STEERING CONTROL VALVE IN RIGHT TURN POSITION
1. Tank return passage.
11. Outlet to cylinders (for14. Outlet to cylinders (for
3. Outlet to tank.
8. Outer spring.
15. Ball resolver valve.
4. Flow control valve.
9. Inner spring.
13. Narrow slots.
5. Pilot valve.
10. Wide slots.
When the steering wheel is turned to the right a few
degrees (SLOW RIGHT TURN), spool (6) is moved out
of the valve body a small amount. This causes
compression of inner spring (9). Pump oil flows from
inlet (2) through narrow slots (13) on the valve spool.
The oil flows into outlet (14) and then to the steering
cylinders. The force of the oil in the cylinders causes the
machine to turn slowly to the right.
If the steering wheel is turned against the stop (FAST
RIGHT TURN), spool (6) will move out of the valve body
some more. There is compression of both the inner and
outer springs (9) and (8). When compression of the
outer spring starts, there is an increase in the force
needed to turn the steering wheel. This lets the operator
feel the spool move to the FAST TURN position.
When the spool is in the FAST TURN position, the
pump oil flows from inlet (2) through wide slots (10) in
the spool. These large slots let more oil flow to the
cylinders than the small slots. The result is a FAST
Return oil that is pushed from the steering cylinders
is sent into the control valve through outlet ( 11). The oil
is sent through slots in the valve spool into return
passage (1). The oil then flows through outlet (3). From
the outlet, the oil flows back to the filter and hydraulic
The pressure of the oil to the cylinders is also felt
through passage (16). When oil goes into passage (16),
the pressure moves ball resolver valve (15). The
pressure of the oil to the cylinders is then felt against
pilot valve (5) and flow control valve (4).
If an outside force keeps the machine from turning, the
pressure in outlet (14) and passage (16) will increase.
This pressure increase is also felt against the pilot valve
and flow control valve. The pressure against the flow
control valve causes it to move to the left. This lets more
oil flow to the cylinders. If the pressure goes above the
relief valve setting of 200025 psi (140.6 1.8 kg/cm2)
(13 790 172 kPa), the pilot valve will open.