Hyundai 35DS-7 Operation Manual page 161

The loss of oil behind poppet C, effected
by the opening of pilot poppet E, causes
poppet C to move back and seat against
pilot puppet E. This shuts off the oil flow
to the area behind relief valve poppet D,
and causes a low pressure area
internally.
The imbalance of pressure on the inside
as compared to that of the high pressure
port HP, forces the relief valve poppet D
to open and relieve the oil directly to the
low pressure chamber LP in the valve.
As anti void
The anti-void unit supplies oil to the high
pressure port HP when cavitation has
occurred. A lower pressure exists in the
port HP compared to the low pressure
chamber LP. The difference between the
effective area of diameter A and G
causes imbalance of the check valve
poppet K which unseats, thus allowing oil
from the low pressure chamber LP to
enter the port HP and fill the void.
K
A
HP
6-17
D353HS20
D353HS21
G
7406S6-28(1)