5: Maintenance 600H, 700, 750, 750H, 750HH, 825, 900, 900H, 1050 T3 CAT User Manual
02250197-981 R01
62 Subject to EAR, ECCN EAR99 and related export control restrictions.
5.11.5.4 Control system adjustment
Refer to Figure 5-5. Prior to adjusting the control system,
it is necessary to determine the desired operating pres-
sure range as well as the maximum pressure at which
the machine is
to operate. This pressure must not exceed
the maximum operating pressure which is stamped on
the machine serial number plate.
1. Start the machine and let it warm-up and
enter full “RUN” mode.
2. Open serv
ice valve slightly until engine tries
to speed up. Slowly close the service valve.
With service valve closed, check and adjust
the pressure at the reducing regulator to a
minimum of 60 psig (4.1 bar) and not to
exceed 75 psig (5.2 bar). With service valve
still closed, and the “HI/LO” switch in the
“LO” position, adjust the low-pressure back-
pressure regulator so the service pressure is
between 115 to 125 psig (7.9 to 8.6 bar) with
the engine at 1400 rpm. Open the service
valve to load the compressor to maintain 100
psig (6.9 bar) discharge pressure. Operating
speed should be 1800 RPM on the instru-
ment panel. If not, repeat step, but adjust the
unload service pressure up or down as
needed until 100 psig (6.9 bar) is maintained
when engine speed is 1800 rpm.
3. For 150 psig (10.3 bar) “H” machines, turn
the “HI/LO” switch to “HI” position. Close the
service valve and set the “HI” pressure con-
trol regulator to maintain 165 to 175 psig
(11.4 to 12.1 bar) discharge pressure. Open
the service valve to maintain 150 psig (10.3
bar) and check for 1800 RPM full-load
speed. If lower speed is observed, raise the
setting of the low pressure control regulator
until rated speed is achieved.
4. For 175 psig (12.1 bar) “HH” machines, turn
the “HI/ LO” switch to “HI” position. Close the
service valve and set the “HI” pressure con-
trol regulator to maintain 190 to 200 psig
(13.1 to 13.8 bar) discharge pressure. Open
the service valve to maintain 175 psig (12.1
bar) and check for 1800 RPM full-load
speed. If lower speed is observed, raise the
setting of the low pressure control regulator
until rated speed is achieved.
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