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31
C L U T C H — G e n e r a l D e s c r i p t i o n — S e r v i c e I n f o r m a t i o n
driver releases this button the v a c u u m operated
control does not I unction and the clutch can be
operated in the conventional way with the clutch
pedal.
The
bleeder plunger regulates the flow of air
out of the air chamber of the power cylinder after
the air by-pass in the piston rod is closed, just as
the clutch starts to engage.
T h e amount of air
bled out of the power cylinder at this time depends
on the number of bleeder holes uncovered by the
bleeder plunger and the speed of the
plunger
movement, the position and movement of which,
in turn, depends on the position and movement of
the accelerator pedal.
Therefore, a slow downward movement of the
accelerator pedal permits a slow escape of air
from the air chamber in the power cylinder and
gives a correspondingly slow engagement of the
clutch.
A faster downward movement of the
accelerator pedal will uncover the bleeder holes
(aster, permitting a more rapid escape of air from
the air chamber in the power cylinder and conse-
quently, a quicker clutch engagement.
T h u s the
rapidity with which the c l u t c h is engaged is con-
trolled by the movement of the accelerator pedal,
insuring smooth
clutch engagement
under all
conditions.
The accelerator pedal must not be pushed, down
while the control button is depressed, until the
car is to be started.
This means that the acceler-
ator pedal cannot be used to speed up the engine
while waiting for traffic.
If the engine is not warm
enough to run at normal idling speed, the hand
throttle should be advanced or the regular clutch
pedal should be used until the engine is warm.
While the accelerator plunger moves with the
bleeder plunger, it functions in conjunction with
the cut-out plunger to open the vacuum chamber-
in the power cylinder to the intake manifold or
to the atmosphere.
E a c h of these plungers acts
both as a valve and an air by-pass.
When the control button is depressed with the
accelerator
in the
released position, the valve
ports in both the accelerator and cut-out plungers
are in line, completing the vacuum passage between
the intake manifold and the power cylinder. The
vacuum then pulls the piston hack and disen-
gages the clutch.
Depressing the accelerator
(with the control
button down) closes the vacuum line and opens
the vacuum chamber to the atmosphere, permit-
ting the chamber to refill as the clutch is engaged.
Releasing
the
accelerator
(with the
control
button down) opens the vacuum line again and
disengages the clutch.
The
accelerator
pedal
must
be
completely
released between shifts.
It is the first half-inch
of travel of the accelerator pedal that operates
the clutch control valve and unless the accelerator
pedal is allowed to come all the way back,
the
clutch will not automatically disengage.
Releasing the control button likewise closes the
vacuum line and opens the vacuum chamber
to
the atmosphere, allowing the clutch to engage.
S e r v i c e I n f o r m a t i o n
1.
M o u n t i n g o f C l u t c h C o n t r o l M e c h a n i s m
T h e
h o o k - u p of the free-wheeling c o n t r o l b u t t o n a n d the
accelerator pedal requires the p i v o t i n g of the bell-cranks o n
the toe a n d floor b o a r d .
T h e toe-board is i n one section a n d ,
since the c o n t r o l b u t t o n is attached to this u n i t , it s h o u l d
not be m o v e d unless absolutely necessary.
T h e floor b o a r d ,
however, is in two sections.
The accelerator pedal c o n t r o l
is p i v o t e d to the large right-hand section, b u t the panel at
the extreme left-hand side m a y be removed w i t h o u t affecting
a n y adjustment.
II the sections to w h i c h these units are
a t t a c h e d a r c m o v e d the controls w i l l require
readjustment.
2.
R e m o v a l o f T r a n s m i s s i o n
E x t r e m e care must be taken when r e m o v i n g the
trans-
mission to s u p p o r t the rear end so as to h o l d the transmission
in perlect a l i g n m e n t w i t h the c l u t c h u n t i l the c l u t c h connec-
tion shaft has been pulled a l l the way out of the c l u t c h h u b .
If the rear end of the transmission is allowed to d r o p d o w n
or
is raised too h i g h while the c l u t c h connection shaft
is
still in the c l u t c h hub, the c l u t c h d r i v e n discs w i l l be s p r u n g
o u t of shape.
This must be a v o i d e d .
3.
V e n t H o l e s i n C o n t r o l V a l v e B o o t
O n some of the first cars shipped, the r u b b e r boot. P a r t
N o . 891917, p r o t e c t i n g the c l u t c h control valves does not have
holes in it to allow the proper passage of a i r for v e n t i n g the
v a c u u m c h a m b e r when the c l u t c h is being engaged.
O n
cars now being shipped, the boot has three
k i - i n c h
holes in the lower side ot the hxx>t.
W i t h o u t
these holes, the
engagement
ot
the
c l u t c h is
d e l a v c d .
In case of improper a c t i o n o l the c l u t c h c o n t r o l ,
the rubber boot should be inspected to m a k e sure it has these
holes belore any adjustments are changed.
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