JPH04307128A - Four-wheel drive vehicle - Google Patents

Abstract

PURPOSE:To install a structure which makes the selector operation of forward- backward movements smoothly performable as well as to form this structure into such as being excellent in durability. CONSTITUTION:A first roller 23 is set up in space between a first inner ring 21 and a second outer ring 31 provided with each of conical surfaces 21S and 31S, setting it down to a forward one-way clutch, and likewise a second roller 24 between a second inner ring 22 and a second outer ring 3 provided with each of conical surfaces 22A and 32S, respectively, setting it down to a backward one-way clutch. When the second outer ring 31 is pushed and pressed to the first inner ring 21 side, the first roller 23 is rolled and held between both these conical surfaces 21S and 31S, and thereby clockwise power for forward movement is transmitted to front wheels from the first roller 23 side. In contrast with this, when the second outer ring 32 is pressed to the second inner ring 22 side, the second roller 24 is rolled and held between both these conical surfaces 22S and 32S, counterclockwise power for backward movement is transmitted to the front wheels from the second roller 24 side.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for absorbing the difference in driving speed between the front and rear wheels of a four-wheel drive vehicle such as a general passenger car or an agricultural tractor.

0002

[Prior Art] Four-wheel drive vehicles are equipped with a structure that transmits power from an engine to the rear wheels via a transmission, and also transmits power branched from the transmission system to the rear wheels to the front wheels. There are things that are. In such a four-wheel drive vehicle, if the front wheels are largely steered to make a small turn,
Due to the difference between the inner and outer wheels of the front and rear wheels, the turning radius of the rear wheels is smaller than that of the rear wheels, and the front wheels may try to rotate faster than the rear wheels. In this case, if the front and rear wheels are driven at the same speed, a phenomenon will occur, especially on the front side, where the front wheels try to rotate at a high speed but are driven at a low speed, resulting in a state where the brakes appear to be applied. (so-called tight corner braking phenomenon).

[0003] As a means to prevent the above situation,
For example, there is a structure as shown in FIG. In other words, the power branched from the differential mechanism for the rear wheels is transferred to the output gear 43, the cylindrical output sleeve 44, and the one-way clutch 4 for forward movement.
5 and an output shaft 46 to transmit the power to the front wheels. This one-way clutch 45 for forward movement is configured to allow the front wheels to rotate forward in the normal rotation side (high speed side of forward movement) during forward movement, and is configured to allow the front wheels to rotate at high speed during the above-mentioned small turn. In this case, the forward rotation one-way clutch 45 allows the front wheels to rotate in advance to absorb the difference in rotation speed between the front and rear wheels.

[0004] As described above, with only the one-way clutch 45 for forward movement, the power during reverse movement does not flow to the front wheels.
The structure is also equipped with a one-way clutch 48 for reversing (which has a function that allows the front wheels to rotate in advance to the reverse side (high-speed side of reversing) when reversing, and when reversing, the rear wheel differential mechanism is The configuration is such that power is transmitted to the front wheels via this one-way clutch 48 for reversing.

[0005]

Therefore, in the conventional structure shown in FIG. 4, it is necessary to select whether to use the one-way clutch 45 for forward movement or the one-way clutch 48 for reverse movement when switching between forward and backward movement. There is. In this case, as shown in FIG. 4, the output sleeve 44 is slid in the horizontal direction in the drawing by the actuator 49, so that the gear part of the output sleeve 44 is engaged with the gear-shaped input part of the one-way clutch 45 for forward movement when moving forward. When traveling in reverse, the gear part of the output sleeve 44 is connected to the one-way clutch 4 for reversing.
An operation is being performed to engage the gear-shaped input section of No. 8.

However, in a type in which the output sleeve is engaged with a one-way clutch for forward or backward movement, if the occlusal side and the occluded side are not in phase, the occlusion may not occur properly, so it is frequently When performing a switching operation or a quick forward/backward switching operation, the one-way clutch for forward or reverse cannot be selected properly, which may cause so-called gear noise, which may lead to damage. In addition, the general forward and reverse one-way clutches mentioned above use a transmission body called a sprag that has a gourd-shaped cross section, which is relatively disadvantageous in terms of strength, so it is not suitable for agricultural tractors that are subject to heavy loads. There are concerns about the durability of the forward and reverse one-way clutches themselves. The purpose of the present invention is to provide a four-wheel drive vehicle equipped with one-way clutches for forward and reverse travel, so that switching operations between forward and reverse can be performed smoothly, and the durability is sufficient. It is said that

[0007]

[Means for Solving the Problems] A feature of the present invention is that the four-wheel drive vehicle as described above is constructed as follows. In other words, [a] a pair of first and second inner rings each having a conical outer periphery are attached to the power transmission shaft on either the front wheel side or the rear wheel side; The first and second outer rings are attached to the other transmission shaft, either the front wheel side or the rear wheel side, with their respective conical surfaces facing the respective conical surfaces of the first and second inner rings. [B] First and second inner rings and the first opposing inner ring
First and second rollers that roll around an axis oblique to the axis of the transmission shaft are arranged between each conical surface of the second outer ring. [C] A first operating means that presses the first outer ring toward the first inner ring side, or the first inner ring toward the first outer ring side, and a first operation means that presses the first outer ring toward the first inner ring side, and a first operation means that presses the first outer ring toward the first inner ring side, and a first operation means that presses the first outer ring toward the first inner ring side, and a first operation means that presses the first outer ring toward the first inner ring side, and a first operation means that presses the first outer ring toward the first inner ring side, and a first operation means that presses the first outer ring toward the first inner ring side, and presses the second outer ring toward the second inner ring side. A second operating means for pressing the second inner ring closer to the second outer ring is provided on the second outer ring. [d] When the transmission shaft on the rear wheel side is rotationally driven in the normal rotation direction while the first operating means is in operation, the first roller is displaced in the axial direction of the transmission shaft due to rolling, and the first inner ring and It is inserted between both conical surfaces of the first outer ring so that the first inner ring and the first outer ring rotate together and forward rotational power is transmitted to the front wheel side, and the transmission shaft on the front wheel side is When the transmission shaft on the rear wheel side rotates in advance toward the normal rotation side, the first roller rolls in the opposite direction to the above-mentioned direction, allowing the transmission shaft on the front wheel side to rotate in advance toward the forward rotation side. [E] When the transmission shaft on the rear wheel side is rotationally driven in the reverse direction while the second operating means is in operation, the second roller is displaced in the axial direction of the transmission shaft due to rolling, and the second inner ring and the second roller are displaced in the axial direction of the transmission shaft. It is inserted between both conical surfaces of the second outer ring, so that the second inner ring and the second outer ring rotate together and reverse rotation power is transmitted to the front wheel side, and the transmission shaft on the front wheel side is connected to the rear wheel side. When the front wheel side transmission shaft rotates in advance in the reverse direction, the second roller rolls in the opposite direction to that described above, allowing the front wheel side transmission shaft to rotate in advance in the reverse direction.

[0008]

[Operation] When constructed as described above, as shown in FIG. 1, for example, during forward movement, the first outer ring 31 is pressed toward the first inner ring 21 side (left side in the drawing) by the first operating means. As a result, the conical surface 31S of the first outer ring 31 is pressed against the first roller 23. In this state, when the transmission shaft 18 on the rear wheel side is rotationally driven in the direction of arrow H, which is the forward movement side, the first roller 23 is rotated by the first outer ring 31 into the conical shape of the first inner ring 21 as shown in FIG. It is slightly rolled on the surface 21S in the direction of arrow J. As a result, the first roller 23 moves between the first outer ring 31 and the first inner ring 21 to the left in the drawing, and the first roller 23 moves between the first inner ring 21 and the first outer ring 31. Conical surface 21S, 3
1S, the first inner ring 21 and the first outer ring 31 are integrated, and the power for forward movement (in the direction of arrow H) of the transmission shaft 18 on the rear wheel side is transferred to the first outer ring 31 and the first outer ring 31. The power is transmitted to the power transmission shaft 19 on the front wheel side via the first inner ring 21 . When the front wheels try to rotate forward at a higher speed than the rear wheels, such as when making a small turn, the transmission shaft 19 on the front wheel side moves forward (in the direction of arrow H) than the transmission shaft 18 on the rear wheel side. If an attempt is made to rotate ahead of time, the action of the first inner ring 21 causes the first roller 23 to roll in the direction opposite to the arrow J (see FIG. 3). In this case, the first
The pinching phenomenon of the rollers 23 does not occur, and the forward rotation of the power transmission shaft 19 on the front wheel side is allowed. On the other hand, the second
On the inner ring 22 and second outer ring 32 sides, the second outer ring 32 is slightly away from the second roller 24 to the left in the drawing, so the transmission shaft 18 on the rear wheel side is moved toward the forward direction (arrow H Even if the transmission shaft 19 on the front wheel side rotates in advance in the forward direction (in the direction of arrow H), the second roller 24 does not roll and no jamming phenomenon occurs. That is, the transmission is always cut off on the second inner ring 22 and second outer ring 32 sides.

In contrast to the above-described forward movement, when the vehicle moves backward, the second outer ring 32 is pressed toward the second inner ring 22 side (to the right in the drawing) using the second operating means. As a result, the conical surface 32S of the second outer ring 32 is pressed against the second roller 24. In this state, when the transmission shaft 18 on the rear wheel side is rotationally driven in the direction opposite to the arrow H, which is the reverse side, the second outer ring 32 causes the second outer ring 32 to rotate.
The roller 24 is connected to the second inner ring 2 as shown in FIG.
2 on the conical surface 22S in the direction of arrow K. As a result, the second roller 24 moves between the second outer ring 32 and the second inner ring 22 to the right in the drawing, and the second roller 24 moves between the second inner ring 22 and the second inner ring 22.
The second inner ring 22 and the second outer ring 32 are sandwiched between both conical surfaces 22S and 32S of the second outer ring 32, and the second inner ring 22 and the second outer ring 32 are integrated. (in the opposite direction) is transmitted to the power transmission shaft 19 on the front wheel side via the second outer ring 32 and the second inner ring 22. Then, when the front wheels try to rotate in the reverse direction at a higher speed than the rear wheels, such as when making a small turn, the transmission shaft 19 on the front wheel side moves to the reverse side (arrow H) than the transmission shaft 18 on the rear wheel side.
If the second roller 24 is to be rotated in advance in the direction opposite to the arrow K (see FIG. 3), the action of the second inner ring 22 causes the second roller 24 to roll in the direction opposite to the arrow K (see FIG. 3). in this case,
The pinching phenomenon of the second roller 24 does not occur, and the forward rotation of the power transmission shaft 19 on the front wheel side is allowed. On the contrary,
On the first inner ring 21 and first outer ring 31 sides, the first outer ring 31 is slightly away from the first roller 23 to the right in the drawing, so the transmission shaft 18 on the rear wheel side is moved to the reverse side ( The first roller 23 does not roll even if it is rotationally driven in the direction opposite to the arrow H, or even if the transmission shaft 19 on the front wheel side rotates in advance in the reverse direction (the direction opposite to the arrow H). No pinching phenomenon occurs. In other words, transmission is always cut off on the first inner ring 21 and first outer ring 31 sides.

As described above, in the conventional structure shown in FIG. 4, the output sleeve is engaged with the forward or reverse one-way clutch when switching between forward and reverse, whereas in the present invention, the output sleeve is engaged with the one-way clutch for forward or reverse. It is sufficient to simply press the first outer ring or the second outer ring for backward movement against the first or second roller (the same applies even if the first and second inner rings are pressed against the first and second rollers). In other words, in contrast to the conventional structure in which occlusion occurs only when the phases of the occlusal side and the occluded side do not match, in the present invention, power is constantly and smoothly applied to the first outer ring and first inner ring on the advancing side, regardless of the phase. , it can flow to the second outer ring and second inner ring on the reverse side. In the present invention, the functions of the one-way clutch are controlled by the first and second rollers, and the first and second rollers have a circular cross section that is more advantageous in terms of strength than the gourd-shaped cross section of the conventional structure.
The present invention is also more advantageous in terms of strength than the conventional structure.

[0011]

[Effects of the Invention] As described above, by using a pressing structure for switching between forward and backward travel instead of an occlusal structure like the conventional structure, it is now possible to perform forward and backward switching operations smoothly at all times, and the four-wheel drive type It was possible to improve the running performance of the vehicle, and also to improve the strength and durability of the transmission part to the front wheels.

0012

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. FIG. 2 shows the structure inside the transmission case 1 of a four-wheel drive agricultural tractor, which is an example of a four-wheel drive vehicle. Power from the engine (not shown) is transmitted from within the main clutch 2 via the first PTO shaft 3 and hydraulic clutch 4 to the second PTO shaft 5 protruding from the rear of the mission case 1.
A PTO system for an agricultural tractor is configured.

Next, the driving power is supplied to the main clutch 2 and the first clutch.
The transmission is transmitted from the cylindrical shaft 6 to the second cylindrical shaft 8 via the synchromesh type, two-speed transmission type first transmission 7, and from the second cylindrical shaft 8 to the synchromesh type, three-speed transmission type second transmission. The signal is transmitted to the first power transmission shaft 10 via the transmission 9 . The power is transmitted from the first transmission shaft 10 to the rear wheels (not shown) via a synchromesh type forward/reverse switching device 11, a second transmission shaft 12, and a constant mesh type two-speed third transmission 13. ) is transmitted to the differential shaft 15 for the differential mechanism 14. The power from the differential shaft 15 is transmitted to the front wheels (not shown) via the gears 16, 17, the third transmission shaft 18, the structure shown in FIG. 1, and the fourth transmission shaft 19. .

Next, the third and fourth transmission shafts 18, 1 for the front wheels
The one-way clutch structure provided between 9 and 9 will be explained. As shown in FIG. 1, the third power transmission shaft 1 on the rear wheel side
8, a fourth power transmission shaft 19 on the front wheel side is supported concentrically, and a casing 20 is fixed to the third power transmission shaft 18 with a key structure. The fourth power transmission shaft 19 has a pair of first and second inner rings 21 and 22 whose outer circumferences are formed into conical surfaces 21S and 22S. Fixed.

On the other hand, on the casing 20 side, there are a pair of first and second holes whose inner peripheries are formed into conical surfaces 31S and 32S.
Outer rings 31 and 32 are installed inside. in this case,
The spline portions 31a, 3 of the first and second outer rings 31, 32 are attached to the spline portion 20a on the inner surface of the casing 20.
2a are engaged so that the casing 20 and the first and second outer rings 31, 32 rotate together, and
The first and second outer rings 31 relative to the casing 20
, 32 are configured to be slidable in the horizontal direction on the paper.

Both conical surfaces 21S of the first and second inner rings 21, 22 and the first and second outer rings 31, 32,
Between 22S, 31S, and 32S, as shown in FIGS. 1 and 3, tapered first and second rollers 23 and 24 are arranged with respect to the axis X of the third and fourth power transmission shafts 18 and 19. The retainer 29 is disposed to be rotatable around the inclined axis Y, and is provided with a retainer 29 for the first and second rollers 23 and 24.

As shown in FIG. 1, the first outer ring 31 is placed between the first and second outer rings 31 and 32 on the right side of the paper (both conical surfaces 21S of the first inner ring 21 and the first outer ring 31). , 31S are separated from each other), and the second outer ring 32 is biased toward the left side (
Disc spring 2 biases the conical surfaces 22S and 32S of the second inner ring 22 and the second outer ring 32 in the direction in which they separate.
6 is provided. Inside the casing 20, there is an oil passage 2 for sliding the first outer ring 31 to the left in the drawing and the second outer ring 32 to the right in the drawing by hydraulic pressure.
7 and an oil passage 28 are provided.

The state shown in FIG. 1 is a state in which the hydraulic oil is removed from the oil passages 27 and 28, and the first and second outer rings 31 and 32 are moved away from the first and second rollers 23 and 24 to the right in the drawing or It is slightly off to the left. From this state, when the forward/reverse switching device 11 shown in FIG. It is pressed by the roller 23 (corresponding to the first operating means). In this state, the third power transmission shaft 18 is rotationally driven in the direction of arrow H, which is the forward direction. Therefore, when the third transmission shaft 18 is rotationally driven in the direction of the arrow H in the above state, the first
The outer ring 31 causes the first roller 23 to slightly roll on the conical surface 21S of the first inner ring 21 in the direction of arrow J, as shown in FIG.

As a result, the first roller 23 moves between the first outer ring 31 and the first inner ring 21 to the left in the drawing, that is, between the first outer ring 31 and the first inner ring 21.
1, and the first roller 23 is sandwiched between both the conical surfaces 21S and 31S of the first inner ring 21 and the first outer ring 31, The first inner ring 21 and the first outer ring 31 are integrated, and the forward power (in the direction of arrow H) of the third transmission shaft 18 is transferred to the fourth transmission via the first outer ring 31 and the first inner ring 21. The signal is transmitted to the shaft 19.

When the front wheels try to rotate forward at a higher speed than the rear wheels, such as when making a small turn, the fourth power transmission shaft 19 on the front wheel side is moved forward (arrow H) relative to the third power transmission shaft 18. If the first roller 23 is to rotate in the direction opposite to the arrow J by the action of the first inner ring 21, the first roller 23 is caused to roll in the direction opposite to the arrow J. In this case, the first roller 23
moves to the side where the distance between the conical surfaces 31S and 21S of the first outer ring 31 and the first inner ring 21 is wide, so that the pinching phenomenon of the first roller 23 does not occur, and the fourth power transmission shaft 19 on the front wheel side This allows advance rotation of .

On the other hand, on the second inner ring 22 and second outer ring 32 side, the second outer ring 3
2 is slightly away from the second roller 24 to the left in the drawing, even if the third power transmission shaft 18 is rotationally driven in the forward direction (in the direction of arrow H), the fourth power transmission shaft 19 will not move forward. side(
Even if the second roller 24 is rotated in advance (in the direction of arrow H), the second roller 24 does not roll and the pinching phenomenon does not occur. That is, the transmission is always cut off on the second inner ring 22 and second outer ring 32 sides.

When the forward/reverse switching device 11 shown in FIG.
Hydraulic oil is supplied to As a result, the first outer ring 31 is pushed to the right in the drawing and separated from the first roller 23 by the action of the disc spring 25, and the second outer ring 32 is pushed to the right in the drawing and pressed against the second roller 24. (corresponding to the second operating means). In this state, the third transmission shaft 18 is rotationally driven in the direction opposite to the arrow H, which is the reverse side. Therefore, in the above state, the third power transmission shaft 18 is
When the second outer ring 3 is rotated in the opposite direction, the second outer ring 3
2, the second roller 24 is slightly rolled in the direction of arrow K on the conical surface 22S of the second inner ring 22, as shown in FIG.

As a result, the second roller 24 moves between the second outer ring 32 and the second inner ring 22 to the right in the drawing, that is, the second roller 24 moves between the second outer ring 32 and the second inner ring 22.
The second roller 24 is sandwiched between the two conical surfaces 22S, 32S of the second inner ring 22 and the second outer ring 32, and The second inner ring 22 and the second outer ring 32 are integrated, and the power for backward movement of the third power transmission shaft 18 (in the direction opposite to the arrow H) is transmitted through the second outer ring 32 and the second inner ring 22. It is transmitted to the fourth transmission shaft 19.

Then, when the front wheels try to rotate in the reverse direction at a higher speed than the rear wheels, such as when making a small turn, the fourth power transmission shaft 19 on the front wheel side is moved to the reverse direction (arrow H) than the third power transmission shaft 18. If an attempt is made to advance the rotation in the direction opposite to the arrow K, the second roller 24 is caused to roll in the direction opposite to the arrow K by the action of the second inner ring 22. In this case, the second roller 24 is connected to the second outer ring 32 and the second inner ring 22.
Since the conical surfaces 32S and 22S are moved to the side where the distance between them is wide, the second roller 24 does not get stuck, and the fourth power transmission shaft 19 on the front wheel side is allowed to rotate in advance.

On the other hand, on the first inner ring 21 and first outer ring 31 sides, the first outer ring 3
1 is slightly away from the first roller 23 to the right in the drawing, even if the third transmission shaft 18 is rotated in the reverse direction (the direction opposite to the arrow H), the fourth transmission shaft 18 Even if the shaft 19 rotates in advance in the backward direction (in the direction opposite to the arrow H), the first roller 23 does not roll and the pinching phenomenon does not occur. In other words, transmission is always cut off on the first inner ring 21 and first outer ring 31 sides.

[0026] For the forward and reverse traveling states as described above, it is also possible to drain the hydraulic oil from both oil passages 27 and 28. In this state, the action of the disc springs 25 and 26 causes the first and second outer rings 31 and 32 to
It will be in a state where it is slightly away from the rollers 23 and 24 to the right or left in the paper. In this state, as described above, even if the third transmission shaft 18 is rotationally driven in the forward direction, the first inner ring 21
And power transmission is not performed on the first outer ring 31 side, and even if the third transmission shaft 18 is rotationally driven in the reverse direction, power transmission is not performed on the second inner ring 22 and second outer ring 32 sides. . In other words, it becomes a rear two-wheel drive state in which power is not transmitted to the front wheels. In this state, stoppers 30 are attached to the first and second outer rings 31 and 32 to prevent the first and second rollers 23 and 24 from rolling and moving in the directions of arrows J and K in FIG. It is being

It is also possible to simultaneously supply hydraulic oil to both oil passages 27 and 28 in FIG. In this state, both the first and second outer rings 31 and 32 are
And it will be in a state where it is pressed by the second rollers 23 and 24. In this state, when the third power transmission shaft 18 is rotationally driven in the forward direction as described above, a pinching phenomenon of the first roller 23 occurs on the first inner ring 21 and first outer ring 31 sides, and power transmission is not performed. The fourth transmission shaft 1
9 tries to rotate forward in advance, a pinching phenomenon of the second roller 24 occurs on the second inner ring 22 and second outer ring 32 sides (in FIG. 3, the second roller 24 (because the wheels roll in the direction of arrow K), the front and rear wheels try to be driven at the same speed.

Conversely, if the third transmission shaft 18 is rotationally driven in the reverse direction, the second inner ring 22 and the second outer ring 3
A pinching phenomenon of the second roller 24 occurs on the second side, and power transmission is performed. A pinching phenomenon of the first roller 23 occurs (in FIG. 3, the first roller 23 rolls in the direction of arrow J due to the action of the first inner ring 21), and the front and rear wheels try to be driven at the same speed. . In other words, the front and rear wheels are always driven at the same speed when moving forward and backward.

[Another embodiment] In the structure shown in FIG. 1, the first and second outer rings 31 and 32 are connected to the fourth power transmission shaft 19 on the front wheel side.
Alternatively, the first and second inner rings 21 and 22 may be fixed to the third power transmission shaft 18 on the rear wheel side. Further, in the structure of FIG. 1, the first and second outer rings 31 and 32 are fixed to the casing 20, and the first and second inner rings 21 and 22 are slid and moved to the first and second rollers 2.
3 and 24 may be configured.

Although reference numerals are written in the claims for convenience of comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

[Figure 1] Longitudinal side view of the vicinity of the one-way clutch for forward and reverse movement

[Figure 2] Schematic diagram showing the transmission structure inside the transmission case of an agricultural tractor

FIG. 3 is a cross-sectional plan view of the vicinity of the first and second rollers and first and second inner rings in FIG. 1;

[Figure 4] Schematic side view of the vicinity of conventional one-way clutches for forward and reverse travel

[Explanation of symbols]

18, 19 Transmission shaft 21 First inner ring 21S
Conical surface 22 of the first inner ring 22S Conical surface 23 of the second inner ring 1st roller 24 2nd roller 31 1st outer ring 31S
Conical surface 32 of the first outer ring 32S Conical surface X of the second outer ring Axis of the transmission shaft

Claims (1)

[Claims] [Claim 1] A four-wheel drive vehicle, wherein the transmission system for the front wheels for driving is branched from the transmission system for the rear wheels for driving, and the transmission system for the front wheels for driving is provided with the configuration described in [A] to [E] below. . [B] A pair of first and second inner rings (21) and (22) whose outer peripheries are formed into conical surfaces (21S) and (22S) are connected to a power transmission shaft (19) on either the front wheel side or the rear wheel side. A pair of first and second outer rings (31), (
32), with each conical surface (31S) and (32S) facing each conical surface (21S) and (22S) of the first and second inner rings (21) and (22), on the front wheel side or It is attached to the other transmission shaft (18) on the rear wheel side. [B] The first and second inner rings (21), (22)
) and the first and second outer rings (31) facing this
, (32), each conical surface (21S), (22S), (31
S) and (32S), the transmission shafts (18) and (19
) first and second rollers (23) and (24) are arranged that roll around an axis (Y) oblique to the axis (X) of the roller. [C] The first outer ring (31) is placed on the first inner ring (21) side, or the first inner ring (21)
a first operating means for pressing the second outer ring (31) so as to bring the second outer ring (31) closer to the first outer ring (31);
2) on the second inner ring (22) side, or the second
A second operation means is provided for pressing the inner ring (22) so as to approach the second outer ring (32). [d] When the transmission shaft (18) on the rear wheel side is rotated in the forward rotation direction while the first operating means is in operation, the first roller (23) is rotated by the transmission shaft (18), (19) Displaced in the axis (X) direction of the first inner ring (21)
and a biconical surface (21S) of the first outer ring (31),
(31S) sandwiched between the first inner ring (21S)
) and the first outer ring (31) rotate together to transmit normal rotational power to the front wheels, and the transmission shaft (
19) rotates in the normal rotation side ahead of the rear wheel side power transmission shaft (18), the first roller (23) rolls in the opposite direction to the above, and rotates the front wheel side power transmission shaft (19) in the normal direction. It is configured to allow advance rotation to the side of rotation. [E] When the transmission shaft (18) on the rear wheel side is rotationally driven in the reverse direction while the second operating means is in operation, the second roller (24) is rotated by rolling to rotate the transmission shaft (18), ( 19) in the axis (X) direction of the second inner ring (22).
and a biconical surface (22S) of the second outer ring (32),
(32S) sandwiched between the second inner ring (22S)
) and the second outer ring (32) rotate together so that reverse rotation power is transmitted to the front wheels, and the transmission shaft (
19) rotates in the reverse direction ahead of the rear wheel side power transmission shaft (18), the second roller (24) rolls in the opposite direction to the above-mentioned direction, causing the front wheel side power transmission shaft (19) to rotate in the reverse direction. The configuration is configured to allow advance rotation to.