Low oil level in hydraulic governors may be caused
by oil leaking from the governor or failure to maintain
the proper oil level. Leakage of oil from a governor can
generally be traced to a faulty oil seal on the drive shaft
or power piston rod, or to a poor gasket seal between
parts of the governor case.
Check the condition of the oil seals if oil must be
added too frequently to governors with independent oil
supplies. Oil seal leakage may or may not be visible on
external surfaces. There will be no external sign if
leakage occurs through the seal around the drive shaft,
while leakage through the seal around the power piston
will be visible.
Oil seals must be kept clean and pliable. Store them
properly so they do not become dirty or dry and brittle.
Leaky oil seals cannot be repaired. They must be
replaced. You can prevent some leakage troubles simply
by following proper installation and storage instructions
for the seals.
Most manufacturers technical manuals supply
information on the governor. Special hydraulic governor
maintenance manuals made available by the Naval Sea
Systems Command are the Marquette Governor
Manual, NAVSHIPS 341-5505 (0341-LP-550-5000),
Woodward Governor Manual, NAVSHIPS
Inoperative Overspeed Safety Devices
Overspeed safety devices are designed to shut off
fuel or air in case of excessive engine speed. These
devices must be maintained in operable condition at all
times. Inoperative overspeed devices may also cause an
engine not to start. They may be inoperative because of
improper adjustment, faulty linkage, or a broken spring,
or the overspeed device may have been accidentally
tripped during the attempt to start the engine.
If the overspeed device fails to operate when the
engine overspeeds, the engine may be secured by
manually cutting off the fuel oil or the air supply to the
engine. Most engines have special devices or valves to
cut off the air or fuel in an emergency.
Insufficient Cranking Speed
If the engine cranks slowly, the necessary
compression temperature cannot be reached. Low
starting air pressure may be the cause of such trouble.
Slow cranking speed may also be the result of an
increase in the viscosity of the lubricating oil. This
trouble occurs during periods when the air temperature
is lower than usual. The oil specified for use during
normal operation and temperature is not generally
suitable for cold climate operation.
IRREGULAR ENGINE OPERATION
As the engine operator, you must constantly be alert
to detect any symptoms that might indicate trouble. Such
symptoms may be sudden or abnormal changes in the
supply, temperature, or pressure of the lubricating oil or
cooling water. Color and temperature of the exhaust may
also indicate abnormal conditions. Check them
frequently. Fuel, oil, and water leaks indicate possible
troubles. Keep the engine clean to make such leaks
easier to spot.
You will soon become accustomed to the normal
sounds and vibrations of a properly operating engine. If
you are alert, an abnormal or unexpected change in the
pitch or tone of an engines noise or a change in the
magnitude or frequency of a vibration will warn you that
all is not well. A new sound such as a knock a drop in
the fuel injection pressure, or a misfiring cylinder are
other trouble warnings for which you should be
constantly alert during engine operation.
The following discussion on possible troubles, their
causes, and the corrective action necessary is general
rather than specific. The information is based on
instructions for some of the engines used by the Navy
and is typical of most. A few troubles listed may apply
to only one model. For specific information on any
particular engine, consult the manufacturers technical
ENGINE STALLS FREQUENTLY OR STOPS
We discussed earlier several of the troubles that may
cause an engine to stall or stop. Such troubles as air in
the fuel system, clogged fuel filters, unsatisfactory
operation of fuel injection equipment, and incorrect
governor action not only cause starting failures or
stalling but also cause other troubles as well. For
example, clogged fuel oil filters and strainers may lead
to a loss of power, to misfires or erratic firing, or to low
fuel oil pressure. Unfortunately, a single engine trouble
does not always manifest itself as a single difficulty but
may be the cause of several major difficulties.
Factors that may cause an engine to stall include
misfiring, low cooling water temperature, improper
application of load, improper timing, obstruction in the
combustion space or in the exhaust system, insufficient