JP2501363B2 - Power extractor for tractor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a power takeoff device for a tractor.

2. Description of the Related Art Conventionally, in a tractor used for work on a lawn or the like, various measures have been taken to reduce slip of main wheels. One of them is a front drive wheel or a rear drive wheel, which is a main drive wheel that is constantly driven by the drive force from the engine, and the other is a sub drive wheel that is connected to the engine through a one-way clutch and is steered. There is something I did. Further, in such a tractor using a one-way clutch, there are a tractor that uses one one-way clutch and a tractor that uses two one-way clutches for forward traveling and backward traveling.

Here, comparing the rotational speed of the rotary shaft connected to the auxiliary drive wheel with the rotational speed of the gear that is loosely fitted to the rotary shaft and that transmits the driving force from the engine to the rotary shaft via the one-way clutch. During normal traveling, the rotation speed of the rotary shaft is set to be slightly higher than the rotation speed of the gear. Therefore, during normal traveling or turning, the driving force from the engine is transmitted only to the main driving wheels, and the auxiliary driving wheels rotate freely while being pushed or pulled by the main driving wheels. Therefore, it is possible to prevent the occurrence of slippage due to the difference in peripheral speed between the main drive wheel and the auxiliary drive wheel, which occurs when both the main drive shaft and the auxiliary drive wheel are driven.

On the other hand, when the main drive wheel slips, the rotation speed of the rotary shaft connected to the sub drive wheel decreases, so that the drive force is transmitted from the gear to the rotary shaft through the one-way clutch, By driving the drive wheels, the slip state of the main drive wheels is quickly eliminated.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In a tractor having one one-way clutch, the one-way clutch operates only when the tractor is moving forward. When the tractor is moving backward, the rotational speed of the rotary shaft connected to the auxiliary drive wheel is higher than the rotational speed of the gear, so that the rotary shaft drives the gear. However, the gear is connected to the drive system of the main drive wheels, and the gear cannot be accelerated by the rotating shaft. For this reason,
If the rotational speed of the rotary shaft is higher than the rotational speed of the gear, there is a drawback that braking that appears as slip of the auxiliary drive wheel occurs.

On the other hand, in a tractor having two one-way clutches for forward travel and for reverse travel, slip occurs due to the difference in peripheral speed between the main drive wheel and the auxiliary drive wheel in each of forward travel and reverse travel. And the occurrence of braking is prevented. However, the one-way clutch selection switching must be performed in conjunction with the forward / backward switching operation of the change lever, which requires a complicated and large one-way clutch switching mechanism. Furthermore, in a tractor using a continuously variable transmission such as a hydraulic transmission,
Since shifting between forward and reverse is continuously performed, there is a drawback that the one-way clutch cannot be switched.

A tractor in which a main drive wheel to which a drive force from an engine is transmitted and a sub drive wheel to which a drive force from the engine is transmitted and which is steered are arranged in front of and behind a vehicle body. A drive force transmission gear connected to the engine is loosely fitted to the outer periphery of a rotary shaft connected to the auxiliary drive wheel, and a drive force from the gear to the rotary shaft is provided between the gear and the rotary shaft. A one-way clutch for transmitting the rotation speed of the rotary shaft is set slightly higher than the rotation speed of the gear during normal traveling, and the operating direction of the one-way clutch is reversed according to the rotation direction of the rotary shaft. A reverse race was set up.

Action When the tractor moves forward and backward, the one-way clutch provided between the rotating shaft and the gear reverses its operating direction by the reverse race according to the rotating direction of the rotating shaft.
Therefore, both during forward movement and during reverse movement, the rotation shaft is prevented from entering the state of driving the gear because the rotation speed of the rotation shaft is higher than that of the gear and the rotation of the rotation shaft and the gear. Braking of the auxiliary drive wheels due to the difference in number is prevented from occurring.

Embodiment An embodiment of the present invention will be described with reference to the drawings. A hydraulic transmission 4 is connected to the engine 2 of the tractor 1 via a joint 3, and the hydraulic transmission 4
A transmission 5 is connected to the. An axle 6 having a main drive wheel differential incorporated therein is connected to the transmission 5, and an access 7 having a sub drive wheel differential incorporated therein is connected via a propeller shaft 8. A pair of left and right main drive wheels 9 to which the driving force from the engine 2 is constantly transmitted is connected to the axle 6, and the driving force from the engine 2 is transmitted to the axle 7 and steering operation is performed. A pair of left and right auxiliary drive wheels 10 are connected.

In the transmission 5, an input shaft 12 connected to an output shaft 11 of the hydraulic transmission 4,
A rotary shaft 13, a main drive wheel output shaft 14, and an auxiliary drive wheel output shaft 15, which is a rotary shaft, are rotatably supported with axes parallel to each other. A slide gear 18 that is selectively meshed with transmission gears 16 and 17 integrally formed with the input shaft 12 is slidably spline-fitted to the rotary shaft 13 and output gears 19 and 20 are fixed. Has been done. The gear 19 meshes with a gear 21 fixed to the main drive wheel output shaft 14, and the gear 20 meshes with a gear 23 loosely fitted to the sub drive wheel output shaft 15 via a bearing 22. There is. The auxiliary drive wheel output shaft 15 is connected to the auxiliary drive wheel 10 via the propeller shaft 8.

Next, a one-way clutch 24 that transmits a driving force from the gear 23 to the auxiliary drive wheel output shaft 15 is provided between the gear 23 and the auxiliary drive wheel output shaft 15. Further, there is provided a reverse race 25 that reverses the operating direction of the one-way clutch 24 according to the rotation direction of the auxiliary drive wheel output shaft 15. As shown in FIGS. 2 and 3, the one-way clutch 24 is interposed between the plate 26 that rotates integrally with the gear 23 and between the plate 26 and the auxiliary drive wheel output shaft 15. The plate 26 is formed with a plurality of rollers 27, and the plate 27 is formed with a recess 28 having an inclination toward the front and rear in the rotation direction of the gear 23. As shown in FIGS. 2 and 3, the reverse race 25 holds the roller 27 at one end, and the other end is brought into contact with the inner peripheral surface of the case of the transmission 5 in a light friction state. There is. During normal traveling, the rotation speed of the auxiliary drive wheel output shaft 15 is equal to the gear speed.
It is set to be slightly higher than the 23 rpm.

On the other hand, a gear clutch 29 is slidably spline-fitted to the auxiliary drive wheel output shaft 15, and a tooth portion 30 with which the gear clutch 29 meshes is formed on the gear 23.

In such a configuration, the driving force from the engine 2 is transmitted to the transmission 5 via the joint 3 and the hydraulic transmission 4. The driving force transmitted to the transmission 5 is transmitted to the main drive wheel output shaft 14 via the gears 19 and 21 by a gear shifting operation in which the transmission gear 18 is slid to selectively engage with the transmission gears 16 and 17. It is transmitted from the gear 20 to the gear 23.

Here, when the tractor 1 moves forward, first, the driving force from the engine 2 is transmitted to the main drive shaft 9, and the main drive wheels 9 are rotationally driven. On the other hand, the driving force from the engine 2 is also transmitted to the gear 23 to rotate the gear 23, but at the time of forward traveling which is the normal traveling, the auxiliary drive wheel output shaft 15 connected to the auxiliary drive wheel 10 is driven. Since the rotation speed is higher than that of the gear 23, the driving force is not transmitted from the gear 23 to the auxiliary drive wheel output shaft 15 via the one-way clutch 24, and the auxiliary drive wheel 10 is pulled by the main drive wheel 9. To rotate freely. Therefore, the occurrence of slippage due to the difference in peripheral speed between the main drive wheel 9 and the auxiliary drive wheel 10 that occurs when both the main drive wheel 9 and the auxiliary drive wheel 10 are driven is prevented, and the work area is roughened by the slip. Is prevented.

In the one-way clutch 24, as shown in FIG. 2, the roller 27 is recessed in the reverse rotation race 25 that is frictionally abutted against the inner peripheral surface of the transmission case 5.
Inside, the auxiliary drive wheel output shaft 15 and the gear 23 are moved to a position rearward with respect to the rotation direction (direction of arrow A).

On the other hand, when the main drive wheels 9 slip during forward movement, the slip causes the rotation speed of the auxiliary drive wheel output shaft 15 to decrease, and when the rotation speed of the auxiliary drive wheel output shaft 15 decreases below the rotation speed of the gear 23, The driving force is transmitted to the auxiliary drive wheel output shaft 15 via the one-way clutch 24, and the auxiliary drive wheel 10 is rotationally driven. Therefore, the slip state of the main drive wheels 9 is quickly eliminated by the rotational drive of the auxiliary drive wheels 10, and the slipping of the main drive wheels 9 prevents the work area from being roughened.

Next, when the tractor 1 is moving backward, as shown in FIG. 3, the reverse race 25 causes the roller 27 to move rearward with respect to the rotational direction of the auxiliary drive wheel output shaft 15 and the gear 23 (direction of arrow B). Have moved to a position. For this reason, the one-way clutch 24 operates in the same way as when moving forward even when moving backward,
In the normal reverse drive state, the rotational speed of the auxiliary drive wheel output shaft 15 becomes higher than the rotational speed of the gear 23, so the auxiliary drive wheel 10 is freely rotated while being pushed by the main drive wheel 9. Therefore, the occurrence of slippage due to the difference in peripheral speed between the main drive wheel 9 and the sub drive wheel 10 that occurs when the main drive wheel 9 and the sub drive wheel 10 are both driven is prevented, and the work area is roughened by the slip. Is prevented. In addition, the reverse race 25
The slippage of the auxiliary drive wheel 10 due to braking that occurs when the tractor 1 is moved backward without using the clutch is prevented.

When the main drive wheels 9 slip during the reverse drive, the auxiliary drive wheels 10 are driven through the one-way clutch 24 in the same manner as when the slip occurs during the forward drive, and the slip state of the main drive wheels 9 is rapidly increased. Will be resolved.

In addition, slide the gear clutch 29 and
When meshed with 30, the driving force transmitted from the engine 2 to the gear 23 is always transmitted to the auxiliary drive wheel output shaft 15 via the gear clutch 29, and the tractor 1 travels in a normal four-wheel drive state.

As described above, the present invention loosely fits a drive force transmitting gear not connected to the engine to the outer periphery of the rotary shaft connected to the auxiliary drive wheel as described above, and changes the rotational speed of the rotary shaft during normal running to a gear. Is set slightly higher than the number of revolutions, and a one-way clutch that transmits the driving force from the gear to the rotating shaft is provided, and a one-way clutch that transmits the driving force from the gear to the rotating shaft is provided between the gear and the rotating shaft. By providing a reverse race that reverses the operating direction of the one-way clutch according to the rotation direction of the rotation shaft, the rotation speed of the rotation shaft is higher than the rotation speed of the gear during both forward and reverse travel. It is possible to prevent the shaft from driving the gear and prevent braking of the auxiliary drive wheel due to the difference in the rotational speed between the rotating shaft and the gear. Since the operation direction of the switch can be automatically reversed, it is possible to eliminate the need for a switching operation with a switching lever, etc., and to simplify the structure by eliminating the mechanism such as the switching lever. Have.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a vertical sectional side view showing a transmission, FIGS. 2 and 3 are explanatory views for explaining reversal of the operating direction of a one-way clutch by a reverse race, and FIG. The figure is a side view showing the entire tractor. 1 ... tractor, 2 ... engine, 9 ... main drive wheel, 10
...... Auxiliary drive wheel, 15 …… Rotary shaft, 23 …… Gear, 24 …… One-way clutch, 25 …… Reverse race

Claims (1)

(57) [Claims] 1. A tractor in which main driving wheels to which driving force from an engine is transmitted and auxiliary driving wheels to which driving force from the engine is transmitted and which is steered are arranged in front and rear of a vehicle body. A drive force transmission gear connected to the engine is loosely fitted to the outer periphery of a rotary shaft connected to the auxiliary drive wheel, and the drive force is transmitted from the gear to the rotary shaft between the gear and the rotary shaft. A reverse race in which a one-way clutch is provided to set the rotational speed of the rotary shaft during normal traveling to slightly higher than the rotational speed of the gear and to reverse the operating direction of the one-way clutch according to the rotational direction of the rotary shaft. A power take-out device for a tractor, which is provided with.