Cadillac 54-6219 1954 Shop Manual page 149

BRAKES
fluid pressure moves tbta piston, It actuatee the
vacuum diaphragm control sha ft
S
iid fu rccs the
diaphragm against the vacittini poppet valve, sealing
off area ''B'' fra, na ni fold vs c
U i IT1
Con duo ed
iiio a a>
-
meat of the pis tan and the dia ph
rapitia
forces
I
a,
attiia.sptie r ic poppet valve o f
of its Ce
at and ad],, its
air under atmospheric prussure thr''agt: are
to area ''C'', Phe pressure differential between
areas
C'' sod ''A'' laccea the vucuom pistuin and
push rod toward the hydrall iic cy I mdcc. The :aosh
rod, attached
to
the hydraulic pistu,:.,
iuilca tljc
hvdra:.liic
piston and y,,'<e away front rite stop
washer, permitting the check valve to close and
trap fLuid undar prc:s.+,,rtc ahead of the p:ston.
From this patint. the total hlydraulic pressure,
develuped an the hydraulic poer c sUndae and trans
-
mittod to the wheel cylinders, le the somof the push
rod pressure act] : 1 tiae. press tire developed in the
rta.ster cylinder. rio. 9-4.
mc degree of poser brake asata: Is rcy,ula:cd in
the v.ncc:um contr, Ivalve assc:r,hlv hy cnnarolling
the pressure c:fferen:iai between arca '''and D'.
Here, hydraulic in .sauve asainat tea piston is ap-
posed by air preasure at:d spring pressorc
at:
the
area R side of rile d:aphranm,whcn rlbediaphragni
ia in contact with the v ac
00111
toppe: valve. A:. the
prcssorc in eros B incroases,i while the atmos
pheric poppet is opetci the fora ,air.stlltevoci:icn
a Lye a aid tI:c diapi Irag In
a
lao
ij Ic ross es,
Ic:jdi
lag
to
cMse the atmospheric valve, 1t,erefore, It's degreo
of power assist is proportionsi to l:vdraoLic ?res-
sure on the small hvdrsuhcp:stouandconsequetitly
it is proportional to font pedal pressure,
Floorboard
/
Grommet shnold just
touch floorboard
when pedal rod
ii
agoinsi slop
Two-piece Peda!
/
ye
line to Mosler Cylinder
Pislons
Bleeder
Connsction
zCever
Wheel Cylinder Cross Section
Fi. 7-5 Rmke Mouter Cylinder aid P&dal