Komatsu ecot3 PC300LC-8 Shop Manual page 179

10 Structure, function and maintenance standard
Main relief valve
1. Spring
2. Poppet
Function
Set pressure of the relief valve is in two stages.
q
q When power is needed, pilot pressure (P) is
turned ON and the set pressure becomes
higher.
Operation
q The set pressure of relief valve is determined
by spring (1) installed load. (1st stage)
Respective setting is not required for both the
q
1st and 2nd stages. Setting the 1st stage com-
pletes the setting of the 2nd stage.
1. If pilot pressure (P) is OFF: Low-pressure
setting
Set pressure is determined by spring (1)
installed load.
2. If pilot pressure (P) is ON: High-pressure
setting
Spring (1) installed load is added with pilot
pressure (P) applied to the area of poppet
diameter (d1), raising the set pressure to
higher level.
PC300, 350-8
SEN01994-01
53