Komatsu PC200-8M0, Shop Manual, Page: 196 / 1254

SEN06120-00
10-402
54
PC200, 200LC, 220, 220LC-8M0
402 Hydraulic system, Part 2
Functions and operation by valve
Operation
When pilot pressure (P) is shut off (high pres-
sure setting)
q
Since pilot pressure (P) is shut off, piston (2) is
pressed to the left by force of spring (3). [Load
at installed length of spring (1) < Load at
installed length of spring (3).]
q The load at installed length of spring (1)
becomes maximum, inducing high-pressure
setting.
q Passage (B) is interconnected to the drain cir-
cuit via passage (C) and chamber (D).
When pilot pressure (P) is supplied (low pres-
sure setting)
q
When pilot pressure (P) is supplied, the pilot
pressure is transmitted to part (A) through pas-
sage (B).
q
The pilot pressure acts on the pressure receiv-
ing diameter at part (A) [(d1) — (d2)] of piston
(2).
q
Piston (2) compresses spring (3) by receiving
pilot pressure and moves to the right until it
contacts holder (4).
q
Since spring (1) is expanded and reducing its
load at installed length, the set pressure is low-
ered.
q
The amount of pressurized oil for stroke of pis-
ton (2) is drained from passage (C) via cham-
ber (D) .