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Патент USA US2120917

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-June 14, i938;
Filed June 3, 1936
www Í
` Patented June 14, 1938
2,120,917 à
Gilbert K. Hause, Dayton„-0hio, assignor to Gen
eral Motors Corporation, Detroit, Mich., a cor
poration of.Delaware
Application June 3, 193s, serial No; 83,185
.5 claims. (criss-_152)
This invention relates to brakes and particu
larly to internal expanding brakes for use on ve
chor pin 2i. At its head, yokeli is recessed at ,
43’ _to rotatably receive a nut 45 threaded upon
a screw ¿I1 forked at its end to engage the web
of shoe 21. The nut has external teeth 49. Ac
An object of the invention is to provide brake
5 mechanism associated with a rotating drumV snapped
into plate
49 isI5.
by removing
of theanut
cap ad5I.
whereby much the larger part of the annular cess to'teeth
,drum surface is frictionally engaged to retard ‘justs the shoe clearance since the nutremains
drum rotation. '
in contact with the yoke.
. “A further object is to provide the same effec-`
Adjacent the anchor l
pin I9, shoe 21 is provided with articulating links
-10 tive retarding action for' either direction of drum`
53 resembling in structure and function the links 10
33 and 35. Also adjacent anchor pin I9, shoe 25
- As a further object the invention aims to mini- _ has a similar- provision for adjustment and for
mize manual _effort through the instrumentality anchoring on the pin I9. This is constituted by
of servo shoes adapted to be brought into drum yoke 55, nut 51 and screw 59.
A fiat plate 6I has an elongated opening 63 15.
15 contact by manual effort and to themselves actu
ate the main shoes. surrounding hub I3 and having a shorterdiam
Still further the main shoes are designed to eter of such length that yit may be guided for
' readily accommodate themselves to the. drum
axial> movement by said hub, and alsoto be free
contour by means o'f an articulated form of an
to rotate about the hub. This plate 5I has an
.;0 chorage.
' opening 65 freely surrounding pin I9 and is ter- 20 ‘
' Other objects and advantages will be under-A minally provided with a servo shoe 61 adapted to
stood from the following description.
engage the drum when projected radially into
The invention is illustrated by the accompanyf- contact with the latter. AA second iiat plate 63
ing drawing in which Fig. 1 is a sectional view has a servo shoe -1I diametrically opposite shoe
25 through the drum, showing in'elevation, partly
in section, the shoes and the operating mecha
'- Fig. 2 is a section on 'line 2-2 of Fig. 1.
Fig. 3 is Ia section on line 3-3 of Fig. 1.
Fig. 4 is a section on line 4-4 of Fig. 1.l Y
Referring by reference characters to the draw
ing, numeral 1 is used to designate a conven
tional brake drum, such a drum asis usually car-`
ried by each of the Wheels of a motor vehi le.
The drawing shows the .invention applied to o e
of the rear Wheels, the similar application to the
`front wheels not being illustrated. To the axle
housing 9 at~ the rear wheels is secured by fas
tening means I2 an anchor plate II to which is
40 secured a pivot hub I3. 4A light backing plate I5
and a -dust and splash shield I1 complete the
closure of the drum. Diametrically opposite an
chor pins I9 and 2| are carried by the anchor
plate I I.> , Within the drum and positioned to fric
The two servo shoes are therefore between ’25
the adjacentfends of main shoes 25 and 21. It
will be observed that the flat plates (plate 69
-in Fig. 3) straddle. the anchor pins Within the
arms of the yoke and also between the links
33 and 35. These plates on either side of the 30
anchor pins have welded thereto reinforcements
13 and 15 atA their edges.
plates' with reinforcement 13 engages the head of ‘
the yoke 4l between its arms 43. The other edge
with its reinforcement 15 engages the end of the 35 y
web of the shoe (shoe 25gin Fig', 3).~ Plate 39 in
wardly adjacent the hub I3 is formed with forked
ends 11 and 19 turned over the' adjacent edges of
plate 3l so the plates 3l and 39 may reciprocate
axially relative to each other but rotate together ‘n
as a unit. Between thefend wall 3l Iof plate
3| and the region 33 between the forked ends of
plate 39 is located what corresponds to the wheelcylinder of a hydraulic brake applying means.
v45 tionally engage its annular Surface ‘23 are main » Tii'ere is a cylinder 35 within which is a hollow 45
shoes 2,5 and 21, each `having suitable frictional piston 31. A cap 39 closes the open end of the~
lining 29. Pivoted upon opposite faces ofthe piston and contacts the wall 3i on one side and
web of shoe 25 at 31 are links 33 and 35. Limited - the ends of the cylinder 35 and piston 31 on its
vmovement about pivot 31 is afforded by a fric
other side. There is a seal29| carried by the
50 'tion pin 3| carried by the links and extending cylinder and engaging the 'piston to preventleak
through an enlarged opening 33 in the shoe. The age. Suitable hydraulic medium from a onven
ends of links 33 and 35 are recessed to engage tionall master cylindennot shown passe hrough
anchor pin 2l as seen in \Fig. l'and Fig. 3.
One edge of these
A y a conduit 93 in the cylinder 35 through an open
yoke 4I. has arms 43 overlapping linksl 33 and 35
ing 35. It will be understood that a conventional
`and-having similar recessed ends to engager an
brake pedal serves as the instrumentality by l,
’ which the master cylinder actuates the wheel
is to move the plates 6| and 69 diametrically
cylinders. The cylinder 85 is iìxed by fastening
into drum contact. Also there is no need to ad
just the servo shoes `because the travel of lthe
wheel cylinder to accommodate the lining wear of
the servo shoes- is always within the range of
means 91 to the reciprocable plate 69 and to ac
commodate itsV motion a suitable opening in the
anchor plate is shown in Fig. 2.
Springs lSil
are attached to the main shoes and to the sliding movement at thel master cylinder provided by
fiat plates and operate to draw the plates 6|A and . one stroke of the brake pedal.
69 together and to release the shoes from con
tact with the drum.
4 Y
1. In a brake, a drum, oppositely located main
shoes, means to anchor either end of each main 10
shoe, servo shoes between the adjacent ends -of
'I'he operation is as follows: The parts may be
assumed to be in the positions shown when the
brake is not operated. When ñuid is forced into
the cylinder 85 the plates 6| and 69 are forced
the main shoes, means to' force said servo shoes
into contact with the drum whereby the servo
shoes apply the main shoes in either direction
of drum rotation, said anchoring means includ 15
apart, the movements being equalized, shoes 81
15 and 'Il engaging the rotating drum. If the drum
is rotating counterclockwise, the direction corre
sponding to forward travel, shoes B1 and 1l are -
similarly rotated With and by the drum. The
upper edge of plate 69 and the lower edge of
plate 6I with their reinforcements engage the
yokes 4I between their arms and push the main
shoes against the drum, these shoes having an
ing anchor pins and articulating links pivoted
to said shoes and engaging said pins.
2. In a brake, a drum, oppositely located 'main
shoes, means to anchor either end of each main
shoe, servo shoes- between the adjacent ends of
the main shoes, means to force said servo shoes
into contact with the drum whereby the servo
shoes apply the main shoes in either direction of
articulated anchorage through the instrumen
tality of links 33 and 35 whereby the shoes may
25 accurately conform tothe drum surface. If the
drum is rotating in the opposite directiomboth
shoes aresimilarly applied, but in this case, the
plates 6I and 68 engage the webs of the shoes and
drum rotation, said means comprising oppositely
reciprocable plates carrying said servo shoes and
a hydraulic cylinder and piston assembly between
said plates.
3. In a brake, a rotatable drum, a fixed
the shoes anchor by means of the articulated
adjustable yokes.
I claim:
plate, Y anchor ` pins
anchor plate, a centrally disposed hub carried by
said anchor plate, main shoes, articulating links
By these provisions a single hydraulic wheel
cylinder only is required. In either direction of
rotation both shoes engage the drum throughout
their complete arcuate surfaces. All the advan35 tages of an articulated anchorage is present.
The manually applied eil‘ort need be only enough
between the ends of said shoes and said anchor
pins, oppositely reciprocable plates guided by and ‘
' jointly rotatable upon said hub, servo shoes car
ried by said plates, means to reciprocate said re
ciprocable plates .and spread' said servo shoes
to oppositely reciprocate the plates 6| and 89, whereby the servo shoes apply said main shoes
whereupon the rotating-drum will serve to rotate as the rotating drum rotates said plates in unison
the two plates as a unit 'about the central hub, about said hub.
40 to apply the two main shoes.
The construction
iscomparatively simple and relatively inexpensive
. 4. The invention defined by claim 3, said means 40
comprising a hydraulic cylinder between said re
, although exceedingly emcient.l It will withstand ` ciprocable plates.
severe treatment _since so large an area of the
v drum is engaged that distortion of the drum is
45 avoided. Preferably the drum is provided with
5. In a brake, a drum, main shoes therein, servo
shoes between the ends of the main shoes, anchors
cooling ribs as shown in Fig. 2 to prevent the vfor said main shoes at either Vend and means to 45
heat, under the influence of severe frictional en . spread said servo shoes. to contactl the drum
whereby the drumV as it rotates «rotates the servo
gagement, from expanding the drum and lessen
ing the braking vemciency. `
shoes which apply the main shoes for either di-~
Another advantageous characteristic is found rection of drum rotation, said means comprising '
in this brake in that.A it avoids the necessity forl ' a hydraulic cylinder rigid with one of said servo
~ adjustment. A_s the lining on the main shoes
shoes and a piston therein movable relatively
wears away, a somewhat greater rotation of the
thereto and engaging a part rigid with 'the other
servo shoestakes place with no sacrifice in pedal servo shoe.
travel, since >the only purpose of pedal travelI
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