JP4662468B2 - Wet disc brake with parking mechanism - Google Patents

Description

  The present invention relates to an improvement of a wet disc brake with a parking mechanism, which is a wet disc brake used for braking a vehicle such as an industrial vehicle such as a forklift, and includes a parking mechanism for keeping the vehicle in a stopped state.

  Conventionally, a dry drum brake has been mainly used for braking industrial vehicles such as forklifts. FIG. 30 shows the structure described in Patent Document 1 among the dry drum brakes. This dry drum brake 101 has an axle shaft 103 inserted through an axle housing 102. A back plate 105 is coupled to an intermediate portion of the axle housing 102 via a frame support 104. A brake drum 106 is disposed around a portion near the outer end of the axle housing 102 (a portion near the left end in FIG. 30), and an inner peripheral surface of a hub 107 fixed to the brake drum 106 and an outer end of the axle housing 102 are arranged. A bearing 108 is provided between the outer peripheral surface and the hub housing 107 rotatably supported by the axle housing 102.

Also, by coupling fixing the outer end of the axle shaft 103 on the outer end face (left end face in FIG. 30) of the hub 107 by bolts 109, the hub 107, it is rotatable together with the axle shaft 103. Further, a pair of brake shoes 110, 110 can be pressed against the inner peripheral surface of the brake drum 106. During braking, the pair of brake shoes 110 and 110 are pressed against the inner peripheral surface of the brake drum 106 by a wheel cylinder (not shown) supported by the back plate 105. Further, when parking, by pressing the pair of brake shoes 110, 110 against the inner peripheral surface of the brake drum 106 via a wire or rod (not shown), parking braking force ("parking braking force" This is the force generated by the operation of the parking mechanism for maintaining the vehicle in a stopped state (the same applies throughout this specification).

  On the other hand, in recent years, in order to extend the life of the brake device and improve the sealing performance, in place of the dry drum brake as described above, braking is performed by frictionally engaging a plurality of discs. It is also considered to use a disc brake. FIG. 31 shows the structure described in Patent Document 2 among such wet disk brakes. The wet disc brake 1 includes a housing 2 and a brake cover 5 fixed to the housing 2 via a shaft member 3 and a sleeve 4. Further, the end of the brake hub 6 is inserted into the inner diameter side of the brake cover 5 and the brake hub 6 is rotatably supported around the shaft member 3 via a bearing (not shown). The brake hub 6 is fixed to a hub (not shown) capable of coupling and fixing a wheel by a bolt (not shown).

  Further, an inward flange-shaped pressure receiving portion 7 is provided on the inner peripheral surface of the outer end portion (left end portion in FIG. 31) of the brake cover 5. In addition, a plurality of stationary side disks 8, 8 are spline engaged with the inner peripheral surface of the brake cover 5, and each stationary side disk is connected to the outer peripheral surface of the inner end portion (right end portion in FIG. 31) of the brake hub 6. In a state where the disks 8 and 8 are alternately arranged, the plurality of rotating disks 9 and 9 are spline-engaged. Further, a piston 11 is fitted in a cylinder hole 10 constituted by the shaft member 3 and the sleeve 4 so as to be axially displaceable.

  The front end surface of the piston 11 is opposed to one stationary side disk 8 that is farthest from the pressure receiving portion 7 among the stationary side disks 8, 8. A male screw portion of a bolt 12 is coupled to the piston 11, and a portion closer to the head of the bolt 12 is fitted into concave holes 13 a and 13 b provided in the housing 2 and the shaft member 3. A spring 14 provided between the head of the bolt 12 and the bottom of the concave hole 13b provided in the shaft member 3 gives the piston 11 an elasticity toward the counter pressure receiving portion 7 side (the right side in FIG. 31). Yes. Furthermore, the front end surface of the adjusting bolt 15 coupled to the shaft member 3 is opposed to the back surface of the piston 11 (the right side surface in FIG. 31).

  When the wet disc brake 1 configured as described above is braked as shown in FIG. 31, pressure oil is fed into the cylinder hole 10 by operating the brake pedal. The piston 11 is displaced in the direction indicated by the arrow A in FIG. As a result, a plurality of stationary disks 8 and 8 and rotating disks 9 and 9 are pressed against the pressure receiving portion 7 by the piston 11, and the respective disks 8 and 9 are frictionally engaged with each other, thereby braking. Done.

In the case of the structure shown in FIG. 31, by adjusting the protruding amount of the adjusting bolt 15 from the outer side surface (left side surface in FIG. 31) of the sleeve 4, the stationary side and rotating side discs 8, 9 are adjusted. Regardless of wear, a desired clearance C ₁ in the axial direction between the front end surface of the piston 11 in contact with the adjustment bolt 15 and the side surface of the stationary disk 8 facing this front end surface is a desired brake clearance. So that the size can be maintained. However, in the case of such a structure shown in FIG. 31, it is not considered to provide a parking mechanism for parking.

  On the other hand, it is conceivable to provide a parking mechanism for the wet disc brake as described above. For example, the driven cover lever is swingably supported by the brake cover 5 and the pressing member connected to the driven lever is pressed directly against the stationary disk 8 without the piston 11 so as to control the parking. It is also possible to generate power (activate the parking brake). In such a structure, the driven lever (generally referred to as “parking lever”) provided on the driver's seat side is connected to the driven lever via a wire provided on the parking cable. Then, the driven lever is swung by swinging the driving lever by pushing and pulling.

  However, when the parking mechanism is provided in the wet disc brake shown in FIG. 31 described above, the pressing member is a brake clearance during non-parking that occurs when the parking braking force is released (the parking brake is released). The gap in the axial direction between the disk and the side surface of the stationary disk 8 (or the rotating disk 9) cannot be adjusted to an arbitrary size. Therefore, when the stationary side disk 8, 8 (or the rotating side disk 9, 9), which is at least one of the stationary side and rotating side disks 8, 9, is worn, the brake when not parking is performed. The clearance becomes large, and the swing margin (swing angle) of the driving side lever on the driver's seat side when the parking braking force is generated becomes large. On the other hand, by providing a second clearance adjustment mechanism that regulates the swing margin (swing angle) of the driven lever, the swing margin of the drive lever is regulated to be constant. Is also possible. However, in this case, the number of parts increases, resulting in an increase in cost. In this case, since the brake clearance that occurs when the vehicle is not parked is different from the brake clearance that occurs when the vehicle is not braked, at least one of the disks, the stationary disk or the rotating disk, is worn. In such a case, two or more portions for adjusting the size of the brake clearance are required, and the adjustment work takes time.

  FIGS. 1 and 2 of Patent Document 1 show that a wet disc brake with a parking mechanism is used to rotate the stationary side through a piston by a spring by discharging the pressure oil in the oil chamber in the brake cover during parking. The structure which presses each side disk toward a pressure receiving part is described. However, even in the case of such a wet disc brake with a parking mechanism described in Patent Document 1, when at least one of the discs is worn, there is a problem between the tip surface of the piston and the side surface of the stationary disc (or the rotary disc). It is not considered to adjust the brake clearance between.

JP 2003-247573 A JP-A-9-112604

  In view of the above-described circumstances, the wet disc brake with a parking mechanism according to the present invention makes it easy to set a brake clearance that occurs during non-braking and a brake clearance that occurs when the parking braking force is released to a desired size. It was invented to realize a structure that can be adjusted.

The wet disc brake with a parking mechanism of the present invention is formed by incorporating a parking mechanism into the wet disc brake.
Of these, the wet disc brake includes a brake cover, a brake hub, a plurality of rotating-side discs and stationary-side discs, and a piston.
Among these, the brake cover is provided with a pressure receiving portion projecting radially inward on the inner peripheral surface on one end side in the axial direction .
The brake hub is rotatably supported with respect to the brake cover in a state where a part of the brake hub is disposed on the inner side of the brake cover, and directly or another member is provided on a portion protruding from the inner side of the brake cover. The wheels can be connected via
The plurality of rotation-side discs are engaged with the outer peripheral surface of the brake hub inside the brake cover so as not to rotate with respect to the brake hub.
Further, the plurality of stationary disks are engaged with the brake cover in a non-rotatable manner while being alternately arranged on the inner peripheral surface of the brake cover with respect to the plurality of rotating disks.
Further, the piston is in the brake cover inner surface axial end portion close to the ring-shaped cylinder hole provided in the axial direction of, and fitted to allow axial displacement.
Further, the piston has a cylindrical fitting portion and an outward flange-like annular pressing portion provided in a state of projecting radially outward from the axial tip portion of the fitting portion. Of these, the fitting portion is fitted in the cylinder hole so as to be freely displaced in the axial direction, and the pressing portion is provided in a state of being farthest from the pressure receiving portion among the stationary disks. It is made to oppose the side surface on the opposite side to this pressure receiving part among the stationary side discs.
Then, each of the rotating side disk and each stationary side disk is pressed against the pressure receiving portion by the piston, and braking is performed by frictionally engaging the rotating side disk and the stationary side disk with each other.

The parking mechanism includes a driven lever, a pressure plate, and a cam mechanism.
Of these, the driven lever has a base end portion coupled and fixed to a base end portion projecting out of the brake cover, of the support shaft that is swingably displaced by the brake cover .
The pressure plate is provided in a portion of the brake cover that is opposed to the back surface of the pressing portion of the piston and is located on the outer side in the radial direction from the cylinder hole, and is concentric with the cylinder hole. In the annular recess, rotation and axial displacement are possible . Then, it rotates in a predetermined direction by swinging in a predetermined direction of the driven-side lever.
Further, the cam mechanism displaces the pressure plate to the pressure receiving portion side by rotation of the pressure plate in a predetermined direction .
Further, when the driven lever is swung in a predetermined direction , the pressure plate causes the rotary disk and the stationary disk to be connected to each other via the pressing part without using the fitting part of the piston. Press toward the pressure receiving part.
A return adjusting device is provided between the brake cover and the driven lever for adjusting the return position when the driven lever swings in the direction opposite to the predetermined direction as the return direction. ing.

  In the case of the wet disc brake with a parking mechanism of the present invention configured as described above, pressure oil is fed into a cylinder hole provided in the brake cover when braking from the running state. Then, by pushing out the piston fitted in the cylinder hole based on the feeding, the piston presses the stationary side disk and the rotating side disk toward the pressure receiving portion, and the stationary side disk and the rotating side disk are A braking force is generated by frictional engagement with each other.

In contrast, when the parking braking force is generated by the parking mechanism during parking, the driven lever is swung in a predetermined direction via the parking cable or the like by the swing of the driving lever on the driver's seat side. . Then, by this swinging, the pressure plate rotates in a predetermined direction with respect to the circumferential direction. With this rotation, the pressure plate is displaced in the axial direction by the cam mechanism, and the piston pressed by the pressure plate is displaced toward the pressure receiving portion. As a result, the piston presses the stationary side disk and the rotating side disk toward the pressure receiving portion, and the stationary side disk and the rotating side disk are frictionally engaged with each other, thereby generating a parking braking force.

For such the present invention, in a non-braking state, the pressure plate comes into contact with the pressing portion of the piston, since the piston return (displacement in the counter-pressure side) is restricted, the shaft for the piston Even when a directional force acts on the counter pressure receiving portion, the brake clearance can be easily maintained at a desired size. In addition, by appropriately adjusting the return adjusting device provided between the driven lever and the brake cover, the brake clearance can be kept constant regardless of wear of at least one of the stationary disk and the rotating disk. Easy to maintain. For this reason, the stroke of the brake pedal used for braking can be maintained stably and substantially constant. It is also easy to change this stroke to an arbitrary size.

Also, when the parking braking force is released (eliminated), the swing displacement in the direction opposite to the predetermined direction, which is the return direction of the driven lever, is regulated by the return adjustment device adjusted as described above. Therefore, the brake clearance when the parking braking force is released can be easily adjusted to a desired size regardless of the wear of at least one of the disks. Accordingly, the stroke (swinging margin) of the driving side lever on the driver's seat side can be maintained stably and substantially constant. It is also easy to change this stroke to an arbitrary size. Further, since only one return adjusting device that functions as a gap adjusting mechanism is provided, the adjustment work of the brake clearance can be easily performed.

  In addition, the parking cable of the parking mechanism incorporated in the dry drum brake that has been widely used in the past and the driving side lever on the driver's seat can be diverted, and the cost can be reduced by sharing parts. Further, the wet disc brake with a parking mechanism of the present invention can be assembled without significantly changing the design of the axle housing and the axle shaft into which the dry drum brake is assembled.

When carrying out the present invention, preferably, as described in claim 2, the return adjusting device is provided with an adjusting bolt coupled to the brake cover or the driven lever, and the driven lever is In the case of swinging in the direction opposite to the predetermined direction with respect to the circumferential direction that is the return direction, the adjustment bolt is not attached to the driven lever or the brake cover or the member fixed to the driven lever or the brake cover. Allows pressing.
According to this preferable configuration, the return adjusting device can be manufactured at a low cost with a simpler configuration. Further, the structure can be easily changed to a structure not provided with the return adjusting device, and the returning adjusting device can be easily added to the structure later.

More preferably, as described in claim 3, the cam mechanism is provided at a plurality of circumferential positions on the side surface of the brake cover, and the depth and the radial direction increase toward the predetermined direction with respect to the circumferential direction. a first recess cam width is reduced, provided at a position aligned with the respective first cam recess in the circumferential direction a plurality of locations of the side surface of the pressure plate, the more toward the predetermined direction with respect to the circumferential direction A second cam recess having a reduced depth and radial width; and a plurality of balls disposed between the first cam recess and the second cam recess facing each other. In the state where the first cam recesses and the second cam recesses are opposed to each other, the first cam recesses are deepened in the circumferential direction, and the second cam recesses are The direction in which the cam recess becomes deeper in the circumferential direction is opposite to each other. Those to which the (a first predetermined direction about the recess cam, a predetermined direction about the second recess cam and opposite to each other in the circumferential direction).
According to this more preferable configuration, it is possible to apply a large axial force in the axial direction toward the pressure receiving portion to the piston only by swinging the driven lever for a short stroke.

  1 to 27 show a wet disc brake 18 with a parking mechanism according to an embodiment of the present invention. The wet disc brake 18 with a parking mechanism is used by being incorporated in an industrial vehicle such as a forklift. As shown in FIGS. 1 to 5, the wet disc brake 18 is incorporated in a wet disc brake 19. Of these, the wet disc brake 19 includes a brake cover 21, a brake hub 22, a plurality of rotating discs 23, 23, a plurality of first stationary discs 24, 24, and a second stationary side. A disk 25 and a piston 26 are provided.

  Of these, the brake cover 21 is formed by connecting a cylinder member 27 and a shell member 28. As shown in detail in FIGS. 8 to 10, the cylinder member 27 has a substantially disk shape in which a protrusion 30 protruding in the radial direction is provided at the upper end portion, and a through hole 29 is provided in the center portion. In addition, the outside of the cylinder member 27 in the axial direction (“outside” with respect to the axial direction) means a side that is outside the width direction of the vehicle when assembled to the vehicle, and the back side of FIGS. 2, 4, 6, 9, 12, 22, 23, 25, 28, 29, front side of FIGS. 10, 13, bottom of FIGS. 7, 24 (B), 26 (B), 27 (B) The same applies hereinafter.) An annular cylinder hole 32 (FIGS. 9 and 10) for fitting the piston 26 is provided in the radial intermediate portion of the surface. Further, the inside of the cylinder member 27 in the axial direction (“inside” with respect to the axial direction means a side closer to the center in the width direction of the vehicle in the state assembled to the vehicle, and the front side in FIGS. 2, 4, 6, 9, 12, 22, 23, 25, 28, 29, the back side of FIGS. 10, 13, and the upper side of FIGS. 7, 24 (B), 26 (B), 27 (B). The same shall apply hereinafter.) One end of the supply / discharge port 33 is opened on the surface, and the other end is connected to the bottom of the cylinder hole 32. In addition, a plate-like protrusion 34 (FIGS. 8 and 9) protruding in the axial direction is provided on the inner peripheral surface of the cylinder member 27 in the vicinity of one end opening of the supply / discharge port 33. Pressure oil is supplied and discharged into the cylinder hole 32 through a brake hose (not shown) connected to the supply and discharge port 33.

Further, an annular recess 35 (FIGS. 9 and 10) concentric with the cylinder hole 32 is provided in a portion of the outer surface in the axial direction of the cylinder member 27 that is out of the cylinder hole 32 in the radial direction. And the 1st cam recessed parts 36 and 36 are provided in the circumferential direction equal intervals several places (6 places in the example of illustration) of the bottom face of this annular recessed part 35. As shown in FIG. Each of the first cam recesses 36, 36 has an arc shape when cut along a virtual plane including the central axis of the cylinder member 27, and is in a predetermined direction (counterclockwise in FIG. 10) with respect to the circumferential direction . The depth and the width in the radial direction become gradually smaller toward the head.

  A support hole 39 penetrating in the axial direction for inserting a support shaft 38 of a driven lever 37 to be described later is provided in a portion near the upper end of the cylinder member 27. A concave hole 40 (FIGS. 9 and 10) is provided in a portion of the support hole 39 facing the one end opening. The lower end of the concave hole 40 communicates with the upper end portion of the annular concave portion 35. Further, on the inner side surface in the axial direction of the cylinder member 27, a columnar protrusion 76 (FIGS. 8 and 9) having a cylindrical outer peripheral surface is provided around the open end of the support hole 39.

  On the other hand, as shown in detail in FIGS. 11 to 13, the shell member 28 has a cylindrical shape, and an inward flange-shaped pressure receiving portion 41 projecting in the radial direction is provided over the entire circumference on the inner circumferential surface in the axial direction. ing. Further, the outer peripheral surface of the upper end portion of the shell member 28 protrudes in the radial direction toward the inner end in the axial direction (the portion near the front end in FIG. 11, the portion near the right end in FIG. 12, and the portion near the rear end in FIG. 13). A protrusion 43 is provided, and a suspension ring 45 (FIGS. 1, 2, and 4) is coupled to a screw hole 44 formed in the upper end surface of the protrusion 43.

  In addition, a feed port 91 (FIG. 13) for feeding cooling lubricant oil to the axially intermediate portion of the upper end portion of the shell member 28 is also used to take out this lubricant oil to the axially intermediate portion of the lower end portion. A take-out port 92 (FIGS. 11 and 13) is provided. The radially inner ends of the inlet 91 and the outlet 92 communicate with the inner peripheral surface of the shell member 28. Further, a drain plug 96 (FIG. 2) can be freely connected to the lower end portion of the shell member 28.

  The first stationary side of the shell member 28 is provided at a plurality of circumferentially equidistantly spaced locations (four locations in the illustrated example) on the inner circumferential surface of the portion of the shell member 28 that is axially inward from the pressure receiving portion 41. First outer diameter side engaging recesses 47 and 47 (FIG. 11) having large axial dimensions are provided for engaging the outer peripheral surfaces of the disks 24 and 24. The axially inner ends of these first outer diameter side engaging recesses 47 are opened on the axially inner side surface of the shell member 28. Further, on the inner peripheral surface of the inner end portion in the axial direction of the shell member 28, a plurality of circumferentially equidistantly spaced locations (examples shown in the figure) whose phases in the circumferential direction are shifted from the respective first outer diameter side engaging recesses 47, 47 In this case, second outer-diameter-side engagement recesses 48, 48 having small axial dimensions are provided for engaging the outer peripheral surface of the second stationary disk 25 at six locations.

  The cylinder member 27 and the shell member 28 are overlapped with each other in a state in which the plurality of through holes 31 and 42 provided at the respective outer peripheral end portions thereof are aligned with each other, and bolts 49 inserted through the respective through holes 31 and 42. 49 and nuts 50 and 50 (FIGS. 1 and 3 to 5) are coupled and fixed to each other to form the brake cover 21 (FIGS. 1 to 5). 2, 4 and 5, the inner end side opening of the supply / exhaust port 33 is closed by a plug 90. In use, the plug 90 is removed and the end of the brake hose is connected. An axle housing 102 (see FIG. 30) is inserted into the inside of the brake cover 21 through the axially inner end portion of the brake hub 22 shown in FIGS. By providing a bearing 108 (see FIG. 30) between the outer peripheral surface of the brake hub 22 and the inner peripheral surface of the brake hub 22, the brake hub 22 is rotatably supported around the axle housing 102. An O-ring 94 (FIG. 2) is provided between the inner peripheral surface of the through hole 29 and the outer peripheral surface of the axle housing 102. The cylinder member 27 is fixed to the axle housing 102 directly or via another member. With this configuration, the brake hub 22 is rotatably supported with respect to the brake cover 21 in a state in which a portion near the inner end in the axial direction is disposed inside the brake cover 21. A seal device 95 is provided between the outer peripheral surface of the brake hub 22 and the inner peripheral surface of the brake cover 21. In addition, a wheel constituting the wheel can be coupled directly or via another member to a portion of the brake hub 22 near the outer end in the axial direction that protrudes from the inside of the brake cover 21 to the outside. Further, the outer end portion of the axle shaft 103 (see FIG. 30) inserted inside the axle housing 102 is coupled and fixed to the outer end surface of the brake hub 22.

  Between the inner peripheral surface of the brake cover 21 and the outer peripheral surface of the inner end portion of the brake hub 22, the plurality of rotating side disks 23, 23, the plurality of first stationary side disks 24, 24, and One second stationary disk 25 is provided. Of these, the rotation side disks 23 and 23 are engaged with the outer peripheral surface of the brake hub 22 inside the brake cover 21 so as not to rotate with respect to the brake hub 22. For this purpose, as shown in detail in FIGS. 14 to 15, each of the rotation side disks 23, 23 is formed in an annular shape with a metal such as iron, and a female spline portion 51 is provided on the inner peripheral surface. Further, friction materials 52 and 52 such as paper facing are attached to a plurality of circumferentially equidistant portions on both side surfaces of each of the rotating side disks 23 and 23. And the female spline part 51 of each said rotation side disks 23 and 23 is spline-engaged with the male spline part 53 (FIG. 2) provided in the inner peripheral part outer peripheral surface of the said brake hub 22. As shown in FIG. As a result, the plurality of rotation-side disks 23, 23 are engaged with the outer peripheral surface of the brake hub 22 so as not to rotate with respect to the brake hub 22.

  The first stationary disks 24, 24 are engaged with the first outer diameter engaging recesses 47, 47 provided on the inner peripheral surface of the shell member 28 constituting the brake cover 21 so as not to rotate. It is combined. For this purpose, each of the first stationary disks 24, 24 is first locked at a plurality of circumferentially equidistant positions (four in the illustrated example) on the outer peripheral surface, as shown in detail in FIG. Each of the first locking protrusions 54 and 54 is engaged with each of the first outer diameter side engaging recesses 47 and 47 of the shell member 28. As a result, the first stationary disks 24, 24 are engaged with the inner peripheral surface of the brake cover 21 so as not to rotate with respect to the brake cover 21. The rotating disks 23 and 23 and the first stationary disks 24 and 24 are alternately arranged in the axial direction.

On the other hand, the second stationary disk 25 is engaged with the inner peripheral surface of the inner end portion in the axial direction of the shell member 28 in a non-rotatable manner. For this purpose, the second stationary side disk 25 is annular, as shown in detail in FIG. 17, and the first locking projections 54, 54 of the first stationary side disks 24, 24 on the outer peripheral surface. Second locking projections 55, 55 are provided at a plurality of circumferentially equidistantly aligned locations (four locations in the illustrated example). Further, the outer peripheral surface of the second stationary disk 25 has a plurality of circumferentially equidistant locations (six locations in the illustrated example) that are out of phase with the second locking projections 55, 55. Three locking projections 56 are provided.

  Then, the second locking projections 55 of the second stationary side disk 25 are provided on the inner peripheral surface of the shell member 28 near the inner ends in the axial direction of the first outer diameter side engaging recesses 47, 47. , 55 are engaged with the respective second outer-diameter-side engaging recesses 48, 48 provided on the inner peripheral surface of the shell member 28. 56 is engaged. Thus, the second stationary disk 25 is engaged with the inner peripheral surface of the brake cover 21 so as not to rotate with respect to the brake cover 21. The second stationary side disk 25 is opposed to the counter pressure receiving part 41 side of the one rotating side disk 23 farthest from the pressure receiving part 41 among the rotating side disks 23, 23. In addition, concave holes 57, 57 are formed in the side surfaces of the shell member 28 facing inward in the axial direction of the respective second outer diameter side engaging concave portions 48, 48, and in the concave holes 57, 57, respectively. A piston return spring 58 (FIG. 6) is provided. Each of these piston return springs 58 opposes each of the third locking projections 56, 56 of the second stationary side disk 25, and each of these third locking projections 56, 56 is on the counter pressure receiving portion 41 side (see FIG. 6 right side).

  The tip surface of the piston 26 fitted in the cylinder hole 32 of the cylinder member 27 is opposed to the side surface of the second stationary side disk 25 on the side opposite to the pressure receiving portion 41. The piston 26 has a cylindrical fitting portion 59 and an annular pressing portion 60, and the fitting portion 59 is fitted in the cylinder hole 32 so as to be freely displaced in the axial direction. ing. Seal rings 93, 93 are provided between the inner and outer peripheral surfaces of the cylinder hole 32 and the inner and outer peripheral surfaces of the fitting portion 59, respectively. Further, the pressing portion 60 protruding from the cylinder hole 32 is opposed to the side surface of the second stationary disk 25 on the counter pressure receiving portion 41 side.

Such a wet disc brake 19 incorporates the parking mechanism 20. The parking mechanism 20 includes a driven lever 37 and a pressure plate 62 supported by the brake cover 21, and a cam mechanism 63. Of these, the pressure plate 62 is made of metal and has an annular shape having a predetermined thickness, as shown in detail in FIG. An outer diameter side locking groove 64 is provided in a part of the outer peripheral surface of the pressure plate 62 in the circumferential direction. In addition, the second cam recess 65, at a position aligned with the first cam recesses 36, 36 provided in the cylinder member 27 at a plurality of circumferentially equally spaced locations on one side of the pressure plate 62, 65 is provided. Each of the second cam recesses 65, 65 has an arc shape when the pressure plate 62 is cut along a virtual plane including the central axis, and is in a predetermined direction (counterclockwise in FIG. 18) with respect to the circumferential direction . The depth and the width in the radial direction become gradually smaller toward the head.

As shown in FIGS. 2 to 3, the pressure plate 62 is placed in the annular recess 35 provided in the cylinder member 27 inside the brake cover 21, and the back surface of the pressing portion 60 of the piston 26 (FIG. 2, 22, and 23) are arranged so as to be capable of axial displacement and rotation. In addition, in a state where the second cam recesses 65 and 65 and the first cam recesses 36 and 36 face each other, the first cam recesses 36 and 36 become deeper in the circumferential direction. The direction and the direction in which each of the second cam recesses 65, 65 becomes deeper in the circumferential direction are opposite to each other. One steel ball 66 is disposed between each of the first cam recesses 36 and 36 and each of the second cam recesses 65 and 65 facing each other. The cam recesses 36 and 65 and the balls 66 constitute the cam mechanism 63. In the cam mechanism 63, the pressure plate 62 faces the brake cover 21 so that the second cam recesses 65, 65 face the shallower side of the first cam recesses 36, 36 facing each other. When rotating in a predetermined direction with respect to the circumferential direction, the pressure plate 62 is displaced toward the pressure receiving portion 41 based on the engagement between the cam recesses 65 and 36 and the balls 66.

  A support shaft 38 of the driven lever 37 is supported on a part of the brake cover 21. The driven lever 37 is composed of a lever main body 67 as shown in detail in FIG. 19 and a support shaft 38 as shown in detail in FIGS. 20 to 21 by a nut 68 (FIGS. 1, 2, 5, etc.). It is fixed. Of these, the support shaft 38 has a cam 69 projecting greatly in the radial direction at a part in the circumferential direction at the tip (left end in FIG. 20). And the external thread part 70 is provided in the base end part (right end part of FIG. 20) of the support shaft 38, and the engagement shaft part 71 of rectangular cross section is provided in the intermediate part.

Then, as shown in FIG. 22, the shaft portion 72 near the tip of the support shaft 38 is inserted into the support hole 39 provided in the cylinder member 27 so as to be able to rotate in the support hole 39, and A cam 69 projecting from the inside of the support hole 39 to the outside of the cylinder member 27 is disposed in the recessed hole 40 and the annular recessed portion 35 of the cylinder member 27. The tip of the cam 69 is engaged with the outer diameter side locking groove 64 of the pressure plate 62 disposed in the annular recess 35. Then, the engaging shaft portion 71 that protrudes inward in the axial direction of the cylinder member 27 from the inside of the support hole 39 is formed at the base end portion of the lever main body 67 (the right end portion in FIG. 19 and the lower end portion in FIG. 22). The nut 68 is screwed into the male screw 70 and further tightened , while being inserted into the provided rectangular through-hole 73 while being impossible to engage with the rotation in the through-hole 73. In this state, the base end portion of the lever main body 67 is sandwiched between the stepped surface 74 between the shaft portion 72 and the engagement shaft portion 71 of the support shaft 38 and the nut 68. With this configuration, the driven lever 37 is supported by the brake cover 21 so as to be able to swing and move around the support shaft 38. During use, the lever body 67 is pushed into the locking hole 75 provided at the tip (the upper end in FIGS. 1 to 3 and the left end in FIG. 19) by the swing of the drive lever provided on the driver's seat side of the vehicle. Join the ends of the wire (not shown) of the parking cable that is pulled. The base end portion of the lever main body 67 and the support shaft 38 may be engaged with each other in a non-rotatable manner by a spline engaging portion including a male spline portion and a female spline portion.

A coil portion 78 of a lever return spring 77 is externally fitted to a columnar projection 76 provided on the inner peripheral surface of the cylinder member 27 in the periphery of the opening end of the support hole 39. A locking portion 79 provided at one end of the lever return spring 77 is locked to one side surface in the circumferential direction of the plate-like protrusion 34 provided on the cylinder member 27. The flange 80 provided at the end is engaged with one side surface of the driven lever 37 closer to the tip of the lever main body 67. A locking groove for locking the flange portion 80 can be provided on one side surface of the lever main body 67. By providing such a lever return spring 77, the driven lever 37 is in the direction opposite to the predetermined direction which is the return direction {FIGS. 1, 3, 5, 24 (A), 26 (A ), 27 (b) clockwise direction}.

In particular, in the case of the present embodiment, a return position is adjusted between the brake cover 21 and the driven lever 37 when the driven lever 37 swings in a direction opposite to the predetermined direction. A return adjusting device 81 is provided. The return adjusting device 81 includes a bracket 82 coupled and fixed to the cylinder member 27 constituting the brake cover 21, and an adjustment bolt 83 coupled and supported by the bracket 82. The bracket 82 is made by bending a metal plate into an L-shaped cross section, and includes a first plate portion 84 and a second plate portion 85. Of these, the first plate 84 is passed through one end in the length direction (the back side end of FIGS. 1, 3, 5, 24 (A), 26 (A) and 27 (A), the left end of FIG. 4). hole forms (not shown), further screwed into the screw hole of the male screw portion is formed on the upper end face of the projection 30 of the cylinder member 27 of the bolt 86 that is inserted through the through hole (not shown) Tightened . Thereby, the bracket 82 is coupled and fixed to the cylinder member 27.

Also, at the other end in the length direction of the second plate 85 (the front end of FIGS. 1, 3, 5, 24 (A), 26 (A), 27 (A), the right end of FIG. 4). A through hole (not shown) is formed, and the male screw portion of the adjusting bolt 83 is inserted into the through hole. Then, the second plate portion 85 is fastened from both sides by two nuts 87 and 87 screwed into the middle portion of the male screw portion. The amount of protrusion of the head of the adjustment bolt 83 from the side surface of the second plate portion 85 is adjusted by loosening and tightening these two nuts 87, 87 with respect to the male screw portion of the adjustment bolt 83. It is free. The head of the adjustment bolt 83 is opposed to the side surface of the lever main body 67 of the driven lever 37 opposite to the side on which the flange 80 is locked. As described above, the driven lever 37 is given elasticity by the lever return spring 77 so as to swing in the direction opposite to the predetermined direction. Elastically pressed. That is, it is possible to press the head of the adjusting bolt 83 against the side surface of the lever main body 67 when the driven lever 37 swings in the direction opposite to the predetermined direction which is the return direction. .

  When the wet disc brake with a parking mechanism of the present embodiment configured as described above is used, the axle bracket 88 (FIG. 3) is fixed to the inner side surface in the axial direction of the cylinder member 27 by a plurality of bolts (not shown). And it fixes to a part of vehicle body which is not shown in figure, or a part of suspension system with four bolts (not shown) inserted in the four through-holes 89 and 89 provided in this axle bracket 88. FIG. In this state, the brake cover 21 and the brake hub 22 are attached in a state of hanging from a part of the vehicle body or the suspension device. However, the axle bracket 88 can be omitted, and the brake cover 21 can be directly fixed to a part of the vehicle body or the suspension device. Further, the end of the brake hose is connected to the supply / discharge port 33 provided in the cylinder member 27.

In the case of the wet disc brake with a parking mechanism of the present embodiment configured as described above and used in the state of being attached to the vehicle as described above, when not braked, as shown in FIG. Since the piston 26 is pressed to the counter pressure receiving portion 41 side (the right side in FIG. 22) via the second stationary side disk 25 by (FIG. 6), this second stationary side disk 25 and one sheet opposed thereto A gap C _{1 in the} axial direction, which is a brake clearance, is generated between the rotating disk 23 and the rotating disk 23. When braking from the traveling state, the pressure oil is fed into the cylinder hole 32 through the supply / discharge port 33 provided in the cylinder member 27. Then, as shown in FIG. 23, the piston 26 having the fitting portion 59 fitted in the cylinder hole 32 is pushed out to the pressure receiving portion 41 side (left side in FIG. 22) as shown in FIG. The pressing part 60 presses the first and second stationary disks 24 and 25 and the rotating disks 23 and 23 toward the pressure receiving part 41 side. As a result, a braking force is generated by frictional engagement between the disks 24, 25, and 23. Further, in the non-braking state, the plurality of piston return springs 58 (FIG. 6) are connected to the piston 26 via the second stationary side disk 25 by discharging the pressure oil from the cylinder hole 32 through the supply / discharge port 33. Is pushed back until it hits the pressure plate 62 toward the counter pressure receiving portion 41 side to generate an axial gap C ₁ (FIG. 22) as a brake clearance.

In contrast, when the parking braking force is generated by the parking mechanism during parking, the lever main body 67 of the driven lever 37 is moved in a predetermined direction via the parking cable by the swing of the driving lever on the driver's seat side. Oscillating in the counterclockwise direction (direction indicated by arrow α) in FIG. Then, by this swinging, the pressure plate 62 rotates in the clockwise direction (the direction indicated by the arrow β) in FIG. 24A, which is a predetermined direction with respect to the circumferential direction . With this rotation, the pressure plate 62 is displaced in the axial direction by the cam mechanism 63. Specifically, as shown in FIG. 24B, the plurality of balls 66 constituting the cam mechanism 63 are provided for the first cam recesses 36 of the cylinder member 27 and the second cams of the pressure plate 62, respectively. The pressure plate 62 is displaced in the direction away from the cylinder member 27, that is, the pressure receiving portion 41 side {the direction indicated by the arrow γ in FIG. 24 (b)}. And as shown in FIG. 25, the said pressure plate 62 presses the press part 60 of the piston 26 to the pressure receiving part 41 side (left side of FIG. 23). As a result, the pressing portion 60 presses the rotation-side disks 23 and 23 and the first stationary-side disks 24 and 24 via the second stationary-side disk 25, and the discs 25, 23 and 24 are A parking braking force is generated by frictional engagement.

On the other hand, when the driving side lever on the driver's seat is swung to release (to eliminate) the parking braking force, as shown in FIG. 26 (a), the lever main body 67 of the driven side lever 37 and the lever return elastic force of the spring 77 is provided between the brake cover 21, swing the lever body 67 to the above predetermined direction is a reverse direction, in the clockwise direction in FIG. 26 (a) (the direction indicated by the arrow alpha) To do. When the lever main body 67 swings in the direction opposite to the predetermined direction as described above , the pressure plate 62 is opposite to the predetermined direction with respect to the circumferential direction. The pressure plate 62 is returned to the counter pressure receiving portion 41 side (right side in FIG. 22) together with the piston 26 (FIG. 22 and the like) by a plurality of piston return springs 58 (FIG. 6). Specifically, as shown in Fig. 26 (b), the plurality of balls 66 constituting the cam mechanism 63 are formed by the first cam recesses 36 of the cylinder member 27 and the second cams of the pressure plate 62, respectively. The pressure plate 62 is displaced toward the cylinder member 27, that is, the counter pressure receiving portion 41 side (the direction indicated by the arrow γ in FIG. 26 (b)). Then, when the side surface of the lever main body 67 comes into contact with the head of the adjusting bolt 83 constituting the return adjusting device 81, the swinging of the lever main body 67 is restricted. In this state, as shown in FIG. 22 described above, the second stationary side disk 25 pressed by the piston return spring 58 and the one rotational side disk 23 opposed to the second stationary side disk 25. In the meantime, an axial gap C ₁ is generated as a brake clearance. As a result, the parking braking force is lost and the wheels can be rotated.

In this embodiment, when the pressure plate 62 abuts against the pressing portion 60 of the piston 26 in the non-braking state, the return of the piston 26 (displacement toward the counter pressure receiving portion 41) is restricted. It is the reason, even if the pressure of the lubricating oil for cooling is applied to the counter-pressure receiving portion 41 side to the pressing portion 60 of the piston 26 can easily maintaining the brake clearance C ₁ to a desired size. On the other hand, unlike the case of the present invention, as shown in FIG. 28, in the case of a wet disc brake without a parking mechanism, the piston 26 is in a non-braking state as shown in FIG. 58 (refer to FIG. 6), the axial clearance C ₂ between the second stationary disk 25 and the rotating disk 23 facing the second stationary disk 25 is largely returned to the bottom of the cylinder hole 32 and is a brake clearance. Will become bigger. Even when the piston return spring 58 is not provided, since the cooling lubricating oil circulates in the space where the disks 23 to 25 exist, the piston 26 is brought to the bottom of the cylinder hole 32 by the pressure of the lubricating oil. It is pushed back to the end. In any case, when the brake clearance C ₂ becomes large, there arises a disadvantage that the stroke of the brake pedal becomes deep. On the other hand, according to the present embodiment, since the return of the piston 26 can be regulated by the pressure plate 62, such inconvenience can be eliminated.

In addition, in the case of the present embodiment, the frictional members 52, 52 of the rotary disks 23, 23 are appropriately adjusted by adjusting the return adjusting device 81 provided between the driven lever 37 and the brake cover 21. The brake clearance C ₁ can be easily maintained constant regardless of wear. For example, the friction materials 52 and 52 of each of the rotating disks 23 and 23 are worn (for example, each rotating disk 23 is worn by 0.3 mm at each of the friction materials 52 and 52 on both sides), and the brake clearance C _1. 27, as shown in FIG. 27, adjustment is made to increase the protruding amount of the head of the adjustment bolt 83 with respect to the side surface of the second plate portion 85 of the bracket 82. Then, as shown in FIG. 27 (b), the plurality of balls 66 constituting the cam mechanism 63 are placed at the intermediate depths of the first cam recesses 36 and the second cam recesses 65. In the displaced state, the side surface of the lever main body 67 is brought into contact with the head of the adjusting bolt 83. Thereby, the axial displacement of the pressure plate 62 and the piston 26 (FIG. 22 and the like) is restricted. In this state, the pressure plate 62 is moved to the pressure receiving portion 41 side {FIG. 27 (B) by the total amount L {FIG. 27 (B)} of the axial wear amount of the friction members 52, 52 on each side of each disk 23, 23. The lever main body 67 can be brought into contact with the head of the adjusting bolt 83 in a state of being positioned below}. As a result, the stroke of the brake pedal used for braking can be maintained stably and substantially constant regardless of the wear of the rotary disks 23, 23. It is also easy to change this stroke to an arbitrary size.

Also, when releasing the parking braking force, the drive lever 37 returns in the direction opposite to the predetermined direction {clockwise in FIG. The displacement is regulated by a return adjustment device 82 that adjusts the amount of protrusion of the head of the adjustment bolt 83 relative to the bracket 82. For this reason, the brake clearance C ₁ (FIG. 22) when the parking braking force is released can be easily adjusted to a desired size regardless of the wear of each of the rotation side disks 23, 23. Accordingly, the stroke (swinging margin) of the driving side lever on the driver's seat side can be maintained stably and substantially constant. It is also easy to change this stroke to an arbitrary size. Further, since only one return adjusting device 81 that functions as a gap adjusting mechanism is provided, the adjustment work of the brake clearance C ₁ can be easily performed.

  In addition, the parking cable of the parking mechanism incorporated in the dry drum brake that has been widely used in the past and the driving lever on the driver's seat side can be diverted, and the cost can be reduced by sharing parts. Further, the wet disc brake with a parking mechanism of the present invention can be assembled without significantly changing the design of the axle housing 102 and the axle shaft 103 (FIG. 30) into which the drum brake is assembled.

Further, the return adjusting device 81 is provided with an adjusting bolt 83 coupled to the brake cover 21, and the driven lever 37 swings in a direction opposite to the predetermined direction which is the return direction. The head of the adjusting bolt 83 can be pressed against the driven lever 37. Therefore, the return adjusting device 81 can be manufactured at a low cost with a simpler configuration.

Furthermore, the cam mechanism 63 is provided at a plurality of circumferential positions on the side surface of the brake cover 21, and the first cam recess having a smaller depth and a radial width toward the predetermined direction with respect to the circumferential direction. 36, 36 and a predetermined direction with respect to the circumferential direction (first cam recess) provided at positions aligned with the first cam recesses 36, 36 at a plurality of locations on the side surface of the pressure plate 62 in the circumferential direction. Second cam recesses 65 and 65 whose depth and radial width become smaller toward a direction opposite to a predetermined direction with respect to 36 and 36, and first cam recesses 36 and 36 facing each other, A plurality of balls 66, 66 disposed between the second cam recesses 65, 65 are provided. Further, in the state where the first cam recesses 36 and 36 and the second cam recesses 65 and 65 face each other, the first cam recesses 36 and 36 are deepened in the circumferential direction. The direction and the direction in which each of the second cam recesses 65 and 65 becomes deeper in the circumferential direction are opposite to each other. For this reason, a large axial force in the axial direction toward the pressure receiving portion 41 can be applied to the piston 26 only by swinging the driven lever 37 by a short stroke.

In the case of the present embodiment, only the brake hub 22 is removed from the state shown in FIG. 2 and a plurality of discs 23 to 25 are set inside the brake cover 21, and then transported to the vehicle assembly manufacturer. Delivery work can be done easily. That is, in this case, the driven lever 37 is swung in a predetermined direction (the clockwise direction in FIGS. 1, 3, and 5) that is the same direction as when the parking braking force is generated, and the piston 26, the pressure receiving portion 41, The driven lever 37 is fixed to the brake cover 21 by an appropriate means with the disks 23 to 25 being sandwiched therebetween. Further, in this state, the phases of the female spline portions 51 provided at the inner peripheral end portions of the respective rotation side disks 23 and 23 are made to coincide with each other. If transported to the assembly maker in such a state, the vehicle including the work of combining the brake hub 22 while the brake hub 22 is later spline-engaged with the female spline portion 51 of each of the rotating side disks 23, 23. The assembly work can be done easily.

  In the case of the present embodiment, the description has been given of the case where the parking cable is coupled to the driven lever 37. However, the rod connected to the driven lever 37 on the driver side is connected to the driven lever 37. By connecting the driven lever 37, the driven lever 37 can be swung by the driving lever.

The perspective view which shows the wet disk brake with a parking mechanism of the Example of this invention. AA sectional drawing of FIG. The perspective view which abbreviate | omitted one part and was seen from the side of FIG. The elements on larger scale seen from the upper part of FIG. The arrow B figure of FIG. The C section expanded cross-section equivalent view of FIG. 2 at the time of cut | disconnecting a brake cover in the part corresponding to a piston return spring regarding the circumferential direction. DD sectional drawing of FIG. The figure which took out only the cylinder member from FIG. 2, and looked to the left from the right side of the figure. EE sectional drawing of FIG. The figure seen from the left side of FIG. 9 to the right. The figure which took out only the shell member from FIG. 2 and looked to the left from the right side of the same figure. FF sectional drawing of FIG. The figure seen from the left side of FIG. 12 to the right. The figure which takes out and shows only the rotation side disk. The figure which expands and shows the GG cross section of FIG. The figure which takes out and shows only the 1st stationary side disk. The figure which takes out and shows only the 2nd stationary side disk. The figure which takes out and shows only a pressure plate. The figure which takes out and shows only the lever main body which comprises a to-be-driven side lever. The figure which takes out and shows only a support shaft similarly. The figure seen from the right side of FIG. 20 to the left. The partial expanded sectional view of FIG. 2 in the time of non-braking. The same figure as FIG. 22 at the time of braking. (A) is the elements on larger scale of FIG. 3, and (b) is HH sectional drawing of (a) in the state which generated the parking braking force. The same figure as FIG. 22 in the state which generated the parking braking force. FIG. 4B is a partially enlarged view of FIG. 3 and FIG. 4B is a cross-sectional view taken along the line II of FIG. 3A is a partially enlarged view of FIG. 3 and FIG. 3B is a cross-sectional view taken along line JJ of FIG. 3A in a state in which the parking braking force is released after adjusting the return adjusting device. The figure equivalent to FIG. 23 in the wet disc brake which does not provide a parking mechanism. FIG. 23 is also a view corresponding to FIG. 22. Sectional drawing which shows an example of the conventional structure of a dry-type drum brake. The fragmentary sectional view which shows an example of the conventional structure of a wet disk brake.

DESCRIPTION OF SYMBOLS 1 Wet disk brake 2 Housing 3 Shaft member 4 Sleeve 5 Brake cover 6 Brake hub 7 Pressure receiving part 8 Stationary side disk 9 Rotation side disk 10 Cylinder hole 11 Piston 12 Bolt 13a, 13b Recessed hole 14 Spring 15 Adjustment bolt 18 Wet with parking mechanism Disc brake 19 Wet disc brake 20 Parking mechanism 21 Brake cover 22 Brake hub 23 Rotating side disc 24 First stationary side disc 25 Second stationary side disc 26 Piston 27 Cylinder member 28 Shell member 29 Through hole 30 Projection 31 Through hole 32 Cylinder Hole 33 Supply / exhaust port 34 Plate-like protrusion 35 Toroidal recess 36 First cam recess 37 Driven lever 38 Support shaft 39 Support hole 40 Recessed hole 41 Pressure receiving part 42 Through hole 43 Projection 44 Screw hole 45 Hanging Ring 47 first outside Diameter side engaging recess 48 Second outer diameter side engaging recess 49 Bolt 50 Nut 51 Female spline portion 52 Friction material 53 Male spline portion 54 First locking projection 55 Second locking projection 56 Third locking projection 57 concave hole 58 piston return spring 59 fitting portion 60 pressing portion 62 pressure plate 63 cam mechanism 64 outer diameter side locking groove 65 second cam concave portion 66 ball 67 lever body 68 nut 69 cam 70 male thread portion 71 engagement shaft Part 72 Shaft part 73 Through-hole 74 Step surface 75 Locking hole 76 Columnar protrusion 77 Lever return spring 78 Coil part 79 Locking part 80 Eighth part 81 Return adjustment device 82 Bracket 83 Adjustment bolt 84 First plate part 85 Second Plate part 86 Bolt 87 Nut 88 Axle bracket 89 Through-hole 90 Plug 91 Inlet 92 Outlet 93 Seal ring 94 O-ring 95 Seal device 9 Drain plug 101 dry drum brake 102 axle housing 103 Axle shaft 104 frame support 105 backplate 106 brake drum 107 hub 108 bearing 109 volts 110 brake shoe

Claims (3)

A brake cover provided with a pressure receiving portion projecting radially inward on an inner peripheral surface on one end side in the axial direction ;
A part of the brake cover is placed inside the brake cover so that the brake cover can be rotatably supported, and the wheel can be fixedly coupled to the part protruding from the inside of the brake cover directly or via another member. A brake hub,
A plurality of rotation-side disks engaged with the outer peripheral surface of the brake hub inside the brake cover so as not to rotate with respect to the brake hub;
A plurality of stationary-side disks engaged with the brake cover in a non-rotatable manner in an alternating arrangement with the plurality of rotating-side disks on the inner peripheral surface of the brake cover;
To the brake cover inner surface axial end portion close to the annular cylinder hole provided in the axial direction of a piston which is fitted to allow axial displacement,
A parking mechanism is incorporated in a wet disk brake that applies braking by pressing each rotating disk and each stationary disk against the pressure receiving portion with the piston and frictionally engaging the rotating disk and the stationary disk with each other. A wet disc brake with a parking mechanism comprising:
The piston has a cylindrical fitting portion, and an outwardly flanged and annular pressing portion provided in a state of projecting radially outward from the axial tip portion of the fitting portion. The fitting part is fitted in the cylinder hole so as to be freely displaced in the axial direction, and the pressing part is provided in a stationary state in the stationary side disk farthest from the pressure receiving part. It is made to face the side of the side disk opposite to the pressure receiving part,
The parking mechanism
Of the support shafts supported by the brake cover so as to be swingable and displaceable, a driven lever whose base end is coupled and fixed to a base end protruding outside the brake cover ;
In the brake cover, in the annular concavity concentric with the cylinder hole, provided in the part of the piston facing the back surface of the pressing part and outside the cylinder hole in the radial direction. It is able to arrange the axial displacement, and the pressure plate to rotate in a predetermined direction by swinging in a predetermined direction of the driven-side lever,
A cam mechanism for displacing the pressure plate toward the pressure receiving portion by rotation of the pressure plate in a predetermined direction ;
When the driven lever swings in a predetermined direction , the pressure plate receives the pressure on the rotary disk and the stationary disk via the pressing part without the fitting part of the piston. It presses to the part side,
A return adjustment device is provided between the brake cover and the driven lever for adjusting the return position when the driven lever swings in the direction opposite to the predetermined direction as the return direction. Wet disc brake with parking mechanism. The return adjusting device includes an adjusting bolt coupled to the brake cover or the driven lever, and the driven lever swings in a direction opposite to the predetermined direction with respect to a circumferential direction as a return direction. The wet disc brake with a parking mechanism according to claim 1, wherein the adjustment bolt can be pressed against the driven lever or brake cover or a member fixed to the driven lever or brake cover when moved. . The cam mechanism is provided at a plurality of circumferential positions on the side surface of the brake cover, the first cam recess having a smaller depth and a radial width toward the predetermined direction with respect to the circumferential direction, and the pressure. A second cam having a depth and a radial width that become smaller toward the predetermined direction with respect to the circumferential direction, provided at positions aligned with the first cam recesses at a plurality of circumferential positions on the side surface of the plate. And a plurality of balls disposed between the first cam recess and the second cam recess facing each other, the first cam recess and the second cam. The direction in which each first cam recess is deeper in the circumferential direction and the direction in which each second cam recess is deeper in the circumferential direction are opposite to each other with the recesses facing each other. The parkin according to claim 1 or 2, wherein Wet disc brakes with mechanism.

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