Vehicle System System Operation 24
3. Tilting down of spool
While unload path is closed, oil from pump opens a
load check through parallel path and flow out from
Port B. With the pressure goes up, oil at Port Are
turn to the tank through the inner path of spool.
When cylinder load is in excess of the rated
pressure of relief valve, the relief valve works and oil
flow into the tank path. The spool returns to the
neutral position by the spring.
4. Tilting lock
If no coming oil, tilt cylinder doesn’t work even
spool-down is performed. When spool is down with
no coming oil, tank path from Port A is closed since
no pressure to open pilot spool. Therefore no action
is done by a tilt cylinder which is in a lock condition.
Working Principle of Accessory Valve Section
1. Neutral Position Oil from the pump returns to tank
through unload path.
2. Spool-up
When unload path is closed, oil opens a load check
through parallel path. Flowing out from Port A,
backflow at Port B return to the tank through tank
path. When cylinder loading is in excess of the rated
pressure of relief valve, the valve works and oil flow
into the tank path. The spool returns to the neutral
position by the spring.
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