Komatsu ecot3 PC300LC-8 Shop Manual page 146

SEN01994-01
Unload valve
1. When the unload valve is actuating
1. LS circuit
2. Valve
3. Pump circuit
Function
q Drains an oil discharge for the portion of the
minimum pump swash plate angle while all
control valves are in the holding.
q The pump pressure will correspond to a set
load of spring (5) inside the valve (this pres-
sure will be P1).
q Since LS pressure is drained from the LS
bypass valve, LS pressure
MPa{0 kg/cm }.
2
20
10 Structure, function and maintenance standard
C C
tank pressure 0
4. Tank circuit
5. Spring
Operation
q Pressure of pump circuit (3) is received by the
end of valve (2).
Since the control valve is in neutral position,
q
pressure of LS circuit (1) is 0 MPa{0 kg/cm
q Pressurized oil of pump circuit (3) stops at
valve (2), and the pressure rises as no relief is
available.
q When this pressure becomes larger than the
force of spring (5), valve (2) moves to the left.
Ports (b) and (c) are interconnected and the
q
pump pressure flows to tank circuit (4).
q
2
}.
PC300, 350-8