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Патент USA US2105560

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Jan. _18, 1938.
E. STIFT
BRAKE MECHANISM
Filed Dec. 30, 1935
2,105,560
Patented
2,105,560
18, 1938
UNITED STATES» PATENT OFFICE
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2,105,560
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BRAKE MECHANISM
, Edward Stift, St. Louis, Mo.
Application December 30, 1935. Serial No. 56,618
5 claims. (c1, 18s-79.5)
This invention relates to brake mechanism for
vehicles and more particularly brakes of the in-`
ternal expansion type.
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f
,y
An object of this invention is to providev brake
Gl mechanism simple in construction and efficient
in operation. which will expand brake shoes
positively in a radial direction to secure uniform
contact with a cooperating surface, or brake
drum, throughout the entire surface'of the brake
10 shoes and which will be self-adjusting to auto-k
matically provide a certain minimum‘and a cer
tain maximum clearance between the brake shoes
and thecooperating surface.
Other and specific objects will be apparent from
15 the following detail description taken in connec
tion with the accompanying drawing.
Fig. 1 is a front elevation of brake mecha
-nism embodying my invention;
' ' Fig. 2 is a vertical section approximately on
l 20 line 2_2, Fig. 1;
Fig. 3 is a rear elevation; and
Fig. 4 is a vertical section approximately on
'
line 4_4, Fig. 2.
<
A cam ring I is mounted for rotation on a
25 lsupport 2 and has a plurality of cam surfaces
3 about its periphery. A plurality of brake shoes
4 are mounted about the periphery of the ring
and are adapted to be pressed outwardly by the
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Inner washers Il and outer washers 'IB on the>
studs I3 engage the faces of the ring I and prop
erly space and hold the ring against axial dis
placement.
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y
Each of the brake shoes ß has a pair of in- 5
wardly extending flanges I6. Pins I'I secured
in the flanges I6 carry rollers I8, which ride the
periphery of the ca_m disc I and which are en
gaged by a cam surface 3. In the specific em
bodiment shown four brake shoes are provided, Io
each having two rollers I8 and there being eight
cam surfaces on the ring.
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The brake shoes are held Íagainst circumfer
ential movement by lugs I9, which are secured
to or integral with the support 2 and extend l5
inwardly to engage the edges oi’ the flanges I6.
The flanges I6 on the respective brake shoes A
provide rigidity .for the shoes which are moved
outwardly as a unit'in a radial direction by the
action of the cam ring I. The side edges of the 2o
ñanges I6 are straight and are parallel to the
radius of movement so that lugs I9 contacting
those edges serve as guides for the shoes, re
straining the shoes from movement in a circum
ferential direction and thereby prevent chat- g;
tering of the brake.,
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Springs 20 connect adjacent ends of the brake
shoes 4 and contract the brake shoes when the
can-i` surfaces 3 upon rotation of the ring. Springs cam disc is rotated to normal position.
30 5 connected between the ring I and the support
In the operation of the device the bell crank ,an
2 return the ring to and tend to hold it in av lever I0 is rotated by a rod 2|, which' may be
ñxed normal position. This normal position is connected to a foot pedal or lever not shown.
automatically ñxed by mechanism . comprising ' The pawl 8 being engaged in 'a notch in the
undercut teeth 8 on the inner surface of the
35 ring and a spring pressed pawl 1 pivotally
mounted on the support 2. The cam ring I is
rotated by a ratchet mechanism comprising a
Y pawl 8 and a raton-9, the pawl being carried by
a bell crank lever I 0 pivotally mounted on the
40 support 2.
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The foregoing comprises a summary of the
embodiment of the invention specifically illus
trated in the accompanying drawing. The es
sential features of the invention are pointed out
ratch 9 will rotate the cam disc I in a clock
wisel direction (Figs. 1 and 4). The cam sur- :z5
faces 3, bearing against the rollers I8, press the
brake shoes outwardly uniformly throughout
their entire surface to contact a cooperating sur
face which may be the inner circumference of a
brake drum, not shown but well understood in 4o
the art. If the clearance between the brake shoes
in their starting position and the brake drum is
excessive due to wear or ,for other reasons the
ring I will be rotated by the ratchet such a dis
tance that the pawl 1 will be urged by its spring 45
22 into a succeeding notch 6. Upon release of
45 in the appendedl claims but the following detail
description will assist in understanding and
practicing the invention.
. the rod 2|, the springs 5 will rotate the cam disc
The support 2, as speciñcally shown, comprises Il in a counter-clockwise direction with the
a plate which is ?lxed to an axle vor'axle hous
springs 20 contracting the brake shoes 4 while
50 ing. A front automobile axle is shown in the' the rollers I8 ride the cam surfaces 3. The teeth 5G
drawing, the support 2 being attached thereto 6 being undercut provide a suiïlcient rotation of
by screws II. 'I'hecam ring I is mounted for va cam disc I in a counter-clockwise direction so
rotation on the support 2 by having its inner as to allow a ñxed minimum clearance between
circumference bearing on rollers I2 which are the brake shoes and the cooperating drum. This
55 supported by studs I3 secured to the support 2.‘ clearance will be in actual practice at least .01 56
'.42'inch.
2,105,500
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It will be seen lthat the function of the
pawi ‘I `and the undercut teeth l is to ilx a nor
mal position for the cam discA l so as to auto-=
position including undercut teeth on the ring and
a spring pressed pawl carried by the support and
engaging the teeth.
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4. In brake> mechanism, the combination com
matically adjust Lthe clearance between the brake
» prisihg a support, a cam ring rotatively mounted
shoes and its cooperating drum.
It `will be understood that various changesV may on the support, a plurality of brake shoes about
be made in the details oi' construction, withinl the periphery‘of said ring- and adapted to be
pressed outwardly by rotation of the ring, yielding
the scope of the appended claims, without de
means for returning and holding the ring to and
parting from the spirit of this invention. _
10
I claim: '
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l. In brake mechanism, a cam ring positioned
and adapted when rotated to expand brake shoes,
and means for automatically iixing a normal po
sition of said ring including undercut teeth on
.in a normal position, yielding means for con
tracting the shoes. a ratch onv the ring, a lever,
a pawl'carried by the lever engaging the ratch,
and means for automatically ilxing such. normal
position including undercut teeth on the ring and
the ring and a spring pressed pawl for'engaging
a spring pressed pawl carried by the support and '
the teeth.
engaging the teeth.
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2. In brake mechanism, a cam ring positioned
5. In a brake mechanism the combination com
and adapted when rotated to expand brake shoes,
prising a support, a plurality of rigid brake shoes.
a ratch on the ring, a lever. a pawl carried by
a pair of inwardly extending ñanges on each or”
20 the lever engaging the ratch, and means for psaid shoes and spaced from each other, a pair
automatically ñxing a normal position of thee'ringA of rollers Journalled between the flanges on each
including undercut teethon the ring and a spring shoe, a ring mounted on the support and havinga cam surface on its outer periphery arranged
pressed pawi engaging the teeth. .
`and adapted to contact all of said rollers and
3. In brake mechanism, the combination com
25 prising a support, a cam ring rotatively mounted thereby upon rotation to press the shoes outward
on the support, a plurality ci brake shoes about ly in a radial direction by its rotation, straight
the periphery _of said ring and adapted to be
pressed outwardly by rotation of the ring, yielding
means for returning and holding the ring to
30 and in normal position, yielding means for con
tractlng the shoes, means for rotating the ring,
and means for automatically ilxing such normal
edges at the ends of the flanges parallel to the
radius of movement of the shoes, Iand means on
the support contacting said edges to restrain the
shoes against circumferential movement.
EDWARD s'rrs'r.
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