JPS621480Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a transmission device for agricultural tractors, etc.
The present invention relates to a type of mechanical transmission in which a shift gear for speed change is provided, which is slidable but cannot rotate relative to the transmission shaft.

In agricultural tractors and the like, it is often desired to quickly stop the inertial rotation of the driven side transmission shaft after the transmission is placed in a neutral state and the power transmission between the driving side transmission shaft and the driven side transmission shaft is cut off. In addition, a constant mesh transmission gear train, which is a mechanical transmission for agricultural tractors, etc., is constructed by constantly meshing a transmission gear fixed to a driving side transmission shaft and an idler gear loosely fitted to a driven side transmission shaft. In the transmission, the free rotating gear, which continues to rotate even in the neutral state of the transmission, frictionally engages the member on the driven side transmission shaft with its end face, causing the driven side transmission shaft to rotate. Tangled rotation is common, and it is desirable to prevent such entanglement.

For this reason, many brake mechanisms have been proposed to prevent inertial rotation or entanglement. Such a brake mechanism is, for example, disclosed in Japanese Utility Model Application No. 49-9703.
As disclosed in Japanese Utility Model Publication No. 55-52424, etc., generally, a brake drum is fixedly attached to the transmission shaft or gear on the driven side of a transmission, and a brake band or a brake system replacing it is attached to the brake drum. It is configured to brake the rotating member on the driven side of the transmission by arranging a brake band or a brake shoe in friction with the brake drum in conjunction with a clutch disengagement operation or gear shifting operation. ing.

This brake mechanism has a much simpler structure than conventional brake mechanisms,
It is disclosed in Japanese Utility Model Application No. 52-70826. In the same publication, the braking force of the leaf spring is applied to the gear by sandwiching the boss part of the gear in the transmission path between the two legs of a substantially chevron-shaped leaf spring that straddles a support rod and is supported by the rod. The structure is such that when the input of driving force is cut off due to disengagement of the clutch, the rotation of the rotating members at the shift position, including the gear, is immediately stopped.

This brake mechanism uses an existing gear or its boss directly as a rotating body to be braked, and uses the elastic force of a leaf spring as a braking force. On the other hand, since there is no interlocking connection mechanism connected to the brake mechanism, the structure of the brake mechanism is extremely simple. However, this structure in which braking force is constantly applied to the gears in the transmission path places an extra burden on the drive source, and the leaf springs, which are constantly in sliding contact with the bosses of the gears that receive rotational drive, wear out relatively quickly. It is recognized that the durability of the brake mechanism is poor, as it loses its elasticity as it is exposed to the impact.

Therefore, this invention has a simplified structure compared to the conventional general brake mechanism as described above, but it is designed to perform a braking action only when the forced drive on the driven side of the transmission is cut off. The object of the present invention is to provide a novel transmission device for agricultural tractors and the like, which is equipped with a brake mechanism that solves the above-mentioned problems.

The configuration of the transmission according to the invention will be explained with reference to the illustrated embodiment.
The figure shows the rear end of a machine such as an agricultural tractor, and a PTO shaft 1 whose rear end extends toward the rear of the machine is provided in this part. This PTO
A transmission shaft 2, which is rotatably driven by the engine via a clutch mechanism, is provided on the front side of the shaft 1 in parallel with the PTO shaft 1.
PTO transmission device 3 for changing the drive rotation speed of the work equipment driven by PTO axis 1 between PTO axis 1
is provided. This PTO shaft transmission 3
On the transmission shaft 2, there are three gears 4, which are formed integrally with the transmission shaft 2 and have different numbers of teeth.
5 and 6, and an idler gear 7 which is loosely fitted in a fixed position on the PTO shaft 1 and always meshed with the gear 4 on the transmission shaft 2, and a PTO shaft. The position of the shift gear 9 spline-fitted to the spline cylinder 8 and the PTO shaft 1 is fixed by using the spline part on the outer surface side of the spline cylinder 8 which is spline-fitted with the spline part on the inside side of the spline cylinder 1. The transmission shaft 2 is provided with another free rotation gear 10 which is loosely fitted and always meshed with the gear 6 on the transmission shaft 2. The shift gear 9, which is supposed to rotate integrally with the PTO shaft 1 via the spline cylinder 8, is slidable on the spline cylinder 8 and can mesh with the gear 5 on the transmission shaft 2. formed into something. The boss portion of each free rotating gear 7, 10 has spline portions 7a, 10 aligned with the spline portion on the outer surface of the spline cylinder 8 in the axial direction of the PTO shaft 1.
A is provided. As described above, the PTO transmission 3 selectively slides and displaces the shift gear 9 on the spline cylinder 8 so that the shift gear 9 straddles the spline cylinder 8 and the spline portion 7a of the free rotating gear 7. By connecting the free rotating gear 7 to the PTO shaft 1, the 1st speed gear ratio can be set, and by meshing the shift gear 9 with the gear 5 on the transmission shaft 2, the 2nd gear gear ratio can be set.
Further, by placing the shift gear 9 across the spline cylinder 8 and the spline portion 10a of the idler gear 10 and connecting the idler gear 10 to the PTO shaft 1, three-speed gear ratios can be selectively obtained. What can be done and what has been done.

As mentioned above, it is a mechanical type with 3 gears.
In the PTO transmission 3, a pin 11 is disposed at the outer periphery of the shift gear 9 at its neutral position as shown in the figure, and is capable of engaging with the teeth of the shift gear 9 with an engagement portion 11a at the tip formed in a substantially spherical shape. It has been done. This pin 11 is attached to the inner end of a support rod 12 that is supported on the back wall of the fuselage housing and inserted into the fuselage housing.
A hole 12a drilled in the inner end is inserted through the hole 12a, and the support rod 1 is supported so as to be movable forward and backward in the direction of the shift gear 9.
The compression spring 13 is urged to move in the direction of the shift gear 9 by a compression spring 13 whose both ends are received by a flat notch 12b formed on the circumferential surface of the inner end of 2 on the shift gear 9 side and the end face of the engaging part 11a. ing. In order to prevent the pin 11 from being pulled out of the hole 12a when the shift gear 9 is moved from the illustrated neutral position to any shift action position, the stopper ring 15, which is prevented from being pulled out by the retaining ring 14, is It is provided on the base end of the pin 11. In FIG. 1, reference numeral 16 denotes a plate that is fixed to the outer surface of the rear wall of the fuselage housing by a fixture (not shown) to fix the position of the support rod 12.

Since the first embodiment shown in FIG. 1 is constructed as described above, when the shift gear 9 is moved from any of the shift action positions to the neutral position shown in the figure and the PTO transmission 3 is brought into the neutral state, In this case, the pin 11 faces into the tooth groove of the shift gear 9 with its engaging portion 11a, and the engaging portion 11a engages with the side surfaces of the teeth on both sides of the tooth groove by the biasing of the spring 13, thereby shifting. Brake gear 9. Therefore, while the PTO shaft 1 is stopped quickly without inertial rotation, the idler gears 7 and 1 continue to rotate even in a neutral state.
The free rotation gears 7, 1 are rotated by frictional engagement between the end surfaces of the spline portions 7a and 10a of the spline tube 8 and the end surface of the spline cylinder 8.
The rotational force is transmitted from 0 to the spline cylinder 8.
Tangled rotation of the PTO shaft 1 and, therefore, generation of noise caused by such tangled rotation is reliably prevented.

Next, a second embodiment shown in FIG. 2 will be described. In this second embodiment, in a transmission equipped with a transmission mechanism similar to that described above, the shift gear 9 is located at the outer periphery of the neutral position of the shift gear 9. A leaf spring 20 is provided with engaging portions 20a at both free ends that can engage with the tooth portions of the leaf spring 20. This leaf spring 20 is attached to a support rod 21 at the center with a fixture 22, and is curved so that both engaging portions 20a face positions on both sides of the shift gear 9.

Therefore, in the second embodiment shown in FIG. The leaf spring 20 engages with the side surfaces of the teeth on both sides of the tooth groove by the urging force of the leaf spring 20 itself, brakes the shift gear 9, and prevents inertial rotation and tangling of the PTO shaft 1.

As is clear from the above description, this invention is based on a shift gear 9 for speed change that is disposed on the driven side transmission shaft 1 and is slidable but cannot rotate relative to the transmission shaft 1.
In a transmission equipped with the above, a substantially arc-shaped member is disposed at the outer periphery of the neutral position of the shift gear 9, faces into the tooth groove of the shift gear 9, and is capable of engaging with the side surfaces of the teeth on both sides of the tooth groove. The engaging bodies 11 and 20 provided with the engaging parts 11a and 20a are mounted on a fixed support part 12 on the vehicle fuselage side,
21 is displaceably supported in the direction of engagement with and disengagement from the shift gear 9, and is biased by springs 13 and 20 in the direction of engagement with the shift gear 9. be effective.

That is, the arcuate engaging portions 11a, 20a of the above-mentioned engaging bodies 11, 20 are pressed against the side surfaces of the teeth on both sides of the tooth grooves of the shift gear 9 within the tooth grooves of the shift gear 9 under the force of the springs 13, 20. The arcuate engaging portions 11a and 20a engage with the side surface of the gear teeth of the shift gear 9 in a direction that restricts its rotation, thereby quickly and reliably achieving the desired inertial rotation and prevention of tangling. Since the shift gear 9 is supposed to be engaged, it does not interfere with the shift operation of shifting the shift gear 9 along its axial direction, but this invention utilizes the existing shift gear 9 as a directly braked rotating body. In particular, the engaging bodies 11, 20
By arranging this at the outer periphery of the neutral position of the shift gear 9, the engaging bodies 11, 20 engage the shift gear 9 only at the neutral position and perform a braking operation, thereby making it possible to prevent the clutch or the speed change operation mechanism from moving. The above-mentioned Utility Model Application Publication No. 52-70826 does not provide an interlocking connection mechanism to connect the brake mechanism, and the desired braking is performed only when it is necessary to prevent inertial rotation and tangle. Almost the same as the one in the publication, the structure is simpler than the conventional general brake mechanism, but the problem with the one in the publication mentioned above, namely, that it constantly exerts braking force, places an extra burden on the drive source and is not durable. It has the effect of solving the problem of poor sex.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view of the main parts of an agricultural tractor equipped with a first embodiment of the invention, and FIG. 2 is a partially longitudinal front view showing the main parts of the second embodiment of the invention. 1... PTO shaft, 2... Transmission shaft, 3... PTO transmission, 4, 5, 6... Gear, 7... Idle gear,
7a...Spline part, 8...Spline tube, 9
...Shift gear, 10...Idle gear, 10a...
Spline part, 11... Pin, 11a... Engaging part, 12... Support rod, 13... Compression spring, 2
0... Leaf spring, 20a... Engaging portion, 21... Support rod, 22... Fixing tool.

Claims (1)

[Scope of utility model registration request] This is a transmission device in which a shift gear 9 for speed change is disposed on a driven side transmission shaft 1 and is slidable but not rotatable relative to the transmission shaft 1, and the shift gear 9 is provided with a shift gear 9 disposed on a transmission shaft 1 on a driven side. Engaging bodies 11 and 20 are provided with substantially arc-shaped engaging portions 11a and 20a that are disposed at the outer periphery of the shift gear 9 and can face into the tooth grooves and engage with the side surfaces of the teeth on both sides of the tooth grooves. The fixed support parts 12 and 21 on the vehicle fuselage side are supported so as to be displaceable in the direction of engagement with and disengagement from the shift gear 9, and are biased by springs 13 and 20 to be displaced in the direction of engagement with the shift gear 9. characterized by the fact that it is provided with
Shift position in agricultural tractors, etc.