JP2536535Y2 - Tractor starting safety device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for starting a tractor, and more particularly, to a safety device for starting a vehicle only when a traveling shift lever and a PTO shift lever are in a neutral position.

[0002]

2. Description of the Related Art
This type of tractor is provided with a start safety device that allows the engine to be started only when the power of the traveling system is cut off in order to prevent the aircraft from starting at the same time as the engine is started. Since the device is constituted by an engine start permitting switch which is turned on based on the depression of the traveling clutch pedal, the engine can be started even when the power of the PTO system is in the transmission state. There was a fear that the department would work. Therefore, various start-up safety devices have been proposed that allow the engine to start only when the traveling transmission lever and the PTO transmission lever are located at the neutral position and the power transmission of the traveling system and the PTO system is cut off. Conventionally, however, this type of starting safety device has a mechanism for directly connecting the two shift levers with a lever position detecting plate, or a device in which the starting safety device is incorporated in a transmission case. However, there is a drawback in that the operability is reduced due to interference through the antenna, and the structure in the transmission case is complicated.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been devised for the purpose of providing a starting safety device for a tractor capable of eliminating these disadvantages. In a tractor having a lever and a PTO shift lever arranged side by side, a swing arm that swings with a shift operation is connected to the traveling shift lever and the PTO shift lever, and one swing arm is connected to a cylinder. The other swing arm is connected to a piston rod that is slidably fitted in the cylinder tube, and the other swing arm constitutes a telescopic cylinder that is interlocked with the shifting operation. An engine start permitting switch that is turned on only when the telescopic cylinder reaches a predetermined length based on the neutral return of the PTO shift lever is provided. That. The present invention provides a safe engine start based on the neutral return of the traveling shift lever and the PTO shift lever without reducing the operability of the shift lever and without complicating the structure of the transmission. Can be performed.

[0004]

Next, an embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a transmission control case. The control case 1 includes a traveling speed change lever 2 capable of four forward speeds and a neutral shift by an H-type speed change operation, and a H-type speed change operation. A PTO speed change lever 3 capable of three forward speeds, one reverse speed, and a neutral speed is provided in parallel with each other, and each speed change lever 2, 3 is connected to a travel speed change mechanism in a transmission case and a PTO speed change lever.
It is operatively connected to the TO transmission mechanism.

[0005] Reference numerals 4 and 5 denote shift shafts which are rotatably and slidably supported on the control case 1. The shift shafts 4 and 5 are connected to one end of a traveling speed change lever 2, While the PTO shift lever 3 rotates based on the operation in the front-rear direction, it slides based on the left-right operation in the neutral position, but slides on the other end protruding from the control case 1 with the shift shafts 4 and 5. Brackets 4b, 5 with a substantially parallel engagement pins 4a, 5a
b is fixed.

On the other hand, 6 and 7 are control cases 1
The swing arms 6 and 7 are pivotally supported at their intermediate portions toward the control case 1 and have upper ends connected to the engaging pins 4a and 5a. U-shaped engaging pieces 6a and 7a to be engaged with each other are provided. That is, the swing arms 6 and 7 are configured to swing based on the forward and backward operations of the traveling speed change lever 2 and the PTO speed change lever 3, respectively.

Further, reference numeral 8 denotes a telescopic cylinder. The telescopic cylinder 8 is composed of a cylinder cylinder 9 and a piston rod 10 which is slidably fitted in the cylinder cylinder 9. Numeral 9 is connected to the lower end of the swing arm 7 so as to be able to swing, while piston rod 10 is connected to the lower end of the swing arm 6 so as to be able to swing. Travel shift lever 2, PTO
It is configured to expand and contract based on the operation of the shift lever 3 in the front-rear direction.

[0010] Further, reference numeral 11 denotes a safety switch (engine start permitting switch) provided in the cylinder tube 9. The safety switch 11 has a detection portion 11 a which can protrude and retract from the inner peripheral portion of the cylinder tube 9. The detection unit 11a is immersed in a state in which the detection unit 11a contacts the outer peripheral surface of the piston unit 12 constituting the piston rod 10 and turns the safety switch 11 into an OFF state. In a state in which the safety switch 11 is engaged with the annular concave groove 12a formed to face, the safety switch 11 is turned on. That is, the annular groove 12a
Is formed at a predetermined position of the piston portion 12 where the detecting portion 11a faces when the traveling speed change lever 2 and the PTO speed change lever 3 are both returned to neutral.

The cylinder rod 10 is composed of a piston portion 12 and a rod portion 13. The base end of the rod portion 13 is screwed into the piston portion 12 so as to be able to advance and retreat, while the tip end portion is swung. The rod length can be adjusted freely by screwing into a joint portion 14 with the moving arm 6 so as to be able to advance and retreat. In addition, 15 is a stop nut, 1
6 is a dust seal, 17 is a bush, and 18 is a seal cap.

In the embodiment of the present invention constructed as described above, when the traveling shift lever 2 and the PTO shift lever 3 are returned to neutral, the telescopic cylinder 8 connected to the shift levers 2 and 3 has a predetermined length. Incidentally, the annular groove 12a of the piston portion 12 and the detecting portion 11a of the safety switch 11 face each other, and in this state, the safety switch 11 is turned on with the protrusion of the detecting portion 11a to allow the engine to start. become.

As described above, according to the present invention, the engine can be started only when the traveling speed change lever 2 and the PTO speed change lever 3 have returned to the neutral position. Is not directly connected by a lever position detecting plate or the like as in the prior art, the neutral return of both transmission levers 2 and 3 is confirmed by detecting the cylinder length of the telescopic cylinder 8, and based on this, the engine start is allowed. Thus, it is possible to prevent the two shift levers 2 and 3 from directly interfering with each other, and as a result, the operability of the shift levers 2 and 3 can be greatly improved.

In addition, since the starting safety device including the telescopic cylinder 8 and the like is provided outside the transmission case, the transmission structure is complicated as in the case where the starting safety device is incorporated in the transmission case. Can be prevented, and as a result, assembling workability at the time of manufacturing can be improved, and also maintainability can be greatly improved.

Further, in the embodiment, since the rod length of the piston rod 10 is configured to be adjustable, the detection accuracy of the lever position detection can be improved, and the safety at the time of starting the engine can be significantly improved. As a result, the assembling workability can be greatly improved by allowing the assembling error at the time of manufacturing.

[0014]

[Effects] In summary, the present invention is constructed as described above.
Although the start of the engine is allowed only when the O shift lever is in a neutral state, the traveling shift lever and the PTO shift lever are directly connected by a lever position detecting plate or the like as in the related art. Instead of checking the neutral return of both shift levers based on cylinder length detection of the telescopic cylinder and allowing the engine to start, the inconvenience of the two shift levers directly interfering with each other is eliminated. As a result, the operability of the shift lever can be greatly improved.

Moreover, since the starting safety device of the present invention can be externally mounted without being incorporated in the transmission case, it is possible to eliminate the inconvenience of complicating the transmission structure. The assembling workability can be improved, and the maintainability can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a side view of a control case portion showing a state where both levers have returned to neutral.

FIG. 2 is a front view of a control case section.

FIG. 3 is a rear view of the same.

FIG. 4 is an upper side view showing an example of an engine start regulation state.

FIG. 5 is a side view of the same.

FIG. 6 is a side view of the same.

FIG. 7 is a side view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control case 2 Traveling shift lever 3 PTO shift lever 8 Telescopic cylinder 11 Safety switch 12a Annular groove

Claims (1)

(57) [Scope of request for utility model registration] In a tractor having a traveling speed change lever and a PTO speed change lever arranged side by side, a swing arm that swings with a speed change operation is connected to the travel speed change lever and the PTO speed change lever, respectively. The swing arm is pivotally connected to a cylinder cylinder, and the other swing arm is pivotally connected to a piston rod slidably fitted in the cylinder cylinder to form a telescopic cylinder interlocked with a shift operation. A tractor starting safety device which is provided with an engine start permitting switch which is turned on only when the telescopic cylinder reaches a predetermined length based on the neutral return of the traveling shift lever and the PTO shift lever.