Komatsu PC200-8M0 Shop Manual page 218

SEN06121-00
The pressurized oil on the supply side flows to
q
chamber (S1) through orifice (E1) and orifice
(E2) of the spool (19).
As the pressure in chamber (S1) goes above
q
the spool selector pressure, spool (19) is
pushed toward right.
Port (MB) and port (PB) are connected, open-
q
ing the motor outlet port side and starting the
motor rotating.
20
10-403
403 Hydraulic system, Part 3
Operation of brake during travelling downhill
If indication of the machine runaway is sensed
q
while travelling downhill, the motor will be
caused to rotate without load to decrease the
inlet side oil pressure.
q Pressure in chamber (S1) is released through
orifices (E1) and (E2).
q As the pressure in chamber (S1) goes below
the spool selector pressure, spool (19) is
returned to the left by spring (20) and outlet
port (MB) is throttled.
The pressure at the outlet port side rises, gen-
q
erating rotation resistance on the motor to pre-
vent the machine from running away.
q The spool moves to a position where the pres-
sure on outlet port (MB) can be balanced
against the machine's own weight and the inlet
port pressure.
Oil flow from the outlet circuit is reduced to
q
ensure the travel speed corresponded to the
pump discharge.
PC200, 200LC, 220, 220LC-8M0
Travel motor