W h e n s t e e r i n g r e s i s t a n c e I s I o w , s u c h a s w h e n d r i v i n g a t h i g h s p e e d s , o r w h e n d r i v i n g s t r a i g h t a h e a d , t h e i n p u

near or in the neutral position, so there is little or no fiow ro any of the

power cylinder orifices. Most oI the feed pressure

f r o m t h e p u m p i s b y p a s s e d t o t h e r e s e r v o i r . B e c a u s e o f t h i s , t h e p r e s s u r e s t a y s t h e s a m e i n b o t h s i d e s o f t h e p o

der, resulting in low or no asslst

VALVE

From PUMP

SECTION A-A

RETURN PASSAGE

lTo RESERVOIRI

POWER CYLINDER

STEERING GEARBOX

High assist at lower speeds:

When steering resistance is high. such as when driving at

low speeds' or when turning the wheel wirh the vehicle

s t o p p e d , t h e d i f f e r e n c e | n a n g | e c r e a t e d b e t w e e n t h e i n p u t s h a f t a n d t h e V a | v e o p e n s t h e f | u i d p a s s a g e o n o n

c | o s e s t h e f l u i d p a s s a g e o n t h e o t h e r s i d e , a t e a c h p a i r o f o r i f i c e s ' T h e f | u i d p r e s s u r e i n c r e a s e s i n t h e s i d e o | t h

be turned with light effort. on the other side of the power cylinder,

the return passage opens allowing the steering tluid to

r e t u r n t h r o U g h t h e i n p u t s h a f t t o t h e r e s e r v o i r ' T h e f | u i d p a s s a g e s t o t h e p o w e r c y | i n d e r a u t o m a t i c a | | y c h a n g

increasing as the steering resrstance increases. In other words, the

passages become larger and power assist increases

when the steering effort would normally be high,

(for example' when parking or making low speed turns)' and the pas-

driving at high speeds or straight ahead).

FLUIO PASSAGE TO

POWER CYLINDER

/t=\

\a!-4,))

=YjJ

RESERVOIR

SECTION A-A