Operation and maintenance manual

Section 220-0100
2
Steering System - Flow Amplifier Valve
SM 1392 Rev 3 10-03
SM - 529
A - Counter Pressure and Anti-cavitation Valve
B - System Relief Valve
C - Priority Spool
D - Shock and Anti-cavitation Valve
E - Amplifier Spool
F - Directional Spool
LS - Load Sensing Pressure
EF - Excess Flow
HP - Pump Supply
PP - Pilot Pressure
P - Pump Supply To Steering valve
HT - Return To Tank
T - Steering valve Tank Return
R - Steering valve Right Turn Oil
CL - Left Turn Cylinder Oil Supply
CR - Right Turn Cylinder Oil Supply
L - Steering valve Left Turn Oil
shock pressures in the steering cylinders to 241 bar
(3 500 lbf/in²). The shock valves sense cylinder
shock pressure when there is no steering taking
place. Shock pressure is absorbed in the cylinder
circuit and is not transmitted to the steering valve.
The anti-cavitation part of the valve prevents
cavitation in the cylinder circuit.
Amplifier spool (8) (Port 'E') controls the amount of oil
flowing into directional spool (6) 'HP' passage.
Directional spool (6) (Port 'F') when moved in either
direction against the return springs, sends oil pressure
to the steering cylinders for right or left turns.
maintains a back pressure of 5 bar (73 lbf/in²) to give
improved suction during steering and prevent
cavitation in the steering cylinder circuit.
System relief valve (1) (Port 'B') is set to control
maximum working pressure in the steering system to
206 bar (3 000 lbf/in²).
Priority spool (7) (Port 'C') directs oil supply from the
pump when engine is running, to steering valve port
'P', through the 'EF' passage to the body control
valve.
Shock & anti-cavitation valves (5) (Port 'D') limit
Fig. 2 - Flow Amplifier Valve Port Identification
HP
EF
LS
B
PP
A
P
HT
T
R
CL
CR
L
C
D
E
F