JPH02175440A - Parking brake device of work vehicle - Google Patents

Abstract

PURPOSE:To securely actuate parking brake by installing a valve mechanism connected to the pressure oil supply line to an oil hydraulic clutch, and a linking means which switches over to a state where the supply of pressure oil is made impossible in linkage with the operation of parking brake. CONSTITUTION:A parking brake is so constituted that a control valve V3 is connected on the upstream side of the oil line a of an auxiliary control valve V2, i.e., the pressure oil supply line to an oil hydraulic clutch C, and the control valve V3 is switched over in a direction to shut off the supply of pressure oil to the auxiliary control valve V2 in linkage with the operation of the operating ever 19 of a parking brake 14. It can be made possible, therefore, when the parking brake 14 is operated, to maintain a changeover valve 17A, of four pilot pressure operating type two-position changeover valves constituting a changeover valve 17, in a shut-off state to fail the supply of pressure oil to the clutch C, i.e., to prevent motive power from being transmitted to driving wheels.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a parking brake device for a work vehicle such as a tractor or a wheel loader, and more specifically, to a transmission for driving an aircraft that is brought into a transmission state by supplying pressure oil. This invention relates to a parking brake device for a work vehicle equipped with a hydraulic clutch for use in the parking lot.

[Conventional technology]

Conventionally, the technology used was to apply the parking brake after locking the gear shift lever that changes the driving transmission in the neutral position with a locking metal fitting, and the parking brake could not be applied unless the driving transmission was in the neutral position. A technique that does this is known. (No literature available) [Problems to be Solved by the Invention] In the former prior art, it is troublesome and time-consuming to operate the lock fitting, and users sometimes forget to lock it. Also, if you forget to lock the parking brake and apply the parking brake, and the lever moves and engages the gear, there is a possibility that the aircraft will start against the parking brake.

In the latter prior art, in order to properly maintain the transmission in a neutral state during braking, a mechanical linkage mechanism between the transmission and the parking brake lever must be manufactured with high precision, resulting in high costs. Furthermore, as the device becomes loose during use, it is necessary to perform frequent maintenance, which is troublesome.

In view of the above circumstances, an object of the present invention is to enable a parking brake to be operated easily, conveniently, and reliably at low cost.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a parking brake system for a working vehicle as described at the beginning, in which a valve mechanism is provided in the pressure oil supply oil passage to the hydraulic clutch to disable the supply of pressure oil to the hydraulic clutch. The valve mechanism is connected to the parking brake and is configured to include a linking means for switching the valve mechanism to a state in which pressurized oil cannot be supplied in conjunction with the operation of the parking brake.

[For production]

According to the above configuration, when the parking brake is operated, the hydraulic clutch is automatically disengaged so that no power is transmitted to the traveling wheels.

〔Effect of the invention〕

Therefore, simply by applying the parking brake, the transmission automatically becomes neutral, so there is no problem of starting against the parking brake, and the parking brake can be applied easily and reliably. Ta.

In addition, the present invention does not check the gear shift lever itself, but
Since it prevents the clutch from operating on the hydraulic circuit, there is no need for a linkage mechanism that requires particularly high-precision machining, and it is sufficient to add a relatively simple valve mechanism, making it cost-effective. It was an advantage.

〔Example〕

Figure 2 shows the transmission structure inside the transmission case (M) installed on the tractor. A synchronized mesh type main gear transmission (H,) which can be switched freely is provided, a friction plate type hydraulic clutch (C) is provided between the first transmission shaft (2) and the second driving transmission shaft (3), Second transmission shaft (
3) a synchromesh type forward/reverse gear transmission (H2) that changes the output from the forward/reverse direction, and a synchromesh type first auxiliary gear transmission (H,
), and the second output from which the output can be freely switched between high and low levels.
Each of the auxiliary gear transmissions (H4) is provided, and the output of the second auxiliary gear transmission (H,) is transmitted to the differential mechanism (4) of the rear wheels (4).
4A) and a differential mechanism (5A) for the front wheels (5).

A synchromesh type gear transmission device (1) that changes the power of the input shaft (1) in four stages and transmits it to the power output transmission shaft (6).
7), as well as a transmission shaft (6) and a power take-off shaft (8).
A relay transmission shaft (9) is provided between the power output shaft (8) and the power output shaft (8).

Next, the speed change operation structure for the driving transmission system will be described in detail with reference to FIGS. 1 and 2.

That is, the main gear transmission (Hl) has two main gear shifters (IOA) that are alternatively activated.

Two operation hydraulic cylinders (IIA), (] and IIB are attached, each of which is interlocked with the (IOB), and
An operating hydraulic cylinder (13) interlockingly connects a first auxiliary gear shifter (12) to a first auxiliary gear transmission (Hl).
) is attached.

Further, two operating hydraulic cylinders (IIA) for the main gear transmission (H3), (11, B) and the first
Hydraulic cylinder for operating the auxiliary gear transmission (H3) (
13) three 3-position switching valves (Sl), (S2) with the piston also used as a sliding spool.

(S3) is configured.

The operating hydraulic cylinder (IIA), (IIB),
(13) and the 3-position switching valves (Sl), (St), and (Sa) are supplied with a Rochley type 9-position valve (V3) as the main control valve (V3).
N, F, ~F8) is performed by operating the switching valve, and this 9
Pressure oil is supplied to the position switching valve (V3) from the hydraulic pump (P) via the pressure reducing valve (15).

The transmission hydraulic clutch (C) is driven by hydraulic pressure supplied from the pressure reducing valve (15) via a pressure adjustment mechanism (16), and is connected to the pressure control mechanism (16) and the hydraulic clutch (C). There are two options: a clutch engaged state in which pressure oil from the pressure control mechanism (16) is supplied to the clutch (C), and a clutch disengaged state in which pressure oil in the clutch (C) is returned to the tank (T). Four pilot pressure-operated two-position switching valves (1, 7) function as switching valves (17) that can be switched freely.
A), (17B).

(17c) and (170) are connected in series, and one pilot pressure operated two-position switching valve (170) is connected in series.
7A) is an auxiliary control valve (v
2), and the remaining three pilot pressure operated two-position switching valves (17B), (17
C) and (17D) are the three-position switching valve (St
), (S2), and (S3), the main gear transmission (Hl), the forward/reverse gear transmission (H2), and the first auxiliary gear transmission (H,
) four pilot pressure-operated two-position switching valves (17A) only when all of them are in the transmission state.

When all of (17B), (17c), and (170) are switched to a state where they are in communication, the state is switched to a clutch engaged state.
The clutch (C) is configured to be automatically switched in conjunction with a gear shift operation.

However, the two hydraulic cylinders (
When one of IIA) and (IIB) is operated to the gear shifting side, the other hydraulic cylinder is operated and held in a neutral position by pressure oil. Further, the second auxiliary gear transmission (H4) is equipped with a shifter that can be freely operated with a speed change lever.

Furthermore, the transmission device (7) relative to the power take-off shaft (8) is configured to be manually operated.

In addition, in the figure, each of (N) and (F3) to (F3) is
The operation position of the main control valve (vl) is shown, and (P) and (
R) indicates the operating position of the auxiliary control valve (■2), (old and (L) indicates the 3-position switching valve (S3) for the first auxiliary gear transmission
Indicates the operating position.

In addition, the transmission (HT
).

Next, the parking brake device will be explained.

As shown in Fig. 1, the oil passage (a) of the auxiliary control valve (v2)
That is, a control valve (3) as a valve mechanism for turning on and off the supply of pressure oil to the auxiliary control valve (v2) is connected to the upstream side of the pressure oil supply oil path to the hydraulic clutch (C), and The control valve (v3) is operated in conjunction with the operation of the operating lever (19) of the parking brake (14), and the auxiliary control valve (V
The parking brake device is configured to switch to cut off the supply of pressure oil to the parking brake.

Therefore, when the parking brake (14) is activated, the control valve (
v3), one of the four pilot pressure-operated two-position switching valves that make up the switching valve (17) is switched on, regardless of the selected position of the auxiliary control valve (■2).
A) is kept in the disengaged state to disable pressure oil supply to the clutch (C), that is, drive wheels (4), (5)
It is possible to prevent power from being transmitted to the

[Another example]

■ As shown in Fig. 3, the control valve (V3) linked to the operating lever (19) of the parking brake (14) may be directly connected to the pressure oil supply line to the hydraulic clutch (C). good.

■ As shown in Fig. 4, a hydraulic clutch (20) is provided for each of the multiple gears of the permanent bite type, and the hydraulic clutch (20) is selectively engaged and operated to achieve the desired result. The present invention may be applied to a transmission configured to obtain the following gears.

In this case, as the oil passage upstream side of the speed selection valve (v4),
A control valve (V5) interlocked with the parking brake (14) is connected.

(2) Also, instead of this control valve (v6), a bypass valve may be connected.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the parking brake device for a working vehicle according to the present invention, in which FIG. 1 is a hydraulic circuit diagram, FIG. 2 is a transmission configuration diagram,
3 and 4 are principal hydraulic circuit diagrams showing other embodiments, respectively. (14)... Parking brake, (H work)...
...Transmission, (C) ...Hydraulic clutch, (a3) ...Oil passage, (V3) ...Valve mechanism.

Claims (1)

[Claims] Hydraulic clutch (C) for gear change that is in a transmission state by supplying pressure oil to the aircraft running transmission (H_T)
A parking brake device for a working vehicle equipped with a valve mechanism (V_
3) and connect this valve mechanism (V_3) to the parking brake (
14) A parking brake device for a working vehicle, which is provided with a linking means for switching to a state in which pressure oil cannot be supplied in conjunction with the operation of item 14).