Note: Descriptions are shown in the official language in which they were submitted.
SHOE RETAINING TORSIONAL SPRING FOR BRAKE AssEr5BLy
Background of the Invention
Field of the Invention
The present invention relates to a brake assembly
for a vehicle and more specifically a brake assembly
wherein a torsional shoe retaining spring is utilized.
The torsional shoe retaining spring includes a first end
connected to one of the brake shoes and a second end
connected to the other of the brake shoes. A substantially
annular portion is interposed between the first and second
ends and is disposed around the anchor pin.
Background of the Invention
Two retaining springs are known in the brake art. In
most of the known brakes the shoe retaining springs are
coil springs. Such coil springs are both expensive and
heavy when compared to the torsional spring of the present
invention.
Summary of the Invention
The present invention relates to a new and improved
brake assembly for a vehicle including a spider member,
a pair of brake shoes, actuating means affixed to one end
of the spider member, anchor pin means supported on the
spider member in a position opposite from the one end
of the spider member on which the actuating means is
secured, each of the brake shoes having one end engaging
and pivotable about the anchor pin means and an opposite
end engaging actuating means, each of the brake shoes
further including a web, a shoe table and friction pad
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means supported on the shoe table, actuation of the
actuating means effecting pivotable movement of the
brake shoes about the anchor pin to brake a vehicle
associated therewith, return spring means and a torsional
shoe retaining spring having first and second ends
connected to the shoe table of one of the brake shoes
and a substantially annular portion disposed around the
anchor pin means and interconnecting the first and second
end portions.
The present invention provides a new and improved
brake assembly for a vehicle as set forth in the next
preceding paragraph wherein the anchor pin means includes
a cylindrical anchor pin having a first end and a second
end, the second end of the anchor pin being rigidly secured
to the spider member to support the ancnor pin in a
cantilevered fashion.
Description of the Drawings
FIG. 1 is a plan view of a brake assembly of the
present invention illustrating the brake in its unactuated
condition.
FIG. 2 is a cross-sectional view taken approximately
along lines 2-2 of FIG. 1 more fully illustrating the
anchor pin and torsional shoe retaining spring.
FIG. 3 is a fragmentary view of the anchor pin and
brake shoes illustrating another embodiment of the
torsional shoe retaining spring.
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Description of the Preferred Embodiment
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Referring to the drawings and more particularly to
FIG. 1 a brake assembly 10 for use with a vehicle
(not illustrated) is provided. The brake assemb~y 10 is
a heavy-duty brake assembly which is preferably utilized
with a vehicle, such as a truck. The brake assembly 10
includes a spider member 12 which includes a plurality of
openings 1~ disposed therein. The spider member 12 is
adapted to be supported on an axle mounting face (not
illustrated) preferably of a truck. To this end, a plurality
of bolts, not illustrated, can be inserted through the
openings 14 disposed in the spider member 12 to secure the
brake mechanism 10 to the axle mounting face in a well-known
manner. A dust shield 15 may be connected to the spider
member 12 to shield the brake mechanism 10 from road
generated dust in a well-known manner.
An air chamber mounting bracket assembly 16 is
rigidly secured to one end of the spider member 12.
The air chamber mounting bracket assembly 16 includes
a tube portion 18. An air chamber, not illustrated, may be
mounted in a well-known manner on the bracket assembly 16.
A cam shaft 22 having an S-cam member 24 disposed at one end
thereof is supported for rotation about the longitudinal
axis of the cam shaft 22 in the tube portion 18 of the air
chamber mounting bracket assembly 16.
An anchor pin 30, more fully illustrated in FIG. 2, is
receiYed within an opening 32 disposed in the spider member 12
in a location diametrically opposite to the location at
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which the S-cam 24 is supported by the spider 12. The
anchor pin 30 includes a cylindrical exterior surface 31
and an end portion 34 which is rigidly secured in the
opening 32 in the spider member 12 in a cantilevered fashion.
The anchor pin 30 includes an opposite end portion 36 having
a ridge 38 formed thereon. The ridge 38 cooperates with
brake shoes engaging therewith to prevent sliding movement
of the brake shoes parallel to the longitudinal axis of the
anchor pin 30.
A reinforcing plate 40 is secured to a flanged portion
42 on the spider member 12. The reinforcing plate 40 includes
an opening 44 disposed therein which receives the one end
34 of the anchor pin 30 therein. Suitable means, such as
welding, is utilized to rigidly secure the one end 34 of
the anchor pin 30 to the reinforcing plate 40. Thus, the
anchor pin 30 is supported in a cantilevered fashion by
the cooperation of the reinforcing plate 40 and the opening
32 in the spider member 12.
A pair of brake shoes 50, 52 are supported by the
spider member 12. Each of the brake shoes 50, 52 includes
a pair of webs 56, a shoetable 58 having one side connected
to the webs 56, and friction pad members 60 connected to the
opposite side of the shoetable 58 in a well-known manner.
The upper end of each of the web members 56, as is illustrated
in FIG. 1, includes an opening 62 in which is journalled a
roller pin 64. The roller pins 64 cooperate with the S-cam
member 24 to effect pivotal movement of the brake shoes 50,
52 as will be described more fully hereinbelow. The lower
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end of each of the webs 56, as is illustrated in FIG. 1,
includes an arcuate anchor pin slot 66 which is adapted
to pivotably engage the cylindrical exterior surface of the
anchor pin 30.
A return spring means 68 interconnects the upper ends
of the brake shoes 50, 52 as is illustrated in FIG. 1, to
bias the brake shoes 50, 52 toward their unactuated position.
The return spring means 68 includes a coil spring 70 which
has one end connected to a pin 72 disposed on the web
10 56 of the brake shoe 50 and a coil spring 74 which has one
end connected to a pin 76 disposed on the web 56 of the
brake shoe 52. The coil springs 70 and 74 are interconnected
by a link member 78 and bias the brake shoes 50, 52 in a
radially inwardly direction against the S-cam 24 toward
15 their unactuated position.
A shoe retaining torsion spring 80 is provided for
interconnecting the lower ends of the brake shoes 50, 52
and for biasing the brake shoes to effect continual engagement
of the anchor pin slots 66 with the cylindrical surface 31
20 of anchor pin 30. The shoe retaining torsion spring 80
includes an annular portion 82 which extends around the
cylindrical surface 31 of the anchor pin 30. The annular
portion 82 includes a first end having a hooked portion 81
disposed thereon and a second end having a hooked portion 83
25 disposed thereon. An opening 84 is disposed in the
shoetable 58 of the brake shoe 50 and an opening 86 is
disposed in the shoetable 58 of the brake shoe 52. The
first hooked portion 81 of the torsion spring 80 is
hookingly engageable with the opening 84 disposed in the
30 brake shoe 50 and the hooked portion 83 is hookingly
engageable with the opening 86 disposed in the shoetable 58
of the brake shoe 52.
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The torsion spring 80 provides a biaslng force via
the hooked portions 81 and 83 on the brake shoes 50 and 52
which bias the brake shoes toward the anchor pin 30 to insure
that the anchor pin slots 66 of the brake shoes 50, 52
remain in engagement with the cylindrical surface 31 of
the anchor pin 30. As is illustrated in FIG. 1, the hooked
portions mav extend from behind the back surface 57 of the
shoetable 58 through to the front surface 59 of the shoetable
on which the friction pads 60 are disposed. Additionally,
as is illustrated in FIG. 3, the hooked portions of the
torsional spring 80 can extend along the front surface 59 of
the shoetables 58 and then extend through the openings 8~,
86 toward the back surface 57 of the shoetable 58. Such a
construction for the torsional spring 80 reduces the cost
and weight of known shoe retaining springs which generally
utilize coil springs which are both heavier and more costly
than the torsional spring utilized in the present invention.
Additionally, the construction of the hooked portions 81, 83
of the torsional spring 80 allows the hooked portions to lie
relatively flat along the surface 59 of the shoetable 58.
This allows the friction pads 60 to wear substantially
without the hooked portions being in contact with the brake
shoe upon application of the brakes. Thus, long life of the
brake mechanism is provided whereby the brake pads 60 can
wear down almost to the shoetables 58 without disturbing the
torsion retaining spring.
The ridge 38 on the anchor pin 30 has a diameter which
is normally greater than the diameter of the annular portion
82 of the torsional spring 80. Thus, the ridge 38 prevents
movement of the torsional spring 80 in a direction parallel
to the longitudinal axis of the anchor pin 30 over the ridge
portion 38 as is illustrated in FIG. 2. The hooked ends 81,
83 of the torsional spring 80 can be biased toward each
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other to thereby increase the diameter of the annular
portion 82 of the torsional spring 80. The diameter of the
annular portion 82 can be increased to a diameter which is
greater than that of the ridge 38 of the anchor pin to allow
the torsional spring 80 to be removed from the anchor pin 30.
Such a construction enables the torsional spring 80
to be easily placed and removed from the anchor pin 30 by
merely compressing the ends 81, 83 toward each other. After
the torsional spring 80 is located on the cylindrical surface
31 of the anchor pin 30, the ends 81, 83 can be released
and the natural resiliency of the torsional spring will
cause the annular portion 82 to assume an inside diameter
slightly greater than the diameter of the cylindrical
surface 31 of the anchor pin 30. The inside diameter of the
annular portion 82 of the torsional spring 80 is slightly
larger than the cylindrical surface 31 of the anchor pin 30
to enable the hooked end portions 81, 83 to stretch apart
to hookingly engage with the openings in the shoetables S8.
When the end portions 81, 83 are stretched apart the inside
diameter of the annular portion 82 will decrease slightly.
The torsional spring 80 may remain on the anchor pin 30
when either of the brake shoes 50, 52 are removed from the
brake assembly 10. To remove a brake shoe, one would
disconnect the shoe return spring 68. This would allow the
brake shoes 50, 52 to pivot in a clam-shell fashion about
the anchor pin 30. The torsional retaining spring 80 would
be hookingly engaged with each of the shoes 50, 52. Each of
the shoes could then be hookingly disengaged from the torsion
spring 80 without removing the torsion spring 80 from the
anchor pin 30. Such a construction and mounting of the
torsion spring 80 allows one of the shoes to be removed
without the other shoe falling off.
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When it is desired to actuate brake mechanism 10, the
S-cam 24 will be rotated in a counterclockwise direction as
viewed in FIG. 1 by actuation of the air chamber, not
illustrated, which will effect rotation of the cam shaft 22
in a well-known manner. Counterclockwise rotation of the
S-cam 24 will cause the S-cam 24 to engage with the roller
pins 64 and effect a pivotal movement in an outward radial
direction of the brake shoes 50, 52 about the anchor pin 30.
This will cause the brake pads 60 to engage with a brake
drum, not illustrated, in a well-known manner to effect
braking of a vehicle associated therewith. When the pressure
in the air chamber is released, the return spring means 68
will bias the brake shoes 50, 52 in a radially inwardly
direction to rotate the S-cam 24 in a clockwise direction
and effect disengagement of the brake pad 60 from the
brake drum. During this entire operation the torsional shoe
retaining spring 80 will insure that the brake shoes 50, 52
continue to engage the anchor pin 30.
From the foregoing it should be apparent that a new
and improved brake assembly for a vehicle has been provided
which includes a spider member, a pair of brake shoes,
actuating means affixed to one end of the spider member for
actuating the brake shoes, anchor pin means supported on
the spider member in a position opposite from the one end
of the spider member on which the actuating means is secured.
Each of the brake shoes has an anchor pin or one end engaging
and pivotable about the anchor pin means and an opposite
or S-cam end engaging the actuating means and a web, a shoe
table and friction pad means supported on~-the shoetable.
Return spring is provided to interconnect the S-cam ends
of the brake shoes for biasing the brake shoes toward a
nonactuated position and a shoe retaining torsional spring
is provided having a first end connected to the shoetable
of one of the brake shoes adjacent the anchor pin end and a
second end connected to the shoetable of the other of
the brake shoes adjacent the anchor pin end thereof.
substantially annular portion is disposed around the anchor
pin means and interconnects the first and second end portions
of the torsional spring.
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