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Патент USA US2106717

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Feb. l, 1938.
A_ B_ CADMAN
2,106,717
BRAKE
Filed Nov. 1, 1935
2/
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2 Sheets-Sheet‘l
INVENTOR"
B @4a/d2' f5. Oar/dwarf?
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ATTORNEYS
Feb. .1, 193s.
A, B, CADMAN '
,l 2,196,717 '
BRAKE
Filed Nov. 1,> 19,35
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f Application November i, i935, Serial No. d?
'
s claims.
(ci. reise)~
that the wrapping action may build up properly
While the venti is susceptible of various
modifications and alternative constructions, I
have shown in the drawings and will herein de
scribe in de
the preferred embodiment, but
it is to vbe .understood that I do not thereby in-v
tend to limit the. invention to the specific form
disclosed, but intend to cover all modiiications
and alternative constructions falling within the
spirit and scope of the invention as expressed
throughout the entire circumference of the ro->
in the appended ci
tateble brake element.'
In the exemplary form shown in the drawings,
the invention is embodied in a vehicle brake of
’fi'his invention reistes generally to friction
brakes of the
rector used on automotive ve
. hicles. end more particularly to a brake of the
type in which a wrapping or self-energizing ac
tion is huilt up when the brake is applied.
ßne obiect of the invention is to provide in a
lb
brake or the bove general character a' novel
means for applying the actuating pressure so
i
The invention also resides in the novel char
actor of the pressure applying mechanism and
„ .
10
the internal expanding type having arotatable
the construction thereof which permits the brake » friction element in the form ci a drum 9 rotat
ably supported from a vehicle axlel iii. The non
» to he actuated by more than one operator. Ä
Another object is to provide a self-»energizingv
brake in which the pressure for initiating the
self-energinng action is applied in e. manner
such es `to avoid the possibility of the non-ro
tatable braking element becoming wedged against
the intended _self#energizing movement.
Still another object is to provide a self-ener
ein brake in which the point of maximum
pressure between the engaging friction surfaces
is shifted circumferentlally as the surfaces wear
' whereby to provide for more even distribution
of wear.
A further object is to provide in a ,self-ener
sizing brake a novel means for preventing lateral
30
shifting of the «non-rotatable braking element
when the latter isin engagement with the drum
rotetable braking member is of the band type
comprising a flexible strip i i oi’ metal to which are
riveted or otherwise secured
ents i2 of suit
able friction material. The band encircles and
is supported for longitudinal movement by means
including a lug i3 on a non’rotatable `anchor
plate it which ciosesthe open end of the drum.
ln the present instance, the band encircles the
entire internal cylindrical surface of the drum
with its ends
sed adjacent each other and
carrying rigid brackets iii _' arranged to abut
againstoppcsite sides of a stop lâ integral with
and 'projecting inwardly from the anchor plate i
is.
`
In the Abreites illustrated, brake actuating'force
is applied to the ends of‘the ‘band by either of ‘
two. independently operable actuators, one of
Other 'objects and advantages of the linven- A which is a power operator and the other of which
tion will become .apparent from the following is adapted for manual operation. The manual
surface.
.
`
'
°
»' detailed description taken in connection` with the
accompanying drawings, in which
.
Figure 1 is a sectional view of a vehicle brake .
operator comprises an equalizing bar adapted for
bodily outward movement and having its’` op
posite ends connected with the ends of the band
embodying vthe features of the present invenf in a- manner lsuch as tofpermit freedom of move
tion, the section being taken along the line I--l ment of one of the band ends away from the
40
of Fig. 2.
.
`
stop I6 when the actuatingr pressure -:is applied.
'
Referring now to the form shown in Figs. l.'
Fig. 2 is a fragmentary sectional view taken
along the line 2_2 of Fig. 1, the parts being in 'to 4, the‘equalizing bar includes a lever I1 piv
oted on an eccentric stud Il rigid with a shaft
brake-released position.
'
.
Fig. 3 is an enlarged view of a portion of Fig. I8 which is journaled in the anchor plate Il and
' 2 showing the parts in brake-applied positions. carries an external crank arm 20 which may be
Fig. '4 is a fragmentary sectional view taken oscillated through the medium of a link 2| in
along the line i--l of Fig. 3.
'
-
Fig. 5 is a sectional vi,V w similar to Fig. 1 show
ing a modiñed form of brake.
50
`
Figs. il and 'I are fragmentary sectional views
any -preferred way. Projecting laterally from the
lever i1 are arman ‘which carry pins 22* on
which Pairs ofêapaced Vrollers 23 are held by «cot
ter pins 28e. The rollers 2l bear against sur 50
taken along the line 8-6 of Fig. 5 and showing
faces 24 formed on the brackets il and extendi
the parts in brake-released and brake-applied
ing in a generally circumferential direction. '
positions respectively;
` Owing to the eccentrlclty of the stud I8, it will
Fig. 8 is a fragmentary section taken y¿long _' be observed that when the operating lever 2B is
56
siennes-401mm?.
swungin either direction from the normal brake
2,106,717
released position shown> in Fig. 2; the equalizing
wardly projecting radial ribs 35 are secured to`
bar formed by the lever I1 and the arms 22 will
be moved' bodily in an outward radial direction
the magnet and are adapted to bear in all an- '
so that the rollers 2l acting through the medium
of the brackets I5 will press the end portions of
the band outwardly against the drum. Assum~
ing that the drum vis rotating in a clockwise di
rection, the friction force applied to the band by
the drum when the segments I2 contact the in
formed by a washer 36 mounted on a bolt 31
ternal drum surface will force the end IIb of
the band toward the stop I4 and carry'the end
II‘ away from the stop as shown in Fig. 3. ' As
a result, a wrapping or self-energizing action will
be built up throughout the length of the band
thereby increasing the eii'ectlve braking action in
a manner well understood in the art. When the
actuating forcev is-relieved, contractile springs 25
~ acting between the band II and the arms 22 op--
erate to return the equalizing bar to the normal
brake-released position shown in Fig. 2., The
parts operate in the same way when thercrank
arm 2l is actuated with the drum rotating in a
counter-clockwise direction. In this case, the.
guiar positions of the magnet against a shoulder
which extends through the anchor plate and
carries a spring 38 pressing the washer against
an adjusting nut 39.
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'
"
.To insure more even wearing of the friction
material surfaces and to avoid wear on the band
supports -such as might be occasioned by lateral 10
weaving of the band under the action of spiral
grooveswhich sometimes form in the drum sur
face, means is provided at circumferentially`
spaced points along the band forr holding the
band against lateral movement while at the same
time permitting of the longitudinal movement in
cident to application of thebrake. One of these
means comprises an elongated lug 40 rigid with
the bandV I I nearthe center thereof and seated
in a groove 4I formed in the lug I3 of the anchor 20
plate.
`
The guide means at the ends of the band com
prises a rib 42 rigid with each bracket l5 and
band end I Il anchors against the stop I9 and the upstanding `from and extending longitudinally of
end -I I b moves with the drum away from the stop. ‘ the bearing surface 24 between the spaced sec
In the movement of the actuated end 'of _the tions of the rollers 23. Since the lever I1 is held
band away from the stop I9, one of the rollers by the shaft I9 and the nut 43 against axial
23 rides along >the surface 24 of the bracket.' To movement, the ends of the band will also be held
insure-freedom of movement of the actuated end against lateral movement by virtue of the en- of the band and avoid the possibility of a reduc'
between the rollers 23 and the ribs 42. 30
tion in the effective braking force by a wedging gagement
In the modiñed‘ form of brake shown in Figs.
of the band end and bracket between the drum 5 to 8, the parts are numbered to correspond to
and the active roller 23, the surface 24 is dis
Figs. 1 to 4, and the equalizing bar is in the form
posed at _a small angle 21 relative to a tangent 28 of a lever 44 pivotedv on a pin 45 on the bracket
to the roller 23 at the point of contact between I5 on one end of the band. The free end 45 of
this roller-and _the surface 24. /By virtue of this the lever isformed with a surface 41 which bears
arrangement, the roller will continue to move against a roller 48 on a pin 49 carried by the
outwardly as the band end continues to move other bracket I5. As inthe case of the surfaces
away from the stop. In thisgway, the possibility’ 24, the surface 4l is inclined at an angle 50 rela
of the movable band end becoming held against tive
to a tangent 5I solas to permit free move
circumferential movement by the actuating ment of the band end Il* away from the stop I5 40
mechanism is effectually overcome and the ne
when the brake is applied withA the drum rotat
_ lcessity for forming the surfaces 24 and locating
ing in a clockwise direction. By virtue of the
them with a high degree of accuracy in manufac
bearing engagement between the roller 48 and
45 ture of the brake is avoided.
,
the surface 41, movement of the band end Il!"
In the present instance, the power actuator away from the stop I6 when the brake is ap
for the brake is of the momentum type compris
plied with the drum rotating in the opposite di
ing an annular magnet ring~29 mounted to os
rection is also permitted.
cillate on a bearing 39 on the anchor plate I4
The operating shaft I9 of this brake carries
50 and adapted when energized to attract an arma
short crank arm 52 on which is supported a 50
ture ring 3| rotatable with the drum and supé \a
roller> 53 bearing against a surface 44 interme
ported for yielding axial movement by the in
diate the ends of the lever‘44. Thus, when the
turned flange 32 of thedrum. It willv be appar-,7 lever
20 is moved from the brake-released posi
ent that when the magnet winding 33 is ener;M tion (Fig._6)
in the actuated position (Fig. 7) , the
55 gized, the magnet will grip the armature and?
equalizing lever 44 will be moved bodily in an
turn therewith. This movement is communicated outward radial direction thereby distributing the
to the lever I1 through the medium of a stud actuating force to opposite ends of the band. If
34 projecting rigidly from the b_ack of the magnet the drum is rotating in a counter-clockwise di
into the bifurcated free end of the lever I1. The
resulting oscillation of the lever I1 about 'the
stud I9, which at this time remains fixed. ap
plies an outward pressure to one end or the other
of 'the band depending on the directionof os
` cillation of the magnet. This results in expan
sion of the band in the manner above described,
it _being apparent'th'at after the clearance be
tween the band and drum have been taken up..
slippage »occurs between the magnet and arma
ture,4 the -brake being held set so -long as the
70 magnet remains energized. When the magnet
is deenergized. the springs 25 act to‘restore the
band, the lever I1l and the magnet to the normal
brake-released position.
A
‘
To maintain the magnet. ring 29 in proper
axial position relative to its bearing support, out
rection, the band end I I b will mo've away from the
stop I9 as indicated in Fig. 7, the surface 41 rid 60
ing along the roller 48. When the actuating force
is relieved, Vsprings 54 acting between the brackets
I5 operate to restore the parts to their released
position shown in Fig. 6. `
In -the modified form of brake. the oscillatory
movement of the stud 34 on the magnet is com
municated to one end or the other of the brake
through the medium of levers 55 pivoted on studs
58 carried by the stop I6 and formed intermedi»
ate their ends with cam surfaces 51 which bear
against the flattened ends of the band brackets
I5. Thus, when the magnet is energized and the
stud 34 moves out of brake-released position, one
or the other of the levers 55, according to the di
i
2,106,717
rection of rotation of the drum, will be moved to
expandthe band.
»
`
Inbrakesvof the character above described, it
will bey apparent that the wrapping or self-ener
gizin'g» action builds up progressively throughout
the length of the band beginning at the point of
lapplicationy of the actuating force.
As a result,
the radial pressure between the band and the
drum increases progressively along the band be
ginning at the point of application of the actuat
ing force, the maximum radial pressure being 1ap
plied at the'anchored end of the band: conse
quently there is a tendency for the friction mate
iimiting the outward radial movement of the
anchored end of the band after the friction seg
ment l2 carried by this end has worn down to
a predetermined permissible degree. In the pres~
ent instance, this means comprises a pin ät pro
jecting rigidly from the surface of the stop i@
against which the band bracket it abuts into a
recess '59 in the bracket.~ The recess is elongated
in a radial direction as shown in’Figs. 7 and 8, so
that as the friction material l2 at the end of the
30 band wears off, ¿the wall t@ oî the slot 5@ moves
closer to the pin ät. LYW'lfien the two engage, iur
ther outwardradial movement of the band end
will be prevented withthe result that in subse
quent applications oí‘ the brake the point of
maximum pressure application will be shifted
along the band away from the stop I S. In this
way, wear on that end portion of the band which
anchors when the brake is applied with the vehicle
moving forwardly is distributed more evenly
40 thereby prolonging the service life of the band
segments. Preferably, the bracket i 5 on the other
end of the band is also formed with a slot 58 so
' that the position of the band in the drum may be
reversed after one end has worn oif to the per
missible degree.
'
-
l I claim as my invention:
l
l
l. A friction brake comprising', in combination,
a rotatable drum, a fixed stop disposed adjacent
the internal drum surface, a friction band extend
50 ing around the internal surface of said drum withv
its ends disposed on opposite sides of and nor
mally drawn into abutment with said stop, a lever
swingable about a pivot adjacent said drum and
55
disposed substantially radially when in brake
released position, oppositely projecting arms rigid
with said lever intermediate the ends thereof and
having bearing engagement with the opposite
end portions oi' said band whereby one or the
other of said end portions will be pressed out
wardly against the drum according to the direc
tion of oscillation of said lever, an operating mem
ber for said lever pivotally connected to the tree
end thereof and mounted for oscillation about the
drum axis, and~ auxiliary actuating means oper-_
able to shift the pivot of said lever outwardly tc
ward said drum surface.
'
2. A friction brake comprising, in combination,
a rotatable drum, a ñXed stop- disposed adjacent
theinternal drum surface, a friction band extend
ing around the internal surface of said drum with
its ends disposed on opposite sides of and normal
ly drawn into abutment with> said stop, a'lever
swingable about a fixed pivot disposed adjacent
said drum, contractile springs acting between
said lever and the end portions of said band to
'
3
released position, means_»on said lever having
_
3. A friction brake comprising, in combination, 10
a rotatable drum, a ñxed stop disposed adjacent
the internal drum surface, a friction band ex
The present invention contemplates prolonging
the service life of the braking element by shifting
the point of maximum radial pressure circum
ferentially along the braking element as the lat'
To this end, means is provided for
’
bearing engagement with the opposite end poi-_.
tions of said band whereby one or the other of
said end portions will be pressed outwardly ina
generally radial direction against the drum ac
cording tothe direction of oscillation of said
lever, and an operating member for swinging~ said
lever about said pivot.
rial on the latter end to wear off more rapidly.
ter wears.
`
maintain the lever substantially in a radial brake
tending around the internal surface of said
drinn with its ends disposed on opposite sides of
and normally drawn into abutment with said 15
stop, a lever swingable about a pivot supported by
said stop adjacent said drum and disposed sub--'
stantially radially u'vhen'in braise-released posi
tion, oppositely projecting arms rigid with said
lever intermediate the ends thereof and having
bearing engagement with‘the'opposite end por
so
tions oi said band whereby one or the other of
said end portions will be pressed outwardly against
the drum according to the direction of oscillation
of said lever. and an operating member for said
lever pivotally connected to the free end thereof
and mounœd for oscillation about the drum axis.
d. A self-energizing friction brake having, in
combination, a rotatablel drum, a ñexible band
extending around the internal cylindrical surface
of said drum, an anchor for one end of the band,
means to press the other end against the drum
surface whereby to cause a self-energizing action
to be built up through the band. and means to
limit the outward movement of the anchored end 36
of the band after the friction surface thereon has
worn down to a predetermined extent whereby
to shift the point of maximum pressure applica
tion away from said anchor end.
I
5. A self-energizing friction brake having, in 40
combination, a rotatable drum, a fiexible band
extending around the internal cylindrical surface of said drum, a stop interposed between
adjacent ends of said band, actuating means as- ‘ '
sociated with said ends to press one end or the 46
other against said drum surface according to
the direction of drum rotation and cause the
other end to anchor against said stop, interen
gaging surfaces on said stop and one end of said
band acting to limit the outward radial move
ment oi' such end and thereby shift the point of
maximum pressure application away from said
end after the surface of the latter has been worn
to a predetermined degree, and means on the
other end of said band adapted for interengage 55
ment with said stop in a similar way when the
position of the band in said drum is reversed.
6. A self-energizing friction brakel having, in
combination, a rotatable drum, an elongated rel
atively dexible element extending along the in-* 60
ternal drum surface and carrying a layer of
friction material, means for anchoring one end .
of said element against circumferential move- y
ment in‘one direction, operating means by ‘which
the other end portionv may be pressed' 'against
' said drum surface to initiate the building up of
e
a self-energizing mtlon throughout said element,
and means associated with the anchored end
and operating to permit a limited „outward radial
movement thereof less than the thickness of said 70'
layer whereby to shift the point of maximumv
radial pressure along said element away from
said anchoring means.
7. Ascii-energizing friction brake having, in
combination, a rotatable drum, an elongated rel
4
2,100,717
atively tiexible element extending along the in
ternai drum surface. a stop against which one
end of said element abuts when the element is
expanded against said surface, and interengaging
Ul
means on said stop and said anchored end act
ing to limit the outward radial movement of said
anchored end after the friction surface thereof
has been worn down to a predetermined degree.
adapted to be pressed against the -drum surface
upon expansion of said member, means for ex- l
-panding said member, and means operating upon
wearing oi! oi said layer to a predetermined de
gree at one point around the drum to positively
prevent 'further outward movement of said mem
ber at such point whereby to'cause distribution `
of the eßective expanding pressure to an adja
8. A friction brake comprising, in combination,l cent portion oi said layer spaced circumferen
point.
10
a
rotatable drum. a relatively ilexibie member tiaily from
10
extending around vthe internal surface o! said
ADDI BENJAMrN CADMAN.
drum and carrying a layer of friction material
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