Sunbeam ALPINE I SERIES: APLINE II SERIES, Workshop Manual

Page: 303 / 413

Page 44
Pressure on the foot pedal released
(CONDITION A)
The pressure drop at the master cylinder results
in a sudden decrease in pressure behind the valve
piston (11) causing air pressure on the back of the
control valve diaphragm (23) to force it back to its
original position.
As a result �f this, vacuum will be re-introduced in
chambers X and Y and the booster diaphragm (9)
will be returned to its original position by the
action of spring ( 14), tak!ng the push rod ( 13)
with it. The hydraulic piston (32) will be returned
to its seat by spring (29). A through passage is
then available for hydraulic fluid from master
cylinder to wheel cylinders.
Servo Unit-to remove
I. Disconnect the vacuum pipe and hydraulic inlet
and outlet pipes from the servo body. Plug
the ends of the hydraulic pipes to prevent loss
. of fluid and entry of dirt.
2. Remove the unit from Its mounting brackets by
removing two nuts and two nuts and bolts
respectively.
To refit
This is a reversal of the removal procedure. It
should be noted that it will be necessary to bleed
the brakes after refittlngas described earlier in this
section under the heading "Bleeding the hydraulic
system".
To dismantle the Servo Unit (Fig. 22)
If the control valve assembly only Is to be serviced,
the Control Valve Repair Kit (part number 5040185)
should be obtained. If the complete unit is to be
overhauled, the Major Repair Kit {part number
5040184) should also be ob_tained.
The dismantling of the control valve assembly only
is covered by operations 1-5.
WSM. 124
Section K (Brakes)
I. Remove the servo unit from the car as pre­
viously described.
2. Hold the unit in a vice by the slave cylinder
body (26), taking care not to over-tighten.
3. Remove the rubber elbow (1).
4. Remove the air valve cover assembly (19) by
withdrawing the five securing screws (ll).
NO ATTEMPT SHOULD BE MADE TO
DISMANTLE THIS ASSEMBLY ANY FUR­
THER.
5. Lift off the control valve diaphragm assembly
(23). This item sh�uld not be taken apart.
6. Remove the valve housing (24) by withdrawing
the four securing screws.
7. Remove the valve piston (11). The simplest
way to carry this out is to place a clean rag
over the piston bore, then apply LOW air
pressure to the hydraulic inlet whilst placing
a thumb over the hydraulic outlet .
8. Remove the seal ( I 0) from the valve piston
( 11 ).
9. Remove clamping screw (3) and nut (4) and
lever off the clamping ring (2). Care should
be taken over this operation since as soon as
the clamping ring is removed, the end cover (5)
is released, together with the booster dia­
phragm assembly which is spring-loaded.
10. Having removed the end cover and booster
diaphragm assembly, release the return spring
(14) from the locking plates (16) inside the
vacuum shell (18).
11. Remove rubber buffer (6) from the outer end
of the push rod ( 13).
12. To separate the various parts of the booster
diaphragm assembly, hold the hexagon of the
push rod ( 13), taking care not to damage the
high surface finish of the rod, and unscrew
the nut (7) from the other side of the dia­
phragm (9).