TM 5-3895-382-24
Priority Valve Operation
Machine Off (no flow)
Priority Flow Divider Valve Body Cross Section.
(1) Priority valve spool. (9) Orifice. (10) Pressure passage. (11)
Control orifice. (12) Damping orifice. (13) Passage. (14) Steering
circuit port. (15) Passage.
When the machine starts up, oil from the steering pump enters
the valve body through pressure passage (10). The oil flows
into the center of priority spool (1), passage (15). It then flows
through control orifice (11) into passage (13) and onto the
steering circuit through steering circuit port (14).
The oil in passage (15) senses pressure on both ends of
priority spool (1). Oil pressure is sensed through damping
orifice (12) on the right hand end and through control orifice
(11) on the left hand end.
No Steering Load
Priority Flow Divider Valve Body Cross Section.
(16) Spring. (11) Control orifice. (14) Steering circuit port. (17) Flow
passage. (18) Flow passage. (19) Charge circuit port. (20) Passage.
Pressure acting on both ends of priority spool (1) creates a
force which moves priority spool (1) to the left compressing
spring (16).
As oil flow increases in pressure port (10), the pressure drop
across control orifice (11) increases until enough force is
generated to move priority spool (1) to the left as shown.
Some oil flow can now pass through passage (20) to the
charge/blade circuit through charge circuit port (19).
As oil flow into the valve increases more, oil flow through
control orifice (11) attempts to increase. This increases the
pressure drop across control orifice (11). Priority spool (1)
moves farther to the left. As priority spool (1) moves to the left,
flow passage (17) decreases and flow passage (18) increases
in size. When flow passage (17) decreases, oil flow to the
steer circuit decreases. When flow passage (18) increases, oil
flow to the charge/blade circuit increases.
14-10
