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BRAKES 5-34
Figure 70
—Relay Valve and A ir Tank
Installed (Typical)
t h e
b r a k e
c a m s h a f t .
P u s h
r o d o p e n i n g a n d f o u r
e q u a l l y s p a c e d h o l e s n e a r c l a m p i n g f l a n g e i n n o n
p r e s s u r e p l a t e p r o v i d e f o r b r e a t h i n g a n d d r a i n a g e .
F o r i l l u s t r a t i o n o f b r a k e c h a m b e r s i n s t a l l e d s e e
f i g u r e
8
( a t f r o n t a x l e ) a n d f i g u r e 9 ( a t r e a r a x l e ) .
B r a k e c h a m b e r s h a v e t w o d i f f e r e n t t y p e c l a m p
r i n g s ;
(
1
) a t w o - p i e c e r i n g w i t h t w o b o l t s a n d (
2
)
a o n e - p i e c e c l a m p r i n g w i t h t w o b o l t s a t t h e c l a m p
r i n g j o i n t .
p r e s s u r e p l a t e . N o l e a k a g e i s p e r m
i s s i b l e . I f l e a k
a g e i s e v i d e n t , t i g h t e n c l a m p r i n g b o l t s .
b .
W
i t h b r a k e s f u l l y a p p l i e d ,
c h e c k f o r l e a k
a g e t h r o u g h t h e d i a p h r a g m b y c o a t i n g t h e p u s h r o d
h o l e
a n d
d r a i n h o l e s i n n o n - p r e s s u r e p l a t e w i t h
s o a p s u d s . N o l e a k a g e i s p e r m
i s s i b l e . I f l e a k a g e
i s e v i d e n t , r e p l a c e t h e d i a p h r a g m .
B R A K E C H A M B E R R E P L A C E M E N T
B R A K E C H A M B E R O P E R A T I O N
A s
a i r
p r e s s u r e
e n t e r s
t h e b r a k e c h a m b e r
b e h i n d t h e d i a p h r a g m , t h e d i a p h r a g m f o r c e s p u s h
r o d o u t w a r d , t h u s a p p l y i n g f o r c e t o t h e s l a c k a d
j u s t e r
w h i c h
r o t a t e s
b r a k e
c a m s h a f t ,
a p p l y i n g
b r a k e s . W h e n a i r p r e s s u r e i s r e l e a s e d f r o m
t h e
b r a k e c h a m b e r , t h e b r a k e s h o e r e t u r n s p r i n g s a n d
t h e p u s h r o d s p r i n g r e t u r n b r a k e s h o e s , c a m s h a f t ,
s l a c k
a d j u s t e r ,
p u s h
r o d , a n d d i a p h r a g m t o r e
l e a s e d p o s i t i o n .
B R A K E C H A M B E R S E R V I C E A B I L I T Y T E S T S
1 . O p e r a t i n g T e s t
A p p l y b r a k e s a n d s e e t h a t t h e b r a k e c h a m b e r
p u s h r o d s m o v e o u t p r o m
p t l y w i t h o u t b i n d i n g . R e
l e a s e b r a k e s a n d s e e t h a t t h e y r e t u r n t o r e l e a s e d
p o s i t i o n w i t h o u t b i n d i n g .
2 .
L e a k a g e T e s t
a .
W
h i l e f u l l b r a k e p r e s s u r e i s b e i n g d e l i v e r
e d a p p l y s o a p s u d s t o c l a m p r i n g h o l d i n g t h e d i a
p h r a g m i n p l a c e b e t w e e n p r e s s u r e p l a t e a n d n o n
1 . R e m o v a l
D i s c o n n e c t a i r l i n e f r o m
b r a k e c h a m b e r . D i s
c o n n e c t p u s h r o d y o k e f r o m
s l a c k a d j u s t e r . R e m o v e
n u t s
f r o m
b r a k e
c h a m b e r
m o u n t i n g
s t u d s , t h e n
r e m o v e b r a k e c h a m b e r a s s e m b l y .
2 . I n s t a l l a t i o n
I n s t a l l
b r a k e
c h a m b e r
o n
m o u n t i n g b r a c k e t
a n d s e c u r e w i t h s t u d n u t s a n d l o c k w a s h e r s . C o n
n e c t p u s h r o d y o k e t o s l a c k a d j u s t e r . A d j u s t b r a k e s
a s p r e v i o u s l y d i r e c t e d u n d e r " B r a k e A d j u s t m e n t . ”
A p p l y b r a k e s a n d m a k e s u r e p u s h r o d i s c o r r e c t
l e n g t h .
A n g l e f o r m e d b y p u s h r o d a n d s l a c k a d
j u s t e r
s h o u l d
b e
g r e a t e r
t h a n
9 0
d e g r e e s
w i t h
b r a k e s
r e l e a s e d ,
a n d w i t h
b r a k e s
a p p l i e d a f t e r
b e i n g a d j u s t e d , t h i s a n g l e s h o u l d s t i l l b e g r e a t e r
t h a n 9 0 d e g r e e s ; i n o t h e r w o r d s , t h e s l a c k a d j u s t e r
s h o u l d n o t g o " o v e r c e n t e r " d u r i n g b r a k e a p p l i c a
t i o n . I f n e c e s s a r y , a d j u s t y o k e o n p u s h r o d t o o b
t a i n t h i s c o n d i t i o n . P u s h r o d m u s t n o t e x t e n d t h r o u g h
y o k e f a r e n o u g h t o i n t e r f e r e w i t h s l a c k a d j u s t e r .
T e s t
a s
d i r e c t e d
u n d e r
" S e r v i c e a b i l i t y
T e s t s . ”
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL
Summary of Contents for 70 Series 1970
Page 1: ...CHEVROLET HEAVY DUTY TRUCK SERVICE MANUAL...
Page 9: ...LUBRICATION 0 2 CHEVROLET SERIES 70 90 HEAVY DUTY TRUCK SHOP MANUAL...
Page 11: ...LUBRICATION 0 4 CHEVROLET SERIES 70 90 HEAVY DUTY TRUCK SHOP MANUAL...
Page 13: ...LUBRICATION 0 6 CHEVROLET SERIES 70 90 HEAVY DUTY TRUCK SHOP MANUAL...
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