 43, the output shaft 45, and the intermediate transmission shaft 70 are arranged in a state where they are positioned in a straight line along the vertical direction of the vehicle body when viewed from the front and rear of the vehicle body, but this is not limited to this. For example, the input shaft 43 and the output shaft 45 may be arranged in a straight line along the vertical direction of the vehicle body, and the intermediate transmission shaft 70 may be displaced laterally relative to the input shaft 43 and the output shaft 45, or the input shaft 43 and the intermediate transmission shaft 70 may be arranged in a straight line along the vertical direction of the vehicle body, and the output shaft 45 may be displaced laterally relative to the input shaft 43 and the intermediate transmission shaft 70, or the input shaft 43, the output shaft 45, and the intermediate transmission shaft 70 may be out of line along the vertical direction of the vehicle body.

(3) In the above embodiment, the first output shaft gear 46B and the second output shaft gear 47B are supported on the output shaft 45 via tapered roller bearings 48, but this is not limited to the above. For example, ball bearings and needle bearings can be used.

The present invention can be applied to the power take-off device of various types of work machines that are equipped with an input shaft, an output shaft to which the power of the input shaft is transmitted, a power take-off shaft that takes the power of the output shaft and outputs it to a driven device, and a gear transmission mechanism that changes the power of the input shaft to power with four different rotational speeds and transmits it to the output shaft.

41 Power take-off shaft 43 Input shaft 45 Output shaft 46 First gear train 46A First input shaft gear 46B First output shaft gear 47 Second gear train 47A Second input shaft gear 47B Second output shaft gear 48 Tapered roller bearing 53 First operating portion 63 Second operating portion 70 Intermediate transmission shaft 71 First intermediate transmission gear mechanism (first intermediate transmission gear)
72 second relay transmission gear mechanism (second relay transmission gear)
Z1: First speed transmission ratio Z2: Second speed transmission ratio Y1: First intermediate speed transmission ratio Y2: Second intermediate speed transmission ratio M: Gear transmission mechanism

Claims (6)

A power take-off device for a work machine includes an input shaft, an output shaft to which power from the input shaft is transmitted, a power take-off shaft that is interlocked with the output shaft and takes off power from the output shaft and outputs it to a driven device, and a gear transmission mechanism that changes the power of the input shaft to power having four different rotational speeds and transmits the power to the output shaft,
The gear transmission mechanism includes:
a first gear train including a first input shaft gear supported on the input shaft so as to be relatively rotatable, and a first output shaft gear supported on the output shaft so as to be relatively rotatable, the first input shaft gear being operatively connected to the input shaft, and the first output shaft gear being operatively connected to the output shaft, thereby transmitting the power of the input shaft to the output shaft at a first speed transmission ratio;
a second gear train including a second input shaft gear supported on the input shaft so as to be relatively rotatable, and a second output shaft gear supported on the output shaft so as to be relatively rotatable, the second input shaft gear being operatively connected to the input shaft, and the second output shaft gear being operatively connected to the output shaft, thereby transmitting the power of the input shaft to the output shaft at a second speed transmission ratio different from the first speed transmission ratio;
an intermediate transmission shaft interlocked with the first output shaft gear via a first intermediate transmission gear mechanism having a first intermediate speed transmission ratio, and interlocked with the second output shaft gear via a second intermediate transmission gear mechanism having a second intermediate speed transmission ratio different from the first intermediate speed transmission ratio,
a first operating portion that selectively interlocks the first input shaft gear and the second input shaft gear with the input shaft;
a second operating unit that selectively interlocks the first output shaft gear and the second output shaft gear to the output shaft,
the output shaft is disposed between the input shaft and the intermediate transmission shaft, and the output shaft and the power take-off shaft are disposed coaxially ,
The gear shift mechanism is disposed in an internal space between a transmission case and a gear case attached to a rear wall portion of the transmission case, and the first gear train is a power take-off device of a working machine located forward of the rear wall portion . The power take-off device of claim 1, wherein the input shaft, the output shaft, and the intermediate transmission shaft are positioned on a straight line along the vertical direction of the machine body when viewed from the front-rear direction of the machine body. the first gear train has only the first input shaft gear and the first output shaft gear in mesh with each other,
3. The power take-off device of a working machine according to claim 1, wherein the second gear train has only the second input shaft gear and the second output shaft gear in a meshed state. the first intermediate transmission gear mechanism is a first intermediate transmission gear that is supported by the intermediate transmission shaft in a state in which it is meshed with the first output shaft gear and is non-rotatable relative to the first output shaft gear,
4. A power take-off device for a work machine according to claim 1, wherein the second intermediate transmission gear mechanism is a second intermediate transmission gear supported on the intermediate transmission shaft in a state meshed with the second output shaft gear so as not to rotate relative to the intermediate transmission shaft. The power take-off device of a work machine according to any one of claims 1 to 4, wherein the first output shaft gear and the second output shaft gear are supported on the output shaft via tapered roller bearings. The power take-off device of a work machine according to any one of claims 1 to 5, wherein the output shaft is interlocked with the power take-off shaft by a spline engagement between the rear portion of the output shaft and the front portion of the power take-off shaft.

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