TM-5-3805-254-14-P-1
TRUCK, DUMP, 20 TON, 6X4, ON-OFF HIGHWAY 71,000 GVW, IHC MODEL F-5070 (CCE)
TECHNICAL MANUAL; OPERATOR'S, ORGANIZATIONAL, DIRECT SUPPORT, GENERAL SUPPORT AND DEPOT MAINTENANCE MANUAL (INCLUDING REPAIR PARTS INFORMATION AND SUPPLEMENTAL MAINTENANCE INSTRUCTIONS)
AUGUST 1980
TM-5-3805-254-14-P-1 - Page 42 of 590
OPERATION
evenly to the most favorable oil clearances.
See
"Engine Warm-up."
When water temperature is too low, the cylinder
walls retard heating of air during compression and delay
ignition.
This
causes
incomplete
combustion,
detonation, excessive exhaust smoke and high fuel
consumption.
Overheating
problems
require
mechanical
correction.
It may be caused by loose water pump belts,
a clogged cooling system, or insufficient radiator
capacity.
Report cases of overheating to the
Maintenance Department for correction.
200 deg.
F (93
deg.
C) maximum engine coolant temperature should
not be exceeded.
Keep thermostats in the engine summer and winter,
avoid long periods of idling, and take necessary steps to
keep water temperatures up to a minimum of 165 deg.
F
(74 deg.
C).
If necessary in cold weather, use radiator
shutters or cover a part of the radiator to prevent
overcooling.
(Refer to "Cold-Weather Operation.")
OIL PRESSURE GAUGE
The oil pressure gauge indicates any drop in
lubricating oil pressure or mechanical malfunction in the
lubricating oil system.
The operator should note loss of
oil pressure immediately and shut down the engine
before the bearings are ruined.
Normal Operating Pressures at 225 deg.
F (107
deg.
C) are:
Table 1-2:
Oil Pressure PSI (kg/sq cm)
Engine
Idle
Rated
Series
Speed
Speed
NH-NT SUPER 250
5/29 (9.4/1.71)
40/75 (2.8/5.3)
For record purposes these readings are more
accurate and reliable when taken immediately after an
oil change.
NOTE:
Individual engines may vary from above
normal pressures.
Observe and record pressures
when engine is new to serve as a guide for
indication of progressive engine condition.
(High oil
pressure during start-up is not cause for
ENGINE EXHAUST OBSERVATION
The engine exhaust is a good indicator of engine
operation and performance.
A smoky exhaust may be
due to a poor grade of fuel, dirty air cleaner, overfueling,
or poor mechanical conditions.
If engine exhaust is smoky, corrective action should
be taken.
ATTENTION OPERATOR
Cummins Diesel Engines have been built by
Cummins to comply with the requirements of the Federal
(U.S.) Clean Air Act.
Proper Maintenance of the Engine,
which is the responsibility of the owner/operator, is
essential to keep emission levels low.
Once the engine is placed in service the
responsibility for meeting state and local regulations
must necessarily be with the owner/operator.
Observation of good operating practices, regular
maintenance and proper adjustments are factors which
will help stay within the regulations.
MAXIMUM HORSEPOWER REQUIREMENTS
Maximum horsepower is attained only at rated
engine rpm.
Whenever engine rpm is pulled down by
overload, horsepower is lost and continues to be lost as
long as the engine continues to lose rpm.
When full
horsepower is needed, operate engine as near rated
rpm as possible.
This rule applies to all applications
(except Power-Torque Engines).
One rule sums up all rules for proper operation to
give the power needed and best performance from the
equipment:
ALWAYS OPERATE SO POWER
REQUIREMENT WILL ALLOW THE ENGINE TO
ACCELERATE TO, OR MAINTAIN, GOVERNED RPM
WHEN ADVANCING TO FULL THROTTLE.
When more power is required, bring engine speed
near the governor.
This will produce the additional
horsepower needed.
SHIFT TO A LOWER GEAR WHEN THE LOAD PULLS
DOWN ENGINE RPM
The practice of shifting gears next to safety
observance is a most important phase of good engine
operation.
The shift point differs from unit to unit depending
upon engine rated speed, torque peak point, and
transmission or gear splits
36
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