JPH0623016B2 - Tractor transmission - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transmission of a tractor, and more particularly to an interlocking device for an auxiliary shift and an ultra-low speed device in the transmission.

(B) Conventional technology Conventionally, a transmission of a tractor is configured such that each of main gear shifting, auxiliary gear shifting, and ultra-low speed devices independently operates. In the high and low speed positions, the main speeds 1st, 2
It is possible to perform a combination operation for each of the third speed and the third speed.

And, in general, when the sub-shift is set to the low-speed position while operating the ultra-low speed, the speed becomes 0.26, 0.38, 0.66 km / H corresponding to the first, second, and third speeds of the main shift, respectively. Set the speed change to the high speed position and the speed will be 1.18, 1.72, 2.96 km / H.

(C) Problems to be solved by the invention However, the speed at which the ultra-low speed is operated and the sub-shift is set to the high-speed position is one of the main speeds when the sub-speed is set to the low-speed position without operating the ultra-low speed. There is almost no need to operate the super-low speed by setting the auxiliary shift to the high speed position, which is almost the same as the second speed.

On the other hand, generally, the gear strength of each transmission is calculated by the engine torque of the positive transmission system transmitted from the engine to the wheels in a range with a small reduction ratio (for example, 4th speed or higher), and in a range with a large reduction ratio (for example, 3rd speed). Up to), the reverse transmission system from the wheel that acts during engine braking, that is, the skid torque applied to the tire is used for the calculation.

Therefore, if the torque is calculated in the order of final reduction ratio → differential reduction ratio → sub-reduction ratio → ultra-low speed ratio, the load on the ultra-low speed gear decreases as the reduction ratio increases, but if the sub-transmission is in the high-speed position, Since the reduction ratio is relatively small, the load on the ultra-low speed gear increases, and therefore the auxiliary transmission gear located downstream of the ultra-low speed gear in the positive transmission system may be damaged.

In particular, in a so-called flat deck type tractor in which a foot space having a flat surface is secured below the driver's seat, it is necessary to make the mission case compact. Therefore, it is desirable to install the ultra-low speed device below the case. However, because of this, the torque of the reverse transmission system directly acts on the ultra-low speed gear and the auxiliary transmission gear that directly meshes with the gear,
There is a high possibility that the gear will be damaged.

(D) Means for Solving the Problems The present invention aims to solve the above problems, and as shown in FIG.
9 and the operation lever 62 for sub-shifting and the like, the pin 65 or the plate 66 having the long hole 67 is fixedly mounted, and the pin 65 and the long hole 67 are engaged with each other to operate the ultra-low speed device and the sub-transmission device. The movements of both levers 59 and 62, which are means, are restrained from each other. A restraint device 69, which is, for example, a plate 66, is extended to the opposite side of the pivot point of one of the levers, and an engaging member 65, which is, for example, a pin 65, is a lever of the pivot portion of the other lever. Installed in the middle part of the side. Then, the engaging member engages with the restraint device 69 with a certain amount of play, so that the ultra-low speed switching lever 59 operates in the operating state C.
In the case of, the auxiliary shift lever 62 is configured so as not to be in the high speed position B.

(E) Action Based on the above configuration, the ultra-low speed switching lever 59 is turned to the cut position D.
When held at, the sub-transmission lever 62 can freely move between the high speed position B and the low speed position A without any interference by the restraint device 69, but when the ultra-low speed switching lever 59 is held at the operating position. , The auxiliary shift lever 62 is a check device 69.
It is not possible to move to the high speed position B due to the restriction. Similarly, when the auxiliary shift lever 62 is held at the low speed position A, the ultra-low speed switching lever 59 can freely move to the operating position C and the off position D, but in the state where the auxiliary shift lever 62 is held at the high speed position B. The ultra-low speed switching lever 59 is restricted by the restraint device 69 and cannot move to the operating position C.

(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 in the front of the machine body, a front chassis 15 is fixed to the lower part of the block 1 so as to project forward, and a clutch housing 2 is provided in the rear part. Is fixed.
Further, a mission case 5 is arranged 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, the clutch housing 2
A steering 19 is installed above the vehicle, and a seat 20 is installed above the mission case 5.
A driver's seat 21 is formed, and the driver's seat 21 has a wide foot space formed of a substantially flat surface because the upper surface 6a of the intermediate case 6 is formed on substantially the same plane as the step surface 7. ing.

As shown in FIG. 3, the clutch housing 2 has the main clutch 22 built therein and the gear transmission 23. The gear transmission 23 is the clutch 2
2 has an output shaft, that is, a gear 26 fixed to a shaft 25 extending coaxially with the engine crankshaft, and a gear 28 fixed to a main transmission shaft 27 which is shifted one step below the shaft 25. The main transmission shaft 27 is located below the engine crankshaft by a predetermined amount by meshing the gears 26 and 28 with each other. Further, the main transmission shaft 2
Reference numeral 7 denotes 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 of the machine body. A front-wheel drive transmission shaft 29 is rotatably fitted in the main hollow transmission shaft 27, so that the transmission shafts 27 and 29 form a double shaft. Further, the front end portion of the front wheel transmission shaft 29 projects from the main hollow transmission shaft 27, and the gear 30 is fixed to the projection portion. Further, the gear transmission 2
3, a front wheel drive shaft 31 is rotatably supported, a front wheel drive switching gear 32 is slidably supported on the drive shaft 31, and a front end portion of the drive shaft 31 is at a clutch housing 2 It protrudes forward from the bottom of the. The gear 30 is releasably interlocked with the switching gear 32 via an intermediate gear 33, and the front wheel drive shaft 31 is connected to the front axle 10 via a short propeller shaft 34. (See Figure 2). On the other hand, the transmission case 5 has a pinion shaft 35 rotatably supported coaxially with the front wheel drive transmission shaft 29, and the pinion shaft 35 has its front end supported by the front wheel drive transmission shaft 2.
The rear end portion is linked to 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.
The gear set 40 is connected to the main hollow transmission shaft 27. A large gear 41 and a small gear 42, which are constantly meshed with the gears of the gear set 40, are rotatably supported on the PTO speed change shaft 37, 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 gear 40b of the gear set 40 based on the operation of the PTO shift lever. Furthermore, the PTO speed change shaft 37
Is connected to a PTO shaft 47, which is shifted downward by one stage, via gears 45 and 46 at its rear end, and the PTO shaft 47 is positioned substantially coaxially with the main transmission shaft 27 and the front wheel transmission shaft 29. is doing. Further, two sets of selection gears 49 and 50 are slidably fitted on the traveling speed change shaft 39, and these gear sets 49 and 50 are operated based on the operation of the main speed change lever 51 (FIG. 2). , Can be meshed with a predetermined gear of the intermediate gear set 40. A sub-gear gear set 52 including a large gear 52a and a small gear 52b is rotatably supported on the rear portion of the speed change shaft 39, and an ultra-low speed selection gear 53 is slidably supported. Further, an ultra-low speed gear set 55 including a large gear 55a and a small gear 55b is provided so as to be connected to the gear set 52. Then, as shown in FIGS. 6 and 7, the ultra-low speed selection gear 53 is engaged with the shifter 57 slidably supported by the shift shaft 56, and the shifter 52 is switched to the ultra-low speed. It is connected to a lever 59 (Fig. 2), and by operating the switching lever 59, the selection gear 53 engages with the internal teeth 52c of the sub-transmission gear set 52, or to the large gear 55a of the ultra-low speed gear set. Can be selectively meshed. As shown in detail in FIGS. 4 and 5, a gear set 60 including a large gear 60a and a small gear 60b is slidably supported on the rear portion of the pinion shaft 35, and the gear set is 60 is a sub-shift lever 62 through a shifter 61
It is interlocked and operated in accordance with (FIG. 2), and selectively meshes with either the large or small gear of the auxiliary transmission gear set 52. In FIGS. 3 and 5, 63 is a reverse gear.

As shown in FIG. 1, the auxiliary transmission lever 62 has a low speed position A where the gear set 60, the large gear 60a and the small gear 52b of the gear set 52 mesh, and a high speed position B where the small gear 60b and the large gear 52a mesh. And the selection gear 53 of the ultra-low speed switching lever 59 is the large gear 55 of the gear set 55 for ultra-low speed.
The ultra-low speed operating position C that meshes with a is switched to the ultra-low speed disengagement position D in which the selection gear 53 directly meshes with the internal teeth 52c of the auxiliary transmission gear set 52. And these (operation) levers 5
The operation ranges of the reference numerals 9 and 62 substantially overlap with each other in a side view, and the pivotal support portion of the auxiliary transmission lever 62 is arranged above the pivotal support portion of the ultra-low speed switching lever 59. Further, a pin 65 is planted at an intermediate position of the ultra-low speed switching lever 59, and a plate 66 is fixedly provided on the side opposite to the pivotal support portion of the auxiliary transmission lever 62, and the plate 66 has a predetermined shape. The long hole 67 is formed. Then, when the pin 65 is engaged with the elongated hole 67 and the ultra-low speed switching lever 59 is in the operating position C, a restraint device 69 for restricting the auxiliary shift lever 62 from being in the high speed position B is configured. There is. That is, in the state where the auxiliary transmission lever 62 is held at the low speed position A, the ultra-low speed switching lever 5
In a state in which 9 moves without interfering with the operating position C and the cut position D and the ultra-low speed switching lever 59 is held in the cut position D,
An elongated hole 67 is formed so that the auxiliary transmission lever 62 can move without interfering with the low speed position A and the high speed position B.

Since the present embodiment is configured as described above, the rotation of the engine block 1 is transmitted to the output shaft 25 via the main clutch 22 and further the main hollow transmission shaft 27 via the gears 26 and 28 of the gear transmission 23. Be transmitted to. Then, it is transmitted to the intermediate gear set 40 installed in the transmission case 5 at the rear of the machine body via the main transmission shaft 27 fitted and inserted in the intermediate case 6, and the PTO gear shift shaft 37 is appropriately shifted from the gear set 40. And separated and transmitted to the traveling speed change shaft 39. That is,
When the intermediate gear 43 is switched, the rotation transmitted from the intermediate gear set 40 to the gear 43 via the large gear 41 or the small gear 42, or directly to the gear 43, and further, the rotation that has been changed to the three stages is transmitted to the PTO gear shaft 3.
7, transmitted to the PTO shaft 47 via the gears 45 and 46. On the other hand, when the main transmission lever 51 is switched, the gear set 4
9 and 50 are selectively meshed, and the rotation of the intermediate gear set advances 3
And the reverse gear is transmitted to the traveling speed change shaft 39,
Further, by switching the selection gear 53 for ultra-low speed, the speed change shaft 3
The rotation of 9 is transmitted to the sub-transmission gear set 52 directly or via the ultra-low speed gear set 55, and the sub-transmission lever selectively engages the sub-transmission gear set 52 with the sub-transmission gear set 52 to shift the gear in two stages. The rotation of the pinion shaft 35 is transmitted to the rear wheel 11 via the differential gear 36 of the rear axle 17.

At this time, the ultra-low speed switching lever 59 is held at the off position D, and the ultra-low speed selection gear 53 is moved to the inner teeth 52 of the auxiliary speed change gear set.
In the super low speed OFF state in which the rotation of the traveling speed change shaft 39 is directly transmitted to the sub speed change gear set 52 without engaging with the super low speed gear set 55, the sub speed change lever 62 has a long hole along the pin 65. 6
7 is guided to move freely between the low speed position A and the high speed position A, and the large gear 60 of the gear set 60 is moved through the shifter 61.
The a and the small gear 60b can be selectively meshed with the large gear 52a or the small gear 52b of the gear 52. However, by holding the ultra-low speed switching lever 59 in the operating position C, the ultra-low speed selection gear 53
Is engaged with the large gear 55a of the ultra-low speed gear set 55 to rotate the traveling speed change shaft 39 through the ultra-low speed gear set 55.
In the super-low speed operation state in which the electric power is transmitted to the long hole 67 and the pin 6
5, the sub-transmission lever 62 cannot move to the high speed position B, and the large gear 60a of the gear set 60 is held in the low speed state in which it meshes with the small gear 52b of the gear set 52. Similarly, when the auxiliary transmission lever 62 is held at the low speed position A, the pin of the ultra-low speed switching lever 59 is guided along the long hole 67, and the ultra-low speed switching lever 59 operates at the operating position C and the cut position D.
However, when the auxiliary transmission lever 62 is held at the high speed position B, it is restricted by the pin 65 and the long hole 67, the ultra-low speed switching lever 59 cannot move to the operating position, and the selection gear 53 moves to the gear set 52. It is kept in a meshed ultra-low speed off state.

(G) Effect of the Invention As described above, according to the present invention, between the first operating means 59 for switching the ultra-low speed device and the second operating means 62 for switching the transmission, for example, the auxiliary transmission. When the ultra-low speed device 55 is in the operating state C via the restraint device 69, the transmission is configured so as not to be in the high speed position B. Therefore, the ultra-low speed device enters and the transmission becomes high speed.
It is possible to avoid a state that is meaningless and extremely disadvantageous to the transmission, and it is possible to ensure the proper quality of the transmission and reduce the manufacturing cost without increasing the strength such as increasing the tooth thickness of the gear. You can Further, since a gear having a thin tooth thickness can be used, the transmission can be downsized, especially in the length direction, and in combination with the position of the ultra-low speed device 55 arranged below the transmission case 5, an intermediate position can be obtained. It is possible to secure a wide foot space in which the upper surface 6a of the case 6 is substantially flush with the step surface.

Then, the first operating lever 59 and the second operating lever 6
In the side view 2, the operation ranges thereof are substantially overlapped with each other, and the check device 69 is provided between the pivotal support portions of both levers.
Since the engaging member 65 is arranged, it is possible to reliably restrict the simultaneous operation of the ultra-low speed operation and the high speed of the transmission, while the transmission can be made compact and the restraint device and the engagement member can be controlled. The joint department is
For example, an extremely simple device including the plate 66 having the long hole 67, the pin 65, and the like is sufficient, and the regulation operation can be reliably maintained for a long period of time.

[Brief description of drawings]

FIG. 1 is a side view of an operating lever portion showing a restraint device according to the present invention, FIG. 2 is a side view showing a tractor to which the present invention is applied, FIG. 3 is a sectional view showing the transmission device thereof, and FIG. FIG. 5 is an enlarged sectional view of the transmission, FIG. 5 is a schematic side view thereof, FIG. 6 is a sectional view showing an ultra-low speed device, and FIG. 7 is a side view thereof. 5 ... Mission case, 40, 49, 50 ... Main transmission, 52, 60 ... Sub transmission, 53 ... Ultra-low speed selection gear, 55 ... Ultra-low speed device (gear set), 59 ... 1
Operating lever (ultra-low speed switching lever), 60 ... second operating lever (sub-shift lever), 65 ... engaging member (pin), 66 ... plate, 67 ... long hole, 69 ... checking device .

Claims (1)

[Claims] 1. A transmission for a tractor comprising a first operating lever for switching an ultra-low speed device between operating and non-operating, and a second operating lever for switching a transmission between a high speed position and a low speed position. In the above, the first operation lever and the second operation lever are arranged close to each other so that their operation ranges substantially overlap with each other in a side view, and one of the pivotal support portions is arranged on the other pivotal support portion. The lever is disposed above the lever, a check device is extended to the opposite side of the pivot point of the one lever, and an engaging member is provided in an intermediate portion of the lever of the other lever on the lever side. Restricting the second operating lever from moving to the high speed position when the first operating lever is in the ultra-low speed operating position, based on engaging the device and the engaging member with a predetermined play; and If the second operating lever is in the high speed position, and regulates that the first operating lever is ultra low speed operation position, the transmission of the tractor.