2-78
When the push rod (9) is stroked, the spool (3) moves downwards.
Then port P is connected with port (1) and the oil supplied from the pilot pump flows through port
(1) to generate the pressure.
When the pressure at port (1) increases to the value corresponding to the spring force set by tilt-
ing the handle, the hydraulic pressure force balances with the spring force. If the pressure at port
(1) increases higher than the set pressure, port P is disconnected from port (1) and port T is con-
nected with port (1). If it decreases lower than the set pressure, port P is connected with port (1)
and port T is disconnected from port 1.
In this manner the secondary pressure is kept at the constant value.
Besides, in some type, when the handle is tilted more than a certain angle, the upper end of the
spool contacts with the inside bottom of the push rod and the output pressure is left to be con-
nected with port P.
Case where handle is tilted
9
3
P
T
Port 1
Port 3
(2)
300L2RL04
