JPH04339033A - Work vehicle travel linkage device - Google Patents

Abstract

PURPOSE:To shorten the braking distance than ever when a work car with a friction gearing transmission stops urgently. CONSTITUTION:A lawn tractor is provided with a mechanical interlocking mechanism B, which operates forcibly a friction type continuously variable transmission to the neutral position mechanically in linkage with operation of a brake pedal 13 only in the case of working the brake pedal 13. The mechanical interlocking mechanism B is constituted by interconnecting a brake arm 22 rod-linked to a transmission pedal 12 to the brake pedal 13, through a mounting cam mechanism C set on a spindle 15 of the brake pedal 13.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear change operation during braking in a work vehicle equipped with a friction transmission type transmission, such as a lawn tractor or a wheel loader.

0002

[Prior Art] Generally, when braking a moving vehicle, a transmission cutoff operation is required, such as returning the accelerator lever or returning the transmission to the neutral position in order to cut off the transmission of driving force to the drive wheels. It is. The same goes for lawn tractors; when braking, the gear pedal of the friction-type continuously variable transmission must be returned to the neutral position, and in agricultural tractors equipped with a hydrostatic continuously variable transmission, the gear pedal is biased to return to neutral when braking. This involves an operation to release the depression operation of the governor pedal of the transmission.

0003

[Problem to be Solved by the Invention] However, in friction type or hydrostatic type continuously variable transmissions, the gear shifting operation is heavy due to the structure in which the gear shifting operation is performed while the transmission state is maintained, and it is only necessary to disengage the gears. Because it is difficult to perform an instant neutral operation like a gear transmission, there is little margin to perform a transmission cutoff operation in addition to the brake operation during sudden braking such as an emergency stop, and the transmission cutoff operation is difficult. There was a risk that the braking distance would increase due to the brakes not being able to catch up and being braked while still in the transmission state. SUMMARY OF THE INVENTION An object of the present invention is to enable a work vehicle equipped with a friction transmission type transmission to shorten the braking distance during an emergency stop compared to the conventional method.

0004

[Means for Solving the Problems] To achieve the above object, the present invention includes a friction transmission type transmission and a brake pedal, and only when the brake pedal is depressed, the transmission changes in conjunction with the depression operation. It is characterized in that it is provided with a mechanical linkage mechanism that mechanically forces it into a neutral state.

[0005]

[Operation] In the above structure, the transmission cut-off operation is automatically performed when the brake is operated, so it is no longer necessary to perform the transmission cut-off operation in addition to the braking operation as in the conventional case. As mentioned above, with a friction transmission type transmission, it is difficult to shift gears, but this operation is performed by using the brake pedal.
Since the machine is linked to the foot pedal operation, which can produce stronger operating force than the hand, it is possible to perform heavy gear shifting operations instantly and forcibly using that powerful operating force.

[0006]

[Effects of the Invention] Therefore, when braking, a transmission cut-off operation is always accompanied, and the transmission cut-off action follows the braking operation as quickly as possible, which is preferable in terms of safety because braking distance can be shortened. We were able to provide a travel linkage device. This effect is particularly effective during an emergency stop.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings in the case of a lawn tractor. FIG. 3 shows a fuselage 3 equipped with a vertical axis type engine 1 in the front, a control unit 2 in the center, and a transmission device A in the rear, with front and rear wheels 4, 5
A lawn tractor is shown that is configured to be able to run on the ground and has a mower 6 suspended from the lower abdomen of the machine. Both the transmission device A and the mower 6 are configured to receive power from the engine 1 through belt transmission mechanisms 7 and 8. The transmission device A is equipped with a friction type continuously variable transmission device 9 (hereinafter abbreviated as CVT) that continuously changes the input power using a taper cone, a forward/reverse switching mechanism (not shown), a differential mechanism, etc. , an operation arm (not shown) for changing the speed of the CVT 9 is connected to the speed change pedal 1 disposed on the floor 11 of the control section 2.
This is a structure in which this is done by the step-down operation in step 2. Further, this tractor is provided with a mechanical linkage mechanism B that mechanically forces the CVT 9 into a neutral state in conjunction with the depression of the brake pedal 13 only when the brake pedal 13 is depressed, which will be described next.

As shown in FIGS. 1 and 2, the shift pedal 12 and the brake pedal 13 are arranged on the right side of the floor 11, and as the shift pedal 12 is depressed, the CVT
9 is operated to increase the speed, and a return spring (not shown) is biased to return the speed change pedal 12 so that the speed change pedal 12 automatically returns to the neutral position when the pedal is released. When the speed change pedal 12 is in the neutral position, the CVT 9 is operated to the neutral position, and the CVT 9 is configured to enter a zero speed state in which the output rotation stops while maintaining the transmission state. is designed to prevent free rotation. The support shaft 15 of the brake pedal 13 has this support shaft 15.
A ball 24 type rising cam mechanism C is constituted by a fixed plate 17 that rotates together with the brake pedal 13 and a cam plate 16 that is fixed to the body side and fitted to the support shaft 15 so as to be relatively rotatable. is fixedly attached to a fixed plate 17. The ball 24 is fitted into a groove formed on the side surface of each of the cam plate 16 and the fixed plate 17, and a disc spring 23 fitted between the driven plate 19 and the fixed plate 17 connects the fixed plate 17 and the cam plate 16 to the ball 24. The fixed plate 17 is brought into contact with the cam plate 1 through the
It is biased toward the 6th side. The driven plate 19 is rotatably fitted to the support shaft 15 while being interlocked and connected to the speed change pedal 12 by the interlocking arm 10 and rod 18 fixed thereto. A brake arm 22 for operating a brake device (not shown) with a rod is attached to the other side. In other words, a mechanical linkage mechanism B is composed of the climbing cam mechanism C, the connecting rod 18, and the like.

To explain the operation, when the brake pedal 13 is depressed and operated, the fixed plate 17 is moved along the support shaft 15 to the left side in the figure by the action of the rising cam mechanism C.
3, the shoe 14 fixed to the fixed plate 17 presses against the driven plate 19, thereby causing the driven plate 19 to
In other words, the speed change pedal 12 is forcibly returned to the neutral position. When the speed change pedal 12 returns to the neutral position while the brake pedal 13 is being depressed, the shoe 14 and the driven plate 19 slide relative to each other. When the brake pedal 13 is released from the depression, the brake pedal 13 is returned and swung by a return spring (not shown), so that the action of the rising cam mechanism C is released and the fixing plate 17 is moved by the restoring force of the disc spring 23. Due to the pressing action, the contact between the fixed plate 17 and the driven plate 19 via the shoe 14 is broken, the brake pedal 13 returns to the initial position when depressed, and the gear change pedal 12 can be depressed independently.

[0010]Although reference numerals are written in the claims for convenience of comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

[Figure 1] Cross-sectional view showing the structure of the mechanical linkage mechanism

[Fig. 2] Side view showing the linkage structure between the brake pedal and the speed change pedal

[Figure 3] Side view of lawn tractor

[Explanation of symbols]

9 Transmission device 13 Brake pedal B Mechanical linkage mechanism

Claims (1)

[Claims] 1. A friction transmission type transmission device (9) and a brake pedal (13) are provided, and only when the brake pedal (13) is depressed, the transmission device (9) is operated in conjunction with the depression operation. A traveling linkage device for a working vehicle, which is equipped with a mechanical linkage mechanism (B) that mechanically forces the vehicle into a neutral state.