JPH0663552B2 - Ultra low speed transmission of tractor - Google Patents

Description

Description: (a) Field of Industrial Application The present invention relates to an ultra-low speed transmission for a tractor, and more particularly to the positions of an ultra-low speed selection gear and an ultra-low speed shifter.

(B) Prior Art Generally, in an ultra-low speed transmission of a tractor, an ultra-low speed selection gear is slidably disposed on an ultra-low speed transmission shaft disposed in front of or in the middle upper part of a transmission case at the rear of an airframe. An ultra-low speed shifter is slidably arranged on an ultra-low speed shifter shaft so that the selected gear slides to mesh with the ultra-low speed gear. The ultra-low speed shifter is slid in a predetermined direction. When moving, the ultra-low speed selection gear meshes with the ultra-low speed gear, and the rotation of the main transmission shaft is decelerated to the ultra-low speed via the ultra-low speed gear and transmitted to the pinion shaft.

(C) Problems to be Solved by the Invention By the way, in the transmission case of the tractor, the traveling speed change shaft is rotatably supported outside the ultra-low speed speed change shaft, and the main speed selection gear is attached to the shaft. A main transmission device is configured by slidably disposed, and further, a main transmission shifter is slidably disposed on a main transmission shifter shaft so that the selected gear slides and meshes with a main transmission gear. Therefore, the transmission case requires a traveling speed change shaft and a main speed change shifter shaft that form the main transmission, and an ultra-low speed change shaft and an ultra-low speed change-shifter shaft that form the ultra-low speed transmission, which requires a large space. I was there.

In addition, a compact transmission has been devised in which the traveling speed change shaft and the ultra-low speed change speed shaft are configured by the same axis, but in this device as well, the main speed shifter shaft and the ultra low speed shift gear for arranging the main speed change are provided. Since the ultra-low speed shifter shaft for disposing the speed shifter is separately configured, the ultra-low speed transmission device is composed of many parts, and assembling the device is a difficult work requiring many steps.

On the other hand, a gear transmission is built in the clutch housing to shift the main shaft downward by one step with respect to the engine crankshaft, and the clutch housing and the transmission case are connected by an intermediate case, and the intermediate case is moved downward. Although a tractor has been proposed in which the tractor is arranged and its upper surface is substantially flush with the step surface, the tractor requires a small mission case due to the lower position of the intermediate case. It was difficult to store the ultra-low speed transmission in the case because of the storage space.

(D) Means for Solving the Problem The present invention is intended to solve the above-mentioned problems, and a main gear selection gear is slid by a main gear shifter,
Alternatively, slide the auxiliary gear selection gear with the auxiliary gear shifter, and further slide the ultra-low speed gear with the ultra-low-speed shifter to engage the main gear, auxiliary gear or ultra-low gear, respectively, to generate power. In the tractor for transmitting the above-mentioned gears and accommodating each of these gears in a mission case, the ultra-low speed gear is detachably attached to the opening of the mission case, and the main gear selection gear and the The ultra-low speed selection gear is slidably arranged on the same shaft, and the sub-transmission gear is fixed to the same shaft and meshed with the ultra-low speed gear, and the ultra-low speed selection gear is provided. Is selectively meshed with the ultra-low speed gear or the auxiliary speed change gear, and the main speed shifter and the ultra-low speed speed shifter are slidably arranged on the same shifter shaft. Super slow speed of the tractor It is in the transmission.

(E) Operation Based on the above configuration, when the ultra-low speed shifter provided on the same shifter shaft (main shifter shifter shaft) as the main shifter is slid in the predetermined direction, the main gearshift selection gear and the same gear (running shift Shaft) is slid, the ultra-low speed selection gear is meshed with the ultra-low speed gear, and The rotation is decelerated to an ultra-low speed via the ultra-low speed gear and transmitted to the pinion shaft.

(F) Example Hereinafter, an example according to the present invention will be described with reference to the drawings.

As shown in FIG. 2, the tractor N has an engine block 1 at the front of the machine body, a front chassis 15 is fixed to the lower part of the block 1 by projecting forward, and a clutch housing 2 is provided at the rear. Is fixed. Further, a mission case 5 is disposed on the rear side of the machine body, and the case 5 and the clutch housing 2 are connected and fixed via an intermediate case 6 to form a machine body 16 of an integral structure type. Further, front wheels 12 are supported on the front chassis 15 via front axles 10, and rear wheels 11 are supported on the mission case 5 via rear axles 17. On the other hand, a steering wheel 19 is installed above the clutch housing 2, and a seat 20 is arranged above the transmission case 5 to form a driver's seat 21. On the basis of the slightly protruding lower upper surface 6a of the intermediate case 6, a wide foot space having a substantially flat surface is formed.

As shown in FIG. 1, the clutch housing 2 has the main clutch 22 installed therein and the gear transmission 23.
Are arranged. The gear transmission 23 is an output shaft of the clutch 22, that is, a shaft extending coaxially with the engine crankshaft.
It has a gear 26 fixed to 25 and a gear 28 fixed to the main transmission shaft 27 which is shifted one step lower than the shaft 25. The gears 26 and 28 mesh with each other to form a main transmission shaft. 27 is located a predetermined amount below the engine crankshaft. Further, the main transmission shaft 27 is a hollow shaft, and the main hollow transmission shaft 27 penetrates the intermediate case 6 and extends to the mission case 5 at the rear part of the airframe. Also, the main hollow transmission shaft 28
A front wheel drive transmission shaft 29 is rotatably fitted therein, and thus these transmission shafts 27 and 29 form a double shaft. Further, the front end of the front wheel transmission shaft 29 projects from the main hollow transmission shaft 27, and the gear 30 is fixed to the projection. Further, in the gear transmission 23, a front wheel drive shaft 31 is rotatably supported, and a front wheel drive switching gear 32 is slidably supported on the drive shaft 31, and the drive shaft 31 The front end portion projects forward from the lower portion of the clutch housing 2. The gear 30 is releasably interlocked with the switching gear 32 via the intermediate gear 33, and the front wheel drive shaft
31 is connected to the front axle 10 via a short propeller shaft 34 (see FIG. 2).

On the other hand, in the mission case 5, as shown in FIGS. 3 and 4, the pinion shaft 35 is coaxial with the front wheel drive transmission shaft 29.
Is rotatably supported, and the pinion shaft 35 is connected to the front wheel drive transmission shaft 29 at its front end,
The rear end portion is interlocked with the differential gear 36 of the rear axle 17 via a bevel pinion. Further, a PTO speed change shaft 37 is rotatably supported above the pinion shaft 35, and a traveling speed change shaft 39 is rotatably supported below the pinion shaft 35. An intermediate gear set 40, which is fitted on the pinion shaft 35 and has a large number of gears with different numbers of teeth, is rotatably arranged, and the gear set 40 is connected to the main hollow transmission shaft 27.
Further, a large gear 41 and a small gear 42, which are always meshed with the gears of the gear set 40, are rotatably supported on the PTO gear shaft 37, respectively, and a middle gear 43 is slidably supported. The intermediate gear 43 can be selectively engaged with the large gear 41, the small gear 42 or the intermediate gear 40b of the gear set 40 based on the operation of the PTO gear shift lever. Further, the PTO transmission shaft 37 has gears 45, 46 at its rear end.
Is connected to the PTO shaft 47 which is shifted downward by one stage, and the PTO shaft 47 is positioned substantially coaxial with the main transmission shaft 27 and the front wheel transmission shaft 29.

Further, as shown in FIGS. 3 and 7, a main gear selection large gear set 49 and a main gear selection small gear set 50 are slidably fitted to the traveling transmission shaft 39, respectively. Cage, these gear sets
49 and 50 can be meshed with a predetermined gear of the intermediate gear set 40 by the operation of a main shift shifter described later based on the operation of the main shift lever 51 (Fig. 1). Further, a sub-transmission gear set 52 is rotatably supported at the rear portion of the speed change shaft 39, and
The ultra-low speed selection gear 53 is slidably supported,
Further, an ultra-low speed gear set 55 is provided so as to be connected to the gear set 52, and the selection gear 53 meshes with the sub-transmission gear set 52 directly or with the ultra-low speed gear set 55 by an ultra-low speed shift shifter described later. Then, the rotation of the transmission shaft 39 is transmitted to the sub-transmission gear set 52 directly or via the ultra-low speed gear set. Further, on the rear part of the pinion shaft 35, there is a gear set operated by an auxiliary transmission lever 56 (Fig. 1).
57 is slidably supported, and the gear set 57 can be selectively meshed with any one of the gears for the auxiliary gear 52.

Then, as shown in detail in FIG. 7, the super-low speed gear set 55 is attached to a bracket 54 which is inserted from the side opening 5a of the mission case 5, and the gear set is rotatably attached to the bracket 54. And a large and small gears 55a and 55b fixed to the shaft 55c. As shown in FIGS. 5 to 8, a main shift shifter shaft 61 is supported by the transmission case 5 on the side of the traveling shift shaft 39, and the main shift lever 61 is attached to one end of the shifter shaft 61. A main gear shift transmission 62 for large gears, which is interlocked with 51, is slidably arranged, and the shifter 62 slides on the fork portion of the main gear selection large gear set 49 to form the small gears of the intermediate gear set 40. Can be selectively meshed with 40c. Further, adjacent to the large gear shifter 62, a small gear main shift shifter 63 which is interlocked with the main shift lever 51 is slidably arranged on the shifter shaft 61, and like the large gear shifter 62,
The main small-gear selection small gear set 50 can be selectively meshed with the middle gear 40b or the large gear 40d of the intermediate gear set 40. Further, at the other end of the shifter shaft 61, there is slidably arranged an ultra-low speed shifter 6 which is interlocked with an ultra-low speed switching lever (not shown). It holds the shaft portion 53a of the above and can selectively mesh the ultra-low speed selection gear 53 with the ultra-low speed gear 55a.

Incidentally, reference numeral 59 in the figure denotes a reverse gear. Further, 6b is a strength member configured by extending both left and right side walls of the intermediate case 6 downward.

Since the present embodiment is configured as described above, when the main gear shifter 62 for large gears or the main gear shifter 63 for small gears is slid in the predetermined direction by switching the main gear shift lever 51, the shifter slides. The main gear selection large gear set 49 or the main gear selection small gear set 50 is selectively meshed with each gear of the intermediate gear set 40 by the movement.
The rotation of the intermediate gear set 40 is transmitted to the traveling transmission shaft 39 after being changed in three forward gears and one reverse gear. Further, when the ultra-low speed switching lever (not shown) is set to the off position, the ultra-low speed shifter 65
Is slid to the left, the ultra-low speed selection gear 53 is meshed with the sub-transmission gear set 52, the rotation of the traveling transmission shaft 39 is directly transmitted to the sub-transmission gear set 52, and the rotation is further transmitted. Shift lever 56
By the selective engagement of the gear set 57 with the sub-transmission gear set 52 by the gear shift, the gear is shifted in two stages and transmitted to the pinion shaft 35, whereby the tractor N travels at the normal speed. When the ultra-low speed switching lever is in the on position, the ultra-low speed shifter 65 is slid to the right, and the ultra-low speed selection gear 53 moves the sub-speed gear set 52.
While being disengaged, the rotation of the traveling speed-change shaft 39 is transmitted to the sub-transmission gear set 52 via the ultra-low speed gear set 55 by being meshed with the ultra-low speed gear 55a. As a result, the rotation of the sub-transmission gear set 52, which has been decelerated to an ultra-low speed, is rotated by the pinion shaft 35 as described above.
And the tractor N travels at an extremely low speed.

(G) Effects of the Invention As described above, according to the present invention, the main gear selection gears 49, 50 and the ultra-low speed selection gear 53 are provided on the same shaft (travel gear shaft) 3.
The main shift shifters 62, 63 and the ultra-low speed shift shifter 65 are slidably mounted on the same shifter shaft (main shift shifter shaft) 61 so that one shaft ( The main transmission selection gears 49, 50 and the ultra-low speed selection gear 53 can be arranged on the traveling transmission shaft 39, and the main transmission shifters 62, 63 and one shifter shaft (main transmission shifter shaft) 61 can be arranged. An ultra low speed shifter 65 can be provided. Therefore, it is possible to reduce the number of parts constituting the ultra-low speed transmission device, to make it compact, and to assemble the device easily.

Further, the ultra-low speed gear 55 corresponds to the mission case 5
Since it is detachably attached to the opening 5a, the ultra-low speed transmission can be easily attached and the maintenance becomes easy.

Further, the auxiliary speed change gear 52 is fixed to the same shaft (travel speed change shaft) 39, and is arranged so as to mesh with the ultra-low speed gear 55,
Since the ultra-low speed selection gear 57 selectively meshes with the ultra-low speed gear 55 or the sub-transmission gear 52, the sub-transmission is also rationally arranged so that the main transmission and the sub-transmission are provided. The ultra-low speed transmission can be arranged in the mission case 5 that has the same while maintaining compactness.

Further, by reducing the number of parts constituting the ultra-low speed transmission, the ultra-low speed transmission can be installed even in a narrow space in the mission case 5, the intermediate case 6 is arranged below, and the upper surface 6a thereof is stepped. Even in the tractor N configured to be substantially flush with the surface 7, it is possible to house the ultra-low speed transmission in the mission case 5.

[Brief description of drawings]

FIG. 1 is a sectional view showing a transmission including an ultra-low speed transmission for a tractor according to the present invention, FIG. 2 is an overall side view showing a tractor, and FIG. 3 is a mission to which the ultra-low speed transmission according to the present invention is applied. The side view showing the gear transmission in the case, 4th
FIG. 5 is a front view thereof, FIG. 5 is a side view showing mounting of an ultra-low speed shifter and a main shifter of an ultra-low speed transmission according to the present invention, FIG. 6 is its front view, and FIG. FIG. 8 is a side view showing the relationship among the gears, the ultra-low speed gear and the ultra-low speed shifter, and FIG. 8 is a front view thereof. 5 ... mission case, 39 ... traveling speed change shaft, 40 ... main speed change gear (intermediate gear set), 49, 50 ... main speed change selection gear (49 ... main speed change large gear set, 50 ...) … Main gear selection small gear set), 52 …… Sub-transmission gear set, 53 …… Super low speed selection gear, 55 …… Super low speed gear set (55a …… Super low speed gear, 5
5b …… Mating gear 55b), 61 …… Main shift shifter shaft, 57…
… Sub gear selection gears, 62, 63 …… Main gear shifter (62 ……
Main gear shifter for large gears, 63 ... Main gear shifter for small gears), 65 ... Ultra-low speed shifter, N ... Tractor.

Claims (1)

[Claims] 1. A main shift selection gear is slid by a main shift shifter, an auxiliary shift selection gear is slid by an auxiliary shift shifter, and an ultra-low speed selection gear is slid by an ultra-low speed shifter. A tractor that transmits power by meshing with a main speed change gear, an auxiliary speed change gear, or an ultra-low speed gear, and stores each of these gears in a mission case, wherein the ultra-low speed gear is the opening of the mission case. The main transmission selection gear and the ultra-low speed selection gear are slidably arranged on the same shaft, and the auxiliary transmission gear is fixed to the same shaft. The super low speed gear is disposed so as to mesh with the super low speed gear, and the super low speed selection gear selectively meshes with the super low speed gear or the auxiliary speed change gear. Slide the shifter on the same shifter shaft Ultra slow transmission of the tractor, characterized by comprising disposed on.