JPH09112582A - Clutch interrupting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent shortage or overabundance of hyraulic fluid by providing an oil reservoir which is connected to both a master cylinder and an air master cylinder and re-supplies hydraulic fluid flown out from one side to the other side of the master cylinder and the air master cylinder to the one side when a valve body makes a move. SOLUTION: When a driver makes a gear shift operation, a change-over valve 78 is turned on by a shift signal being inputted into a controller 72, air pressure is supplied to a master cylinder 42 through an air pressure piping 62, and a clutch 8 is operated to be disrupted. At the time of manual manipulation of the clutch 8, oil pressure is supplied or discharged from a master cylinder 10 accompanying the operation of a clutch pedal 9 and causes a booster 7 to actuate. The change-over valve 78 is off at this time but a reservoir tank 58 is connected to the master cylinder 10 and the air master cylinder 42 and hydraulic fluid flown out from one side to the other side is supplied to the one side through the reservoir tank 58 thereby balance of the hydraulic fluid quantity is kept.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a clutch connecting / disconnecting device, and more particularly to a clutch connecting / disconnecting device capable of automating a vehicle clutch.

[0002]

2. Description of the Related Art Recently, there has been an increasing demand for automatic shifting of large vehicles such as buses and trucks. Since these vehicles generally have a large vehicle weight and a large payload, and use of a fluid torque converter such as that employed in a passenger car as a clutch type causes a large loss and is disadvantageous in terms of fuel efficiency, so in such a large vehicle, In particular, the friction clutch is turned on and off by automatic operation, the output of which is sent to a transmission, and this transmission is also automatically operated, thereby achieving automatic transmission. As a clutch intermittent device for automatically operating the clutch, a device provided with a booster (clutch booster) for intermittently operating the friction clutch by supplying and discharging air pressure is generally used.

On the other hand, when the vehicle is started, the operation of the clutch is delicate, and if the operation is to be performed by automatic control, the device becomes complicated and expensive. Therefore, only in this case, a manual operation using a clutch pedal is required. ) There is a system which can be operated so as to simplify the device and reduce the price (so-called semi-auto clutch system). In this case, the hydraulic pressure is supplied and discharged from the master cylinder by operating the clutch pedal, and the supply and discharge of the hydraulic pressure is performed to supply and discharge the pneumatic pressure to and from the booster.

[0004] By the way, at the time of automatic shifting except at the time of starting, air pressure is supplied / discharged to the booster without operating the clutch pedal. Further, when the air pressure is supplied, the booster pushes an internal power piston to operate the clutch in a disconnecting direction.

In the conventional configuration, a passage for sending hydraulic pressure from the master cylinder communicates with a hydraulic cylinder of a booster whose volume changes according to the movement of the power piston. That is, when clutch separation control is performed by the power piston without operating the clutch pedal, when the hydraulic piston (hydraulic piston) moves due to the pushing of the power piston, a negative pressure is generated in the hydraulic passage and air bubbles are mixed in, so that the clutch is disengaged. There is a possibility that the accurate operation of the is difficult.

In order to prevent such a negative pressure from occurring, Japanese Utility Model Publication No. 4-8023 discloses a mechanism for canceling a manual operation and an automatic operation at a hydraulic output portion of a booster.
The change in volume in the hydraulic passage during automatic operation is prevented. However, such a structural change of the booster has to employ a complicated structure with a small space, which leads to an increase in cost and a problem in reliability and durability.

Therefore, the applicant of the present invention solves the above-mentioned problems by not changing the structure of the booster and operating the master cylinder not only by the clutch pedal but also by another driving means (pneumatic or hydraulic). I made a proposal for a clutch engagement and disengagement device. (Japanese Patent Application No. 7-176353)

[0008]

In order to solve the above-mentioned problems, in addition to such a clutch engagement / disengagement device, in addition to a normal master cylinder that works with a clutch pedal, a hydraulic pressure is supplied by introducing air pressure. It is conceivable to provide an air master cylinder to do this. By controlling the introduction of the air pressure, the automatic disengagement of the clutch is achieved.

However, as disclosed in Japanese Utility Model Publication No. 4-8023, when a mechanical three-way valve is used for switching the hydraulic pressure supply passages from the master cylinder and the air master cylinder, the clutch on / off operation by one master cylinder is performed. When the other master cylinder is operated, the valve element moves inside the three-way valve, causing movement or outflow of hydraulic oil between both master cylinders, and one hydraulic oil is insufficient at an early stage and the other is excessive. Is concerned.

[0010]

DISCLOSURE OF THE INVENTION The present invention relates to a booster for dividing and operating a clutch by supplying air pressure, a hydraulically operated valve for opening and closing an air pressure supply path to the booster, and a clutch pedal operation. A master cylinder that interlocks to supply hydraulic pressure to the hydraulically actuated valve, an air master cylinder that supplies pneumatic pressure to the hydraulically actuated valve by introducing air pressure by pneumatic pressure supply control by a controller, the master cylinder and the air The valve body is moved based on the hydraulic pressure difference from the master cylinder, and a first hydraulic pressure supply path from the master cylinder to the hydraulically operated valve and a second hydraulic pressure supply path from the air master cylinder to the hydraulically operated valve are provided. It is connected to both the three-way valve for switching and the master cylinder and the air master cylinder, and when the valve body moves, the master cylinder and the air master cylinder One hydraulic fluid flowing out to the other from those in which an oil reservoir for refill on one.

According to this, since the oil reservoir is shared by the master cylinder and the air master cylinder,
The operating oil that has flowed out from one side to the other side can be resupplied to that one side via the oil reservoir, and thus a situation in which the operating oil is insufficient or excessive can be prevented.

[0012]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram showing a clutch connecting / disconnecting device according to the present invention. The clutch connecting / disconnecting device 1 has pneumatic supply means 2 for supplying pneumatic pressure. The pneumatic supply means 2
A compressor 3 which is driven by an engine (not shown) to generate air pressure (air pressure); an air dryer 4 for drying air from the compressor 3; an air tank 5 for storing air sent from the air dryer 4; 5
And a check valve 6 provided on the inlet side of the valve.
The air pressure from the air pressure supply means 2 is sent to a booster (clutch booster) 7, and the booster 7 operates the friction clutch 8 to the separating side (right side) A by supplying the air pressure. ing. The booster 7 will be described in detail later,
The hydraulic pressure is also supplied from the master cylinder 10 or the air master cylinder 42.

FIG. 2 is a vertical sectional view showing details of the booster 7. The booster 7 is configured in the same manner as the conventional one. As shown, the booster 7 has a cylinder shell 12 connected to its body 11,
2, a piston plate (power piston, booster piston) 13 is provided by a return spring 14 and urged toward the pneumatic pressure introduction side (left side in the figure). A pneumatic nipple 15 is attached to one end of the cylinder shell 12,
The air pressure nipple 15 forms an air pressure inlet to introduce air pressure from the air tank 5 through the air pressure pipe 34 (FIG. 1).
When air pressure is introduced, the piston plate 13 is pushed to the right, and when this happens, the piston plate 13 pushes the piston rod 16, the hydraulic piston 17, and further the push rod 18 to move the clutch lever 8a (Fig. 1). Push to the disengagement side A to disengage the clutch 8.

On the other hand, inside the body 11, a hydraulic passage 20 is formed which communicates with a hydraulic nipple 19 which is a hydraulic pressure inlet. The hydraulic passage 20 includes a hole 21 formed at one end (lower end) of the body flange portion 11a, a hydraulic cylinder (hydraulic cylinder) 22 that accommodates the hydraulic piston 17 (formed on the body cylinder portion 11b), and a hydraulic cylinder. It is mainly formed by the control hole 23 on the other end (upper end) side communicating with the lick cylinder 22 via the small hole 23a. When the hydraulic pressure of the hydraulic piping 54 (FIG. 1) is introduced from the hydraulic nipple 19, the hydraulic pressure passes through the above passage and passes through the control hole 23.
And pushes the control piston 24 rightward along the control cylinder 25. In this way, the body flange portion 11a
As will be described in detail later, a control valve section 7a (hydraulic actuated valve) for controlling the supply of pneumatic pressure to the booster 7 is formed on the upper end side.

The control valve portion 7a is defined by a control body portion 26 protruding to the right. The control body portion 26 is formed with a control chamber 27 and a pneumatic port 28 that coaxially communicate with the control cylinder 25. The control section 27 of the control piston 24 is provided in the control chamber 27.
However, a poppet valve 30 is slidably accommodated in the pneumatic port 28. Nipple 3 in pneumatic port 28
The nipple 31 is provided with a pneumatic piping 67.
(FIG. 1) is connected and air pressure is always supplied.

Normally, the poppet valve 30 is biased to the left by pneumatic pressure and a poppet spring 32, and closes a communication port 33 which connects the control chamber 27 and the pneumatic port 28. Therefore, the air pressure from the nipple 31 is cut off at the position of the poppet valve 30. However, when hydraulic pressure is supplied from the hydraulic piping 54, the control unit 29 of the control piston 24 pushes the poppet valve 30 to the right to open the communication port 33. When this happens, the air pressure that has entered the control chamber 27 from the communication port 33 is
The cylinder shell 12 enters the above-described cylinder shell 12 through a pneumatic pipe 34 (indicated by a phantom line) communicating with the control chamber 27, and acts on the pneumatic action surface 13a on the left side of the piston plate 13 to push it to the right. Is operated to the dividing side.

Here, the booster 7 can operate the clutch 8 for a predetermined stroke in accordance with the magnitude of the supplied hydraulic pressure. That is, for example, when the hydraulic pressure is increased by a relatively small value, the piston plate 13 is pushed to the right by the above-described pneumatic action, and in conjunction with this, the hydraulic piston 17 is pushed to the right by a predetermined stroke. . Then, the volume of the hydraulic passage 20 increases and the hydraulic pressure in the control hole 23 decreases, and when this occurs, a balance state occurs in which the poppet valve 30 closes the communication port 33 while the control unit 29 of the control piston 24 presses the poppet valve 30. Accordingly, a predetermined air pressure is held in the control chamber 27, the air pressure pipe 34, and the air pressure introduction chamber 12b on the air pressure acting surface 13a side of the piston plate 13, and the piston plate 13 is held at a predetermined stroke position. , The clutch 8 is held at a predetermined half-clutch position.

When the hydraulic pressure is completely released, the control hole 2
3, the control piston 24 is returned to the leftmost home position as shown. In this case, the control unit 29 is separated from the poppet valve 30, and the open port 36 provided inside the control unit 29 communicates with the control room 27 and the like. Then, most of the retained air pressure passes from the open port 36 through the atmospheric pressure port 39 to the atmosphere chamber 1 on the side opposite to the air pressure introduction chamber 12b.
2a, the air pressure that pushed the piston plate 13 to the right by this, this time the return spring 14
In cooperation with, push it to the left side on the opposite side to operate the clutch 8 to the connecting side (left side) B. The remaining air pressure is released to the atmosphere through the breather 37.

In the booster 7, 38 is a seal member for partitioning the cylinder chamber 12a and the hydraulic cylinder 22 in an oil-tight manner, 40 is an atmospheric pressure port, and 41 is a bleeder for the working oil when loosened. Be a breeder.

As shown in FIG. 1, the hydraulic pipe 54 includes a shuttle valve, which is a three-way valve, or a double check valve (hereinafter referred to as D.
CV) 69, and two more hydraulic lines 43, 44 extend from the DCV 69, one 43 for the master cylinder 10 and the other 44 for the air master cylinder 4
2 is connected. Especially master cylinder 10 and booster 7
The hydraulic pipes 43 and 54 that connect to each other form a first hydraulic pressure supply passage, and the hydraulic pipes 44 and 54 that connect the air master cylinder 42 and the booster 7 form a second hydraulic supply passage. Then, these hydraulic pressure supply paths are appropriately switched by the DCV 69.

The master cylinder 10 has a normal structure, that is, when the driver operates the clutch pedal 9, the internal piston moves via the push rod 49, thereby supplying / discharging the hydraulic pressure from the hydraulic pressure supply section 53. To do.

FIG. 3 is a vertical sectional view showing the structure of the air master cylinder 42. This is similar to the booster 7 above,
The internal pneumatic piston 45 is pushed by the pneumatic pressure from the pneumatic pipe 62 connecting the air tank 5 and the air master cylinder 42. As a result, the hydraulic piston 46 is pushed through the rod 48, the hydraulic oil in the hydraulic chamber 50 is compressed, and the hydraulic pressure is supplied to the hydraulic pipe 44. Since the pneumatic piston 45 has a larger diameter than the hydraulic piston 46, a boosting effect is exerted.
The pneumatic piston 45 is biased toward the return side by the return spring 47, and the inside of the pushing side (right side) chamber of the pneumatic piston 45 is breathed to the outside by the exhaust port 51.

A check valve mechanism 55 is provided between the rod 48 and the hydraulic piston 46, and the rear side (left side) of the hydraulic piston 46 is an oil chamber in which hydraulic oil of normal pressure (about atmospheric pressure) is stored. It is 56. The oil chamber 56 is the oil passage 60.
Is connected to an oil supply nipple 57 that forms an oil supply port. When the hydraulic piston 40 is located at the left side original position as shown in the drawing, the check valve mechanism portion 55 communicates the oil chamber 56 with the hydraulic chamber 50 and sets the working oil in the hydraulic chamber 50 to the normal pressure. On the other hand, when the hydraulic piston 46 is pushed to the right,
The oil chamber 56 and the hydraulic chamber 50 are shut off to allow pressurization of the hydraulic oil in the hydraulic chamber 50.

The oil supply nipple 57 is connected to the oil supply pipe 5
9b, and supplies or replenishes the hydraulic oil in the reservoir tank 58 (oil reservoir) shown in FIG. 1 to the oil passage 60 and the oil chamber 56 through the pipe 59b. Hydraulic piston 4
Although the volume of the oil chamber 56 changes due to the movement of 6, the hydraulic oil is appropriately supplied and discharged in the oil supply nipple 57 according to the change in the volume.

A pressure mechanism 71 is attached to the oil supply nipple 57.
And the pressurizing mechanism 71 appropriately pressurizes the hydraulic oil in the oil passage 60 and the oil chamber 56 only when the hydraulic piston 46 is in the original position. The rod 48 is slidably inserted into the seal member 61, and the seal member 61 is press-fitted and fixed to seal the oil chamber 56 and the pneumatic piston 45 pushing side chamber.

As shown in FIG. 1, a reservoir tank 58
Is also connected to the oil supply nipple 10a of the master cylinder 10 via another oil supply pipe 59a. This allows
The reservoir tank 58 is connected to both the master cylinder 10 and the air master cylinder 42, and supplies hydraulic oil to both of them appropriately as described later.

The DCV 69 utilizes the pressure difference of the hydraulic pressure from the master cylinder 10 and the air master cylinder 42 to
The hydraulic pressure supply path is automatically and mechanically switched.

The structure is as shown in FIG. 4 (see especially FIG. (A)), and the DCV 69 has a valve body 64.
It has a check ball 65 (valve body) inside. The valve body 64 has three hydraulic ports 68a branched in three directions.
68b and 68c are partitioned and formed, one 68a reaches the hydraulic pipe 43 leading to the master cylinder 10, one 68b reaches the hydraulic pipe 44 leading to the air master cylinder 42, and the other 68c reaches the booster 7. It is connected to the hydraulic pipe 54.
In particular, the two hydraulic ports 68a and 68b are arranged in a straight line, and the remaining hydraulic ports 68c are orthogonal to them. A valve body accommodating chamber 70 is defined at the branch center position of the hydraulic ports 68a, and the check ball 65 moves in the valve body accommodating chamber 70, so that either of the hydraulic ports 68a, 6
By contacting the seat surfaces 74a and 74b of 8b, DC
The V 69 is designed to switch the hydraulic path.

That is, when the hydraulic pressure is sent from the master cylinder 10, the check ball 65 is moved by the hydraulic pressure to close the hydraulic port 68b as shown in FIG.
While connecting 3, 54, the hydraulic pipe 44 is shut off. On the other hand, if hydraulic pressure is sent from the air master cylinder 42,
(C) As shown in the figure, the check ball 65 has the hydraulic port 6
8a is closed, whereby the hydraulic pipes 44 and 54 are connected and the hydraulic pipe 43 is shut off. In this way, if hydraulic pressure is supplied from any of them, the hydraulic pressure is sent to the booster 7 to operate the booster 7 on the dividing side A as described above.

If the clutch pedal 9 is operated to operate the master cylinder 10, the manual discontinuity of the clutch 8 is achieved. On the other hand, if the air pressure supply to the air master cylinder 42 is controlled, the clutch 8 is automatically disengaged. Is achieved.

This pneumatic pressure supply control is achieved by controlling ON / OFF of the electromagnetic switching valve 78 provided in the pneumatic pipe 62 by the controller 72 incorporated in the computer. Switching valve 78
Means that when it is ON, the upstream side (air tank 5 side) and the downstream side (air master cylinder 42 side) are connected to allow air pressure supply, and when it is OFF, the upstream side is shut off and the downstream side is opened to the atmosphere, The air pressure of the air master cylinder 42 is discharged to the outside. Therefore, when the switching valve 78 is turned on, the hydraulic pressure is supplied from the air master cylinder 42 to disconnect the clutch 8, and when the switching valve 78 is turned off, the hydraulic pressure is returned to the air master cylinder 42 and the clutch 8 is connected. .

As described above, the master cylinder 10, the hydraulic pipes 43 and 54, the DCV 69, the booster 7, the pneumatic supply means 2, and the pneumatic pipes 62, 67 and 34 are operated by the clutch pedal 9 to operate the clutch pedal. 8 constitutes a manual interrupting means for performing manual interrupting.

On the other hand, the pneumatic supply means 2 and the pneumatic pipes 62, 6
7, 34, air master cylinder 42, hydraulic piping 44, 5
The DCV 69, the booster 7, the switching valve 78, and the controller 72 constitute an automatic connecting / disconnecting means for automatically connecting / disconnecting the clutch 8.

The pneumatic pipe 67 is branched at a branch 63 between the air tank 5 of the pneumatic pipe 62 and the switching valve 78. Then, branch 63 from the air tank 5, control valve portion 7
a, pneumatic pipes 62, 67 connecting the pneumatic nipple 15 in order,
The numeral 34 constitutes an air pressure supply path leading to the booster 7.

Further, the controller 72 includes a clutch 8
A clutch stroke sensor 88 provided in the vehicle, an emergency switch 73 for stopping the control when a control trouble occurs, and the like are connected.

The clutch connecting / disconnecting device 1 is linked with a transmission (not shown) provided separately from the clutch connecting / disconnecting device 1. The transmission is configured to perform automatic shifting, that is, when the shift position is selected by the manual shift lever, the shift signal by the electric switch is transmitted to the controller 7.
2, the actuator (not shown) is operated,
Substantial gear shifting operation is performed instead of the driver's operation.

Next, the operation of the above device will be described.

First, the clutch 8 is included in the outline of automatic shifting.
Automatic intermittent operation will be described. When the driver performs a shift operation, a shift signal is input to the controller 72, and the controller 72 turns on the switching valve 78 accordingly.
Then, the air master cylinder 42 is passed through the pneumatic piping 62.
Pneumatic pressure is supplied to the clutch 8. As a result, the clutch 8 is disengaged as described above. After that, the shift operation of the transmission is completed by the actuator, the switching valve 78 is turned off, the air pressure of the air master cylinder 42 is released to the atmosphere, and the clutch 8 is released.
Perform the connection operation of to complete the shift.

Particularly, in the above structure, the automatic disengagement of the clutch 8 is performed by operating the air master cylinder 42 different from the master cylinder 10, thereby preventing the generation of negative pressure in the hydraulic passage. doing.

That is, referring to FIG. 2, conventionally, there is no air master cylinder 42, and another pneumatic pipe is connected to the pneumatic nipple 15 of the booster 7, and the pneumatic pressure from this pneumatic pipe is used. By the supply control, the piston plate 13 is pushed without operating the master cylinder 10. However, in this case, the hydraulic piston 17 moves to the right in conjunction with the piston plate 13, thereby increasing the volume of the hydraulic cylinder 22 filled with the hydraulic oil, thereby increasing the hydraulic passage 20 and the hydraulic pipe 54. (Also referred to as a hydraulic passage), a bubble is mixed in the hydraulic oil, and a problem arises in that accurate manual operation of the clutch 8 becomes difficult.

In view of this, in the present apparatus 1, when the clutch 8 is automatically disengaged, the air master cylinder 42 is operated to pressurize the hydraulic passage while supplying pneumatic pressure to the booster 7. As a result, it is possible to prevent the pressure in the hydraulic passage from becoming negative, and to prevent trouble.

Next, the manual connection / disconnection operation of the clutch 8 is performed by supplying or discharging the hydraulic pressure from the master cylinder 10 by depressing or returning the clutch pedal 9 and operating the booster 7 as described above. Here, the switching valve 78 is turned off and the air master cylinder 42 is not operated. Also at this time, since the inside of the hydraulic passage is pressurized, the negative pressure does not occur.

In this way, the automatic and manual engagement / disengagement of the clutch 8 can be achieved. With this configuration, the above-mentioned conventional problems are solved as follows.

In the DCV 69, in the process of shifting from the state shown in FIG. 4A, that is, the state in which the clutch 8 is manually disengaged by the clutch pedal 9 to the state in which the air master cylinder 42 automatically disengages the clutch 8. Four
As shown in (b), the flow of hydraulic oil from the hydraulic port 68b on the air master cylinder 42 side causes the check ball 65 to move to the clutch pedal 9 side.
The hydraulic pressure ports 68a, 68b, 68c communicate with each other for a short time. In this case, the hydraulic pressure port 68b on the side of the air master cylinder 42 moves from the master cylinder 10
The hydraulic oil port 68a on the side allows the hydraulic oil to move or flow out, though it is a small amount. On the contrary, the clutch pedal 9 is released from the automatic intermittent state by the air master cylinder 42.
The same problem will occur in the opposite direction when shifting to manual division.

If an oil reservoir is provided for each of the master cylinders 10 and 42, the hydraulic oil will be insufficient or excessive early (overflow) in either one of manual interruption and automatic interruption. A problem arises. Even after switching, the seat surface 74
Leakage from a and 74b causes hydraulic oil to flow out.

Therefore, in the above configuration, the master tank 10 is provided with the reservoir tank 58 as an oil reservoir.
And the air master cylinder 42, that is, the reservoir tank 58 is shared, and the operating oil that has flown from one side to the other side is resupplied or circulated to the one side via the reservoir tank 58, or the outflow amount. By replenishing the working oil corresponding to the above from the reservoir tank 58, the balance of the working oil amount is maintained, and the problem of early shortage or excess of working oil is solved.

This structure is also effective for the spool valve type in addition to the check ball type three-way valve described above.

Although the preferred embodiments of the present invention have been described above, the present invention can be implemented in various forms other than the above-mentioned forms.

[0050]

The present invention exhibits the following excellent effects.

(1) It is possible to prevent a situation such as shortage or excess of hydraulic oil for each master cylinder due to the outflow of hydraulic oil inside the three-way valve.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a clutch connecting / disconnecting device according to the present invention.

FIG. 2 is a vertical sectional view showing a booster.

FIG. 3 is a vertical sectional view showing an air master cylinder.

FIG. 4 is a vertical sectional view showing a three-way valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Clutch connecting / disconnecting device 7 Booster device 7a Control valve section (hydraulic actuated valve) 8 Clutch 9 Clutch pedal 10 Master cylinder 34, 62, 67 Pneumatic piping (pneumatic supply path) 42 Air master cylinder 43, 44, 54 Hydraulic piping (Hydraulic supply path) 58 Oil reservoir 65 Check ball (valve body) 69 Double check valve (three-way valve) 72 Controller

Claims (1)

[Claims] 1. A booster device that divides and operates a clutch by supplying air pressure, a hydraulically actuated valve that opens and closes an air pressure supply path to the booster device, and a hydraulically actuated valve that operates in conjunction with clutch pedal operation. A master cylinder that supplies oil pressure, an air master cylinder that supplies air pressure to the hydraulically actuated valve by introducing air pressure by air pressure supply control by a controller, and a hydraulic pressure difference between the master cylinder and the air master cylinder. A three-way valve for moving the valve body to move a first hydraulic pressure supply path from the master cylinder to the hydraulically operated valve and a second hydraulic pressure supply path from the air master cylinder to the hydraulically operated valve; Connected to both the air master cylinder and the air master cylinder, and when the valve body moves, the work flowed out from one of the master cylinder and the air master cylinder to the other. A clutch engagement / disengagement device comprising an oil reservoir for resupplying hydraulic oil to one side.