JPS6013698Y2 - Traveling power transmission device for agricultural tractors, etc. - Google Patents

Description

[Detailed description of the invention] This invention is a traveling work vehicle such as an agricultural tractor (in other parts of this specification, 1 agricultural tractor, etc.) which is provided with a hydraulic clutch type transmission and a mechanical transmission connected in series. It's called yo.

) relates to a traveling power transmission device with a novel design that facilitates the speed change operation of the mechanical transmission described above.

As shown in Japanese Unexamined Patent Application Publication No. 53-45830, the applicant of the present application has previously proposed that, in agricultural tractors such as those mentioned above, a hydraulic clutch type transmission device is arranged at the end of the transmission shaft on the driven side of the hydraulic clutch type transmission. A brake plate that is slidably but not relatively rotatable on the transmission shaft and is located facing the fixed housing surface, and a brake plate that is located facing this brake plate on the opposite side of the fixed housing surface. a piston, a compression spring disposed on a reciprocating rod and biasing the brake plate to move in a direction to press the brake plate against the fixed housing surface via the movable spring support on the retractable rod and the piston; and the compression spring force. A pressure oil chamber is provided for displacing the piston against the pressure, and the pressure oil chamber is connected to the oil supply circuit for the hydraulic clutch in the hydraulic clutch type transmission, and the movement rod is connected to the movable spring receiver. In addition to forming an engaging portion, the advancing/retracting lever is used as an operating tool for the main clutch, and when the main clutch is disengaged, the advancing/retracting lever is displaced in one direction while engaging with the movable spring receiver at the upper engaging portion. a traveling power transmission device that is interlocked so as to compress the compression spring and release the biasing action of the spring;
developed.

The above-mentioned brake plate is configured such that when the hydraulic clutch type transmission is in a transmission state, the hydraulic pressure applied to the hydraulic clutch in the transmission is applied to the pressure oil chamber, and the piston is moved away from the brake plate. Since it is displaced, no braking action is performed.

However, when the hydraulic pressure applied to the hydraulic clutch in a hydraulic clutch transmission is released to bring the transmission into a neutral state, the compression spring applies braking via the piston by releasing the hydraulic pressure to the pressure oil chamber. The plate is brought into pressure contact with the fixed housing surface, so that the above-mentioned braking of the transmission shaft is effected with a relatively small braking force.

Therefore, when the hydraulic clutch type transmission is in a neutral state, the hydraulic clutch of the transmission will be slightly engaged due to a constant rotational torque transmitted to the transmission from the engine or the direction of the wheels that are about to rotate automatically on a slope. The clutch is engaged by the resultant force,
This eliminates the inconvenience of unexpected power transmission.

In addition, in the above-mentioned traveling power transmission device, the urging action of the above-mentioned compression spring is released in conjunction with the disengaging operation of the main clutch, that is, the braking action of the brake plate to which the braking force is applied by the compression spring is The purpose of releasing this is to facilitate the gear shifting operation of the mechanical transmission.

That is, this shift operation is performed after disengaging the main clutch, but at this time, the hydraulic pump for supplying oil to the hydraulic clutch of the hydraulic clutch type transmission is stopped, so the hydraulic pressure to the pressure oil chamber is reduced. When the action is released, the brake plate performs a braking action.

At that time, the rotating bodies in the mechanical transmission will also be in a braked relationship, so if the gear shifting rotating bodies that are mechanically engaged with each other due to gear meshing etc. are not in the correct holding position, they will be able to move to the correct engaged position. Since the brake cannot be rotated and the gear shift operation becomes difficult, the brake was designed to be released in conjunction with the main clutch operation.

As described above, there are still other factors that make it difficult to perform a gear shifting operation with a mechanical transmission.

That is, when the main clutch is disengaged prior to performing this shift operation, the switching valve that controls the gear stage of the hydraulic clutch type transmission remains in one of the operating positions, and the hydraulic pressure corresponding to the operating position is maintained. Since the hydraulic oil is not actively discharged from the hydraulic clutch in a clutch-type transmission, a slight clutch engagement state persists, creating resistance to rotation, and this resistance also acts on the rotating body of a mechanical transmission. Because it does.

In particular, as shown in Japanese Unexamined Patent Application Publication No. 52-131065, a one-way clutch is attached to a hydraulic clutch type transmission device to engage the vehicle as the vehicle moves forward even when the engine is stopped, thereby making it easier to start the engine. In some cases, it becomes large.

In other words, since such a one-way clutch has the function of interlocking and connecting two transmission shafts in a hydraulic clutch type transmission with the rotation of the driven-side transmission shaft, this one-way clutch is associated with a hydraulic pressure. If a hydraulic clutch other than the clutch maintains a slight clutch engagement state as described above even after the main clutch disengages, both the part of the hydraulic clutch that maintains this clutch engagement state and the one-way clutch part mentioned above This is because the two transmission shafts are interlocked and connected, and the transmission shaft becomes unable to rotate due to the interlocking connection between the two parts having different gear ratios.

This invention aims to provide a novel running power transmission device for agricultural tractors, etc., which has a simple structure that skillfully utilizes the braking mechanism described above, and which eliminates the above-mentioned disadvantages.

Regarding the illustrated embodiment, the configuration of the traveling power transmission device according to the invention will be described. As shown in FIG. The transmission is conducted inside the rear housing 5 through the clutch housing 2 housing the main clutch 3 and the transmission case 4, and is configured to drive the left and right rear wheels 6 to cause the aircraft to travel. This invention has been implemented in the agricultural tractor developed in the following manner.

That is, as shown in FIG. 2, in the illustrated agricultural tractor, a hollow shaft 8 is provided on the drive shaft 8 that extends toward the rear of the machine and transmits the power of the engine 1 in the direction of the circular axis 7 (FIG. 1). A hydraulic clutch type transmission 1, which is a main transmission for traveling power, is disposed between the drive shaft 9 and a power shift shaft (transmission shaft) 10 disposed below the drive shaft 9, and is disposed at the front inside the mission case 4.
1, and is connected in series to this hydraulic clutch type transmission 11 to connect the power shift shaft 10 and the transmission shaft 12 disposed on an extension thereof with an appropriate gear ratio. A mechanical transmission 13, which is a traveling power sub-transmission, is provided at the rear inside the mission case 4.

For convenience of explanation, the structure of the hydraulic clutch type transmission 11 will be described first.As shown in FIG.
4, the F2 speed change gear 15, the F3 speed change gear 16 and the R speed change gear 17, and the R intermediate gear, which is loosely fitted onto the power shift shaft 10 and directly connected to the corresponding speed change gears 14-17 on the hollow drive shaft 9; F1 idler gear 18, F2 idler gear 19, F3 idler gear 20 and R, which are indirectly meshed through 17a.
The free rotating gear 21 and each free rotating gear 1 on the power shift shaft 10
F1 hydraulic clutch 22, F1 arranged at 8-21
2 hydraulic clutch 23, F3 hydraulic clutch 24, and R hydraulic clutch 25.

This hydraulic clutch type transmission 11 selectively supplies hydraulic oil to each hydraulic clutch 22 to 25 by a hydraulic pump 26 driven by a hollow drive shaft 9, and when the F1 hydraulic clutch 22 is actuated, the F1 idler gear is 18 to power shift shaft 10
The F2 idler gear 19 is coupled to the power shift shaft 10 by the operation of the F2 hydraulic clutch 23 to set the gear ratio F1 for the first forward speed, and the F3 hydraulic clutch 2
4, the F3 idler gear 20 is connected to the power shift shaft 10 to set the forward gear ratio F3, and the R hydraulic clutch 25 is activated to connect the R idler gear 21 to the power shift shaft 10 to set the reverse gear ratio F3. The gear ratio R of each speed can be selectively obtained.

A spacer plate 27 is sandwiched between the clutch housing 2 and the transmission case 4, and the above-mentioned hydraulic pump 26 is mounted on the clutch housing 2 on the hollow drive shaft 9 with the pump case attached to the front face of the spacer plate 27. It is located at the rear end of the inside.

FIG. 3 shows a hydraulic circuit that controls the operation of the hydraulic clutch type transmission 11, including an oil supply circuit 29 that guides hydraulic oil from the oil tank 28 toward the hydraulic clutches 22-25 by the hydraulic pump 26, and the hydraulic clutch 22-25. A switching valve 31 as shown, that is, a full hydraulic clutch 22-25, is connected to an oil drain circuit 30 that leads hydraulic oil from the 25 direction to the oil tank 2B.
In addition to the neutral position N in which the hydraulic clutches 22, 23, 24, or 25 are inactive, hydraulic oil is selectively supplied to one hydraulic clutch 22, 23, 24, or 25, and oil is drained from the other three hydraulic clutches. l
The switching valve 3 has four operating positions: speed position F1, forward second speed position F2, forward third speed position F3, and reverse first speed position R.
1 is a provision.

The hydraulic pressure of the hydraulic oil supplied to the hydraulic clutches 22-25 is
It is set by the pressure regulating valve 32.

As shown in FIG. 4, from inside the mission case 4,
A seal housing 33 attached to the front surface of the intervening plate 27 is fitted onto the front end of the power shift shaft 10, which passes through the clutch housing 2 and extends into the clutch housing 2.

A plurality of annular grooves formed in the front end of the power shift shaft 10 form a plurality of oil distribution chambers 34F1-34F2-34.
F3, 34R are formed in the seal housing 33, and the hydraulic oil led from the hydraulic pump 26 via the switching valve 31 is once led into this oil distribution chamber 34, and from there to the power shift shaft 10. It is guided to each hydraulic clutch 22-25 via an oil passage (not shown) inside.

Although not shown, the switching valve 31 is built into the seal housing 33.

Similarly, as shown in FIG. 4, a flat notch 10a is formed near the front end of the power shift shaft 10, and a brake plate 35 is attached onto the power shift shaft 10 using this flat notch 10a. is mounted so that it cannot rotate relative to the shaft 10 but can slide freely.

This brake plate 35 is positioned facing a brake surface (fixed housing surface) 36 formed by a step on the inner surface of the seal housing 33.

A piston 37 is provided on the opposite side of the braking surface 36 and is fitted into the seal housing 33.
Rotation is prevented by inserting a pin 38, which is positioned facing the TFL control plate 35 and supported by the housing lid 33a of the seal housing 33, into the hole of the piston 37.

The piston 37 is shaped to have a step in the middle, and at this step, a pressure oil chamber is provided within the seal housing 33 for moving the piston 37 backward (forward in the longitudinal direction of the aircraft). 39 is in full form,
This pressure oil chamber 39 is connected to the oil supply circuit 29 described above through a connection circuit 39a shown in FIG.

In particular, the piston 37 has an oil passage 41 that communicates the pressure oil chamber 39 with a space 40 within the housing lid 33a.

This oil passage 41 is opened in the space 40 at the center of the piston 37, but the opening end of the oil passage 41 is in a tapered hole 41a.
The ball 42 is formed in the tapered hole 41a.
It is inset.

Further, the housing lid 33a supports a sliding rod 43 arranged concentrically with the piston 37.
The advancing/retracting rod 43 is formed to have a large-diameter head 43a at its tip.

A movable spring receiver 44 is slidably provided on the advancing/retracting rod 43, and a compression spring 45 is provided on the advancing/retracting lever 43 with both ends received by the movable spring receiver 44 and the inner surface of the housing cover 3a. There is.

A ball holder 44a is integrally fixed to the tip of the movable spring receiver 44, and is fitted and supported in a support hole 37a formed in the piston 37 concentrically with the tapered hole 41a. This is for receiving the ball 42 described above.

A clearance α is particularly provided between the head 43a at the tip of the advancing/retracting rod 43 and the movable spring receiver 44 in the axial direction of the advancing/retracting rod 43, and when the advancing/retracting rod 43 is displaced in the drawing direction, the above clearance α is
When the advancing/retracting lever 43 is displaced in the drawing direction by a certain amount corresponding to , the advancing/retracting lever 43 engages with the movable spring 44 at the head 43a, and when the advancing/retracting lever 43 is pulled out further. , the movable spring receiver 44 is pushed by the head 43a.
is designed to be displaced together with the reciprocating rod 43 while compressing the compression spring 45.

As described above, the compression spring 45 is
4 to move and urge the ball 42 in the direction of closing the tapered hole 41a, that is, in the direction of blocking the oil passage 41 of the piston 37. The brake plate 35 is biased to move in a direction in which it comes into pressure contact with the brake surface 36.

However, if the switching valve 31 is set to any of the operating positions F, F2.
In F or R, when the hydraulic clutch transmission 11 is transmitting gears, the oil pressure set by the pressure regulating valve 32 is transferred from the oil supply circuit 29 to the pressure oil chamber 39 via the connection circuit 39a. Since the piston 37 is moved backward against the force of the compression spring 45, the brake plate 35 is not pressed against the brake surface 36, and the brake plate 35 is pressed against the power shift shaft 1.
0 braking is not performed.

Further, in this state, as described above, the ball 42 comes into close contact with the surface of the tapered hole 41a due to the force of the compression spring 45, and the oil passage 4
1 is blocked.

When the switching valve 31 is moved to the neutral position N and the hydraulic clutch type transmission 11 is placed in the neutral state, the oil supply circuit 29 is directly connected to the oil drain circuit 30, and the oil pressure in the oil supply circuit 29 is released. The hydraulic pressure in the pressure oil chamber 39 is also released, and the braking plate 35 is brought into pressure contact with the braking surface 36 by the biasing action of the compression spring 45 and becomes unrotatable, and the power shift shaft, which cannot rotate relative to the braking plate 35, 10 brakings are performed.

Therefore, when the hydraulic clutch type transmission 11 is in the neutral state, the problem that the hydraulic clutches 22-25 are unexpectedly engaged due to the rotational torque acting on the transmission 11 does not occur.

Note that even in this state, the oil passage 41 is blocked by the ball 42.

The advancing/retracting rod 43 is pulled out toward the front of the machine body in conjunction with the disengagement operation of the main clutch 3, and is configured to release the biasing action of the compression spring 45.

To explain the mechanism for this purpose, as shown in FIGS. 4-6, a pin 46 extending along the transverse direction of the body is fixed to the base end of the retractable rod 43 facing outside the housing lid 33a.

Further, an operating shaft 47 is provided which is supported on one side wall of the clutch housing 2 and is rotatable around an axis.The above-mentioned pin 4
6 is provided with a pair of left and right operating arms 48a that engage from the rear side of the fuselage.

As usual, the main clutch 3 is disengaged by depressing a main clutch pedal 50 rotatably supported around a fulcrum shaft 49, and the main clutch 3 is disengaged by sliding displacement. The sleeve 51 and the main clutch pedal 50 are interlocked and connected as shown in FIG.

That is, the pedal arm 50a of the main clutch pedal 50 is fixed to the rotating cylinder 52 on the fulcrum shaft 49, and the rotating arm 53 is also fixed, and the pedal arm 53 is fixed to the end of the operating shaft 54 extending in the transverse direction of the fuselage. The rotary arm 55 and the rotary arm 53 are connected by a forward and backward lever 56, and a shifter 57 that engages with the bearing sleeve 51 is fixed to the operating shaft 54, and when the main clutch pedal 50 is depressed, , the above-mentioned series of operating mechanism members 50at 52t
53t 5L 55.54.57 to advance the bearing sleeve 51 to obtain disengagement of the main clutch 3.

The operating shaft 47, which is related to the forward/retractable lever 39, has a rotating arm 59 fixed to the operating shaft 47 with a pin 58 outside the clutch housing 2, and a rotating arm 59 that is fixed to the operating shaft 47 with a pin 58.
and a retractable lever 6 whose both ends are pivoted to the above-mentioned rotating arm 55.
0 and the rotating arm 5 in the main clutch 3 operating mechanism.
It is connected to 5.

As described above, when the rotating arm 55 is rotationally displaced in the direction of the main clutch 3 disengagement operation, the operating shaft 47 is rotationally displaced in the direction of arrow C in FIG. As a result, the actuating arm 48a of the actuating hardware 48 pushes the pin 46 and displaces it forward, so that the advancing/retracting rod 43 to which the pin 39 is fixed is pulled out.

Note that the advance/retreat rod 60 in the connection mechanism is provided with an adjustment portion 60a that enables timing adjustment by adjusting its length.

Therefore, when the main clutch pedal 50 is depressed to disengage the main clutch 3, the head 43a engages with the movable spring receiver 44 after the advance/retreat lever 43 has been pulled out by the above-mentioned clearance α. By pushing the movable spring receiver 44, the spring 40 is compressed and pulled out, and the biasing action of the compression spring 40 on the movable spring receiver 44, the ball 42, the piston 37, and the brake plate a5 is released.

Therefore, when the main clutch 3 is disengaged, not only the braking of the power shift shaft 10 by the brake plate 35 is released, but also the hydraulic pressure in the pressure oil chamber 39 loses its biasing effect on the ball 42, and the ball 42 Since it can be freely displaced in the direction of extraction from the tapered hole 41a, it is immediately released.

As a result, the oil supply circuit 2 connected to the pressure oil chamber 39
9, and therefore from the hitherto operating hydraulic clutch 22, 23, 24 or 25, which is also connected to the oil supply circuit 29 via the switching valve 31, the main clutch 3 is released. This will be done promptly upon departure.

That is, the oil passage 41, the ball 42, and the compression spring 45 are connected to the following unload valve 61, that is, to the oil supply circuit 29 as shown in FIG. When the main clutch 3 is disengaged, it takes the operating position I, and when the main clutch 3 disengages, it takes the unloading operating position ■, and the oil supply circuit 29 and the first hydraulic clutch 22 connected thereto,
23, 24, or 25 constitute an unload valve 61 for unloading hydraulic pressure.

As shown in FIG. 2, a one-way clutch 62 is interposed between the F3 free rotating gear 20 and the power shift shaft 10.

When this one-way clutch 62 is driven in a relatively forward rotation direction from the power shift shaft 10 side, it engages with the F
The three idler gears 20 are engaged with the power shift shaft 10.

When the F1 hydraulic clutch 22 or the F2 hydraulic clutch 23 is activated, the power shift shaft 10 rotates in the normal direction, but since the F3 idle gear 20 rotates in the normal direction at a higher rotation speed than the power shift shaft 10, the one-way clutch 62 Relatively, the F3 idler gear 20 side is driven to rotate in the normal direction, and the clutch is not engaged, so that there is no problem in transmission of the speed change.

When such a one-way clutch 62 is provided, even when the engine 1 unexpectedly stops or when the capacity of the battery for starting the engine 1 decreases, normal rotation of the power shift shaft 10 by moving the vehicle forward can be used. Since the directional clutch 62 is engaged and the F3 idler gear 20 is coupled to the power shift shaft 10, and the transmission path is not cut off at the hydraulic clutch type transmission 11, the engine 1 can be easily started. It becomes possible.

Next, the configuration of the mechanical transmission 13 described above will be explained with reference to FIG. 2. A hollow transmission shaft 63 is provided on the drive shaft 8 in the rear half of the mission case 4.
This hollow transmission shaft 63 is connected to the power shift shaft 10 in a deceleration manner by meshing a large diameter gear 65 at the base end with a small diameter gear 64 at the end of the power shift shaft 10 .

On the hollow transmission shaft 63, there are three speed change gears 66, 67, 6.
8 is fixedly provided.

Further, outside the hollow transmission shaft 63, there may be provided a creep gear shift gear 69 which is interlocked and connected to the smallest diameter shift gear 66 among the shift gears 66-68 via a gear reduction device (not shown). be.

Furthermore, on the transmission shaft 12, there are a shift gear 70 that can mesh with the transmission gears 69 and 66, a shift gear 71 that can mesh with the transmission gear 67, and a shift gear 72 that can mesh with the transmission gear 68. A shift gear 72, which has a pawl 72a that can engage with a pawl 10a formed at the end of the shift shaft 10, is provided so as to be slidable only.

As described above, the mechanical transmission 13 has shift gears 70, 7.
1.72 is selectively slidably displaced on the transmission shaft 12, the gear ratio of creep traveling gear 66.70 is set by meshing gears 69 and 70, and the gear ratio of 1st speed is set by meshing gear ratio 66.70 of gear gear 67. 7
The meshing between gears 10 and 72 changes the gear ratio of 2nd speed, the meshing of the gears 68 and 72 changes the gear ratio of 3rd speed, and the meshing of the pawls 10a and 72a creates the gear ratio of 4th speed. The ratio,
Each can be obtained selectively.

In FIG. 4, reference numerals 73 and 74 indicate lubricating oil passages formed between the spacer plate 27 and the seal housing 33, which open into the space 40 as shown in FIG.

Lubricating oil is supplied from within the space 40 to the front end oil chamber 76 of the power shift shaft 10 via an oil passage 75 formed in the piston 37.
An oil passage (not shown) in the power shift shaft 10
is led to hydraulic clutches 22-25 via.

Further, in FIG. 1, 77 is the main shift lever for displacing the switching valve 31, 78 is the shift gear 70,
Reference numerals 71 and 72 (Fig. 2) indicate a sub-shift lever that changes the gear position of the mechanical transmission 13, and 79 indicates a shift lever that operates a PTO transmission (not shown) provided at the rear of the rear housing 5.゛This is the gear shift lever.

The illustrated traveling power transmission device has the following advantages.

That is, the advantages are based on the braking action by the brake plate 35, and the main clutch 3 prior to the gear shifting operation of the mechanical transmission 13.
The advantage based on the fact that the braking action of the brake plate 35 is released by the disengagement operation is as explained above.
Note that other valve bodies such as a poppet may be used in place of this ball.

) is released to block the oil passage 41, and the pressure oil chamber 3
The zero oil pressure and therefore the oil pressure in the oil supply circuit 29 is released very quickly.

Therefore, even if the switching valve 31 is in the first forward speed position F1 or the second forward speed position F2, the F1 hydraulic clutch 22
Alternatively, the hydraulic pressure from the F2 hydraulic clutch 23 is released very quickly.

This means that when the main clutch 3 is disengaged and the mechanical transmission 13 is then operated to change gears using the sub-shift lever 77, the operation can be easily performed.

That is, as stated at the beginning, it is F that the shafts 9 and 10 are connected in both the transmission path for the 3rd forward speed equipped with the one-way clutch 62 and the transmission path for the 2nd forward speed for the 1st forward speed.
1 hydraulic clutch 22 or F2 hydraulic clutch 23 no longer occurs, so that the mutually meshed rotating bodies 66, 67, 6 in the mechanical transmission 13
8.69. This is because even when 10a and To, 71, 72, and 72a are not in the correct meshing dubbing, rotation to the correct meshing dubbing is easily performed when the gears 70, 71, and 72 are shifted.

In the illustrated case, a movable spring receiver 44 on the advance/retreat lever 43
and the head 4 which is the engagement part of the advancing/retracting rod 43 to the movable spring receiver 44.
3a, since the clearance α as described above is provided,
As described above, although the gear shifting operation of the mechanical transmission 13 is facilitated, other inconveniences do not occur.

That is, either the clearance α as described above is not provided, or the movable spring receiver 44 is omitted, and the tip of the compression spring 45 is received by the head 10a of the reciprocating rod 43, and the ball 42 is pushed by the end face of the head 10a. When using this structure, the biasing force of the compression spring 45 acts on the advance/retreat lever 43 at all times, which causes the inconvenience that the initial depression resistance of the main clutch pedal 50 becomes large and the operation of the pedal 50 becomes heavy. to pedal 5
0, the hydraulic clutch type transmission 11 becomes neutral due to hydraulic unloading, which may cause inconveniences such as unexpected stopping of the aircraft. This eliminates the occurrence of such inconveniences.

As is clear from the above description, the traveling power transmission device of this invention is the same as that described at the beginning, but the piston 37 is provided with an oil passage 41 for releasing the hydraulic pressure in the pressure oil chamber 39. The oil passage 41 is configured to be blocked by the valve body 42 which is moved and energized by the compression spring 45 via the movable spring receiver 44, and the brake plate 35 is connected to the movable spring receiver 44. and the above valve body 4
2 and the piston 37, the compression spring 45 moves and urges the movement, and furthermore, the above-mentioned advance/retreat rod 43
After the advancing/retracting rod 43 is slightly displaced in the one direction due to the disengaging operation of the main clutch 3, the retaining part 43a is connected to the movable spring receiver 4 between the engaging part 43a and the movable spring receiver 44.
When the main clutch 3 is disengaged prior to the gear shifting operation of the mechanical transmission 13, the displacement of the advance/retreat lever at that time causes the compression spring to be engaged. The auxiliary force of 45 is released and the valve body 42
Since this unblocks the oil passage 41, hydraulic oil is discharged from the pressure oil chamber 39, and therefore from the full hydraulic clutches 22-25 in the hydraulic Clara type transmission 11, while the braking action by the brake plate 35 is released. The above-mentioned problem of difficulty in shifting the mechanical transmission 13 due to the hydraulic oil trapped in the hydraulic clutches 22, 23, 24, and 25 is resolved, and the intended purpose is achieved. , which facilitates the gear shifting operation of a mechanical transmission device, has the following advantages in particular.

That is, in order to facilitate the gear shifting operation of the mechanical transmission, the traveling power transmission device of this invention reduces the hydraulic pressure applied to the hydraulic clutch in the hydraulic clutch type transmission in conjunction with the main clutch disengagement operation prior to the gear shifting operation. The unloading valve for unloading is constructed with an oil passage formed in the piston of the braking mechanism and a valve body that blocks the oil passage under the force of a compression spring in the braking mechanism, particularly as described above, In addition, the piston and the brake plate are energized by the compression spring through the valve body, so that a single compression spring can be used both as an unload valve spring and as a brake mechanism spring, and vice versa. As the brake can be released and the unload valve operated by simply releasing the biasing force of the compression spring when the main clutch is disengaged, the structure of the various mechanisms that bring out the above-mentioned advantages has been extremely simplified. There is.

In particular, a movable spring receiver 44 is mounted on the advance/retreat rod 43 as described above.
By arranging the
and the movable spring receiver 44, so that the retaining portion 43a is engaged with the movable spring receiver 44 after the advancing/retracting rod 43 is slightly displaced in one direction as the main clutch 3 is disengaged. Since such a play α is actually provided, when the main clutch 3 is disengaged by its operating tool 50, the operating resistance due to the load of the compression spring 45 is The play α eliminates the inconvenience of starting from the beginning and making the operation of the operating tool 50 difficult, and even if the operator accidentally touches the clutch operating tool 50, the play α is still present. Thus, the hydraulic unloading valve body 42 is moved to the unloading operating position, thereby avoiding unexpected stoppage of the aircraft.

[Brief explanation of the drawing]

Figure 1 is a side view of an agricultural tractor equipped with an embodiment of this invention, Figure 2 is a longitudinal side view of the main parts of the same tractor, Figure 3 is a circuit diagram of the hydraulic circuit in the same embodiment, and Figure 4 is a side view of an agricultural tractor equipped with an embodiment of this invention. FIG. 5 is a partially cutaway side view of the main parts of the tractor, and FIG. 6 is a longitudinal sectional front view of only the main parts of the same embodiment. 3...Main clutch, 9...Hollow drive shaft, 10...Power shift shaft (transmission shaft), 10a
...Flat cutout, 11...Hydraulic clutch type transmission, 12...Transmission shaft, 13...
・・Mechanical transmission, 22, 23. 24, 25...
... Hydraulic clutch, 26 ... Hydraulic pump, 27
...Interval plate, 29...Oil supply circuit, 30.
...Oil drain circuit, 31...Switching valve, 33.
... Seal housing, 33a ... Housing lid, 35 ... Brake plate, 36 ...
Braking surface (fixed housing surface), 37... Zestone, 39... Pressure oil chamber, 39a... Connection circuit, 41... Oil path, 41a... ...Tapered hole, 42...Ball, 43...Advancing/retracting rod, 43a...Head, 44...Movable spring holder, 44a... ...Ball receiver, 45...
...Compression spring, 46...Zen, 47...
Operating shaft, 48... Operating hardware, 48a...
・Operating arm, 50...Main clutch pedal, 5
5... Rotating arm, 59... Rotating arm, 60... Advance/retreat rod.

Claims (1)

[Scope of utility model registration request] In agricultural tractors, etc., in which a hydraulic clutch type transmission and a mechanical transmission are connected in series, the transmission shaft is disposed at the end of the transmission shaft on the driven side of the hydraulic clutch type transmission, and is mounted on the transmission shaft so that relative rotation is not possible. However, there is a brake plate that is slidably mounted and is located facing the fixed housing surface, a piston that is located facing this brake plate on the opposite side of the fixed housing surface, and a brake plate that is mounted on the retractable rod. a compression spring that moves and biases the braking plate in a direction that presses the brake plate against the fixed housing surface via the movable spring support on the reciprocating rod and the piston; and a compression spring that displaces the piston against the force of the compression spring. a pressurized oil chamber is provided, the above-described pressurized oil chamber is connected to an oil supply circuit for the hydraulic clutch in the hydraulic clutch type transmission device, and an engaging portion for the movable spring receiver is formed on the forward/retractable lever. At the same time, the advancing/retracting lever is used as an operating tool for the main clutch, and when the main clutch is disengaged, the advancing/retracting lever engages the movable spring receiver at the engaging portion and is displaced in one direction, thereby compressing the compression spring and causing the spring to release. The traveling power transmission device is interlocked and connected so as to release the energizing action of the piston, and the piston has an oil passage for releasing the hydraulic pressure in the pressure oil chamber, and the oil passage is connected to the piston. The brake plate is configured to be blocked by a valve element moved and energized by the compression spring via a movable spring receiver, and the brake plate is moved and energized by the compression spring via the movable spring receiver, the valve element, and the piston. Furthermore, there is a play between the engaging portion of the forward/retractable lever and the movable spring receiver so that the forward/retractable lever is slightly displaced in the one direction as the main clutch is disengaged. A traveling power transmission device characterized by providing a gap.