Warming Up Operation; Warming Up In Cold Weather - Hitachi EX27U Operator's Manual

WARMING UP OPERATION

The normal operating temperature of hydraulic oil is from
50 to 80°C (122 to 176°F). Hydraulic components may be
seriously damaged if the machine is operated with hydrau-
lic oil temperature below 20°C (68°F).
Before starting work, be sure to follow these warm-up pro-
cedures until the temperature of the hydraulic oil reaches
above 20°C (68°F).
Warm-Up Procedures:
1. Run the engine at 100 to 200 min
idle speed for 5 minutes.
2. With the engine speed control lever at the medium
position, run the engine for 5 to 10 minutes.
3. Extend and retract each cylinder several times and
lightly operate the swing and travel motors to warm
up them.

WARMING UP IN COLD WEATHER

IMPORTANT: 1. In cold weather, be sure to thoroughly
warm-up the motors and cylinders.
2. If the hydraulic circuit is continuously
relieved for a certain amount of time,
the temperature in the control valve
would rise excessively. Never operate
to stroke end more than 30 seconds.
After relieving any function, up to 30
seconds, be sure to have a 5-10 sec-
ond intermission.
1. Run the engine at medium speed for 5 minutes
(longer if the air temperature is extremely low).
2. Do not change the engine speed during this time.
3. Extend and retract each cylinder several times and
lightly operate the swing and travel motors to warm
up them.
4. Extend the bucket cylinder to the stroke end.
5. Be sure not to hold the bucket lever in this position for
more than 30 seconds.
6. Retract the bucket cylinder to the other stroke end.
7. Be sure not to hold the bucket lever in this position for
more than 30 seconds.
8. Repeat steps 4. to 7. until the bucket cylinder cycle
time becomes normal.
OPERATING THE MACHINE
-1
(rpm) above slow
5-10