JP3685015B2 - Brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake device capable of ensuring durability of a wedge cylinder coupled to a wheel cylinder. SOLUTION: The brake device comprises a wheel cylinder 13 to effect brake operation of a pair of brake shoes 14 through operation to move forward and backward a wedge 16 between a pair of pistons p1 and p2 inserted in a fit-in state in a cylindrical body 131 supported at a brake support frame 9 extending from a rear axle 1; a gear housing 4 integrally coupled to the rear axle 1; a wedge cylinder 31 on which a wedge piston 32 to transmit a press force from a spring chamber 27 supported at the gear housing 4 to the wedge 16 is mounted in a fitted-in state; and an elastic cylinder member 33 in which the wedge 16 is loosely fitted and which has one end coupled to the wedge cylinder 31 and the other end coupled to the cylindrical body 131.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brake device including a wheel cylinder that brakes a pair of brake shoes, and in particular, a pair of brakes that are interlocked with a piston by advancing and retracting a wedge-shaped wedge between a pair of pistons housed in the wheel cylinder. The present invention relates to a brake device that brakes a shoe.
[0002]
[Prior art]
The vehicle is equipped with a braking device for applying braking force to the wheels. For example, a drum-type braking device that easily strengthens the braking force is used as a service brake on a truck or bus that has a relatively large body weight. In many cases, a wedge-type parking brake using an actuator-driven wedge that has a large braking force and is easy to ensure safety is used.
[0003]
In this wedge type parking brake, a wheel cylinder is attached to an end portion of an axle housing of a vehicle via an end base frame such as a back plate, and this is also used as a service brake. A wheel cylinder has a pair of pistons inserted into its cylindrical body, and a pair of pistons are pressed against a brake drum in the diameter-expanding direction in conjunction with the contact and separation of the pistons to generate a braking force during service braking. . Moreover, a wedge-shaped wedge is moved forward and backward in a direction intersecting the longitudinal direction of the cylindrical body between the pair of pistons in the cylindrical body, thereby braking the brake shoe interlocked with the pair of pistons to control the parking. Power is generated. Here, the wedge of the parking brake system is connected to an actuator serving as a drive source via a piston in the wedge cylinder and a link mechanism.
[0004]
For example, in the brake device disclosed in Japanese Utility Model Publication No. 7-19939, a structure in which a wedge cylinder is integrally coupled to a cylindrical body of a wheel cylinder supported by a back plate, and a drive link mechanism and a spring chamber are coupled thereto. Is disclosed. The push rod of the drive link mechanism is connected to the piston in the wedge cylinder so as to be relatively displaceable, whereby the drive link mechanism supported on the axle housing side and the wheel cylinder and wedge cylinder sides supported on the back plate It is possible to transmit the pressing force while allowing the relative displacement with respect to.
[0005]
By the way, in recent years, many buses have been designed to lower the floor. The axle of such a route bus is formed so that the ground height of the central axle body is lower than the end axle extending from the left and right ends in order to facilitate lowering the floor. Are often equipped with gearboxes with built-in reducers.
[0006]
When a wedge-type parking brake is attached to such a rear axle, when the wheel cylinder and the wedge cylinder are integrally attached to the back plate supported by the end axle, the drive link mechanism connected to the wedge cylinder is a gear box. A layout is adopted in which the actuator is connected to an actuator supported on the axle side. In this case, in order to reduce the relative displacement between the push rod of the drive link mechanism and the gear box, the inner end of the wedge cylinder is coupled to the gear box, and the push rod is coupled to the piston for driving the wedge inside the gear box. It will be.
[0007]
[Problems to be solved by the invention]
However, in the case of adopting a configuration in which one end of the wedge cylinder is integrally coupled to the back plate and the other end is integrally coupled to the gear box in this way, the wheel cylinder supported on the back plate side during braking operation of the wheel cylinder and the integral with this The wedge cylinder tends to elastically rotate and displace around the axle center line upon receiving braking torque from the wheel side. In this case, since the wedge cylinder is coupled to the back plate and the gear box, a stress concentration portion may be generated due to a torsional force around the axle center line due to relative displacement.
An object of the present invention is to provide a brake device that can improve the durability of a wedge cylinder coupled to a wheel cylinder based on the above-described problems.
[0008]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the invention according to claim 1 is a pair in which the cylindrical main body is supported by the end base frame extending in the diameter-expanding direction from the end of the axle housing, and is fitted into the cylindrical main body. A wheel cylinder that brakes a pair of brake shoes via the pair of pistons by advancing and retracting a wedge-shaped wedge from a direction intersecting the longitudinal direction of the cylindrical body between the pistons, and the end base frame An opposing wall member that is located on the inner side of the vehicle body and is integrally coupled to the axle housing; and a wedge cylinder that is supported by the opposing wall member and fitted with a piston that slides to transmit the pressing force from the actuator to the wedge; An elastic cylinder member having elasticity, wherein the wedge is loosely fitted, and one end is connected to the wedge cylinder and the other end is connected to the cylindrical main body.
[0009]
At the time of braking operation, a wedge disposed between a piston in a wedge cylinder supported by the opposing wall member and a wheel cylinder supported by the end base frame brakes a pair of pistons in the wheel cylinder. The wheel cylinder that receives the braking force is elastically rotated and displaced about the center line of the axle housing, and is relatively displaced with the wedge cylinder supported by the opposing wall member, but the elastic cylinder member that couples the wheel cylinder and the wedge cylinder is provided. Elastic deformation can be performed according to the displacement.
In this way, the elastic cylinder member that joins the wheel cylinder and the wedge cylinder can be elastically deformed, so that even if the wheel cylinder receiving the braking force is elastically displaced around the center line of the axle housing together with the end base frame, the displacement is absorbed. Thus, the durability of the same part can be improved.
[0010]
Preferably, the piston may be formed with an input side recess for connecting the shaft end of the push rod extending from the actuator side at one end and an output side recess for connecting the shaft end of the wedge at the other end. . In this case, in particular, even if the axial direction of the push rod on the actuator side connected with the piston sliding inside the wedge cylinder is relatively large and the axial direction of the wedge are relatively large, the displacement in the pressing direction is allowed. The wedge can be reliably braked by the pressing force from the actuator side, and the degree of freedom in layout of the device is increased.
Further, one end of the piston may be integrally coupled to a push rod extending from the actuator side, and an output side recess for connecting the shaft end of the wedge may be formed at the other end. In this case, in particular, the piston and the push rod are integrally coupled, and the other end of the long piston is connected to the actuator side after passing through the opposing wall member, so that the assembly workability is improved.
[0011]
According to a second aspect of the present invention, in the brake device according to the first aspect, the opposed wall member is a housing of a speed reducer that decelerates the input rotation of the axle shaft and outputs it to the wheel side.
Even if the wedge cylinder is integrally supported by the axle housing of the reducer on the axle side, when the reducer side and the end base frame side supporting the wheel cylinder are relatively displaced around the center line of the axle housing Even if the elastic cylinder member is elastically displaced, generation of concentrated stress can be prevented and durability can be improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a parking brake 11 to which a brake device according to an embodiment of the present invention is applied. The parking brake 11 is mounted on a rear axle 1 of a low floor bus. The rear axle 1 is long in the vehicle width direction Y, and is connected to the vehicle body side via an air suspension (not shown). Opposing central part is deployed at a relatively low position.
The axle housing of the rear axle 1 includes a gear box 4 that is an opposing wall member that houses an axle main body 2 that forms a central portion, and a speed reducer 3 (see FIG. 3) at the left and right ends (right end omitted), And an end axle 5 projecting outward from the upper portion in the vehicle width direction Y. In the axle housing, a differential (not shown) that forms a rotation transmission system, left and right axle shafts 52 (only the left side is shown), and left and right speed reducers 3 that transmit the rotation of the axle shaft 52 to the end drive shaft 6 while decelerating the transmission. Only the left side is shown).
[0013]
The gear box 4 projects a cylindrical end axle 5 from the side wall to the outside of the vehicle, and an end drive shaft (only one shown in FIG. 1) 6 is fitted into the gear box 4. An annular flange portion 501 protrudes from the outer periphery of the end axle 5 closer to the inside of the vehicle, and a brake support frame 9 serving as an end portion base frame is fastened and fixed concentrically thereon. A dust cover 8 is concentrically stacked on the annular end of the brake support frame 9 and is bolted. A wheel hub 601 and a brake drum 7, which are integrally coupled to the left end drive shaft 6, are pivotally attached to the outer periphery of the end axle 5.
In addition, the part shown with a broken line in the brake drum 7 on the left side in FIG. 1 was shown especially as a schematic end surface in the AA line direction shown by the arrow in FIG.
[0014]
As shown in FIGS. 1 and 3, the brake support frame 9 includes a central base portion 903 that overlaps the flange portion 501 and upper and lower bent ends that extend in the direction of a line L1 that is inclined by a predetermined amount of an inclination angle α with respect to the vertical line L2. Portions 901 and 902 are formed. The upper bent end portion 901 of the oblique upper portion is formed in a bracket shape that can be pin-coupled to the end portion of the brake shoe 14 as shown by a broken line in FIG. As shown by a broken line in FIG. 1, the lower bent end portion 902 of the oblique lower portion is formed to be bent outward in the vehicle width direction Y by a predetermined angle with respect to the center base portion 903, and the wheel cylinder 13 is attached thereto. The other ends of the pair of brake shoes 14 are attracted and urged to each other by a tension spring 49, and are pressed against the wheel cylinder 13 so as to sandwich it. In addition, since the lower bent end 902 protrudes to the lower side and the wheel cylinder 13 is provided there, the region a (see FIG. 3) where the meshing positions of the upper and lower gears 301 and 302 of the speed reducer 3 can be avoided. A parking brake link mechanism R, which will be described later, can be provided.
[0015]
As shown in FIG. 2, the wheel cylinder 13 receives the braking hydraulic pressure from the service brake 12 side to the pressure chamber r in the cylindrical main body 131, so that the pair of pistons p <b> 1 and p <b> 2 in the cylindrical main body 131 are brought into contact with and separated from each other. The brake shoe 14 interlocked with this is displaced in the diameter increasing direction and is brought into sliding contact with the brake drum 7 to obtain a braking force, and is attached in a direction orthogonal to the longitudinal direction (vertical direction in FIG. 2) of the cylindrical main body 131. When the wedge 16 received receives a braking operation force F from the parking brake link mechanism R side, the brake shoe 14 interlocked with the pair of pistons p1 and p2 is brought into sliding contact with the brake drum 7 to obtain a braking force. Is provided.
[0016]
As shown in FIG. 1, the service brake 12 is an air over hydraulic brake that receives high pressure air from an air tank 21 from a high pressure air pipe 22 and sends out the pressure adjusted according to the depression amount of the brake pedal 17. A hydraulic pressure booster (hydraulic air servo) 23 that receives the pressure adjusted by the valve 18 and the brake valve 18 through the pressure-regulating air pipe 19 and outputs a boosted hydraulic pressure corresponding to the air pressure, and a hydraulic booster And a hydraulic pipe system 24 that transmits the output hydraulic pressure to the wheel cylinders 13 on the front and rear wheels.
[0017]
The parking brake 11 includes a parking switch 26 that forms a parking brake operation system, a spring chamber 27 that is an actuator on the driving side, an air tank 21 that supplies high-pressure air to the spring chamber 27 via an air pipe 28, and an air pipe 28. A switching valve 29 that is provided in the middle and supplies high-pressure air to the spring chamber 27 when the parking switch 26 is turned off and releases the high-pressure air in the spring chamber to the atmosphere when the parking switch 26 is turned on, a wheel cylinder 13 that also serves as the service brake 12, A wedge 16 that displaces the pair of brake shoes 14 in the diameter-enlarging direction via a pair of pistons p1 and p2 (see FIGS. 2 and 3) in the cylindrical main body 131, and a braking operation force from the spring chamber 27 to the wedge 16 Parking brake phosphorus transmitting F And a mechanism R.
[0018]
As shown in FIG. 2, the wheel cylinder 13 has its cylindrical main body 131 fastened to a bent end 902 with a bolt (not shown), and an annular connecting portion 132 is extended from the side wall of the cylindrical main body 131 to support the brake. It protrudes from a through hole b formed in the frame 9. The leading end of the wedge 16 is loosely fitted into the opening formed by the annular coupling portion 132, and the leading end is fitted into the gap e between the pair of pistons p1 and p2 in the cylindrical main body 131. An annular groove is formed in the inner peripheral wall of the annular connecting portion 132, and the spring receiver 35 is fitted to the same portion with a stop pin 40 without deviation. The spring receiver 35 has a central hole for loosely fitting the wedge 16 and is formed so as to lock one end of a return spring 36 described later. The wedge 16 is a shaft member having a wedge-shaped tip, and is disposed between the wheel cylinder 13 and the wedge cylinder 31 as shown in FIG.
[0019]
The wedge cylinder 31 is fitted to the mounting boss 401 on the vertical wall of the gear box 4. The mounting boss 401 is formed with a small-diameter hole h1, a stepped portion h2, and a large-diameter hole h3 successively in this order from the center of the vehicle body (right side in FIG. 2), and the cylinder body 311 of the wedge cylinder 31 is provided in the small-diameter hole h1. The flange 312 is closely engaged with and integrated with the portion h2. The opening of the large-diameter hole h3 is opposed to the back plate 8 and the brake support frame 9, and the shaft end of the wedge 16 on the center side of the vehicle body projects there, and the coaxial end is fitted into the outer recess 321 of the wedge piston 32. ing.
The wedge piston 32 constituting a part of the parking brake link mechanism R is formed with an inner recess 322 on the vehicle body center side (right side in FIG. 2), and a push rod 37 described later is fitted in the same portion. Further, a return spring 36 disposed so as to be compressed and displaceable is in contact with the wedge piston 32 between the spring receiver 35 and the return spring 36 is directed toward the wedge 16 and the wedge piston 32 in the direction of the braking operation force F. A pressing force is applied in the reverse return direction, thereby facilitating the forward / backward movement s1 of the wedge 16.
[0020]
The elastic cylinder member 33 is entirely formed of rubber, and covers the wedge 16 from the outside while maintaining airtightness. One end of the elastic cylinder member 33 is fitted on the annular coupling portion 132 on the wheel cylinder 13 side, and is coupled without displacement by the tightening ring 34. The outer peripheral surface on the other end side of the elastic cylindrical member 33 is in contact with the inner peripheral wall of the large-diameter hole h3 formed relatively deep, and the engaging portion 133 that bulges from the end is the deepest portion of the large-diameter hole h3. It is formed so as to be closely fitted in the annular inner circumferential groove h4. Thereby, even if the elastic cylinder member 33 receives a slight tensile force in the longitudinal direction, the elastic cylinder member 33 can be prevented from being detached from the large-diameter hole h3 due to expansion and contraction.
[0021]
As shown in FIG. 1, the main body 38 of the spring chamber 27 is attached to the rearward wall fb of the axle main body 2 via a bracket 39. The main body 38 has a compression spring compressed therein via a piston that is pressed and urged by compressed air (not shown), and includes a piston rod 41 that extends outward from the piston and a pressure chamber (not shown). The main body 38 is connected to an air pipe 28 on the parking brake 11 side at a position facing a pressure chamber (not shown). In the parked state, the spring chamber 27 does not receive high-pressure air from the air pipe 28 side. At this time, the piston and the piston rod 41 protrude with the spring force of a compression spring (not shown), and the braking brake force R is applied to the parking brake link mechanism R. Add During traveling, the spring chamber 27 receives high-pressure air from the air pipe 28 side, retreats the piston rod 41 side with air pressure against the spring force of a compression spring (not shown), and performs a braking operation of the parking brake link mechanism R. Force F can be eliminated.
[0022]
A movement direction conversion crank portion 50 that forms a part of the parking brake link mechanism R includes a bracket 42 that has a base portion fixed to the rearward wall fb of the axle body and formed in a vertical direction on the bearing portion, and a substantially bell crank that is pivotally attached to the bearing portion. The rotation member 43 is provided. The rotating member 43 has a lower lever member 431 that is bent and extends from the lower end of the main shaft (not shown) and an upper lever member 432 that is bent and extended from the upper end. The rotating end of the lower lever member 431 is connected to the tip of the piston rod 41 via the ball joint B, and the rotating end of the upper lever member 432 is connected to one end of the push rod 44 via the ball joint B. The movement direction converting crank portion 50 allows a deviation between a driving side pressing direction which is a substantially horizontal direction of the piston rod 41 and a driven side pressing direction which is an inclination direction of the push rod 44, and the spring chamber 27. The braking operation force F can be transmitted to the push rod 44. Reference numeral 45 denotes a bellows-like boot attached to the gear box 4, thereby closing a gap between a through-hole (not shown) formed in the gear box 4 and a push rod 44 fitted therein.
[0023]
The push rod 44 that forms a part of the parking brake link mechanism R penetrates through the gear box 4 and can avoid the meshing position of the upper and lower reduction gears 301 and 302 of the reduction gear 3 therein (see FIG. 3). And the other end is connected to the wedge piston 32. The wedge piston 32 receives the braking operation force F from the spring chamber 27 from the push rod 44 and transmits it to the wedge 16 at the other end. The right spring chamber (not shown) may have the same configuration as that on the left side, and the above-described parking brake link mechanism R is eliminated, and a wheel cylinder is provided at a relatively upper portion, and the wedge is opposed to the wheel cylinder. Can be configured to be driven directly by a spring chamber.
When the brake pedal 17 of the service brake 12 in FIG. 1 is operated, the air regulated by the brake valve 18 is sent to the hydraulic booster 23 according to the depression amount, and the hydraulic pressure boosted by the air pressure is increased. It is supplied to each wheel cylinder 13 via the hydraulic pipe system 24, and each wheel cylinder 13 brakes the brake shoe 14 of each wheel and applies a braking force to each wheel.
[0024]
On the other hand, when the parking switch 26 is turned on during parking, the air pipe 28 is cut off, the spring chamber 27 is opened to the atmosphere, and a braking operation force F of a compression spring (not shown) is transmitted to the wedge 16 via the parking brake link mechanism R. The wedge 16 is inserted into a gap e between the pair of pistons p1 and p2 in the cylindrical main body 131 and operates to displace the pair of brake shoes 14 in the diameter increasing direction via these pistons. Apply braking force when parking.
When the parking switch 26 is turned off so as to enter the running state from the parking state, high pressure air is supplied from the air tank 21 to the spring chamber 27, and when the piston rod 42 side moves backward against the elastic force of a compression spring (not shown), In conjunction with the parking brake link mechanism R, the wedge 16 is moved backward, the pair of pistons p1 and p2 in the cylindrical body 131 are moved closer to each other, the pair of brake shoes 14 are released from the brake, and the parking brake is operated. Release the braking force.
[0025]
When the service brake 12 and the parking brake 11 in FIG. 1 are braked, the braking force from the wheel is applied to the brake support frame 9 via the brake shoe 14 and the wheel cylinder 13 each time. The brake support frame 9 is supported on the end axle 5 side, elastically pivoted and displaced T (see FIG. 2) around the center line L of the end axle 5, and relatively to the inoperative gear box 4. Displace. At this time, since the both ends of the wedge 16 are in the fitted and connected state, the wedge 16 can be easily displaced according to the relative displacement, and at the same time, the return spring 36 can be easily displaced. On the other hand, the elastic cylindrical member 33 has one end coupled to the annular connecting portion 132 by the tightening ring 34, and the engaging portion 133 at the other end is closely fitted in the annular inner circumferential groove h4, so that a tensile force is generated in the longitudinal direction. Is elastically extended and deformed, and when the brake is released, it is elastically reduced to return to the steady state (the state shown in FIG. 2).
[0026]
Since the elastic cylinder member 33 can be elastically deformed in this way, even if the brake shoe 14 and the wheel cylinder 13 that have received the braking force are elastically displaced around the center line L0 of the axle housing together with the brake support frame 9, the elastic cylinder member 33 is elastically associated with the displacement. The cylindrical member 33 extends and deforms, and stress concentration does not occur as in the case of a metal member, and durability can be improved. Furthermore, it is possible to reliably prevent foreign matter from entering the sliding surfaces of the wedge 16 and the wedge piston 32 between the pair of pistons p1 and p2 in the wheel cylinder 13 and the forward and backward movement s1 thereof, and premature wear of the same. .
As described above, the wedge piston 32, which forms part of the parking brake link mechanism R, has the push rod 37 inserted into the input side recess 322 and the wedge 16 inserted into the output side recess 321 to thereby fit the spring chamber 27. Even if the inclination direction of the push rod 37 on the side and the inclination direction of the wedge 16 are deviated, the deviation 16 is allowed and the wedge 16 can be reliably operated in the braking direction by the braking operation force F from the spring chamber 27 side. The degree of freedom in layout could be secured. However, in some cases, a parking brake link mechanism R ′ as shown in FIG. 4 may be used.
[0027]
The parking brake link mechanism R ′ shown in FIG. 4 is used in the same manner as the parking brake link mechanism R shown in FIG. 1, and only the configuration of the wedge cylinder 31a and the wedge piston 32a fitted therein is different. Is abbreviated.
The wedge cylinder 31 a used in the parking brake link mechanism R ′ of FIG. 4 is fitted to the mounting boss 401 a on the vertical wall of the gear box 4. The mounting boss portion 401a is formed with a small diameter hole h1a and a stepped portion h2a in this order from the vehicle body center side (right side in FIG. 4) in this order. Are closely engaged and integrated. The cylinder body 311a protrudes from the opposite end to the back plate 8, which is the outer end of the vehicle body, and forms a relatively large-diameter annular mounting portion 313.
[0028]
The wedge piston 32a inserted into the wedge cylinder 31a is formed as a relatively long shaft member in which the push rod 44 and the wedge piston 32 extending from the movement direction changing crank portion 50 are integrated. An output side recess 321a for connecting the wedge 16a is formed at the output side end portion, and the input side end portion is connected to the upper lever member 432 of the movement direction converting crank portion 50 through the universal joint 51 and the ball joint B. Is done.
One end of a rubber elastic cylindrical member 33 a is fitted on the annular mounting portion 313 and is fastened and coupled by a fastening ring 46 so as not to be detached. The other end of the elastic cylinder member 33a is tightened and coupled to the annular coupling part 132 on the wheel cylinder 13 side by a tightening ring 34 without deviation. The wedge 16a is connected in the same manner as the wedge 16 of FIG. 1, and in particular, a wedge-side spring receiver 48 is fitted on the middle portion of the wedge 16 in the longitudinal direction. The wedge-side spring receiver 48 is engaged with a stop pin 47 penetrating the wedge 16 without deviation, and a return spring 36 is attached by being compressed and urged between this and the spring receiver 35 of the annular connecting portion 132.
[0029]
In this case, the same effect as described with reference to FIG. 1 is obtained. In particular, a relatively long wedge piston 32a is used, and this is moved from the wedge piston 32 side through the gear box 4 to the motion direction converting crank portion 50 side. It can be inserted as much as possible to improve workability during assembly.
In the above description, the opposing wall member integrally coupled to the axle housing has been described as a speed reducer housing, but is not limited thereto, and may be various brackets on the suspension side integrally coupled to the axle housing, A configuration in which the push rod 44 is disposed so as to penetrate these may be employed, and in the case of these opposing wall members, the same operational effects as described in FIG. 1 can be obtained, and the present invention can be effectively used.
[0030]
【The invention's effect】
As described above, according to the first aspect of the present invention, the elastic cylinder member that couples the wheel cylinder and the wedge cylinder can be elastically deformed, so that the wheel cylinder that receives the braking force moves around the center line L0 of the axle housing together with the end base frame. Even if it is elastically displaced, the displacement is absorbed, and it is possible to reliably prevent foreign matter from entering the sliding surface of the wedge that moves forward and backward between the pair of pistons in the wheel cylinder, and the same part can be prevented from being prematurely worn.
[0031]
According to the invention of claim 2, the facing wall member is a housing of a reduction gear. Thus, even when the wedge cylinder is integrally supported by the housing of the reducer on the axle side, the reducer side and the end base frame side supporting the wheel cylinder are relatively positioned around the center line of the axle housing. Even if the cylindrical member is elastically displaced when displaced, it is possible to reliably prevent foreign matter from entering the wedge side inside the elastic cylindrical member and premature wear of the same, thereby effectively utilizing the present invention.
[Brief description of the drawings]
FIG. 1 is a schematic rear view of a main part of a rear axle portion of a low floor bus to which a parking brake to which a brake device according to an embodiment of the present invention is applied is attached.
2 is a partially enlarged cross-sectional view of a wheel cylinder and a wedge cylinder used in the parking brake of FIG. 1. FIG.
FIG. 3 is a schematic side view of a back plate portion of the parking brake of FIG. 1;
4 is a partial enlarged cross-sectional view of a wedge cylinder portion employed in a modified example of the parking brake of FIG. 1. FIG.
[Explanation of symbols]
1 Rear axle 2 Axle body 4 Gear housing (opposite wall member)
9 Brake support frame (end base frame)
13 Wheel cylinder 131 Tubular body 14 Brake shoe 16 Wedge 27 Spring chamber (actuator)
31 Wedge cylinder 32 Pistons 33, 33a Elastic cylinder members p1, p2 A pair of pistons s1 Advancing and retracting

Claims (2)

From the direction intersecting the longitudinal direction of the cylindrical body between a pair of pistons that are supported by an end base frame that extends in the diameter-expanding direction from the end of the axle housing and is fitted into the cylindrical body. A wheel cylinder that brakes a pair of brake shoes via the pair of pistons by advancing and retracting a wedge-shaped wedge, and an opposing wall that is located on the inner side of the vehicle body from the end base frame and is integrally coupled to the axle housing A wedge cylinder fitted with a member and a piston which is supported by the opposing wall member and slides to transmit the pressing force from the actuator to the wedge, and one end of the wedge is loosely fitted and the other end is the wedge cylinder. An elastic cylinder member having elasticity connected to a cylindrical main body. 2. The brake device according to claim 1, wherein the facing wall member is a housing of a speed reducer that decelerates the input rotation of the axle shaft and outputs it to the wheel side.

Images