pump control logic at the PLCC for use in con-
inlet is at the opposite end from the water inlet,
trolling the number of pumps in service and pump
resulting in counterflow heat transfer.
speeds.
The RTD provides a signal to the ECSS for
LUBE OIL FILTER.---A duplex filter is
the following uses:
installed in the piping downstream from the lube
oil cooler to remove particulate matter from the
1. Meter reading of header temperature at the
lube oil. The filter consists of a single cast steel
PACC and the PLCC
body mounted on a fabricated steel base. The
2. HEADER TEMPERATURE HI/LO in-
filter body contains two filter chambers and a
dicator light and audible alarm at the
diverting valve assembly. The diverting valve
PACC and the PLCC
connects the filter chambers to the inlet and outlet
3. Alarm logging
ports. The filter chambers are covered by bolted
steel plates.
The pressure switch provides the permissive
A manually operated changeover assembly
for the MRG turning gear.
positions the diverting valve to place the right or
left filter element in service. The selector lever is
positioned over the chamber selected. A hydraulic
Attached Lube Oil Pump.--The attached lube
interlock prevents the shifting of oil flow to
oil pump is of a similar design to the motor-driven
an open (nonpressurized) filter chamber. An
pumps. The principal difference is in the larger
interlock cylinder is connected to each of the filter
size and greater rated capacity. The attached
chambers. When a differential pressure exists
pump is rated at 1,140 gpm at 60 psig discharge
between the chambers, the cylinders engage a
pressure and 1,220 rpm (approximately 168 shaft
notch in the diverting valve cam plate and
rpm).
positively lock the selector lever. The changeover
The attached pump is supported by a bracket
assembly also contains a balancing valve that is
immediately above the lube oil sump top. It is
used to equalize pressure between the chambers
driven by the MRG lower inboard second-
to allow shifting. The assembly also fills the filter
reduction pinion shaft through a right-angle drive.
chamber after cleaning. Each filter chamber is
The angle drive is equipped with a manually
provided with a vent and a drain.
operated disconnect device that may be used to
The liftout filter elements are constructed of
disconnect the attached pump when the main shaft
pleated wire cloth, supported by inner and outer
is stopped. The attached pump takes suction from
perforated metal tubes. Magnets supported inside
the sump through an individual suction line and
each filter element remove ferrous particles from
discharges into the lube oil service piping system.
the oil.
The pump speed is proportional to shaft speed;
A differential pressure gauge and switch are
therefore, the attached pump does not deliver
connected to the inlet and outlet flanges for local
enough oil by itself to lubricate the MRG and to
and remote monitoring. The differential pressure
cool the GTE synthetic oil until higher shaft
switch opens at 10 psid and sends a signal to the
speeds are reached.
ECSS. The ECSS activates the STRAINER DP
HI light and alarm at the PACC and the PLCC,
LUBE OIL COOLER.--A lube oil cooler is
and provides data for alarm logging.
installed in each lube oil service system
downstream from the lube oil pumps to maintain
UNLOADING VALVE.--An unloading
the oil outlet temperature at 120F. The cooler
valve is located between the main lube oil header
consists of a shell assembly, a tube bundle, and
and the MRG sump. It is controlled by a pressure
inlet and outlet water boxes.
sensor located at the MRG oil inlet. It is set to
The cooler is a single-pass shell and tube
maintain reduction gear inlet oil pressure at 15
type of heat exchanger. Seawater is used as the
psig minimum under steady state conditions.
cooling medium. It enters the inlet water box
through the inlet connection, makes one pass
LUBE OIL HEATER.--One lube oil heater
through the tubes, and is discharged through the
is installed in each engine room. The heater has
outlet water box. Seawater flow is regulated by
connections to the purifier and to the lube oil
a pneumatically operated valve controlled by a
service piping system. The heater is used to heat
temperature sensor installed in the lube oil
the oil during purification and to heat oil during
piping downstream from the cooler. The lube oil
lube oil service system warm-up.
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