JPS6132820Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to a speed change operation device for agricultural tractors, etc.

Conventional technology A device for preventing erroneous operation of the speed change lever in a conventional hand dozer is designed to prevent the speed change lever from accidentally entering the medium speed guide groove while being used on the low speed guide groove side, and vice versa. The Jikosho version has a rotary arm rotatably placed in the center of the gear shift lever guide hole to prevent it from accidentally entering the low speed guide groove during use.
It is known as Publication No. 47-20081.

Problems that the invention aims to solve: With the conventional devices described above, the gear shift lever cannot be switched between low speed and medium speed unless the rotating arm is removed from the guide hole, so it is suitable for urgent gear shifting operations. do not.

Measures to solve the problem Therefore, the technical problem of this proposal is to enable or disable switching from the low gear side to the very low gear side, and to make it possible to change from the very low gear side to the low gear side. The purpose of the present invention is to provide an agricultural tractor that is suitable for urgent gear shifting operations in which only the auxiliary gear shift lever can be operated. In the case where a shift operation is performed to switch from the auxiliary shift lever to the very low gear side, a shift operation lid corresponding to the vicinity of the boss portion of the fork of the shift shaft operated by the auxiliary gear shift lever is provided with a member to prevent the fork from entering the very low gear side. The blocking member is configured to be biased by a bullet toward the fork entry blocking path side, and configured to be able to operate the entry blocking member in a direction away from the boss of the fork by a handle against the bullet, The structure is such that, as the fork moves from the very low gear side to the low gear side only by operating the sub-shift lever, the entry blocking member can automatically move toward the fork entry blocking path side with the bullet. This makes it possible to switch to the very low gear side, and also allows the switching operation from the very low gear side to the low gear side to be performed by operating only the sub-shift lever.

Effect of the Invention According to this technical means, since the lever having the entry prevention member cannot be operated in the release direction before switching to the extra-low speed range, switching to the extra-low speed range due to erroneous operation, etc. is prevented. Therefore, compared to a system without an erroneous mechanism, it has the advantage of preventing damage to the transmission due to fatigue caused by excessive use.

In particular, the present invention allows even when a sudden operation is required to return to the original low speed side after switching to the ultra-low speed side, there is no need to operate any approach prevention mechanism.
It is convenient and requires only the sub-shift operation mechanism to be operated.

In addition, since the entry blocking member is attached using the mounting lid portion of the gear shift operation mechanism, it is not only convenient to assemble, but also easy to operate because it can be located near the auxiliary gear shift operating lever.

Example The embodiments shown in the drawings will be described below.

In Fig. 1, 1 is a transmission case, and its transmission chambers are a main transmission chamber 1a and an auxiliary transmission chamber 1b.
It is made up of.

2 is a transmission case 1 in the sub-transmission chamber 1b.
The gears are loosely mounted on the PTO shaft 6 mounted above and have gears 2a, 2b, 2c, and 2d, and the gear 3 is similarly loosely mounted on the PTO shaft 6, which is connected to the gears 3a, 3.
It starts from b.

Further, below the gears as described above, sliding gears 4 and 5 are spline-fitted to the sub-transmission shaft 7, and the gear 5 consists of gears 5a and 5b.

Further, the tip of the sub-shift shaft 7 is mounted in the inner hole of the main shift shaft in the main shift chamber, and a gear 8 formed in this part
consists of large and small gears 8a and 8b, of which the small gear 8b meshes with internal teeth (not shown) of the sliding gear 4, and the large gear 8a constantly meshes with the gear 2a.

In gear transmission in the auxiliary transmission chamber 1b as described above, firstly, the power shifted in the main transmission chamber 1a is transmitted from the main transmission shaft to the gears 8a, 2a, 2d, and 5b, and drives the auxiliary transmission shaft 7 to shift the first speed of the auxiliary transmission. can get.

Next, gears 8a, 2a, 2c, 5a from the main transmission shaft
Then, the sub-shift shaft 7 is driven to obtain the second sub-shift.

Next, the auxiliary transmission shaft 7 is driven from the main transmission shaft via the gears 8a, 2a, 2b, and 4, thereby obtaining the third auxiliary transmission speed.

Next, on the main transmission shaft, by meshing the internal teeth of the gear 4 with the small gear 8b, the 4th speed of the auxiliary transmission can be obtained.

Therefore, by sliding the sliding gear 5 to the right and meshing the gear 5b with the gear 3a, a very low speed gear stage can be obtained. Although not shown, the gear 2d
Needless to say, there is an intermediate gear that constantly meshes with the gear 3b and the gear 3b.

The above-mentioned sub-shift is performed by the sub-shift lever 9, and by operating the fork 11 of the shift shaft 10, the sliding gears 4 and 5 are moved left and right.

The present invention is for switching the vehicle speed sub-shift operation mechanism from the low gear side to the very low gear side, and the following mechanism is arranged.

That is, in FIG. 2, a member 12 for preventing entry to the very low gear side is provided near the boss portion of the sub-shift lever 9.

The entry prevention member 12 is fixed to a pivot pin 14 provided on the speed change operation lid 13, and has both ends engaged with the lid 13 and the entry prevention member 12, and is prevented from entering by a spring 15 wound around the pivot pin 14. The blocking member 12 is biased to the side of the entry blocking path of the shift operation fork 11.

Reference numeral 16 denotes a handle which is centered around the pivot pin 14 and is adapted to operate the entry prevention member 12. Figures 3 and 4 show its operating state.

When the intrusion prevention member leaves the boss of the fork 11 by operating the handle 16, the fork can be operated with the auxiliary shift lever 9 to shift to the ultra-low gear side described above. In order to be able to remain in the position rotated by the fork 11, and to switch the sub-shift lever 9 to the low gear side, on the contrary, the entry prevention member must come into contact with the inclined surface 11a of the fork 11 on the very low gear side. Therefore, when the fork 11 moves to the low gear side, the entry blocking member does not pose any obstacle, and the spring 15 automatically restores the entry blocking member, and in the restored position, the fork moves to the very low gear side. This can prevent it from moving to the side.

The one shown in FIG. 5 is a modified embodiment, in which a handle 17 is attached to the lid 13 so as to be slidable up and down, and a spring 20 is interposed between the washer 19 associated with the pin 18 and the lid 13. As a result, the handle 17 is always energized downward, and the tip of the handle 17 is energized downward so that the tip of the handle 17 cannot move to the very low gear side.
1 and facing in the direction of movement.

Therefore, the handle 17 resists the force of the spring 20.
When the fork 11 is pulled up, the entry prevention member 12 is also pulled up, and the movement of the fork 11 is not obstructed, so the sub-shift lever 9 can be operated to the very low gear side. At that time, the entry prevention member 12
When the steering wheel 9 is switched to the low gear side due to an object running over the fork, the entry prevention member 12
The gear slides out of the fork and restores itself to its original state, making it impossible to shift to an ultra-low gear in the restored position.

FIG. 6 shows a guide plate for the sub-shift lever 9.

In any case, this proposal is for switching the vehicle speed sub-shift operation mechanism from the low gear side to the very low gear side, and it is possible to switch to the very low gear side by releasing the entry prevention member on the very low gear side. It is characterized by being configured so that the gear can be switched to the ultra-low gear side only after the lever with the entry preventing member is operated in the release direction, so there is no possibility of erroneous operation, and therefore the transmission is not damaged. After switching to the very low gear side, if a sudden operation is required to return to the original low gear side, the entry prevention member must be operated. It has the characteristic that it can be operated without any trouble.

[Brief explanation of the drawing]

Fig. 1 is a partially omitted cutaway front view showing the transmission device of an agricultural tractor, Fig. 2 is a cutaway front view of the first embodiment of the proposed device, and Figs. 3 and 4 are plan views showing the operating axis of the same. , Figure 5 shows the second part of the proposed device.
FIG. 6, which is a cutaway front view of the embodiment, is a plan view of the guide plate of the sub-shift lever. 9...Sub-shift lever, 10...Shift shaft, 11
...Fork, 12...Entry prevention member, 13...
Lid, 14... Pivot pin, 15, 20... Spring, 1
6,17...handle.

Claims (1)

[Scope of utility model registration request] In a device that switches the vehicle speed sub-shift operation mechanism from a low gear side to a super-low gear side, there is a shift operation lid located near the boss of the fork of the shift shaft operated by the sub-shift lever to switch the vehicle speed to the super-low gear side. A fork entry blocking member is provided, the entry blocking member is biased by a bullet toward the fork entry blocking path, and a handle moves the entry blocking member from the boss of the fork against the bullet. In addition, as the fork moves from the very low gear side to the low gear side only by operating the sub-shift lever, the entry prevention member is moved by the bullet toward the fork entry prevention path side. A speed change operation device for agricultural tractors, etc., which was once configured to be able to move automatically.