Operation and maintenance manual

Section 220-0100
5
SM 1392 Rev 3 10-03
RL
7
PT
LS
CR
CL
8
8
R
5
EF P PP HP LS HT T L
A
TANKSUPPLY FROM
MAIN HYDRAULIC
PUMP
LEFT HAND
CYLINDER
RIGHT HAND
CYLINDER
Steering System - Flow Amplifier Valve
SM - 6666C
Fig. 5 - Hydraulic Schematic - Left Turn
REMOVAL
WARNING
To prevent personal injury and property
damage, be sure wheel blocks, blocking
materials and lifting equipment are properly
secured and of adequate capacity to do the job
safely.
1. Position the vehicle in a level work area, apply the
parking brake and switch off the engine. Turn
steering wheel in both directions several times to
relieve any pressure in the steering circuit.
2. Block all road wheels and place battery master
switch in the 'Off' position.
3. Remove blanking cap from remote drain line at the
bottom of the hydraulic tank. Install a length of hose
on remote drain fitting, open drain cock and drain
hydraulic oil into a suitable container. Close drain
cock, remove hose and reinstall blanking cap.
4. Disconnect mounting hardware securing hydraulic
guard to the unit and remove hydraulic guard.
the right hand end of directional spool (6). This
pressure moves directional spool (6) to the left allowing
a pilot pressure to act on the right hand end of amplifier
spool (8). Pilot pressure overcomes spring pressure on
the left hand end of amplifier spool (8) moving amplifier
spool (8) to the left. This movement allows the main oil
flow from priority spool (7) and pilot flow through
directional spool (6) to merge at directional spool (6)
and flow through port 'CL' to the steering cylinders.
Return oil from the opposite ends of the steering
cylinders flows into port 'CR' and through directional
spool (6). Oil then flows through counter pressure &
anti-cavitation valve (2) and back to tank.
In this condition, remaining oil supplied from the main
hydraulic pump, is available for the body hydraulics or
is returned to tank.
5 - Flow Amplifier Valve
7 - Steering Valve
8 - Steering Cylinders