12 PC800, 850-8
SEN00788-02 30 Testing and adjusting
Testing and adjusting main
pump control pressure
a Devices for inspecting and measuring main
pump control oil pressure
Measurement
a Measure the piston pump control oil pressure
under the following conditions:
• Hydraulic oil temperature: 45 – 55°C
k Lower the work equipment to the ground and
stop the engine. Operate the control levers sev-
eral times to release the residual pressure in the
piping, and then loosen the oil filler cap of the
hydraulic tank slowly to release the internal
pressure of the hydraulic tank.
1. Measuring EPC valve output pressure
a Since the basic pressure of the EPC valve is
the control circuit pressure, check that the
control circuit pressure (self pressure reduc-
ing valve) is normal before measuring the
EPC valve output pressure.
a The EPC valve is controlled with the com-
mand current from the pump controller. (For
details, see Structure, function and mainte-
nance standard.)
1) Open the pump room cover.
2) Remove oil pressure pickup plug (1) or (2).
a Plug (1) is on the front pump side and
plug (2) is on the rear pump side.
3) Install nipple M3 and connect oil pressure
gauge [1] of hydraulic tester M1.
a Use the oil pressure gauges of 6.0 MPa
{60 kg/cm
2
}.
4) Start the engine and set the working mode
switch in the P-mode position.
5) Set all the control levers in neutral and
measure the EPC valve output pressure
under the following condition.
i) Set all the control levers in neutral.
ii) Run the engine at high idle and measure
the output pressure.
6) Drive the travel motor idle and measure the
EPC valve output pressure under the follow-
ing condition.
i) Raise the track shoe to be measured by
using the boom and arm
ii) Run the engine at high idle, drive the
travel motor idle and measure the output
pressure.
Symbol Part Number Part Name
M
1
799-101-5002 Hydraulic tester
790-261-1204 Digital hydraulic tester
2 799-401-2701
Differential pressure
gauge
3
799-101-5220 Nipple (10 × 1.5 mm)
07002-11023 O-ring
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