April 17, 1956
J. H. GEIGER
2,741,896,
APPARATUS RoR HYDRAULIC BRAKE SYSTEMS
Filed May 221 1951
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JNVENTOR.
JOHN H. GEIGER
lATTORNEY
, United States PatentQf ice
Patented Apr. 17,1956
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i ` Figure 2 of the drawing illustrates partially in> cross seca
ytion a second 'modification ofthis invention.` ,
Figure 3 of the drawingillustrates a third modification
of `this invention.
Figure 4 of theA drawing isa cross section‘taken on line>
" 2,741,396
I APPARATUS FoR HYDRAULIC BRAKE SYSTEMS s _
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of Figurel'Z.l
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In accordanceiwith this invention,»th`ere is provided
'a vmaster»cylinder-‘andv brake pedal operating Vmechanism
John H. Geiger, Kimmel, ma.
s Application May z2, 19s1,seria1lN0. 227,650 ~
17 claims. (ci. str-54.6)
comprising ‘the master cylinder 101(Fígure l)„a‘bracket
10 `11, a foot pedal operated lever 12, and an operating arm
13. Bracket 11 may be iixed to the master cylinder 10 by
means of bolts 16 and 17, which screw into the master
cylinder casting as illustrated in Figure-1 of the draw
ing. The foot pedal lever`12 may be pivoted at 4its lower.
end of the bracket y11 by means of a suitable bolt 18 am
chored to` the outer endof the bracket. Bolt 18 is in
' This invention relates generally to hydraulic brake sys
tems and more particularly to a master cylinder and a v
i mechanism for operating it.
tended to provide apivot point lying on an extension
of thev~ longitudinal axis of the` master cylinder. The op
According to conventional practice, passenger auto
erating> arm 13 may Vbe pivotally mounted on the lever 12
mobiles andlight or medium trucks are equipped with
mechanical or hydraulic brake systems. Heavy 'trucks 20 by means of a bolt 19, mounted tor rotational movement
in lever 12 in conventional fashion. Bolt 19 may be
’ provided with athreaded bore 20 for adjustably receiving
s are equippedY with air operated brake systems, but such
systernsare not economically feasible for use in small or
the threaded `outer end 21 of arm l13 and maybe locked
'medium sized trucks. Mechanical brake systems have
to bolt 19 by means of lock nut 22. Theoperating arm
been found to be generally inadequate in medium sized
trucks, principally because it is diiiicult and sometimes 25 may be arranged at its inner end to `engage the pis~
ton 23 which is’ sli‘dably mounted within cylindfer~24 of
impossible for'the truck driver to apply suliicient pressure f
master cylinder 10. The piston 23 is provided with a
to the brake pedal to obtain the braking power which
conically recessed end for receiving the rounded end V25
is necessary to meet emergency conditions. Hydraulic
’ of arm 13. Thus, theportion 27 of lever 12 together
brake systems which include the conventional type of
master ,cylinder are also inadequate'inlmedium trucks 30 with operating. arm 13 formsa toggle joint linkage be
for the same reason. In the prior art `hydraulic systems, A
special master cylinders, comprising compound cylinder
arrangements, have been devised for increasing the ef~
¿fective braking pressure as applied by the truck operator.
Such systems, however, are subject to the objection that
tweenfthe pedal lever 12"and the piston23 which is mov
able into alignment with the longitudinal axis of master
cylinder 10». Lever arm 13 is provided with a boot 28
' which `is conventionally mounted over the end of cylinder
35 ` 10 so‘ that dirt and other debris may be prevented from
they are exceedingly costly and, because of complex struc
ture,osubject to certain faults such as leakage and other
_types'of failure which necessitate frequent repair and
\- expense.
entering the cylinder.`
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s The -master cylinder. 10 comprises a casting which `is
formed to provide a reservoir 30 having a filler plugl 31.
Reservoir 30 may be connected with the master >cylinder
Accordingly, it is the principal object of this invention 40 24 by means of a` breather port 33, which permits ñow
of brake iluid between the reservoir and the cylinder 24
to provide'a novel master cylinder and foot pedal operat
as the piston 23 moves forward and back, and a replenish
ing linkage for hydraulic brake systems.
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f Another object of this invention is to .provide a novel
ing port 33a which connects thereservoir with the cylin
master cylinder for hydraulic brake systems.
der 24 when piston 23 is fully retracted.
. i Stillanother object off this invention is to provide 45
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"The master~ cylinder casting kis also provided with a
compensating cylinder 34, the purpose Yof which will be
described subsequently. `This vcylinder includes a cap
35 which `is threaded> at 36y to the master Scylinder cast
a novel brake pedal and connecting linkage for operat
ing the master cylinder of a hydraulic brake system.
`A `still further'object of this invention is to provide
ing. vWithin the` cylinder 34 there is provided a piston
a brake pedal and connecting linkage for operating ahy
:38
and a cup leather l39, both of which are normally
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-draulic cylinder having a mechanical advantage for mul
tiplying the operating pressure applied by the truckV ymaintained in the position shown in Figurev l by means
of a spring V40. The compensating cylinder _isprovided
driver.
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with a port 42, which permits the flow .of brake ñuid
Still another object of this’invention is to provide _a
between reservoir 30 and cylinder 34 whenever the piston
master cylinder for hydraulic brake systems which is
adapted to co-operate with a mechanical linkage of the 55 -38 is moved upwardly or downwardly. There is also pro
vided >a p_ort 43 and a port 45, both of which commu
nature of a toggle joint or other linkages having high me- v
nicate with the cylinder 24 to permit the flow of brake
_ chanical advantage.
fluid to“ and from cylinders 24 and34.
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In accordance with- this invention there 1s provided
' `Piston '23 is provided ‘Y with a first cup leather 47
a mechanical brake operating linkage of the type which
sealing the piston with respect to thek cylinder so
provides a certain mechanical yadvantage and has `a lim 60. for
that’forward movement of the piston creates pressure
ited effective operating motion together with‘a hydraulic
‘ within the cylinder which maybe transmitted to an auto
master cylinder which is adapted totake up the slack rin
motive hydraulic brake'system (not shown) through the
the brakes regardless of the degree of wear of the brake
"opening 48. The rear end of piston 23 includes a head
shoes and said limited motion.
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portion 49 to which istitted acup leather or washerStl,
For a better understanding of the invention, together 65 which
seals the rear end of the piston with respect to the
with other and further objects thereof, reference is made
cylinder
to prevent the escape of brake i'luid from cylin~
to the following description, taken in connection with the
- der 24. For returning the piston 23'an`d the‘brake-lever
accompanying drawing, and its scope will be pointed out
12 to' the normal inoperative position there isv provided a
_in the appended claims.
70 spring 52, which rests between the outer end of cylinder
’ In the accompanying drawing:
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24 andfthe cup leather 47. Piston 23 is prevented from
’ Figure 1 of the drawing illustrates in cross section a
preferred embodiment of this invention.
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being'withdrawn 'or ejected from cylinder v24 by means of
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a wáshen‘SS, which may be retained in position by an
take up the slack in the brakes at some time during the
""initiabmovement ‘of‘the brake pedaland'regardless ‘of
'expansion"ring"56"‘resting" within ' 'an' ~annular ”sl`ot" in' 'ac
cordance with conventionaly practice.
the amount of wear on the brake shoes.
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Then, at the
From the foregoing description it will belapparent-that
time that the mechanical linkage consisting of arms 13
the ‘forward movement otpistonl23 ÍsJimit'ed because of 5 and 27 is at a position where the mechanical advantage
the fact that "it reachesïts' -outermost' foriivar'rd` position
is approaching a maximum, the brake shoes are always
’Whenp'ortion' 27 of lever' Y12 and arm' 13 arein alignment
applied to the brake drums despite varying degrees of
with one another. Therefore, unless l_special provisions
wear.
‘are'ma'deg ‘the maximum forward movement .ot piston 23 '
*Y Az-di?’ierent .modification of- 1 the inventionr-is . disclosed
.will not move the brake shoes into `contact with" the brake
in Figure 2 and like reference character‘s'are4 utilized Vfor
designating parts corresponding'to‘th'osev‘of Figure l. In
îdrnrns' after'the" brake Íshoes. become Worn to a certain
" degree. To"the end thatl the `brake'shoes may be moved
steady of. thetoggle joint betweenthe.. brake pedal .and the
piston `v'of the master cylinder there is providedY a cam 60
having a cam=surface'tofflsuchxcnrvature that increased
_master
'into’g'contact
'cylinder
witlr’the
of 'thisinvention
brake drums-isvin_spite
designedof.togapplyß
wear,".the '
limited ’pressure 'to‘ the >brake system' during initial, move
"me'nt ‘ofi the‘lever' 12..and .until portion" 27 .of lever- 12 vis
moved :to within. approximately V15 degrees of .alignment
“With? the longitudinal. axis of master cylinder 10. Ports
"43 and" 45 controLñow of _lìuid` during this initial .move
mechanical advantage is obtained when the brake pedal
approaches the limit of its operational movement. A
cam follower 63 co-operates with the cam surface 61
and is mounted on the .end of an _operating Ãarm.64. by
meansv of -’the'follower;'riiouriting'6fí >Arm'lî4l may be
->thread'edinto mounting '65 and locked withlrespect _there
to by lock nut 66. For guiding'arm' 64"there` is provided
ment ’and ‘are situated so'that cup lea-ther'47 will not
coverïthem until portion 27 is in?the >15 degree position.
`Port 43 may be of larger fdiameter Athan port '4S whereby
an >apertured strut’ 67 extending" b_etween.the side.' walls
-"the‘rate‘oi" ñow ’of‘ñuid into cylinder 34 is decreased when
of' bracket'Í-ìl. "For preventing .access -of'for‘eign 'matter
`port"43'is ‘closed by. cup leather`47. VVThis provides a
.tomaster cylinder '10‘there is provided a boot' §68 which
'cushion-like'effect on `the motion 'of the brake pedal. The 25 may include an aperture. (nlot"shown)”for accommodat
'piston 38 and spring 40 co-operate with. ports .43 and
Vifngístrut' 67 and‘ be conventionally mounted between'the
"45“'to further control .the pressure in .cylinderf 24. since
`e?idl 69 'of "master cylinder '10. and’the.mounti_ng 'mem
l spring 4t) is designed, in etïect, to create a back pressure
"ber- 65.
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.inïcylinder 24 sufficient to insure `that the brakeshoes will
In this Vmodification of the invention"there..is_ pro
'have contacted' theldrums when cupI leather.f4’7f..ñnally 30 'videda ‘pvoppet valve'in'ste'ad of a cornpensating'c'yliiider
'covers port í45.
"for controlling îthe flow of brake"iluidduringithdtime
` The modification ofthis invention which has been '.de
Ith‘at`thefbrake shoes _are' being ."tak'en' up. ‘ The 'poppet
_'scrib‘ed in Figure 1' of the drawings operates. asfollows.
vval've‘consis'ts of a ball'70,'seated in a port 71', and"mainvWhen the brake 'lever 12`is depressed,` its initial move
tained inlposition by_'means`.of a spring`73’which >is in
ment' does not multiply except to a limited» extent the 35 itu‘rn'ih'eld'injpositionqby‘rneans of an adjustable :screw
`.pressure which is impressed by the operator’s foot on the
'.75 mounted in a 'plug"76. threaded to the reservoir. ""By
"brake pedal; but as the lever travelsv.to...the right, „the
rotatifngl the 'screw‘ 7.5.' 'the' tension on' Yspring'f '73. 'may' 4’be
"mechanical advantage of arm 27f.and.the. operating arm
‘adjusted to, in turn', adjust'the pressure Which‘is' required
"13’increases asthe angle increases between. arm'..13 and
'to'unseat'ithefball‘70. ."Port‘ 71 'corresponds‘withf port
the portion27 of the lever 12. Piston 23 ’moves foivvard 40 '2255 'ofÍFigure‘l and accomplishes‘the-same'purpose.
’under pressure of. arm 13 and brake lfluid llowslhrough
`‘Asiri' the'case‘oñ'the lirst mo'diñcation of this' invention,
‘opening ‘48 into‘the’ brakesystem forinitiallytaking up
when ‘pressure ‘ is ' initially 'applied "to "the" fot'ot pedal,` fthe
cam 61.moves operating arm 64 and .therewith pis'tori"23
'the slack between the brakeshoes and the brakefdrums.
.The initial movement of piston 23 creates arelativÍelylarge
llow Tof oil at a relatively low pressure by reason vof .the
>fact‘that .brake fluid is permitted to Í-i’lowv` through. the
auxiliary port 43 and the compensating cylinder .port 45
vforward within the cylinder 24. The. pressure increases
' within the cylinder 24'"_taki'ng up'ïthefsiack.of'the'brake
.shoes as .in the modification” described in Figure 1. "~ This
pressure is determined‘byfthefstrength’and adjustment of
„spring 73 'ort"the.poppet valve‘ '70.' This springs'ho'uld> be
until arm. 27 reaches its 15 degree position as explained
-previously. During'this inítiahmovement ot .piston 23,
only enough pressure is createdtq Apick _.11p..Í.the.sla`ck...in
" the brake’shoes, 'after which the pressure .necessarily-in
creases within themaster. cylinder .sú?îcientlyto over
` adjusted vto >crea'te'jorily- süfñcient pressure'td 'take‘up‘ the
50 slack between -the ¿brake shoes andtthe'brake‘idriim.
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. Port >71 l is situated '. so i.' that "fthe Vcup"fle'àther VA"47
covers .the"port'T/l‘after‘approximately‘:25’ degress of
movement “of cam ‘60,’ at’v whichv time maximum pressure
' come the pressure exerted `byfspring` 40, whereby piston
v‘38 and cup leather 39 move upwardly. .-.At-. this. point oil
.ís` `cre‘atedffbyY ‘reason -orìthe *fact L'thatl` the‘ñu'id 'can‘ no
.' is permitted to' ñow through the port` 42 into thereservoir 55 ' longer`~ flow into'the 'reservoirîâtl- and' also 'by reasonì'of
î30£`whereby only limited back .pressure iscreated within
the .fact that .the .lever l2. has moved the carn ’surface
the cylinder 34. . Piston 23 eventuallyclosesthenport-43
“61' Lto." 'the point` "where ^ it: ‘provides’ 'l the A'irra'xi'murn‘’rne
'at’which timefflowbf brake l?luid is .restricted -. to .the
port 45 so that there is a marked .decrease in Yrate of. flow
and a corresponding increase ,in pressurewithimthemas 60
ter cylinder. Thus, the, pressure.increasesonfthe brake
.,shoesto initiate .ellec'tiveapplicationof theebrakes. f-Pis-Y
ton‘ 23 .continues to moveíorward .until port 4Szis closed,
at whichtirne the pressure withinthemaster,cylinderand
within' the brake >system increasesy at a .veryzliigh Tate. .#«At
this. time> the arm. 13 and ¿the arm- 27 are. at arelatively
-large’ angle- to one .another whereby.theimeehanical-»ad
vantage .of the .toggle > joint'Y becomesY veryfgreat». so- -that
.- pressure .on >the foot .pedaL ismultiplied «as muchsas twenty
...brakes by:reasonf.of„the-fact'-that- theipiston haszprogressed
» beycindpm‘t 45 to theipointwhereß?ul‘i >pressuresis exerted
. .onnthe brakesystem. .Thus-.the ports AìandMSapei-mit
_. a. limitedñow .of =;oil.intof.theœompensating _cylinder »34,
.The modification illustrated_..in Figure' 3‘ïof’thedraw
’j_n'gs' isïsirnilar'to th’at‘ illustrated itr'F-igure"2,f'except-^that
‘ Vprovisions. are ‘made ‘for preventing'fracture> 'of‘ the cup
VAleather. " This `modification.‘may 'include either-of me
’ "chani'cal 'linkagesofFigure 1 ora-2. It has been *found
’ bY-experiment"that"pressure"'within the` cylinder‘some
"timesïises'to'such a-‘point thatfwhen‘the Icup'leather is
opposite the equalizing port"71,"fo1' example,"theI pres
sure'is s‘úñîcient to 'fracture .the cup leather and allow
70 >leak/age. ‘Accorditiglyg >inlthe `modiiication oiïfígurc 3
.fofthef.drawingslthelequaliziiig port 71.is situated so -the
cup'- leather' 47 moves beyond- equalizmg .port '.71fdùripg
the initial and 10W pressurepartof Íthe..st'roke.~.ofrthe
¿.piston. . There is provided. acompen'sating -cylinder; sími
.but .at....the- same...tirne, suñ[email protected] 75 lar in some respects-to thatfslnowmin> Eigure Abithe
'9,741,896
drawings having a port 80 which is beyond the outerA ex-
comprising a master cylinder,` aA piston therein,- pedal oper
tremity of the stroke of piston 23. The compensating
i ating means connected to said piston comprising a pedal
lever pivoted at one end thereof and a pressure arm con
nected between said., lever and said piston atfan obtuse
cylinder differs from that shown in Figure 1 in that there
is provided a stop 81 which is threaded to the cap 35
and can be adjusted and locked by means of thelock nut
82. During initial forward movement of piston 23 pres- '
sure is created as` described in connection with Figure
angle to said lever to form a knee of a toggle joint whereby _. _
movement ofvsaid pedal lever moves said lever and arm ,I
» into a straight line relationship and therewith' said piston
vfrom -a retracted position to a >forward position, >said mas
ter cylinder comprising a reservoir, a valve between said
2, and after port 71 is covered and the slack ofthe brakesv
is taken up, piston 38 and cup leather 39move upwardly
as the pressure in cylinder 24 increases until suchtime
`reservoir and said'cylindcrfor providing a limited, brake
operatingpressure zoneV during advance of said piston,
as piston 38 engages with the stop 81. Oil can no longer
and; a compensatingv cylinder connected to said master
flow through port 80 and therefore maximum pressure is
cylinder beyond themostforward position of‘said piston
» applied to the brake shoes, This occurs, at the time that
`>and comprising a piston in said compensating cylinder,
the toggle linkage or thecam is providing the maximum
mechanical advantage.A
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for creating greater brake »operating'pressurm ‘and an .
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adjustable means in the path of said compensatingcylinder
From‘the foregoing description it is apparent that there
piston for limiting the Imovement thereof to create max
is provided in accordance with this invention a simple
brake operating mechanism having high mechanical ad
imum brakefoperating pressure.
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4 4. Brake control `apparatus for hydraulic brake systems
comprising a master cylinder, a piston therein, pedal op
vantage with simple and` economical structure. Clt should
be further noted that this mechanism always applies the `
brakes after the same angle of movement of the pedal.
Even though this is true, the slack is always taken up in
the brake shoes before the pedal reaches its brake appli
cation angle of movement.
v erating»meansxconnected >to said »piston comprising a pedal
lever pivoted at one end thereof and a pressure arm con
nected between said lever and said piston at an obtuse>
angle to said lever to form a knee of a toggle joint whereby
movement of said pedal lever moves saidlever ’and arm
`While this invention has been disclosed as includingy
intoy a straight'line :relationship and therewith said piston
from aretracted position tota forward position, said mas
ter cylinder comprising a reservoir, a 'replenishing port
Aof elements may be substituted by those skilled in the
connecting’said cylinder and said reservoir slightly in ad
art. `For example, there are other forms of mechanical
linkages which may provide sufficient mechanical advan 30 vance` of the retracted‘position of said piston, a spring
biased valve in advance of said replenishing'port for pro
tage in accordance with the inventive concept. Other
viding a limited, brake operating pressure zone during ad
forms of'pistons, cup leathers, poppetvalves and compen
vancevof said piston'beyond said replenishing port, and
sating cylindersr will also be obvious to those skilled in
a compensating cylinder connected to said master cylinder
the art.
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While there has been described what is at present con~ a VV~beyond the most forward position of said piston and com~
, certainV forms of elements which make up the complete
assembly, it should be clearly understood that other forms
,-prising a piston in l said compensating cylinder, a com»
sidered the preferred embodiment of the invention, it will
pensating cylinder port for connecting said master »cylin
der and said compensating cylinder for creating greater
be obvious to those skilled in the art that various changes
and modifications may be made therein without departing
brake operating pressure,'and an adjustable stop in the
path of said compensating ‘cylinder piston for limiting the
from the invention, and it is, therefore, aimed in the ap~
t pended claims to cover all such changes and modifications `
movement thereof‘to create maximum brake operating
as fall within the true spirit and scope of the invention.`
I claim:
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pressure.
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5. » Brake control apparatus for hydraulic brake systems
l. Brake control apparatus for hydraulic brake systems
comprising a master cylinder, a piston therein, pedal op
comprising a master cylinder, a piston therein, pedal oper
ating means connected to said piston comprising a pedal 45 erating means connected to said piston comprising a pedal
lever pivoted at one end _thereof and a pressure arm con
lever and a pressure arm connected to said piston to form
nected between said ,lever and said piston at an obtuse
va knee of a toggle joint whereby movement of said'pedal
, angle to said lever to form a knee of a toggle joint‘whereby
lever moves said lever and arm into a straight line rela
»movement of said pedal lever moves said lever and arm
to a forward position, said master cylinder comprising a 50 into a straightline relationship and therewith said piston
from a retracted position to a forward position, said master
l >compensating cylinder having'a compensating port, means
cylinder comprising a reservoir, a replenishing port con
for controlling llow in said port and `providing a limited,
tionship and therewith said piston from a retracted position
Í brake operating pressure zone during initial advanceof
said piston, said piston being movable beyondisaid port
to stop ñow of ñuid therethrough and to create maximum 55
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brake operating pressure.
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necting said cylinder and said reservoir slightly in advance
'of the retracted position of said piston, _an equalizing port
`in advanceof said replenishing port, a spring biased valve
for controlling flow` in said equalizing port and providing
a limited, brake operating pressure zone during advance
v2. Brake control apparatus for hydraulic .brake `systems
of said piston between said replenishing and equalizing
comprising a master cylinder, a piston therein, pedal oper
ating means connected to said piston comprising ay pedal
ports, and a compensating cylinder connected to said mas
lever pivoted at one end ,thereof and a pressure arm con-4 60 ter cylinder beyond the most forward position of said
piston and comprising a spring biased piston in said corn
nected between said lever and said piston at an' obtuse
l pensating cylinder, a compensating cylinder port for con
Yangle to said lever to form a knee of a toggle joint whereby
nectingsaid master cylinder and said compensating cyl
movement of said pedal lever moves said lever Yand arm
into astraight line relationship and therewith said piston
from a retracted position to a forward position, said mas
65
inder for creating greater brake operating pressure and
an adjustable stop in the path of said spring biased piston
for _limiting the movement thereof to create maximum
ter cylinder >comprising a reservoir, a spring biased valve
brake operating pressure. y
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' connecting said reservoir and said cylinder for providing
6. Brake controlapparatus for hydraulic brake systems
a limited, brake operating pressure zone during initial ad
>'comprising a master cylinder, a piston therein, pedal op
vance of said piston, and a compensating cylinder con
nected to said master cylinder beyond the most forward 70 erating >means connected to said piston comprising a me
position of said piston and comprising a chamber of
chanical linkage having >a mechanical advantage which
limited capacity for permitting limited displacement of
increases from a minimum in a retracted position to a
.fluid from said master cylinder, thereby to create maximum
. brake operating pressure after said chamber4 is `filled. ~
maximum at an advanced. position, said'master cylinder
. comprising a reservoir, and means for controlling ñow of
j 3. Brake control apparatus for hydraulic brake systems 75 fluid fromv said cylinder _to said reservoir and providing
saigner-,ace
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»pedal-foperatingfmeans connected to isaid-piston compris
:fingfa'ftog‘gle`v joint wherebyimovement of saidpedal =lever
~aflimitedgbrakeoperating-pressure'fzone»and
‘- brake operating »pressure ¿zonet duringZV1 advance ‘» 'of?ßsa’id
~piston. '
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ffrr'ioves-fs’aid> leverßand arm into aA straight line yrelationship
v>andftherewith Ysaid-piston from a retracted position lto a
*forward'Iposition,ßsa'idzmaster cylinder-having a compen
` 7.="^Brake -control apparatus for-hydraulic brake systems
, ‘comprising almaster cylinder,à a»piston--therein;>pedal-opY = erating: mea-ns connectedl to‘saidj piston comprising- aime
~Ísating Vlcylinderfconnected thereto adjacent the most-for
ward position> of .said piston- for» providing alimited, brake
< chanical Vlinkage ~ having a; - mechanical = `advantage 1 tand* a
~ limited stroke ‘at'fthe'ß'end‘?of whichf ‘maximumI mechanical
f operating pressure-zone lduring Aadvance of said piston
-Ladvantage-occurs,v said- master cylinder comprising a Areser
*between said compensating cylinder and A'said retracted po
-»sit»íon-.
1: 13. ‘Brake control'l apparatus for -hydraulic brake. sys
elvoir, an equalizing-port connecting said cylinder and-‘said
reservoir-'in advancey of the retracted position of said- pis
l' tom-tandl means‘- for-controllingïñow in »said port and~pro:'viding-y a îlimited,> ~ -brake ¿operating Lpressure îzone “during
ï-te'msreomprising-almastercylinder; a piston therein; pedal
iopera'tingr--means `connected toV -said-Í pistonA comprising - a
¿advance >ofÁ said-piston --betweenïthe ‘retracted’ position ’of
Lperlal»~lever~pivrâ=ted~at-one end=thereof anda pressure `varm
.said piston- and »_equalizing-»port
15 connected between said lever and said-piston at--an obtuse
ëî 8.~ r`Brake control--appar-atus'ífor hydraulic Abra-ke ’ systems
`v-I'anfgle"tofsaid-lever tri-'formA ay knee of a'togg'le-'jointf-where~
A{by ~-ïmovement -=of ïsaid- pedal lever- moves Ísaid l-leverx and
~-comprising a - master cylinder; -aA piston ' thereináy - pedal»~ op
erating means connected-to-said-piston comprising a-pedal
" larrn-in'to'» a A~straight li-ne relationship and ytherewithfsaid
#levert and’~ pressurev arm connected »to formAvv a ~ knee of
« a togglejointwherîeby‘movement-of said pedal :lever moves
Apiston ifrom» a-fretïrac'ted- position -to-awforward position,
Vsa'iderria''ster' cylindet‘fhaving a compensating cylinder con
1 said lever» »and »arrn 'finto- a fstraight': line ‘relationship and
`4nected'ftliereto'»adjacent the :most forward - position ` of
- therewith said f piston ‘from’ `a1retracted»«position »to a' - for
-s'aid-v piston for providing» a limited,- brake-operatingpres
'sure- zone”during-~advance^of~said~piston between said
voir, anequalizing port connecting-said cylinder and ¿said
compensating cylinder and said` retracted position Vtand
reservoir in adv-ance >ofíthe »retracted position of 'said - pis
:comprising a `slgiring'biased pistonf-insaid compensating
ton,~ and»l means for’ controlling-110W :in Isaid-port- and» pro
cylinder, -«and» a compensating- cylinder port for connect
'-.viding` a limited,A brake-'operating pressure» zone t during
Iing-«said - master’c-ylinder and -said compensating cylinder
»f advance f of- said npistr'Jn`^'-betw`een ' the retracted i position
‘for icreatirig-A limited brake operating pressure,
e 'of said piston Vand‘fsaid equalizing-port.
I"idf-"tirelire control apparatus for~ hydraulic brake -sys`
19.’- Brake `control apparatus‘fëfor-hydraulic'- brakeesys "30 'items comprising a master cylinder, a-pis'ton- therein,> pedal
- tems `comprising a master-cylinder; afpistonï therein-,-~pedal
`- operated `Ã~`means connected --to said piston rto provide-in
~ wardV position;- said l`-rnaster cylinder comprisingl a reser
>‘operating - means - conneeëtedf- to :said piston* comprising» a
creased «rnechanical' ¿advantage vwith* increased» angular
*movement'vof-‘said “pedal 'íneans ande-means adjacent‘the
f-‘pedalflever pivotediat one endithereofand a pressure arm
connected between said-'levenaudls‘aîd piston at- -an> obtuse
'tangle to~-said.. leverf'toïforïma a-'fknee- of~r a toggle~'--joint
'- wherebyy movement‘ of rsaid »pedalïlever =moves V'said -lever
“andf armi-into a`- stra-ight line-«relationship and therewith
»said piston from a retracted-positionfto a forward position,
‘fsaid- master-»cylinderl comprising» a reservoir; an- equaliz
most forward position of said piston for providing a
“li-mitedàbrake loperating» pressure -zoner during initial ad
ïvancefof‘said `pistolrand- thereafter for providing a 4higher
ïbrake“operating'¿pressurezone >locatedY forwardly of ‘the
ï-«lirñited'pressure `zone.
> 15;' Brakecontrolapparatus> for hydraulic _brake A'sys
ï-ing -port connecting: s'aid'tcyliriderßfand' said :reservoir-»in
`v~tems-corriprisinga‘fmaster‘cylinder; a piston' therein, pedal
aadvance of -the lretraeted‘-position‘l‘of ~sa`id~pistonf~and a
operating l@means connected to -said piston comprising a
valve for controlling flow in said port and providing-.a
cam mechanism connected to said piston, said camV having
t ar‘s'urA-facer" designedv toxprovide increasedmechanical ad
ïï'limited; brakeoperating pressure--z'one'- dur-ingfadv-ance of
`said»piston«»betweenîthe ¿retracted-position ofsaidfpiston `
» and said- equalizing port.
"
- `V10.ï`IBrake Y-control-jappar-atus èfor hydraulicv ‘brake sys
4vtems comprising aêm-aster'cylinder', apistonfthereinypedal
`.operating - means 'connected toffsaid‘- piston ivcorïnprising- a
-pedal »lever pivotediat one'endfthereof‘and a-‘pressure' arm
» connected YbetweenV s‘a'id lever and -sa‘id f» ¿piston-«iat »an- ob
Átuse angle-to sa‘icldever` tolfo‘rm a-imee of a ~toggleïïjoint
whereby :movement-"ofI said‘ [')edal«'leverrnlovesl said ‘lever
>-and- «arm into: a* straighti line 'relationship- and l"therewith
saidy piston :from ametractedjposition- to a'forward--posi-tion, »said 4master cylinder-'comprising a»~--reserv`<'>ir,5v a 're~
l plenishingl >port~`coiineetingrsaid"cylinder :and »sa-id' ‘reser
- voir slightly» in 4advance> "" ‘the-retracted' 'positiony `‘of ‘said
- v piston; Yan equalizinglportïirr"advance of* said 'replenishing
port, Aandl a `spring*biased"valve'forcontrollingá ilow ~in‘
"said »port vand-providing a limit‘ech---brake'operatingpressure
zone-f during `advance ¿of saidä‘piston* between' saidy vcom
_ vantage'with- increased ‘angular movement, and means for
D
Àproviding' a~1imit`edg1brake- operatingV pressure zoneA -dur
" `ing` initialA advance of 'said piston 'andthereafter' for pro
”viding“ a' higher‘brake `operating pressure zone located
`forwardly; of' the f limited pressure zone.
*^'1;6.'<Brake’ control apparatus forbydraulic br-ake sys
Ltems ~-'-comprising~ av master cylinder,Y a - piston therein,
lp'e'dal operating means connected to’said piston compris
fing' aîlînklage‘idesigned -to provide increased mechanical
>^`advantage with'fincreased angular movement thereof, and
“"-nieaiis‘jassociat'ed' with‘ said cylinder „for providing _ a
~‘li1nited,‘¿brake 'operating -pressure zone iduring initial
advance `of >said piston _and thereafter «for providing a
v`'higher brake ’operating pressure-zone located' forwardly
f ïofï'the “limited pressure zone.
' ‘17." Brake’` jcontrol _apparatus V«for hydraulic >brake sys
.'tènis comprising ' aamaster cylinder, apiston therein,
pensating -"and-equfaliz-ir1g`îpoi'ts.
_`.pedal.ppcratingmeans connected to ,said piston .compris
llf’Bra'ke controllïapparatusfifor hydraulic’brakef'sïys
tems 4corriprising a'mîast'ei‘icy‘linder, aïpiston' therein;A pedal.
ling~ aypedalßlever; and- a pressure _arm :connected iQ Said
,-.pistontorforrn a kneeof a toggle joint whereby movement
„of-_ 1said-l- pedalvfleverymoves l:said-flever ¿and ¿arm-_ into'ì a
.-.Lstiîaightulinei relationship and: therewith` ysaid; Ápistons from
- operating »means >cor'meézted‘itci >saidelpiston-- con'lprisingY a
linkage - having' aemechanical :advantage- which »increases
from a minimum in a retracted' positie-nto' a' maximum
~ ’at an ladvanced-»positionìsaéithmaster ¿cylinder comprising
a attretractedYA position to a forwardzposition, s_aidvmaster
-ìcylinider vhavingna-ßreservoir in combination` .therewith
>:which-containsV> ñuidmnder atmospheric~ pressure, l means
t vot" :saidw tpiston‘frfon v'providingi `airlimited;,-¿brïake operating
- pressure. zoney `dtiring'advance:of-'said piston» between-said
t :compensating cylinder. ‘and'ísa‘id firetfracted position.
:12Tl Brakeucontr-olfl apparatus -sfor-‘liydraulicìlbra'ke:sys
¿tems :comprising i a- :master 1c`yl=irider,r,` aI - ïpistonH therein, `
@operative- to» seïvensaid-y corun'iunicationjupon'v ~first protrac
i 'tile‘lf?tovementàiofffsaid-piston; equalizing--rneans effective
'-Tafter'ethe-“z'rffiresaidi ¿first piston `moverri'ent ‘forâ providing- a
-¿limited?‘brakefoperating- pressure rzone`v during Ysubsequent
pistonladvanceme'nt; and-»meansïforïdisabling-said equaliz
5 ing'îïmcansf'upo?ïfurther -advance-fpistonïmovement' where
2,741,896
10
by maximum brake operating pressure is created near
the limit of the piston’s protractile stroke.
References Cited in the ñle of this patent
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Frock _______________ .__ May 29, 1923
Dodge ______________ __ Nov. 24, 1925
Hirschler _____________ __ Oct. 4, 1927
Blasdel ______________ __ Dec. 13, 1927
Cox _________________ __ Oct. 20, 1936 10
Heidloiî ______________ __ Sept. 7, 1937
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FOREIGN PATENTS
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France ______________ __ Mar. 25, 1935
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