80 psig protects the discharge piping from over-
elements rated at 65 microns. The filter elements
pressurization. if the service pumps restore
can be cleaned and reused. Vent and drain
connections are provided for each filter housing.
normal system pressure to 15 psig, a pressure
switch opens and the air solenoid valve that
controls airflow to the pump motor closes and
LUBE OIL SUMP TANK.--The sump tank
stops the coast-down pump. The coast-down
is located below the propulsion reduction gear and
pump also stops if the propulsion shaft comes to
is attached to the gear drain pan by an expansion
a stop.
joint. The tank capacity at the normal oil level
is 1,400 gallons. The two service pumps and the
LUBE OIL UNLOADING VALVE.--The
coast-down pump each have an independent
air-pilot-operated valve senses the oil pres-
suction tail pipe from the tank.
sure at the reduction gear's hydraulically
Spent oil returns to the sump through an
most remote bearing and regulates the oil
opening around the bull gear cover. Main ship's
supply flow to maintain 15 psig at that
structural members in the tank act to smooth the
bearing. If the sensed pressure exceeds 15
psig, the valve will open and return excess
turbulence in the oil return area. The pump
s y s t e m flow to the lube oil sump tank.
suctions are located away from the turbulent area
The valve is fully open at a sensed pressure
so that the oil is permitted to deaerate before
of 20 psig. Control air from the ship's LP
entering the suctions.
vital air main is used for the operation of this
valve.
ATTACHED EQUIPMENT
LUBE OIL TEMPERATURE-REGULAT-
The attached equipment, as we mentioned
ING VALVE.- The air-pilot-operated valve is
earlier in this chapter, consists of the turning gear
located at the inlet to the lube oil cooler and
motor assembly, the attached lube oil and CRP
regulates the amount of oil flow through the
pumps, the electrostatic vent fog precipitator,
cooler. The temperature-sensing element is
the dehumidifier, the shaft tachometer, the
mounted in the oil supply piping to the reduction
revolution counter and elapsed time indicator, the
gear. Based on the signal from the temperature
MRG instrumentation, the turbine brakes, and
sensor, the valve regulates the amount of flow
the propeller shaft brakes.
through the cooler and bypasses the rest. The
valve is set to maintain a 110 5 F oil temperature
With the exception of the MRG turning gear,
to the reduction gear. Control air from the ship's
all of the attached equipment is similar between
LP vital air main is used for operation of this
the DD, DDG-993, CG, and FFG class ships.
valve.
LUBE OIL COOLER.--This cooler is made
Turning Gear Motor Assembly
of two shell and tube type of heat exchangers
piped in series. Seawater from the main seawater
The turning gear motor assembly is mounted
cooling system circulates through the tubes in a
on the aft end of the port HS pinion. It is
single pass through each shell of the cooler in
primarily used to rotate the entire reduction gear
series. The lube oil flows through each shell in
train for inspection and maintenance purposes.
series. The oil enters the cooler through the
It can also be used on some ships to lock the main
upper shell and leaves the cooler through the lower
shaft.
shell. Vent connections are provided on both the
upper shell and water box, and drain connections
DD AND DDG-993 CLASS SHIPS.--The
are provided on the lower shell and water box.
turning gear is an electric-motor-driven, double-
reduction gear mounted on the upper casing
LUBE OIL DISCHARGE FILTER.--This
of the MRG. When engaged and operating,
filter consists of two separate filter housings
it rotates the propulsion shaft at approxi-
connected by interlocked inlet and outlet valves
mately 0.1 rpm. The turning gear drives the
arranged so that only one housing is in operation
upper outboard second-reduction pinion through
at a time. Each filter housing contains 14 filter
a manually operated engagement sleeve. A
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