U.S. patent application number 10/076601 was filed with the patent office on 2002-08-22 for drum brake.
This patent application is currently assigned to Akebono Brake Industry Co., Ltd.. Invention is credited to Arita, Masatoshi, Yokokura, Hisanori.
Application Number | 20020112930 10/076601 |
Document ID | / |
Family ID | 18904230 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020112930 |
Kind Code |
A1 |
Arita, Masatoshi ; et
al. |
August 22, 2002 |
DRUM BRAKE
Abstract
A mount bracket attached to a vehicle body is formed by pressing
a metal plate to constitute a structure substantially in a shape of
a flat plate having a circular plate portion overlapping a circular
disc portion of a backing plate and a flange portion extended from
an outer periphery of the circular plate portion as a portion
attached to the vehicle body. A pair of brake shoes, a shoe drive
mechanism and an anchor pin are constituted to be directly attached
to the circular plate portion of the mount bracket without
interposing the backing plate.
Inventors: |
Arita, Masatoshi; (Tokyo,
JP) ; Yokokura, Hisanori; (Tokyo, JP) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Assignee: |
Akebono Brake Industry Co.,
Ltd.
|
Family ID: |
18904230 |
Appl. No.: |
10/076601 |
Filed: |
February 19, 2002 |
Current U.S.
Class: |
188/106A |
Current CPC
Class: |
F16D 51/18 20130101;
F16D 2200/0004 20130101; F16D 2051/003 20130101; F16D 2250/0023
20130101 |
Class at
Publication: |
188/106.00A |
International
Class: |
F16D 065/14 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 19, 2001 |
JP |
P2001-041853 |
Claims
What is claimed is:
1. A drum brake comprising: a drum; a pair of brake shoes arranged
opposedly to each other in said drum; a shoe drive mechanism for
expanding said brake shoes toward an inner peripheral face of said
drum; an anchor pin applied with a brake torque by being brought
into contact with end portions of said brake shoes in braking; a
backing plate including a circular disc portion, on which a side
edge of each of said brake shoes slidingly moves, and a cover
portion extended from an outer periphery of said circular disc
portion in an axial direction for covering an outer peripheral
portion of said drum; and a mount bracket for attaching said
backing plate, said mount bracket formed in a shape of a
substantially flat plate and including a circular plate portion
overlapping said circular disc portion of said backing plate and a
flange portion extended from an outer periphery of said circular
plate portion for being attached to a vehicle body, wherein said
brake shoes, said shoe drive mechanism and said anchor pin are
directly attached to said circular plate portion of said mount
bracket without interposing said backing plate.
2. The drum brake according to claim 1, wherein said mount bracket
is formed by pressing a metal plate.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a drum brake preferable for
an industrial vehicle such as a fork lift truck. Specifically, the
present invention relates to an improvement in achieving a
light-weighted structure for reducing production cost and achieving
promotion of maintenance performance.
[0003] 2. Description of the Related Art
[0004] FIG. 5 and FIG. 6 show a conventional example of a drum
brake for braking a front wheel of a fork lift truck.
[0005] The drum brake 1 is disclosed in JP-A-11-201203 and is
constituted by providing a drum 5 formed in a headed cylindrical
shape and integrally rotated with a front wheel tire 3; a pair of
brake shoes 7 and 8 arranged to be opposed to each other at the
inside of the drum 5; a shoe drive mechanism 9 for expanding the
brake shoes 7 and 8 toward an inner peripheral face of the drum 5;
an anchor pin 11 applied with brake torque by being brought into
contact with end portions of the brake shoes 7 and 8; a backing
plate 13 having a circular disc portion 13a on which side edges 7a
and 8a of the respective brake shoes 7 and 8 slidingly move and a
cover portion 13b extended from an outer periphery of the circular
disc portion 13a in an axial direction for covering an outer
peripheral portion of the drum 5; and a mount bracket 15 having a
portion thereof attached with the backing plate 13 and fixed to a
vehicle body.
[0006] As shown in FIG. 5, the mount bracket 15 is integrally
formed with a first flange portion 15a fastened to a frame 17 on
the vehicle side by a screw 19; a second flange portion 15c formed
with a shaft inserting hole 15b inserted with a drive shaft 21 of
the front wheel tire 3 at its center; and a sleeve 15d formed in a
cylindrical shape concentric with the shaft inserting hole 15b. The
mount bracket 15 is formed by casting or the like.
[0007] The illustrated shoe drive mechanism 9 is a wheel cylinder
9a arranged between opposed ends of the pair of brake shoes 7 and 8
on one side and operated by hydraulic pressure. The pair of brake
shoes are expanded by urging the end portions of the pair of brake
shoes in directions separating from each other.
[0008] The wheel cylinder 9a is fixed to the circular disc portion
13a of the backing plate 13.
[0009] The pair of brake shoes 7 and 8 are supported by the
circular disc portion 13a of the backing plate 13 operable to
expand by shoe hold-down pins, not illustrated.
[0010] As shown in FIG. 6, the backing plate 13, attached with the
pair of brake shoes 7 and 8 and the shoe drive mechanism 9, is
fixed to the second flange portion 15c of the mount bracket 15 via
a stud bolt 23.
[0011] The cover portion 13b of the backing plate 13 functions as a
dust cover for preventing foreign matter from invading from the
outside into the drum 5.
[0012] The anchor pin 11 is fixedly fastened by a screw member 25
in a state of being inserted to both of the circular disc portion
13a of the backing plate 13 and the second flange portion 15c of
the mount bracket 15.
[0013] In the case of the above-described conventional drum brake
1, the backing plate 13 is formed by pressing. On the other hand,
since the mount bracket 15 is constructed by a three-dimensional
structure in which the sleeve 15d is projected relative to the
first flange portion 15a and the second flange portion 15c, casting
or forging is needed as a method of producing the mount bracket 15.
Therefore, there poses a problem that production cost is increased
highly since there are needed not only a pressing facility but also
a facility for precision casting or the like in a production line.
Furthermore, according to the mount bracket 15 produced in this
way, its weight is increased.
[0014] Moreover, the circular disc portion 13a of the backing plate
13, on which the side edges 7a and 8a of the brake shoes 7 and 8
slidingly move in braking, is worn by repeating braking operation
and needs to be replaced. However, according to the above-described
conventional drum brake 1, the backing plate 13 is attached with
the brake shoes 7 and 8, the shoe drive mechanism 9 and the anchor
pin 11; therefore, when the backing plate 13 is replaced due to
wear thereof, an article to be replaced is obliged to reassemble
again after temporarily removing all of attached parts. This poses
a problem that maintenance performance is poor in replacing the
backing plate or the like.
SUMMARY OF THE INVENTION
[0015] The present invention has been carried out in view of the
above-described situation and it is an object thereof to provide a
drum brake capable of forming a mount bracket by pressing and
capable of reducing production cost by omitting a facility for
precision casting or the like in a production line. At the same
time, it is an object of the present invention to provide a drum
brake capable of achieving a light-weighted structure of a product,
further, excellent in maintenance performance by dispensing with
removal or reattachment of a brake shoe, a shoe drive mechanism and
the like when a backing plate is replaced in accordance with wear
of a sliding portion thereof.
[0016] In order to achieve the above-described object, according to
the invention, there is provided a drum brake comprising: a pair of
brake shoes arranged opposedly to each other in a drum; a shoe
drive mechanism for expanding the brake shoes toward an inner
peripheral face of the drum; an anchor pin applied with a brake
torque by being brought into contact with end portions of the brake
shoes in braking; a backing plate having a circular disc portion on
which side edges of the respective brake shoes slidingly move and a
cover portion extended from an outer periphery of the circular disc
portion in an axial direction for covering an outer peripheral
portion of the drum; and a mount bracket having a portion for
attaching the backing plate and fixed to a vehicle body,
[0017] wherein the mount bracket is constructed by a structure
substantially in a shape of a flat plate having a circular plate
portion overlapping the circular disc portion of the backing plate
and a flange portion extended from an outer periphery of the
circular plate portion to constitute a portion for attaching the
vehicle body, and
[0018] wherein the pair of brake shoes, the shoe drive mechanism
and the anchor pin are directly attached to the circular plate
portion of the mount bracket without interposing the backing
plate.
[0019] Further, according to the above-described constitution, the
mount bracket is constructed by the structure substantially in the
shape of the flat plate which is a simple two-dimensional
structure; therefore, the mount bracket can be formed by pressing
similar to the backing plate or the like.
[0020] Further, there is constructed a constitution in which the
pair of brake shoes, the shoe drive mechanism and the anchor pin
are directly attached to the circular plate portion of the mount
bracket without interposing the backing plate; therefore, when the
backing plate is replaced in accordance with wear of a sliding
portion (edge face) thereof, it is not necessary to remove or
reattach the brake shoes, the shoe drive mechanism or the like.
That is, only the backing plate may be removed by itself, and a
part to be replaced may newly be attached thereto.
[0021] Further, according to the present invention, the drum brake
may be characterized in that the mount bracket is formed by
pressing a metal plate.
[0022] Further, by constructing the above-described constitution,
in comparison with the conventional cast product or forged product,
a considerable light-weighted structure can be realized.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a front view of an embodiment of a drum brake
according to the present invention.
[0024] FIG. 2 is a sectional view taken along line II-II of the
drum brake shown in FIG. 1.
[0025] FIG. 3 is a sectional view taken along line III-III of the
drum brake shown in FIG. 1.
[0026] FIG. 4 is a view of FIG. 3 taken in a direction of arrow
mark IV and showing a mount bracket of the embodiment.
[0027] FIG. 5 is a disassembled perspective view of a conventional
drum brake.
[0028] FIG. 6 is a vertical sectional view of the conventional drum
brake shown in FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0029] Hereinafter, a preferred embodiment of a drum brake
according to the present invention is described in detail with
reference to the drawings.
[0030] FIG. 1 through FIG. 4 show an embodiment of a drum brake
according to the present invention. FIG. 1 is a front view of an
embodiment of a drum brake according to the present invention. FIG.
2 is a sectional view taken along line II-II of the drum brake
shown in FIG. 1. FIG. 3 is a sectional view taken along line
III-III of the drum brake shown in FIG. 1. FIG. 4 is a view of FIG.
3 taken in a direction of arrow mark IV and showing a mount bracket
of the embodiment.
[0031] The drum brake 31 is a drum brake of a duo-servo type for
braking a front wheel of a fork lift truck and is provided with a
drum 33 formed in a headed cylindrical shape and integrally rotated
with a front wheel tire, not illustrated; a pair of brake shoes 35
and 36 arranged opposedly to each other at the inside of the drum
33; a shoe drive mechanism 39 for expanding the brake shoes 35 and
36 toward an inner peripheral face of the drum 33; an anchor pin 41
applied with brake torque by being brought into contact with end
portions of the brake shoes 35 and 36 in braking; a backing plate
43 having a circular disc portion 43a, on which side edges 35a and
36a of the respective brake shoes 35 and 36 slidingly move, and a
cover portion 43b extended from an outer periphery of the circular
disc portion 43a in an axial direction for covering an outer
peripheral portion of the drum 33; and a mount bracket 45 having a
portion for attaching the backing plate 43 and fixed to a vehicle
body.
[0032] As shown in FIG. 4, the mount bracket 45 is constructed by a
structure substantially in a shape of a flat plate having a
circular plate portion 45a overlapping the circular disc portion
43a of the backing plate 43 and a flange portion 45b extended in an
outer direction from an outer periphery of the circular plate
portion 45a along the circular plate portion 45a. The flange
portion 45b constitutes a portion attached to the vehicle body.
[0033] As shown in FIG. 4, the circular plate portion 45a of the
mount bracket 45 is provided with anchor attaching holes 51a and
51b for fixedly positioning the anchor pin 41 and an anchor block
47; a drive mechanism attaching hole 52 for fixedly positioning a
hydraulic type wheel cylinder 39a constituting the shoe drive
mechanism 39; a plate attaching hole 53 for fixedly positioning the
circular disc portion 43a of the backing plate 43 by
screw-fastening; and a pin attaching hole 54 for supporting a shoe
hold-down pin 49 for displaceably supporting the pair of brake
shoes 35 and 36 toward an inner periphery of the drum 33. Further,
a central portion of the circular plate portion 45a is provided
with a shaft inserting hole 56 for inserting a drive shaft of a
front wheel, not illustrated.
[0034] Different from the conventional structure, each of the pair
of brake shoes 35 and 36, the shoe drive mechanism 39 and the
anchor pin 41 are directly attached to the respective attaching
holes on the circular plate portion 45a of the mount bracket 45
without interposing the backing plate 43.
[0035] That is, the circular disc portion 43a of the backing plate
43 is formed in a ring-like shape cutting off a central portion
thereof by a large amount to escape positions of attaching the pair
of brake shoes 35 and 36, the shoe drive mechanism 39, the anchor
pin 41 and the anchor block 47. Further, the circular disc portion
43a has a slitting portion 43c at a lower portion thereof.
[0036] According to the above-described drum brake 31, the brake
shoes 35 and 36, the shoe drive mechanism 39, the anchor pin 41,
the anchor block 47 and the like are directly attached to the mount
bracket 45. Therefore, according to the embodiment, the backing
plate 43 attached with the constituent parts inherently functions
as a dust cover for preventing foreign matter from invading into
the drum 33 by the cover portion 43b.
[0037] Further, the backing plate 43 is formed by pressing a metal
plate.
[0038] Further as a supplementary explanation of a general
structure of the duo-servo type drum brake, the pair of brake shoes
35 and 36 arranged opposedly to each other are urged at both ends
thereof on one side in a direction of approaching each other.
Further, both ends of the pair of brake shoes 35 and 36 on other
side are urged to a state of being brought into contact with an
adjuster unit 66 by a shoe-to-shoe-spring 64.
[0039] The adjuster unit 66 is extended by driving to rotate an
adjusting gear 68 with pivotal movement of an adjuster lever 67 in
cooperation with expanding operation of the brake shoes 35 and 36
to thereby maintain constant clearances between the respective
brake shoes 35 and 36 and the drum 33.
[0040] In the case of the above-described drum brake 31, the mount
bracket 45 is constructed by the structure substantially in the
shape of the flat plate and can be formed by pressing similar to
the backing plate 43 owing to the simple two-dimensional structure.
Accordingly, in comparison with the case of the conventional mount
bracket 15 constructed by the three-dimensional structure for
mounting the sleeve, production cost can be reduced by omitting a
facility for precision casting or the like in a production line and
at the same time, a considerable reduction in weight is
achieved.
[0041] Further, since there is constructed the construction in
which the pair of brake shoes 35 and 36, the shoe drive mechanism
39, the anchor pin 41 and the like are directly attached to the
circular plate portion 45a of the mount bracket 45 without
interposing the backing plate 43, when the backing plate 43 is
replaced in accordance with wear of the sliding portion, it is not
necessary to remove or reattach the brake shoes 35 and 36, the shoe
drive mechanism 39 and the like. That is, the backing plate 43 can
be removed by itself by expanding only the screw-fastened backing
plate 43 to the left side and to the right side at a portion of the
slitting portion 43c by utilizing elastic deformation, and a new
part to be replaced may be attached. Therefore, operation of
replacing the backing plate 43 is simplified, and excellent
maintenance performance can be achieved.
[0042] Further, the present invention can naturally be utilized not
only for a fork lift truck but also as drum brake for a general
vehicle.
[0043] As described above, according to the drum brake of the
present invention, the mount bracket is constructed by the
structure substantially in the shape of the flat plate, which is
the simple two-dimensional structure; therefore, the mount bracket
can be formed by pressing. In comparison with the case of the
conventional mount bracket constructed by the three-dimensional
structure for mounting the sleeve, production cost can be reduced
by omitting a facility for precision casting or the like in a
production line and at the same time, a light-weighted structure
thereof can be achieved in comparison with a conventional cast
product or forged product.
[0044] Further, owing to the constitution in which the pair of
brake shoes, the shoe drive mechanism and the anchor pin are
directly attached to the circular plate portion of the mount
bracket without interposing the backing plate, when the backing
plate is replaced in accordance with wear of the sliding portion,
it is not necessary to remove or reattach the brake shoes, the shoe
drive mechanism and the like. That is, only the backing plate may
be removed by itself, and a new part to be replaced may be
attached. Accordingly, operation of replacing the backing plate is
simplified, and excellent maintenance performance can be
achieved.
* * * * *