the attached pump is not controlled and is
Correct temperature of the oil in the lube oil
proportional to shaft speed. Primary system
service system must be maintained. If the
pressure regulation is accomplished by the
temperature of the oil in the lube oil service system
unloader valve. When the ship's speed increases
is below 90F, the oil must be heated prior to
and the total pump output exceeds the regulating
propulsion plant operation. A motor-driven lube
oil service pump may be used to assist in the
capacity of the unloader, MRG inlet pressure
increases. The ECSS pump control logic then
heating of the oil by circulating it through the lube
sequences the motor-driven pumps to change to
oil heater. The purifier is isolated from the heater
a slower speed or to cut off to maintain pressure
when this procedure is used. During this
in the operating range. When the pump control
operation, a portion of the lube oil service pump
logic has sequenced both motor-driven pumps to
discharge is diverted through the lube oil heater
cut off, the attached pump supplies the total lube
and returned to the MRG sump. The remaining
oil system requirements. A similar control se-
service pump discharge oil is circulated around
quence operates to maintain oil pressure when
the service system in the normal flow path. This
shaft speed decreases.
warms up the total system for plant operation.
Motor-Driven Lube Oil Service Pumps.--Two
MAIN REDUCTION GEAR LUBE OIL
identical lube oil service pumps are located in each
SUMP.--The MRG lube oil sump is located in
engine room. Each pump assembly consists of a
the inner bottom beneath the MRG. The sump
vertical-screw, positive-displacement pump that
contains the supply of oil for the main lube oil
is flexibly coupled to a two-speed electric motor
service system. It collects and retains oil as it
returns from the MRG, main thrust bearing, and
mounted on a common steel bracket. Resilient
mounting is used between the bracket and the
propulsion turbine synthetic lube oil system
ship's structure. The pump is rated at 700 gpm
coolers. The lube oil return from the MRG to the
at high speed and 250 gpm at low speed at a
main sump consists of a convoluted flexible
discharge pressure of 60 psig. The pumps take
connection bolted between the MRG oil pan and
suction from the MRG sump through a common
the top of the sump. The normal operating
suction line and discharge to the lube oil service
capacity is 1,500 to 1,550 gallons, and the low
piping.
operating level is 1,400 gallons. When the sump
A mechanical seal is located in the top end
is filled to the operating level, the pump suction
bellmouths will be submerged under all operating
cover to prevent leakage along the pump shaft.
Provision is made for installation of ring pack-
conditions. The sump is designed to allow free
ing above the seal. Packing should not be used
drainage of pockets formed by stiffeners inside
unless there is a failure of the mechanical seal.
the sump and to allow access for inspection and
Lubrication is provided by the lube oil being
cleaning. Lube oil return drains are located as far
pumped. The mechanical seal is lubricated
as possible from suction bellmouths. The sump
through a tube and needle valve connected to the
is equipped with a sludge pit located at the lowest
discharge end of the pump.
point. It is also equipped with a liquid level
The pumps may be controlled locally at their
transmitter, an RTE, pump and purifier suction
respective controllers. With the LOCAL-RE-
connections, and oil return connections.
MOTE selector switch in LOCAL, the STOP-
SLOW-FAST selector switch is operative. With
PUMPS.-- Three positive-displacement lube
the LOCAL-REMOTE selector switch in the
oil pumps are installed in each engine room, two
REMOTE position, control is transferred to the
motor-driven and one attached to and driven by
ECSS.
the MRG. The attached lube oil pump is engaged
The inlet to the MRG lube oil header is
or disengaged by a lever attached to the pump
provided with a pressure gauge, a thermometer,
coupling. These pumps supply lube oil to the
a pressure transducer, an RTD, and a pressure
MRG and cooling oil to the two LOSCAs for the
switch.
propulsion gas turbines. The motor-driven pumps
The pressure transducer signal provides a
supply oil to the system when the propulsion shaft
meter reading at the PACC and the PLCC, a
is stopped and augment the attached pump at low
HEADER PRESS HI/LO light and alarm at the
shaft speeds. When a lead pump has been selected,
PACC and the PLCC, and information for data
the motor-driven pumps are controlled by the
logging. It also provides a high-low signal for
ECSS pump logic as a function of pressure at the
alarm logging and provides information to the
inlet to the MRG lube oil header. The output of
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