Patriot State was the training ship of the Massachusetts Maritime Academy from 1986 to 1998.
Emergency power requirements for the Patriot State are provided for by a 200 kW alternating current diesel driven generator. The engine is a Detriot Diesel Engine, model 8V71, and it is installed in the emergency diesel generating room, which is located on the bridge deck between frames 124 to 128, port side. It is located there because Coast Guard Regulations do not permit the emergency generator to be located within the main machinery spaces. Also, it is near the atmosphere for intake, exhaust, and ventilation purposes.
The function of the emergency diesel generator is to supply power to the emergency switchboard in the event of a low voltage available at the main switchboard. A low voltage situation would occur when the bus voltage is 300 volts or less. The main switchboard would go into a low voltage situation if a casualty occured where the ship's service generators were unable to supply rated voltage to the main switchboard. The emergency diesel generator is capable of supplying all the loads fed by the emergency switchboard.
The emergency diesel generator is also used during cold ship starting and emergencies to supply limited power to engineroom machinery. If the main switchboard is deenergized, you can defeat the interlock on the bus tie breaker, and feed power back to the main switchboard. This will give you a very limited amount of power for loads such as the forced draft fan, fuel oil pump, etc. In addition, Machinery space lighting can be fed from the emergency switchboard without energizing any part of the main switchboard. The emergency diesel generator may not be paralleled with any of the ships service generators due to the interlock on the bus tie breaker.
The emergency generator will start automatically in the event of the a power failure. When the emergency diesel starts, it is important to check it soon after it has picked up the emergency load.
The emergency alternating current diesel driven generator is rated at 200 kw, 450 volts, 0.8 power factor, 60 Hz, and it generates three phase electricity. The generator is designed to run at 1800 rpm The emergency diesel generator was not designed with an overload rating and must not be used outside the normal service ratings.
General Data
Model number 70837305
Cycles (stroke) 2
Number of cylinders 8
Bore (in) 4.25
Stroke (in) 5
Total displacement 568
rpm 60 Hz at 1800 rpm
Compression ratio 17:1
Firing order 1L-3R-3L-4R-4L-2R-2L-1R
Starting system Hydraulic
Crankshaft rotation Right
Cylinder arrangement V
Recommended Operating Conditions
Lube oil pressure 50 - 70 psi
Fuel oil injection pressure 2200 - 3000 psi
Lube oil temperature 200 - 250°F.
Cooling water temperature 160 - 185°F. Do not exceed 210°F.
Fuel pump pressure 58 - 70 psi
Compression pressure 450 psi
The fuel system consists of the fuel injectors, fuel pipes, fuel pump, fuel strainer, fuel filter and the necessary connecting lines.
A restricted fitting is located in the outlet passage in one of the cylinder heads to maintain pressure in the fuel system.
Fuel is drawn from the supply tank through the fuel strainer and enters the inlet to the fuel pump. The gear type fuel pump raises the fuel pressure and forces the fuel through the fuel filter. The fuel passes through the fuel filter into the fuel inlet manifold where it passes through fuel pipes into the inlet side of each fuel injector. The fuel is filtered through elements in the fuel injectors and atomized through small spray tip orifices into the combustion chamber. Surplus fuel, returning from the injectors, passes through the fuel return manifold and connecting fuel lines back to the fuel tank.
The continuous flow of fuel through the injectors helps to cool the injectors and remove air from the fuel system.
The fuel injector combines in a single unit, all of the parts necessary to provide complete and independent fuel injection at each cylinder. The injector creates the high pressure for fuel injection, meters the proper amount of fuel, atomizes the fuel, and time the injection into the combustion chamber.
The fuel oil transfer system originates in the lower engine room machinery spaces. A machinery space tank (port side D.B.) supplies fuel to the diesel oil day tank located on the flying bridge deck which holds 350 gallons and flows into a day tank in the emergency diesel room.
The combination of the two tanks holds approximately 750-800 gallons of oil and is enough of a supply for 24 hours of diesel generator operation under full load.
Normal suction from the day tank is accomplished by the fuel oil booster pump which is engine driven, and mounted on the auxiliary drive housing. It draws fuel oil from the day tank through a Raycor suction filter and discharges it through the pressure filter to the fuel oil header. From this header, fuel oil flows to the individual fuel injection pumps which deliver the fuel oil to the injection nozzles in the proper quantity.
There is a pressure relief valve which is between the transfer pump and the pressure filter which is set to open at 100 psi. When this valve opens, the fuel oil is by-passed back to the fuel oil day tank.
A pressure relief valve connected to the fuel oil header is set to open at a pressure of 35 pounds. When this valve opens, the fuel oil is by-passed back to the fuel oil tank. The lighter the load on the engine, the greater will be the quantity of oil passing through this valve, thus maintaining a constant head of fuel oil.
The cooling system is of the closed type with the cooling water flowing from a radiator holding approximately 8.8 gallons.
Coolant is drawn from the lower portion of the radiator by the water pump and is forced through the oil cooler housing into the cylinder block. From the cylinder block, the coolant passes up through the cylinder heads and when the engine is at normal operating temperature, through the thermostats and into the upper portion of the radiator. The coolant passed down a series of tubes where its temperature is lowered by the air stream created by the revolving fan.
A centrifugal pump driven from the engine camshaft at the pump end of the engine circulates the water through the system.
The oil pump on the 8V engines is placed in the crankshaft front cover and consists of a pair of spur gears, one large and one small, which mesh together and ride in a cavity inside the crankshaft cover. The larger gear is concentric with and splined to a pump drive hub on the front end of the crankshaft. The pump idler gear is much smaller and runs on a bushing and hardened steel shaft pressed into the crankshaft cover.
The oil is drawn by suction from the oil pan through the intake screen and pipe to the oil pump where it is pressurized. The oil then passes from the pump into a short gallery in the cylinder block to the oil cooler adaptor plate. At the same time, oil from the pump is directed to a spring loaded pressure relief valve mounted on the cylinder block. This valve discharges excess oil directly to the oil sump when the pump pressure exceeds 100 psi (689 KPa).
From the main oil gallery, the pressurized oil flows through drilled passages to each main bearing then passes to an adjacent pair of connecting rods by means of grooves in the unloaded halves of the main and connecting rod bearings and drilled passages in the crankshaft. The rifle drilled connecting rods carry oil from the rod bearings to the piston pin bushings and to the nozzles at the upper end of each connecting rod which provides the cooling oil spray for the piston crown.
At the rear of the block, two diagonally drilled oil passages which intersect the main oil gallery carry oil to two rear camshaft end bearings. Oil is then conducted through the rifle drilled camshaft to the intermediate and front end bearings. Oil from the camshaft intermediate bearing is directed against the camshaft lobes and cam rollers which run in an oil bath. This oil from the intermediate bearing provides lubrication of the cam lobes immediately after starting the engine when the oil is cold and before camshaft bearing oil flow and oil drainage from the cylinder head have had time to build up.
The diagonally drilled oil passage on the right side of the rear of the block intersects with a vertical passage to carry oil to the right bank cylinder head. A short gallery also intersects with the diagonal passage to lubricate the idler gear bearings. Another gallery intersecting the diagonal passages at the front of the block supplies oil to the left bank cylinder head.
Drilled passages, intersecting longitudinal galleries which parallel the camshaft, lead to blowers and supply oil for the blower drive gears and bearings.
A gear driven crankcase exhauster is provided to pull a slight vacuum on the crankcase at all times. This provision prevents the formation of dangerous pockets of gas accumulation in the crankcase and assures that gasket leakage will be maintained at a minimum for all crank pit covers and cylinder block closures.
Spring Loaded explosion covers, quick opening and quick closing, are provided at each end of the engine. These covers are of sufficient area to relieve pressure above 13 psi which may build up in the crankcase due to mechanical troubles or explosions due to local hot spots.
Engine speed is maintained by an Woodward governor which is hydraulic and of the isochronous type. An isochronous governor will maintain the desired engine speed regardless of load. A hand speed control lever is furnished to control speeds between idle and 1800 rpm (full speed). Load should be applied only when the throttle is up all the way. The engine is also equipped with a mechanical overspeed trip in case of governor failure.
The movements of the governor power mechanism are transmitted through the lever and link connections to the fuel pump control rod. These connections are fitted with hardened pins and needle bearings which require oil periodically. A light spring fastened to the control rod takes up lost motion due to linkage wear. A bell crank and block located near the governor can be adjusted to give proper rack travel of 18mm maximum. A compression link assembly is provided between the fuel pump control rod governor, to disconnect the governor from the fuel pump control rod when the overspeed trip is tripped. When the overspeed trip is reset, the compression link assembly returns to its normal position.
Engine starting is acomplished by a hydraulic starting system. Hydraulic fluid is stored in four nitrogen charged accumulators at a pressure of 2800 psi. To start the engine, a hydraulic control valve is pulled forward, hydraulic fluid is released through a high pressure hose to the starter mounted on the left side of the Detroit Diesel. The starter motor turns over the engine, and the hydraulic fluid returns to the hydraulic resevoir tank.
The accumulators can be recharged by an electric motor or by a hand crank when electrical power is not present.
In order to insure proper operation of the engine at all times, preventive maintenance is an absolute necessity.
When not being used under normal operation, this engine should be run for at least a half hour once a week. Lube oil filter should be changed every 30 hours of operation. Along with this, lube oil filters and fuel oil filters should be changed when they become heavy with sludge and dirt particle. Always check that the crankcase contains oil up to the operating level, and that there is a sufficient amount of fresh water in the engine for proper cooling before starting up.
Always keep a sufficient level of fuel oil in the day tank during engine operation (at least half full). Maintaining at least that level ensures against stirring up dirt and sludge that may be at the bottom of the tank.
Direct comments to William Haynes whaynes@maritime.edu
Mon, Jul 1, 1996
TSPS Engineering Manual ©1995 Massachusetts Maritime Academy