Yanmar Engine 8N21(A)L-EV

Cylinder Block & Cylinder Liner

The cylinder block is a box structure made of cast iron employing the double wall system w/c integrally cast the cam case, charge manifold, main oil and main cooling water gallery in bloc.
The structure of a main bearing is of the suspension metal type, and at its lower part, and oil pan is fitted. The cylinder liner is made of special cast iron, and at its upper inner diameter part, a protection ring is mounted.

Crankshaft, Main Bearing & Thrust Bearing

The crankshaft is a stamp forgings made of specials steel and has been induction hardened/quenched together with crank pins and journals.
To attain the dynamic balance, two balance weights per throe, 12 balance weights in total are fitted, and on the output side at the shaft rear end, the flywheel is mounted.
At the frontal part on the another end, shrink fitted crankshaft gear and gear case are arranged to form a structure to drive the timing gear and intermediate gear that are incorporated on the side of cylinder block. The main bearing is a split bearing made of aluminum alloy. The cylinder block side employs and oil grooved bearing; the main bearing cap side, a bearing without oil groove. It is a structure to lock by means of the main bearing cap which is incorporated by two bolts and two hydraulically tightened nuts on the cylinder block side. Besides, the thrust bearings are provided on both sides of the shaft rear end journal and form a structure to support the load in the front to rear direction.

Connecting Rod & Bearing

The connecting rod is a forgings made of carbon steel, and its big end part is obliquely split and serrated. The connecting rod bolt is hydraulically tightened in the same way as for the nut of main bearing cap. The bearing is of a type without oil groove for both the big end part and the small end part alike. The big end part employs as split bearing made of aluminum alloy; the small end part, a lead bronze bush with back metal.

Piston & Piston Rings

The piston is thin solid/integral structure made of ductile cast iron. The top and second ring grooves are laser hardened/quenched on both the upper and lower faces, Besides, for cooling of the upper part, the oil cooling cocktail shaker system to use lubricating oil w/c is injected by a cooling nozzle arranged on the lower end side of the cylinder inner part is employed.
Piston rings consists of four rings, three compression rings and one oil ring. Each ring has been chrome plated on the sliding surface.

Cylinder Head

The cylinder head of which upper side is made of thick cast iron while the explosion surface is made obliquely ribbed thin cast iron, is a structure fixed to the cylinder block by four hydraulically tightened nuts. The suction and exhaust valves are arranged in tandem and linked to the charge bend of the cylinder head integrated type and set up the swirl suction port.
The cooling water channel within the cylinder head employs a flow channel to cool the outer periphery of a nozzle sleeve provided at the center after cooling the exhaust valve seats with cooling water flowed in from two out of four spots in the cylinder block as well as the inter-suction/exhaust valve area with cooling water flowed in from other two spots in the cylinder block.

Suction/Exhaust Valve & Valve Mechanism

Suction and exhaust valves are four valves of the valve bridge type and so constructed to actuated two valves simultaneously through the valve bridge and valve rotator. The valve bridge is systemized to actuate through the camshaft, swing arm, roller, push rod and rocker arm. The valve mechanism is the fully enclosed type whereas its all parts are enclosed in the cylinder block, cylinder head and bonnet. The suction/exhaust valve is made of heat resistance steel with the seat part filled with stellite. At the stem part, a stem seal is fitted together with the suction/exhaust valve.
The exhaust valve made of nimonic alloy.
The suction/exhaust valve seat is such that stellite is filled to the seat part, and the exhaust valve seat is of the water cooled type and so constructed to provide an O-ring for cooling water tightness on the outer periphery of the valve seat.

Camshaft

The camshaft is made of carbon steel and integrates the induction hardened cam and the bearing part and adopts the longitudinally split-in-two type.
The cam shapes are such that the suction/exhaust cam is provided with shock absorbing/buffer, curve and the fuel cam adopts a profile having a big-diameter base circle.

Timing Gear & Intermediate Gear

The gear train is arranged inside the gear case opposite to the output side. The respective gears drive the camshaft, governor and pumps such as lubricating oil pump, cooling water pump and fuel feed pump of the marine diesel oil specification. Gear types are bevel gear for governor driving and helical gears for all other. Each gear adopts chrome-molybdenum steel carburized on the entire surface.

Fuel Injection Pump

The pump arranges the discharge valve equipped with two-way delivery valve at its uppermost part and is an 147MPa (1,500 kgf.cm2) high-pressure pump of the plunger barrel top closed type.

Fuel Injection Valve & Pipe

The injection valve is a multiple opening nozzle having a long stem and adopts the low inertia type having a low mass of the moving part.
For cooling of the injection valve, the indirect cooling system to cool the nozzle holder by the nozzle sleeve is adopted. The injection pipe is of the cylinder head through type, and the joint part is of the cone tight type at all points.

Lubricating Oil System

Lubricating oil sent out of the auxiliary tank under pressure by the lub oil pump is branched to two ways. In one way, lubricating oil flows to the main gallery through a cooler equipped with a thermostatic valve, strainer (B) and lub oil pressure regulating valve; in another way, lubricating oil flows out to the oil pan through the strainer (A). Besides, the pipe channel is so constituted that the lubricating oil overflowed from the oil pan is fed by the priming pump to the inlet side of the strainer (B) through the auxiliary tank. Lubricating oil in the main gallery lubricates main bearings of the crankshaft and bearings of piston pins through the journals and connecting rods as well as cools the piston, blowing out of a cooling nozzle provided at the gallery side part. Furthermore, lubricating oil is delivered for lubrication of valve parts of a cylinder head such as the rocker arm, valve guard and valve rotator, tappet and swing arm for camshaft and fuel injection pump of cylinder block and bearings of gears and the sliding parts inside the gear case. In addition to the aforementioned, this lubricating oil is forcedly fed to the turbocharger, furthermore to bearings of governor through the gear. Moreover, the lubricating oil constitutes a lubricating oil circuit to supply oil splashed to bearings of the fuel feed pump from gears. The lub. Oil pump is of the gear type while the priming pump (standby pump) equipped is the motor driven type.
The lub oil cooler equipped on the engine non-operating side of the multi-tubular type available in two specifications for fresh water and sea water and is provided with the inlet and outlet for cleaning washing fluid at its both ends.
The lub oil strainer (A) for bypass is of the centrifugal type while the strainer (B) found below the lub oil cooler adopts the duplex changeover notch wire type.

Suction/Exhaust System

The supercharger equipped on the flywheel side of the engine is an air-cooled exhaust gas turbine and of a single-stage, single-shaft structure which combines a radial-flow turbine with a centrifugal compressor. The exhaust manifold is made of carbon steel pipe and adopts the 4-division type of 3-group configuration for three cylinders.
The surrounding of the exhaust manifold is so constructed to cover the exhaust manifold with a cover sandwiching glass wool in steel sheet for sound insulation and fireproofing.

Cooling Water System

The cooling water system is available in three specifications of fresh/sea water dual line cooling, dual fresh water attachment independent cooling and dual fresh water line cooling.

Dual Fresh/Sea Water Line Cooling Specification
The cooling system is dual fresh/sea water dual line cooling. Cooling water pump up by the sea water pump cools the respective coolers for lubricating oil, charge and fresh water. On the one hand, fresh water cooled in the fresh water cooler is sent under the pressure to the engine cooling water pump.
After cooling the engine, the water branches off in two ways. In one way, the water flows to the cooling water pump through the expansion tank. Another way forms a return circuit to the former fresh water pump.
The charge cooler equipped on the engine non-operating side is a box structure of the plate finned multi-tubular type.
A centrifugal pump is adopted for cooling water pump.

Duel Fresh Water Line Cooling Specification

By this specification fresh water cools the engine body and all attachments equipped to the engine. Besides, the fresh water pump for cooling water and its control devices adopts a system completely separated from the engine and independent of the engine. There are two lines for cooling water being fed from the fresh water cooler. In one line, fresh water is sent under the pressure to the engine together with the preheating hot water that passes through the valve via the cooling water pump. After cooling the engine, the water branches off to the expansion tank pipe line and the main cooling water pipe line and returns to the fresh water cooler through both branches.
In another line, the water flows through the lub oil cooler and then the charge cooler. The line is a cooling system for the water to return to the former fresh water cooler in the same way as the engine cooling system. The charge cooler equipped on the engine non-operating side is a box structure of the plate finned multi tubular type. A centrifugal pump is adopted for cooling water pump.

Fresh Water Attachment Independent Cooling Specification

By this specification, sea water is used for cooling the fresh water cooler only while fresh water cools the engine body and all attachments equipped to t he engine. The cooling system adopted is so-called mixing cooling system consisting of the high-temperature engine body side water channel and low-temperature attachment side water channel equipped with the respective cooling water pumps, cooling water of both channels joining together after cooling various parts.
Cooling water for the engine body passes through t he fresh water cooler and cooling water pump P1 and is sent under pressure to the engine together with preheating hot water w/c comes passing through valves. After cooling the engine, cooling water branches off. In one way, it flows the suction side of cooling water pump P1 & pump P2 after passing through the expansion tank. In another way, cooling water returns to the fresh water cooler after passing through the thermostatic valve T1. Besides, a branch from the thermostatic valve T1 forms a return circuit to the suction side of the cooling water pump P1 for shortening the warming-up time. Cooling water for the attachment side forms a mixing water channel where the water is sent under pressure from the fresh water cooler by the cooling water pump P2 passes thought the lub oil cooler and charge cooler, joins together with cooling water w/c comes passing thought the thermostatic valve T1 after cooling the engine and finally returns to the former fresh water cooler.
The charge cooler equipped on the engine non-0operating side is a box structure of the plate finned multi tubular type. Centrifugal pumps are adopted for both cooling water pumps P1 & P2 Besides, the thermostatic valve T1 adopts an automatic temperature control valve of the wax type.

Fuel System

Two specifications on fuel burning are available for this engine; specially, for marine diesel oil and for low-quality heavy fuel oil, and the fuel circuit differs between the marine diesel oil specification and the heavy fuel oil specification.
In a section enclosed by an alternate long and short dash line in both aforementioned figures, various attachments and pipe line for such as pressurizing, circulation, cleaning & separation related to fuel are set up, but since this system is generally set in consideration of conditions of use of the engine, quality of fuel used, etc, the nature of combination of attachments diverges.
Consequently, for details of a section enclosed by the alternate long and short dash line, please refer to the Fuel System Diagram drawn by your constructor. The fuel circuit on the engine side is described here.


Marine Diesel Oil Specification

Fuel sent out from the marine diesel oil tank by the fuel feed pump is fed to fuel injection valves through the fuel strainer, injection pumps and injection pipes.
The pump circulating fuel from respective injection pumps, on the other hand, flows through the collecting pipe and returns to the former fuel tank through a pressure regulating valve w/c serves to keep the fuel pressure constant.
Besides, oil overflowed from the injection valves directly returns to the fuel tank through the collecting pipe. Moreover the pipe line is such to return both the oil leaked from the fuel injection pipe section and the drain from the fuel injection pump housings to the drain tank through the leak detector and collecting pipe, respectively.
The fuel feed pump equipped on the anti-flywheel side is a gear pump integrated with a safety valve. The fuel filter adopts the duplex changeover notch wire type of manual back-washing specification; the leak detector, the float type.

Heavy Fuel Oil Specifications

Two specifications are available for heavy fuel oil burning. One is the heavy fuel oil exclusive specification to use heavy fuel oil entire from a start and a load run to a stop. Another is the marine diesel oil jointly using specification to use marine diesel oil in starting and stopping. Incidentally, the constitution of the fuel circuit is the same for both specifications, only differing in starting and stopping preparatory works.

Heavy Fuel Oil Exclusive Specification

The fuel oil pipe line is diagramed by a combination of heavy, alternate long and short dash line and continuous line.
Fuel from the heavy fuel oil tank is sent under pressure by the motor-driven fuel feed pump (B) and fed to fuel injection valves through the hear-insulating fuel filter, seal pot, fuel injection pumps and injection pipes on the engine side.
On the other hand, pump circulating fuel from the respective fuel injection pumps flows through the collecting pipe and returns to the former heavy fuel oil tank through a pressure regulating valve w/c serves to keep the fuel pressure constant. Besides, the pipe line is such to return both the oil leaked from the fuel injection pipe section and the oil overflowed from the injection valves as well as drain from the fuel injection pump housings to the drain tank through the leak detector and collecting pipe, respectively.
The fuel feed pump (A) equipped on the anti-flywheel side is a gear pump integrated with a safety valve. Furthermore, a motor-driven gear pump is suggested for fuel feed pump (B). The fuel filter adopts the heat-insulating, duplex changeover notch wire type of manual-backwashing specification; the seal pot, the box type filled with ethylene glycol; the leak detector, the float type.

Marine Diesel Oil Jointly Using Specification

By this specification, marine diesel oil is used in starting and stopping. The fuel oil pipe line for such time is diagramed by a combination of heavy, broken line and continuous line.
Fuel sent from the marine diesel oil tank by the fuel feed pump (A) branches into two ways at the outlet of the fuel feed pump. In one way, such fuel flows through a pressure regulating valve and returns to the former fuel tank. In another way, fuel is fed to fuel injection valves through the heat-insulating fuel filter, seal pot, fuel injection pumps and injection pipes.
On the other hand, pump circulating fuel from the respective fuel injection pumps flows through the collecting pipes and returns to the former marine diesel oil tank through a pressure regulating valve w/c serves to keep the fuel pressure constant. Besides, the pipe line is such to return both the oil leaked from the fuel injection pipe section and the oil overflowed from fuel injection valves as well as drain from the fuel injection pump housings to the drain tank through the leak detector and collecting pipe, respectively.
After starting, the changeover valve of the fuel pipe line is operated to change over the fuel to heavy fuel oil during a run. The heavy fuel oil pipe line for such time is diagramed by a combination of heavy, alternate long and short dash line and continuous line.
Fuel oil from the heavy fuel oil tank is sent under pressure by the motor-driven fuel feed pump (B) and fed to the heat-insulating fuel filter on the engine side. From the fuel filter and on, constitution of the respective pipe lines on the engine side and the flow of fuel are the exactly same as starting or stopping the engine with marine diesel engine.
Nevertheless, the pipe line is such that pump circulating fuel from the respective injection pumps branches at the outlet of a pressure regulating valve and returns to the heavy fuel oil tank.
The fuel feed pump (A) equipped on the anti-flywheel side is a gear pump integrated with a safety valve. Furthermore, a motor driven-gear pump is suggested for fuel feed pump (B).
The fuel filter adopts the heat-insulating, duplex changeover notch wire type of manual-backwashing specification; the seal pot, the box filled with ethylene glycol; the leak detector, the float type.

Air & Engine Control System

The air supplied from the air tank branches in to two ways through the reducing valve and safety valve. In one way, such air is sent to the air motor driving main circuit, and in another way, the air further branches off after passing through the shut-off valve V1 for protection of the turning device and the starting valve V2, passes through air motor pinion working cylinder and branches off just after the starting valve V2 reaches the air cylinder through the speed control valve V3.
The air motor to drive the ring gear is of the turbine type; the starting valve V2 integrated with the motor, a solenoid valve equipped with a manual operating valve; the shutoff valve V1 of the turning device section, mechanical; the stopping valve V4 for the engine stopping, a solenoid valve. For air piston, the double piston type equipped with one piston each for limiting and stopping injection fuel is adopted.


Engine Stop

The stopping air circuit is diagram by broken line. The circuit is a pipe line provided with a globe valve and the stopping valve V4 of the solenoid valve type on the way to the air cylinder.

Engine Rotation Control

The control is accomplished by use of the governor, start/stop lever, fuel injection pumps, air piston and link mechanism of such as levers and shafts so interlocking fuel injection pumps to limit the fuel injection volume, actuates the control valve to gradually release limiting and works to stop the injection in stopping. Incidentally, an engine side stopping is done by operating the start/stop lever. The governor equipped on the operating side of the engine rear parts adopts the hydraulic type; the fuel injection pump, the Bosch type.

Instrument & Electrical Parts

Subjects of alarming and remote monitoring are pressures of fuel, lubricating oil, cooling water, charge and air system. Apparatus of instrumentation such as pressure switch & test valve and transmitter use in direction, for instance, of these parameters excluding the fuel system are arranged in the centralized manner in the neighborhood of gauge panel provided on the operating side of the engine of the engine frontal part. Incidentally, apparatus for the fuel system are arranged together with the seal pot, pressure gauge, differential pressure gauge, etc. on the operating side of the engine frontal part.

Common Bed & Engine Vibration Insulation Device

The common bed is welded structure made of steel plate, and an auxiliary tank for lubricating oil is built in the common bed.
The engine vibration insulation specification is such a structure that some numbers of rubber vibration insulators of special construction are arranged on both sides of the common bed.