JPH0534539B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is characterized in that a first gear and a second gear of different sizes and numbers of teeth are fixed to a rotating shaft in a power transmission path to a rear wheel. , a small-diameter idling gear that always meshes with the large-diameter first gear and a large-diameter idling gear that always meshes with the small-diameter second gear are connected to a speed change shaft on a lower side of the power transmission side than the rotating shaft. a shift sleeve that selectively engages and connects one of the idling gears to the speed change shaft by shifting in the axial direction; The present invention relates to a traveling transmission structure for a four-wheel drive agricultural tractor that constitutes a transmission mechanism and has a front wheel gear fixed to the transmission shaft for extracting power to the front wheels.

[Conventional technology]

For agricultural tractors, the introduction of a super-reduction mechanism is sometimes required for work that requires running at extremely low speeds, such as deep excavation work using a trencher, and various ultra-reduction mechanisms have been proposed in the past. .
For example, planetary speed reduction means and differential speed reduction means are examples.

[Problem that the invention seeks to solve]

Conventional super-reduction mechanisms often use multiple gears and variable speed shafts to obtain a sufficient reduction ratio, or use complex mechanisms such as planetary reduction means or differential reduction means as described above. Furthermore, the installation space is large and the assembly process is difficult.

The present invention aims to provide a transmission structure for a four-wheel drive tractor that is extremely simple in structure and easy to assemble, yet can obtain a desired reduction ratio.

[Means for solving problems]

The technical means of the present invention taken to solve the problem is, in the traveling transmission structure of the four-wheel drive agricultural tractor described above, a small-diameter attached gear is attached to the large-diameter idling gear on the opposite side of the shift sleeve. are integrally connected to each other, the front wheel gear is arranged on the side of the attached gear, and a third bearing bracket having a large diameter that engages with the attached gear is attached to a bearing bracket that closes the opening of the transmission case in which the transmission mechanism is installed. A gear and a small-diameter fourth gear that meshes with the front wheel gear are attached via a support shaft,
The attached gear and the front wheel gear are configured to be able to be interlocked and disengaged, and a super deceleration mechanism that can transmit transmission when the speed change mechanism is in a neutral state is constructed, which has the following functions and effects.

[Effect]

In other words, the attached gear connected integrally with the large-diameter idling gear for low-speed rotation functions to use the gear system used for normal shifting as a gear for super deceleration, and the low-speed rotation taken out from this attached gear The power is further reduced in two stages by large and small third and fourth gears supported on separate shafts. In order to extract power to the front wheels, the front wheel gear has the function of returning the rotational power reduced by the third and fourth gears to the speed change shaft.

〔Effect of the invention〕

Therefore, according to the technical means of the present invention, the low-speed transmission system originally provided in the transmission mechanism and the gears necessary for driving the front wheels can be effectively used as a configuration for super-deceleration. As a result, the desired super-deceleration can be achieved with a simple and compact structure without using many gears or transmission shafts or special deceleration means.

Moreover, since the third and fourth gears of the super-reduction mechanism are attached to removable bearing brackets, it is also possible to change the specifications of the super-reduction mechanism to a reduction ratio as required.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 3 shows an agricultural tractor equipped with the traveling transmission mechanism of the present invention. In this tractor, an engine 2 and a transmission case 3 are connected to the front and rear of a main frame 1, and a transmission shaft 9 is connected to a main clutch housing 4 directly connected to the rear surface of the engine through a transmission shaft 9 and a pair of universal joints 10, 10. Power is axially transmitted to the system case 3. Steering front wheels 5, 5, which are driven by receiving power from the transmission case 3, are supported below the front of the main frame 1, and rear wheels 6, 5 are supported on both left and right sides of the transmission case 3.
6 is supported by a drive shaft, and the rear part of the transmission case 3 is equipped with a hydraulically driven lift arm for raising and lowering the working machine, and a PTO shaft 8 is provided to protrude rearward. In this embodiment, the main clutch housing 4 shown in FIG. 4 is formed by die casting, and includes a fuller portion 4a that slidably supports the release hub 11 of the clutch, a bearing 12, and an oil seal. The assembly portion 4b of 13 uses the cast surface as it is to simplify machining, and the transmission shaft 9 that transmits power from the main clutch housing 4 to the transmission case 3.
has an extensible structure using splines.

The transmission structure of the four-wheel drive agricultural tractor described above is shown in FIGS. 1 and 2. This transmission structure incorporates a main transmission mechanism A for driving, a sub-transmission mechanism B, a super deceleration mechanism C, a front wheel drive switching mechanism D, and a PTO transmission mechanism E, and each mechanism will be described in detail below.

(): Main transmission mechanism A An input shaft 17 that receives power from the main clutch housing 4 is protruded from the upper front surface of the transmission case 3, and the input shaft 17 and the first transmission shaft 18 disposed below are connected to the gear G ₁ and _G2 . A second speed change shaft 19 is disposed below the first speed change shaft 18, and has gears meshing with gears G ₂ , G ₃ , and G ₄ fixedly attached to the first speed change shaft 18 .
G ₅ , G ₆ , G ₇ , and a gear G ₉ that is always engaged with a back gear (not shown) that is always engaged with a gear G ₈ that is fixed to the first shift shaft 18 are attached to the second shift shaft 19, respectively. It is loosely fitted. Further, the second transmission shaft 19 has the gear _G5 or the gear _G6 and the shaft 1.
a first shift sleeve S ₁ that selectively connects and disconnects gear G ₇ or gear G ₉ and shaft 19;
A second shift sleeve S2 is attached to selectively connect and release the _two . Therefore, if the first shift sleeve S ₁ is connected to the left and the shift gear G ₅ is connected to the shaft 19, the third forward speed can be obtained, and if the gear is similarly shifted to the right, the first forward speed can be changed to the first forward speed. 2 Shift sleeve S ₂ If you shift 2 to the left, the 2nd
If the speed is shifted to the right, a reverse state can be obtained.

(): Sub-transmission mechanism B The sub-transmission mechanism B of this embodiment corresponds to the transmission mechanism according to the present invention. Said second gear shift shaft 1
A concentric rotating shaft (hereinafter referred to as the third gear shift shaft) 20 spline-connected to the rear of the transmission gear 9 has a large-diameter first gear G ₁₀ and a small-diameter second gear G ₁₁ with different numbers of teeth.
and a gear _G12 with an intermediate diameter are fixedly installed.
A transmission shaft (hereinafter referred to as the final transmission shaft) 16 disposed above the third transmission shaft 20 has a large diameter idling gear that is always engaged with the second gear G ₁₁ .
G ₁₃ and a small-diameter free rotating gear G ₁₄ that is always engaged with the first gear G ₁₀ are loosely fitted, respectively, and both the gears G ₁₃ and G ₁₄ are selectively connected to and released from the shaft 16. Moreover, a third shift sleeve _S3 is attached, in which a gear _G15 that can mesh with the gear _G12 is integrally formed. Therefore, if this third shift sleeve S ₃ is shifted to the left and gear G ₁₃ is connected to the shaft 16, a low speed transmission state will be established, and if this third shift sleeve S 3 is shifted to the right and gear G ₁₄ is connected to the shaft 16, a high speed transmission state will be established. If the gear G ₁₂ and the gear G ₁₅ are engaged with each other in the middle of the transmission state, a medium speed transmission state can be obtained.

(): Drive switching mechanism D A wide front wheel gear 16 for extracting the rotational driving force of the final shift shaft 16 to the front wheels 5, 5 is fixed to the final shift shaft 16, and the third shift shaft 20 is a gear that meshes with the front wheel gear _G16 .
G ₁₇ and gear G ₁₈ integrated therewith are loosely fitted and supported. A shift gear G ₁₉ that can freely engage with the idling gear G ₁₈ is spline-fitted to the front wheel transmission shaft 15 disposed below the third transmission shaft 20, and transmission is performed by shifting the gear G ₁₉ . The shaft 15, that is, the front wheels 5, 5 can be driven or freely rotated.

(): Super speed reduction mechanism C A bearing bracket 21 that can be attached and detached from the outside is attached to the opening 14 formed on the left side of the transmission case 3. Large and small third and fourth bearing brackets are attached to this bracket 21 via a support shaft 22. Gear G ₂₀ ,
G ₂₁ is integrated and supported with a loose fit so that it can be shifted freely. On the other hand, the large gear G ₁₃ of the sub-transmission mechanism B
A small-diameter accessory gear G ₂₂ is integrally connected to the fourth gear G 21 , the fourth gear G ₂₁ is always engaged with the wide front wheel gear G ₁₆ , and the third gear G ₂₀ is connected to the accessory gear G 22 .
It is configured so that it can be freely interlocked with G ₂₂ . That is, with the sub-transmission mechanism B in neutral, the gears G ₂₀ and G ₂₁ are shifted to the left in the figure to shift to the third gear.
By meshing the gear G ₂₀ with the attached gear G ₂₂ , a state can be obtained in which the final speed change shaft 16 is driven at a large speed.

(): PTO transmission mechanism E A PTO system first transmission shaft 23 is provided behind the input shaft 17, and a gear G ₂₃ rotatably attached to the rear of this shaft 23 is fixed to the first transmission shaft 18. The installed gear _G8 is always engaged. A shift gear spline-fitted to the first transmission shaft 23
G ₂₄ is provided so as to be able to selectively engage with the outer periphery of the boss of the free rotating gear G ₂₃ , the outer periphery of the boss of the gear G ₁ of the input shaft 17, and the gear G ₄ of the main transmission mechanism A. The rotation of the first transmission shaft 23 is configured to be variable in three stages. Note that the reference numeral 24 in the drawings is a second PTO shaft that is driven by the rotation of the PTO shaft 8.

[Another example]

In this embodiment, the third and fourth gears G ₂₀ and G ₂₁ that constitute the super reduction mechanism C in the previous embodiment are
As shown in FIG. 5, the gears are divided into individual gears and loosely fitted onto the support shaft 22, and these two gears G ₂₀ and G ₂₁
is always engaged with the front wheel gear G ₁₆ and the attached gear G ₂₂ , and a pawl clutch 25 is configured between the third gear G ₂₀ and the fourth gear G ₂₁ to turn on and off the speed change. This is an example of what was done.

[Brief explanation of the drawing]

Figure 1 is a side view showing the gear train of the truss transmission, Figure 2 is a side view of the super reduction mechanism, Figure 3 is an overall side view of the four-wheel drive agricultural tractor, and Figure 4 is a side view of the main clutch housing. Partially cutaway side view,
FIG. 5 is a side view of another embodiment corresponding to FIG. 2. 3...Mission case, 5...Front wheel, 6...
... Rear wheel, 14 ... Opening, 16 ... Gear shift shaft, 20
... Rotating shaft, 21 ... Bracket, B ... Speed change mechanism, G ₁ to _{G 24} ... Gear, S ₃ ... Shift sleeve,
C... Super deceleration mechanism.

Claims (1)

[Claims] 1 A first gear G 10 and a second gear G ₁₀ of different sizes with different numbers of teeth are attached to the rotating shaft 20 in the power transmission path to the rear wheels 6, 6.
A gear G ₁₁ is fixedly installed, and a large-diameter first gear
A small-diameter idling gear G ₁₄ that always meshes with G ₁₀ and a large-diameter idling gear G ₁₃ that always meshes with the small-diameter second gear G ₁₁ are loosely fitted, and between these two idling gears G ₁₃ and G ₁₄ . A shift sleeve S ₃ is spline-fitted onto the speed change shaft 16 to selectively engage and connect either of the idle gears G ₁₃ and G ₁₄ to the speed change shaft 16 by shifting in the axial direction. In the traveling transmission structure of a four-wheel drive agricultural tractor, the transmission mechanism BB is configured, and a front wheel gear G ₁₆ for outputting power to the front wheels 5, 5 is fixed to the transmission shaft 16. G ₁₃ has a small diameter attached gear on the opposite side of the shift sleeve S ₃ .
G ₂₂ are integrally connected to each other, the front wheel gear G ₁₆ is arranged on the side of the attached gear G ₂₂ , and the bearing bracket 21 closes the opening 14 of the transmission case 3 in which the transmission mechanism B is housed; A large-diameter third gear G ₂₀ that meshes with the accessory gear G ₂₂ and a small-diameter fourth gear G ₂₁ that meshes with the front wheel gear G ₁₆ are attached via a support shaft 22 to connect the accessory gear G ₂₂ . and gear G ₁₆ for the front wheels
A traveling transmission structure for a four-wheel drive agricultural tractor, comprising a super-deceleration mechanism C that can be configured to be interlocked and disengaged, and can transmit transmission when the transmission mechanism B is in a neutral position.