JP2002147506A - Drum brake with shoe clearance automatic adjusting mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately perform shoe clearance automatic adjustment by surely rotating an adjuster wheel with an adjuster lever. SOLUTION: An adjuster lever 52 is rotated around an attachment shaft 56 according to an expansion amount of a pair of brake shoes 12, 14 to rotate an adjuster wheel 44 with a pawl part 52a for shoe clearance adjustment. The adjust lever 52 is composed of metal spring plate material and the spring plate material is bent in a U shape. Consequently, the adjust lever 52 is positioned in an opposite side to the pawl part 52a over the adjuster wheel 44 and provides a sliding contact engagement part 52c allowing rotation of the adjuster wheel 44 in one direction while contacting and sliding on an outer circumference part to prevent shift of the pawl part 52a caused by rotation resistance of the adjuster wheel 44.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drum brake having an automatic shoe gap adjusting mechanism, and more particularly to an improvement in a mechanism for automatically adjusting a shoe gap by rotating an adjuster wheel by an adjust lever.

[0002]

2. Description of the Related Art (a) A pair of first strut member and second strut member respectively engaged with a pair of expandable brake shoes, and at least one of the pair of strut members is disposed between the pair of strut members so as to be relatively rotatable. An adjuster wheel screwed to the strut member, and a strut that defines a standby position of the pair of brake shoes during non-braking, and (b) an engagement adjuster that is engaged with the adjuster wheel. The strut and one of the pair of brake shoes are provided so as to be rotatable around one axis, and the rotation device rotates around one axis in accordance with the amount of expansion of the pair of brake shoes during braking. And an adjust lever for rotating the adjuster wheel in one direction by the engagement adjusting portion by being rotated to (c). The length of the strut is extended by the action of a screw with the rotation of the adjuster wheel in the one direction, and the stand-by position of the pair of brake shoes is separated at the time of non-braking, so that the shoe between the strut and the rotating drum is rotated. 2. Description of the Related Art A drum brake having an automatic shoe gap adjusting mechanism for automatically adjusting a gap to a substantially constant value is widely used as a service brake for a vehicle, a parking brake, and the like. The device described in Japanese Patent Publication No. 54-4026 is an example of such a device, in which an adjust lever is provided on a strut, and a pair of brake shoes are expanded by an urging means constituting a rotating device. It is configured to be mechanically rotated around the one axis in accordance with the amount.

[0003]

However, in such a conventional drum brake with an automatic shoe clearance adjusting mechanism, when the adjuster wheel is rotated by the rotation of the adjust lever, the posture of the adjust lever is caused by the rotational resistance of the adjuster wheel. The adjuster escapes from the adjuster wheel due to change or elastic deformation of the adjuster, or the adjuster lever is impaired due to twisting or uneven wear at the mounting portion, and the adjuster is rotated. There was a possibility that the wheel could not be rotated stably and the accuracy of automatic adjustment of the shoe gap could be impaired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to rotate an adjuster wheel reliably by an adjust lever so that automatic adjustment of a shoe gap is performed with high accuracy. Is to do so.

[0005]

In order to achieve the above object, the first invention comprises (a) an adjuster wheel which is rotated about an axis to displace a standby position of a brake shoe by the action of a screw; (b) an engagement adjuster that is engaged with the adjuster wheel, and is rotated about one axis by a rotation device in accordance with the amount of movement of the brake shoe during braking, and the engagement adjuster is An adjust lever for rotating the adjuster wheel in one direction, and (c) displacing the stand-by position of the brake shoe with the rotation of the adjuster wheel in the one direction, thereby allowing the adjuster wheel to rotate with the rotating drum. In a drum brake provided with a shoe gap automatic adjusting mechanism for automatically adjusting the shoe gap to substantially constant,
(d) The adjust lever is located on the opposite side of the adjuster wheel with respect to the adjuster wheel, and slides on the outer peripheral portion of the adjuster wheel while allowing the adjuster wheel to rotate in the one direction. The sliding contact engagement portion is provided integrally.

According to a second aspect of the present invention, (a) a pair of first strut members and a second strut member respectively engaged with a pair of expandable brake shoes, and are disposed between the pair of first strut members and second strut members so as to be relatively rotatable. An adjuster wheel screwed to at least one strut member, the strut defining a standby position of the pair of brake shoes during non-braking, and (b) an engagement engaged with the adjuster wheel. An adjusting portion is provided, and is disposed so as to be rotatable around one axis on any one of the strut and the pair of brake shoes, and according to an amount of expansion of the pair of brake shoes during braking by a rotating device. An adjusting lever that rotates the adjuster wheel in one direction by the engagement adjusting portion by being rotated about the one axis; (C) With the rotation of the adjuster wheel in the one direction, the entire length of the strut is extended by the action of a screw, and the standby position of the pair of brake shoes during non-braking is separated by rotating the strut. In a drum brake provided with a shoe gap automatic adjusting mechanism for automatically adjusting a shoe gap between the drum and the shoe gap to a substantially constant value, (d) the adjust lever includes the engagement adjusting section with the adjuster wheel interposed therebetween. Located on the other side,
A sliding contact engaging portion is provided integrally with the outer peripheral portion of the adjuster wheel while allowing the adjuster wheel to rotate in the one direction.
This second invention substantially corresponds to one embodiment of the first invention.

A third aspect of the present invention relates to (a) a pair of first strut members and a second strut member which are respectively engaged with a pair of expandable first and second brake shoes, and between the pair of first and second strut members. An adjuster wheel disposed so as to be relatively rotatable and screwed to at least one strut member, and a strut for defining a standby position of the pair of first and second brake shoes when braking is not performed; (B) is disposed on the first strut member so as to be rotatable around one axis, and is urged by an urging means in one rotation direction in which the first strut member is engaged with the first brake shoe. As the brake shoe and the second brake shoe are expanded, the strut is integrally moved toward the second brake shoe, and An adjusting lever that is rotated in one rotation direction in accordance with the expansion amount of the first brake shoe and the second brake shoe, and an engagement adjusting unit is engaged with the adjuster wheel to rotate in one direction. Have
(c) The length of the strut is extended by the action of a screw with the rotation of the adjuster wheel in the one direction, and by separating the standby positions of the first brake shoe and the second brake shoe during non-braking. A drum brake having an automatic shoe gap adjusting mechanism for automatically adjusting a shoe gap between the rotary drum and the rotating drum to a substantially constant value. (D) The adjust lever is provided on the adjust lever with the adjuster wheel interposed therebetween. A sliding contact engaging portion which is located on the side opposite to the portion and which is allowed to slide on the outer peripheral portion of the adjuster wheel while allowing the adjuster wheel to rotate in the one direction. . This third invention is substantially equivalent to one embodiment of the first invention and the second invention, and includes a rotating device of the first invention and the second invention including biasing means for biasing the adjustment lever. You.

According to a fourth aspect of the present invention, there is provided the drum brake with an automatic shoe gap adjusting mechanism according to the third aspect of the present invention, wherein (a) the adjusting lever is formed of a metal spring plate, and the spring plate is bent into a U-shape. By being processed, the engagement adjusting portion is provided on one side wall portion and the sliding contact engagement portion is provided on the other side wall portion, while (b) provided on both side wall portions thereof. The first strut member is rotatably provided around the one axis via the mounting hole, and a spring portion functioning as the urging means when engaged with the first strut member is provided with the spring member. It is characterized by being provided continuously and integrally with the back of a U-shape.

According to a fifth aspect of the present invention, in the drum brake with an automatic shoe gap adjusting mechanism according to the third or fourth aspect, the adjust lever distributes the strut across the first brake shoe and the second brake shoe. Prior to installation, a stopper that is attached to the first strut member and that is engaged with the first strut member to prevent excessive rotation according to the urging force of the urging means is integrally formed. It is characterized by having.

[0010]

According to the drum brake with the automatic shoe gap adjusting mechanism of the first to third aspects of the present invention, the sliding engagement portion is provided on the opposite side of the engagement adjusting portion across the adjuster wheel. The position of the adjusting lever is positioned by the engagement adjusting portion and the sliding engagement portion, and escape of the engagement adjusting portion caused by the rotational resistance of the adjuster wheel is prevented, so that the adjuster wheel can be surely rotated. In addition, the twisting and uneven wear of the mounting portion are suppressed, and the turning operation of the adjusting lever is stabilized, so that the automatic adjustment of the shoe gap can be performed with high accuracy over a long period of time.

In the fourth invention, the adjusting lever is made of a metal spring plate material, and a spring portion functioning as a biasing means is integrally provided in addition to the engagement adjusting portion and the sliding engagement portion. Therefore, the number of parts can be reduced, the structure can be simplified and inexpensively, and the first strut member can be compactly arranged.

In the fifth invention, the adjusting lever is attached to the first strut member before disposing the strut over the first brake shoe and the second brake shoe, but the adjusting lever is adjusted according to the urging force of the urging means. Since the stopper for preventing the lever from rotating excessively is provided, the operation of assembling the strut between the first brake shoe and the second brake shoe can be performed easily and quickly.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is applicable to various drum brakes such as a leading / trailing type, a two-leading type, and a duo servo type. Although it is preferably applied, it is also possible to apply it to drum brakes of various rotary braking devices other than those for vehicles. The vehicle includes a car, a train, a motorcycle, and the like.

The adjuster wheel for adjusting the shoe gap is provided on the strut as in, for example, the second and third aspects of the present invention so as to separate the standby position of the pair of brake shoes. Various modes can be adopted, such as one that is disposed on a pressing device such as a wheel cylinder that presses the drum, and that displaces the support position (such as the piston position) of the brake shoe in the direction approaching the rotating drum.

The turning device is preferably configured to include, for example, the urging means of the third invention, and is preferably an interlocking mechanism for turning the adjustment lever mechanically in accordance with the amount of movement (or the amount of expansion) of the brake shoe. It is adopted, but the amount of movement and expansion of the brake shoe during braking is detected by a sensor, and the adjust lever is electrically rotated around one axis by an electric motor etc. according to the amount of movement and expansion. The one that adjusts the shoe gap may be used. In the case of the interlocking mechanism, an urging means such as a spring for moving the strut following the second brake shoe or an engagement device, and an urging means such as a spring for rotating an adjustment lever in accordance with the movement of the strut, or a coupling means. Various modes are possible, such as providing a joint device separately. In the case of the third invention, the adjusting lever has the first position.
An interlocking engagement portion that is engaged with the brake shoe is provided, and when the pair of brake shoes are expanded during braking, the interlocking engagement portion and the The strut as a whole is relatively moved toward the second brake shoe by engagement with the first brake shoe.

[0016] The automatic adjustment of the shoe gap by the adjustment lever can be performed by rotating the adjuster wheel by rotating the adjustment lever accompanying movement of the brake shoe during braking (such as when the pair of brake shoes is expanded) or by releasing the brake when braking is released. The adjuster wheel may be rotated by the rotation of the adjust lever accompanying the movement of the brake shoe (for example, when the pair of brake shoes approach). The adjuster wheel is provided with, for example, a saw tooth on an outer peripheral portion, and is configured to be engaged with an engagement claw portion as an engagement adjustment portion, so that the strut can be rotated only in one direction to extend the strut. In addition, various modes are possible, such as rotation in one direction by frictional engagement with the engagement adjusting section and prevention of rotation in the opposite direction by a one-way clutch or the like. When the saw teeth are provided, the shoe gap is adjusted within a predetermined range determined by the pitch. However, in the case of frictional engagement, the shoe gap can be maintained almost constant. The adjustment accuracy (variation amount) of the gap slightly varies depending on the engagement mode, but is adjusted to be substantially constant.

The adjuster wheels according to the second and third inventions may be screwed to at least one of the pair of strut members, but the twist is screwed to both strut members via opposite screws. You may do it. In the case where only one of them is screwed, the other strut member may be connected so as to be relatively rotatable via a fitting shaft or the like.

The pair of brake shoes are expanded by, for example, a hydraulic wheel cylinder or a pressing device such as an electric type during braking, while a return spring is provided across the pair of brake shoes during non-braking. Although it is configured to be brought close to the strut by being approached by a tension coil spring or the like, various modes are possible, such as being able to be expanded and approached by the pressing device. As the pressing device, various modes are possible, such as a device that separates a pair of brake shoes via a link mechanism such as a strut by a brake lever or the like that is mechanically rocked by a manual operation of a driver or the like. In implementing the first invention, it is not always necessary to provide a pair of brake shoes, and a single brake shoe may be used to generate a braking force.

In the third invention, one axis on which the adjust lever is rotatably arranged is substantially perpendicular to a plane including the center line of the strut (or adjuster wheel), that is, a pair of the first brake shoe and the second brake shoe. It is set substantially perpendicular to the direction in which the brake shoes expand. In short, the rotation direction of the adjustment lever may be set so as to include a component in the direction in which the brake shoe expands.

In the third invention, the adjusting lever is provided on the first strut member. However, when the second invention is carried out, the adjusting lever is provided on the first brake shoe, and the first strut is provided by the urging means. You may make it engage with a member.

In the fourth aspect, the biasing means is provided integrally with the adjust lever. However, in other embodiments, a spring member such as a torsion coil spring, a compression coil spring, or a tension coil spring is provided separately. You may do it. Further, the spring portion can be provided continuously and integrally from a portion other than the U-shaped back portion.

In the fifth invention, the excessive rotation is prevented by the stopper portion.
Means a rotation that allows the rotation required for automatic adjustment of the shoe gap and does not impair the workability of assembling the pair of brake shoes. It is desirable to set the rotation amount.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing a leading / trailing type vehicle drum brake 8 to which the present invention is applied, and FIG. 2 is an enlarged view showing the vicinity of an automatic shoe gap adjusting mechanism 54. A pair of brake shoes 12, 14 having an arc shape are provided on a backing plate 10 fixed to a vehicle body-side member supported by the vehicle so as to be able to expand mutually by shoe hold-down devices 16, 18. The brake shoes 12, 14 are fixed to a shoe web 20 positioned substantially parallel to the plate surface of the backing plate 10, a shoe rim 22 fixed to an outer peripheral edge of the shoe web 20, and fixed to an outer peripheral surface of the shoe rim 22. Linings 24 are provided. In the present embodiment, the brake shoe 12 functions as a leading shoe with the first brake shoe, and the brake shoe 14 functions as a trailing shoe with the second brake shoe.

One end (upper end) of the pair of brake shoes 12 and 14 is engaged with both ends of a wheel cylinder 26 fixed to the backing plate 10, respectively, so as to brake the service brake, that is, a brake operating member. When the brake pedal is depressed, the wheel cylinder 26 is expanded in a direction in which the brake pedal is separated from each other, and is pressed by a rotating drum 27 that rotates together with the wheels to generate a braking force. The wheel cylinder 26 corresponds to a pressing device, and has a pair of pistons each protruding outward by hydraulic pressure. At a position near the wheel cylinder 26 and on the inner peripheral side of the backing plate 10, a return spring (a tension coil spring in the embodiment) 28 is stretched across the brake shoes 12 and 14 so as to approach each other. While being energized,
A strut 30 is provided to pass through the inside of the return spring 28, and the return spring 2
The standby position of the pair of brake shoes 12 and 14 that are brought close to each other in accordance with the urging force 8 is defined. The other ends (lower ends) of the brake shoes 12 and 14 are connected to anchors 3 fixed to the backing plate 10.
2, respectively.

On the surface of the shoe web 20 of the brake shoe 14 on the backing plate 10 side, an axis of a mounting shaft 36 substantially perpendicular to the shoe web 20 at a position where the parking brake lever 34 is located on the wheel cylinder 26 side. The strut 30 is attached so as to be rotatable around the center, and is disposed so as to straddle the parking brake lever 34 and the other brake shoe 12. Therefore, when the parking brake operation lever provided in the driver's seat is operated and the parking brake lever 34 is rotated counterclockwise through the mounting cable 36 via the brake cable 38, the brake shoe 12 moves rightward through the strut 30. Direction, and is pressed by the rotating drum 27 to generate a braking force.
The brake shoe 14 is moved to the left along with the mounting shaft 36 by the reaction, and is pressed by the rotating drum 27 to generate a braking force. The parking brake lever 34 is held at a fixed standby position where the engagement protrusion 34a abuts on the shoe rim 22 of the brake shoe 14 by the action of the return spring 28 when the parking brake is not operated, and the brake shoe 14 releases the parking brake lever 34. The standby position is defined by the strut 30 through the intervening position.

FIG. 2 is a view showing the vicinity of the strut 30.
(a) is a cross-sectional view substantially perpendicular to the plate surface of the backing plate 20 as viewed from above in FIG. 1, and (b) is a cross-sectional view taken along the line BB in (a) and a left side view of (c) FIG. 2C is a front view showing the vicinity of the right end of the strut 30, that is, FIG.
FIG. 3A is a view from below, in which the brake shoe 12 is omitted. As is apparent from these figures, the strut 30 includes a first strut member 40 that is non-rotatably engaged with one brake shoe 12 and a shoe web 20 of the other brake shoe 14 via a parking brake lever 34. A second strut member 42 non-rotatably engaged with the strut member 40 and an adjuster wheel 44 rotatably disposed between the strut members 40, 42. The disc-shaped adjuster wheel 44 includes:
A screw shaft 48 provided with a male screw and a cylindrical fitting shaft 50 are integrally provided on a center line so as to protrude in opposite directions, and the screw shaft 48 is provided in a screw hole provided in the second strut member 42. On the other hand, the fitting shaft 50 is fitted in a fitting hole provided in the first strut member 40 so as to be relatively rotatable.

The adjuster wheel 44 constitutes an automatic shoe gap adjusting mechanism 54 together with an adjust lever 52 disposed on the first strut member 40. The adjust lever 52 causes the adjuster wheel 44 to move in one direction (adjustment direction; When rotated in the clockwise direction in FIG. 2B), the second strut member 42 is separated from the adjuster wheel 44 by the action of the screw, and
0 is extended and the standby position of the pair of brake shoes 12 and 14 at the time of non-braking is separated, so that the brake shoe 1
The shoe gap (total of both) between 2, 14 and the rotating drum 27 is kept substantially constant.

FIGS. 3A and 3B are diagrams showing the adjusting lever 52 alone. FIG. 3A is a plan view, FIG. 3B is a left side view of FIG. 3C, and FIG. 3C is a front view. a) Corresponds to (c).
The adjust lever 52 is made of a metal spring plate, and the spring plate is bent into a U-shape to form an engagement claw on one of the side walls located on the upper side in FIG. A portion 52a and an interlocking engagement portion 52b are provided, and the sliding contact portion 52 is provided on the other side wall portion located on the lower side in FIG.
c is provided. In addition, they are rotatably mounted on the mounting shaft 56 provided on the first strut member 40 through mounting holes 52h provided on both side walls thereof, and engage with the first strut member 40. 2A, the spring portion 5 for urging the adjustment lever 52 to rotate counterclockwise to the mounting shaft 56 in FIG.
2d is provided continuously and integrally with the U-shaped back portion 52s. The spring portion 52d indicated by a solid line in FIG.
Is an elastically deformed arrangement state, and the shape of the spring portion 52d in the natural state is a dashed line, and is bent into a substantially U-shape.

The mounting shaft 56 corresponds to one shaft, and the strut 3
0 (or the adjuster wheel 44) is substantially perpendicular to a plane including the center line, ie, a pair of brake shoes 1
The first and second strut members 40 are integrally attached to the first strut member 40 by caulking or the like in a posture substantially perpendicular to the expanding directions of the two. As is apparent from FIG. 2C, a spacer 60 is provided between the side walls of the adjustment lever 52 and the first strut member 40 around the mounting shaft 56, respectively.
62 are inserted, and the engagement claw portion 52a and the sliding contact engagement portion 52
c is positioned at a position substantially opposite to the center line of the adjuster wheel 44 so as to be engaged with the outer peripheral portion of the adjuster wheel 44. Note that the arrangement of the mounting shaft 56 can be changed as appropriate. For example, the mounting shaft 56 can be press-fitted and fixed to the first strut member 40 using a straight pin or the like.
0 and 62 can be omitted.

The mounting shaft 5 is formed by the spring portion 52d.
6 is always urged in the counterclockwise direction, so that the interlocking engaging portion 52b is always in the shoe web 20 of the brake shoe 12.
, And relatively urges the first strut member 40 in a direction away from the brake shoe 12. Accordingly, when the pair of brake shoes 12 and 14 are expanded at the time of braking by the service brake, the strut 30 is moved to follow the brake shoes 14 with the expansion, and the adjustment lever 52 is The strut 30 is rotated around the mounting shaft 56 with the relative movement between the strut 30 and the brake shoe 12. The amount of rotation of the adjust lever 52 corresponds to the amount of expansion of the brake shoes 12 and 14, that is, the shoe gap during non-braking, and when the amount of rotation exceeds a certain amount, the engaging claw 52a moves the adjuster wheel 44 in one direction. Rotate to extend strut 30. The spring portion 52d corresponds to an urging means, and the spring portion 52d and the interlocking engaging portion 52b constitute an interlocking mechanism that functions as a rotating device.

When the service brake is released, the brake shoe 12 and the first
As the strut 30 is moved rightward until it comes into contact with the strut member 40, the adjusting lever 5
2 is rotated clockwise back of the mounting shaft 56 against the urging force of the spring portion 52d. A saw tooth 44t whose tip is inclined in a direction opposite to one direction is provided on the entire outer periphery of the adjuster wheel 44, and the adjust lever is used when braking (when the brake shoes 12, 14 are expanded). 52 is rotated in one direction by being engaged with the engaging claw 52a of the adjuster wheel 52. However, when the adjust lever 52 returns and rotates when braking is released, the adjuster wheel 44 is rotated by frictional resistance of the screw shaft 48 and the like. The return rotation is prevented, and the engaging claw 52a gets over the saw tooth 44t. Further, the sliding contact engaging portion 52c cannot engage with the saw tooth 44t, and the reciprocating rotation of the adjust lever 52 and the adjuster wheel 44 at the time of braking and releasing the service brake.
The one-way rotation is always allowed, and the outer peripheral portion of the adjuster wheel 44 is always slidably contacted. The engagement claw 52a corresponds to an engagement adjustment unit.

The adjusting lever 52 is attached to the first strut member 40 by an attaching shaft 56 before the strut 30 is disposed across the pair of brake shoes 12 and 14, and is provided with a spring portion 52d. A stopper 52e for preventing excessive rotation according to the force is integrally provided. The stopper portion 52e is provided so as to extend from the back portion 52s in a direction opposite to the spring portion 52d, and is engaged with the first strut member 40. The adjust lever 52 at the time of normal automatic shoe gap automatic adjustment is provided. While allowing a pair of brake shoes 12,
In order not to impair the workability of the assembling of the motor 14, it is prevented from rotating more than a predetermined amount.

In such a vehicle drum brake 8, the engaging claw 52a is sandwiched between the adjuster wheels 44.
Is provided on the opposite side to the position, the position of the adjusting lever 52 is determined by the engaging claw portions 52a and the sliding contact engaging portions 52c, which is caused by the rotational resistance of the adjuster wheel 44. The engaging claw portion 52a is prevented from escaping, the adjuster wheel 44 can be reliably rotated, and twisting and uneven wear on the mounting shaft 56 are suppressed, so that the turning operation of the adjusting lever 52 is stabilized. Thereby, automatic adjustment of the shoe gap can be performed with high accuracy over a long period of time.

The adjusting lever 52 is made of a metal spring plate, and has a spring portion functioning as an urging means in addition to the engaging claw portion 52a, the interlocking engaging portion 52b, and the sliding contact engaging portion 52c. Since 52d is provided integrally,
The number of parts can be reduced, the structure can be simplified and inexpensive, and the first strut member 40 can be compactly arranged.

The strut 30 is connected to the brake shoe 1
Before being placed across 2 and 14, the adjust lever 52 is attached to the first strut member 40,
Since the stopper 52e is provided to prevent the adjusting lever 52 from excessively rotating in accordance with the biasing force of the spring 52d of the adjusting lever 52, the interlocking engaging portion 52b of the adjusting lever 52 is
Struts 30 to engage with the shoe webs 20 of the
Can be easily and quickly assembled between the brake shoes 12 and 14.

Next, another embodiment of the present invention will be described. FIGS. 4A and 4B show another embodiment of the urging means for urging the adjust lever 52 to rotate around the axis of the mounting shaft 56. FIG. 4A shows a waveform spring instead of the spring portion 52d. In the case where the portion 70 is provided, (b) shows a case where the S-shaped spring portion 72 is provided integrally, and in each case, the same effect as that of the above embodiment can be obtained. (C) shows a case where a spring member (compression coil spring in the embodiment) 74 is provided separately instead of providing the spring portion 52d. It should be noted that FIGS.
Are diagrams corresponding to FIG. 2A.

Although the embodiments of the present invention have been described in detail with reference to the drawings, this is merely an embodiment,
For example, if the engaging claw portion 52a and the sliding contact engaging portion 52c are connected in the vicinity of the adjuster wheel 44, escape by elastic deformation of the engaging claw portion 52a itself can be more effectively prevented. Various modifications and improvements can be made based on knowledge.

[Brief description of the drawings]

FIG. 1 is a front view illustrating a drum brake for a leading / trailing type vehicle to which the present invention is applied.

FIGS. 2A and 2B are diagrams showing the vicinity of struts of the drum brake of FIG. 1, wherein FIG. 2A is a cross-sectional view substantially perpendicular to a plate surface of a backing plate, FIG. 2B is a cross-sectional view taken along line BB in FIG. c) is a front view showing the vicinity of the right end of the strut, with the brake shoes omitted.

3A and 3B are diagrams each independently showing an adjustment lever of the drum brake of FIG. 1, wherein FIG. 3A is a plan view, FIG. 3B is a left side view of FIG.
(c) is a front view, which respectively correspond to (a) to (c) of FIG.

FIG. 4 is a view showing another embodiment of the urging means for urging the adjustment lever, and is a view corresponding to FIG. 2 (a).

[Explanation of symbols]

8: Drum brake for leading / trailing type vehicle 12: Brake shoe (first brake shoe)
14: Brake shoe (second brake shoe) 2
7: Rotating drum 30: Strut 40: First strut member 42: Second strut member 44: Adjuster wheel 52: Adjust lever 52a: Engagement claw portion (engagement adjustment portion) 52b: Interlocking engagement portion (rotary device)
52c: sliding engagement portion 52d, 70, 72: spring portion (biasing means, rotating device) 52e: stopper portion 5
4: Shoe gap automatic adjustment mechanism 56: Mounting shaft (uniaxial)
74: spring member (biasing means, rotating device)

Claims (5)

[Claims] 1. An adjuster wheel, which is rotated about an axis to displace a standby position of a brake shoe by the action of a screw, and an engagement adjuster that is engaged with the adjuster wheel. An adjusting lever that is rotated around one axis in accordance with an amount of movement of the brake shoe during braking by a moving device, and that rotates the adjuster wheel in one direction by the engagement adjusting unit. A drum brake including an automatic shoe gap adjusting mechanism that automatically adjusts a shoe gap between the brake drum and the rotating drum to be substantially constant by displacing the standby position of the brake shoe with the rotation in one direction. The adjust lever is located on the opposite side of the adjuster wheel from the engagement adjusting portion with the adjuster wheel interposed therebetween. A drum brake with an automatic shoe clearance adjusting mechanism, wherein a sliding contact engaging portion that slides on the outer peripheral portion of the adjuster wheel while allowing the one-way rotation of the adjuster wheel is provided integrally. 2. A pair of first strut member and second strut member respectively engaged with a pair of expandable brake shoes, and at least one strut member disposed between the pair of first strut members and the second strut member so as to be relatively rotatable therebetween. An adjuster wheel that is screwed into the strut, and a strut that defines a standby position of the pair of brake shoes during non-braking; and an engagement adjustment unit that is engaged with the adjuster wheel. A strut and one of the pair of brake shoes are disposed so as to be rotatable around one axis, and are rotated around the one axis by a rotation device in accordance with an amount of expansion of the pair of brake shoes during braking. And an adjust lever for rotating the adjuster wheel in one direction by the engagement adjusting portion. The entire length of the strut is extended by the action of the screw with the rotation of the wheel in the one direction, and the stand-by position of the pair of brake shoes is separated at the time of non-braking, so that the shoe gap between the strut and the rotating drum is reduced. In the drum brake provided with a shoe gap automatic adjusting mechanism for automatically adjusting the adjusting wheel to be substantially constant, the adjusting lever is located on a side opposite to the engagement adjusting portion with the adjusting wheel interposed therebetween. A drum brake with an automatic shoe gap adjusting mechanism, wherein a sliding contact engaging portion is provided integrally with the outer peripheral portion of the adjuster wheel while allowing rotation in one direction. 3. A pair of first strut members and a second strut member respectively engaged with a pair of expandable first brake shoes and second brake shoes, and are disposed so as to be relatively rotatable therebetween. An adjuster wheel that is screwed to at least one strut member, the strut defining a standby position of the pair of first and second brake shoes when braking is not performed, and the first strut member The first brake shoe is urged in one rotation direction to be engaged with the first brake shoe by an urging means.
The strut is integrally moved toward the second brake shoe as the brake shoe and the second brake shoe are expanded, and the expansion amount of the first brake shoe and the second brake shoe is increased. An adjusting lever that is rotated in the one rotation direction in accordance with the rotation of the adjuster wheel and is engaged with the adjuster wheel to rotate in one direction. As a result, the overall length of the strut is extended by the action of the screw, and by separating the standby positions of the first brake shoe and the second brake shoe during non-braking, the shoe gap between the rotating drum and the shoe is automatically set. In the drum brake provided with a shoe gap automatic adjusting mechanism for adjusting the substantially constant, the adjust lever is provided with the adjuster wheel. And a sliding contact engaging portion which is located on the opposite side to the engagement adjusting portion and which is allowed to slide on the outer peripheral portion of the adjuster wheel while allowing the adjuster wheel to rotate in the one direction. A drum brake with an automatic shoe clearance adjusting mechanism. 4. The adjusting lever is made of a metal spring plate, and the spring plate is bent into a U-shape to provide the engagement adjusting portion on one of the side walls. The sliding contact engaging portion is provided on the other side wall portion, and the sliding contact engaging portion is provided on the first strut member so as to be rotatable around the one axis through mounting holes provided on both side wall portions thereof. 4. A spring which functions as said urging means by being engaged with said first strut member is provided continuously and integrally with said U-shaped back. 4. A drum brake with an automatic shoe gap adjusting mechanism according to item 1. 5. An adjusting lever attached to the first strut member before disposing the strut over the first brake shoe and the second brake shoe, wherein the first strut member is provided. 5. The automatic shoe gap adjusting mechanism according to claim 3, wherein a stopper portion is integrally provided with the stopper portion, the stopper portion being prevented from rotating excessively according to the urging force of the urging means by being engaged with the shoe. With drum brake.