Nmlc ef1 module 1

EXCELLENCE AND COMPETENCY TRAINING CENTER INC.
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NMLC-EF1-Module 1
Function 1:
Marine Engineering at the
Management Level
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NMLC-EF1-Module 1

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NMLC-EF1-Module 1
COVERAGES:
Module 1 – Manage the operation of
propulsion plant machinery
Module 2 – Plan and schedule operations
Module 3 – Operation surveillance, performance assessment
and maintaining safety of propulsion plant and auxiliary
machinery
Module 4 – Manage fuel, lubrication and ballast operations
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NMLC-EF1-Module 1

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NMLC-EF1-Module 1
OBJECTIVES:
Function 1: Marine Engineering at the Management Level
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■ Upon successful completion of the training under
this Function, trainees shall be expected to have
gained the minimum knowledge, understanding
and proficiencies needed to carry out and
undertake at the management level the tasks,
duties and responsibilities in marine engineering
on ships powered by main propulsion machinery
of 3,000 kW propulsion power or more.
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Operation and Maintenance of Marine Diesel
Engines

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Reviews the Essential Engine Components
❑ Bedplate
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▪ A one piece structure that may be of cast iron, prefabricated
steel, cast steel, or a hybrid arrangement of cast steel and
prefabricated steel.
▪ For many years however, cast iron was the preferred material
since it gave a stress free, easily machined and at times a
cheap structure.
▪ When welding techniques and methods of inspection improved
and larger furnaces became available for annealing, the switch
to prefabricated steel structure with its saving in weight and
cost was made.

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Bedplate
FABRICATED
BEDPLATE
TIE RODS
WELD
CAST STEEL
SADDLE
CRANKSHAFT
MAIN BEARING CAP

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❑ Crankshaft
▪ It is the backbone of the reciprocating diesel engine.
▪ It must be extremely reliable as the cost of replacement would
be high, and to say nothing of the dangerous situation that may
arise on the high seas if it failed.
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Types:
Fully built-up - webs are shrunk on to the journals and crank pins.
WEB.
JOURNAL
(a) FULLY BUILT-UP

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❑ Crankshaft
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Types:
Semi built-up - webs and crankpin as one unit shrunk on to the
journals.
WEB & CRANKPIN
FORGED IN ONE PIECE.
JOURNAL.
(b) SEMI-BUILT UP: CRANKPIN
BORED OUT.

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❑ Crankshaft
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Types:
One piece - one piece of material either cast or forged.
WEBS CRANKPIN & HALF
JOURNAL FORGED IN ONE
PIECE.
(c) WELDED: CRANKPINS & JOURNALS
BORED OUT.

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❑ Crankshaft
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Uses:
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Large marine diesel engines : fully built or semi-built crankshafts.
Medium speed diesel engines: semi-built.
High speed diesel engines : one piece construction.

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❑ Crankshaft defects and their causes
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Misalignment
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1. Worn main bearings – caused by incorrect bearing adjustment,
choked lubricating oil supply pipe causing lubrication starvation,
contaminated lubricating oil, and vibration forces.
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2. Excessive bending of engine framework – caused by incorrect
cargo distribution but is unlikely, more probable cause would be
grounding of the vessel.

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Vibration
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This can be caused by:
1. Incorrect power balance,
2. Prolonged running at or near critical speeds,
3. Slipped crank webs on journals,
4. Light ship conditions leading to impulsive forces from the
propeller (e.g. forcing frequency four times the revs. for a four
bladed propeller), the near presence of running machinery.

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Other causes:
1. Incorrect manufacture leading to defects is fortunately a rare
occurrence. In the past, failure has been caused by: slag
inclusions, heat treatment and machining defects (badly
radiused oil holes and fillets).
2. Crank webs have slipped on journals; this could be caused by
seizure of some component, e.g. bearing, guide shoe, piston
rod in gland or piston in liner, bottom end bearing bolt failure,
or starting the engine with the turning gear in, have also caused
slip due to shock load.
3. Bottom end bearing bolt failure exceeding fatigue stress limit.

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Fretting corrosion
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1. It occurs where two surfaces forming part of a machine, which
in theory constitute a single unit, undergo slight oscillatory
motion of a microscopic nature.
2. Fretting damage increased with load, amplitude of movement
and frequency. Hardness of the metal also effects the attack,
in general damage to ferrous surfaces is found to decrease as
hardness increases.

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Bearing corrosion
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1. In the event of fuel oil and lubricating oil combining in the
crankcase, weak acids may be released which can lead to
corrosion of copper lead bearings.
2. Water in the lubricating can lead to white metal attack and the
formation of a very hard black incrustation of tin oxide. T h i s
oxide may cause damage to the journal or crankpin surface by
grinding action.

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❑ Bearing Clearances and Shaft Misalignment
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1. Bearing clearances can be checked in a variety of ways, a rough
check is to observe the discharge of oil, in the warm condition,
from the ends of the bearings.
2. Feeler gauge can be used, but for some of the bearings they
can be difficult to maneuver into position in order to obt ain
readings.
3. Clock gauges can very effective and accurate providing the
necessary relative movement can be achieved, this can p r o v e
to be very difficult in larger types of engines.

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❑ Bearing Clearances and Shaft Misalignment
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1. Main bearing clearances, should be zero at the bottom, if not,
then the crankshaft is out of alignment. Obviously, if the main
bearing clearance is not zero at the bottom the adjacent
bearing or bearings are high by comparison and the shaft is out
of alignment.
2. Crankshaft alignment can be checked by taking deflections that
is the relative movement of the distance between the crank
webs when rotating the shaft one revolution. A clock gauge
arranged horizontally between the webs opposite the crankpin
is used to measure the change in distance.

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1. Bearing Clearances and Shaft Misalignment
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1. The difference in the TDC reading and BDC reading gives the
vertical defection, while the difference in port reading and
starboard reading gives the horizontal deflection.
1. Vertical and horizontal misalignment can be checked against
the permissible values supplied by the engine builder, often in
the form of a graph.

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1. Bearing Clearances and Shaft Misalignment

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❑ Cylinder Liners
1. Upper and lower liners are made thin to give good heat transfer
and have the supporting ribs for strength and cooling water
passage.
2. Steel rings are shrunk on to the supporting ribs to give additional
strength to withstand combustion loads.
3. The lower water jacket, exhaust and combustion belts are bolted
together.

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❑ Cylinder Liners
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Main advantages:
1. Liners are simple, short, hard wearing iron castings which can be
relatively easily manufactured.
2. Each half (top or bottom) of the liners can be separately replaced
if necessary.
3. Strong cast steel can be used for the combustion belt whose
wearing properties does not have to match up to the cylinder
liners.
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A main disadvantage is the spigot copper joints, with some
arrangements of cylinders there are no joints, or possibly one.

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❑ Cylinder Liner Wear
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1. With correct cylinder lubrication,
2. Correctly fitted piston rings and
3. Warming through of the diesel engine before starting,
4. Together with good combustion, and
5. Properly timed fuel injection, cylinder liner wear can be kept to a
minimum.

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❑ Cylinder Lubrication
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1. To separate sliding surfaces with an unbroken oil film.
2. To form an effective seal between piston rings and cylinder liner
surface to prevent blow-by.
3. To neutralize corrosive combustion products and thus protect
cylinder liner, piston and rings from corrosive attack.
4. To soften deposits and thus prevent wear due to abrasion.
5. To remove, dissipate and cause the loss of deposits to exhaust,
hence preventing seizure of piston rings and keeping engine
clean.
6. To cool hot surfaces without burning.

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❑ Correct position of lubricating points:
1. They must not be situated too near the ports; oil can be scraped
over the edge of ports and blown away.
2. They should not be situated too near high temperature zone or
the oil will burn easily.
3. There must be sufficient points to ensure as even and as
complete coverage possible.

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❑ Cylinder Covers must:
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• seal off the top part of the cylinder gastight.
• withstand the high combustion pressure and temperature under
operation.
• create (together with the piston crown) the important
combustion space shape.
• accommodate the essential engine parts like valves, fuel
injector and starting air valve.

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❑ Cylinder Covers
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• Cylinder covers are exposed to high forces and very high
combustion temperatures. To withstand these high forces the
material should be thick.
• On the other hand, to cool the material efficiently and to prevent
thermal stresses in the material, the material should be as thin as
possible.
• To solve these opposite requirements a modern cover is
equipped with bore-cooling, which means that the bottom plate
(flame plate) of the cover is thin and cooled by cooling water
flowing through bores allowing the water to pass very close to
the combustion chamber.

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❑ Cylinder Covers
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• The forces are transmitted to and taken by the much thicker
upper part of the cover.
• More modern engines, which operate at higher temperatures and
pressures, have one piece forged steel cylinder covers with bore
cooling close to the combustion chamber surface.
• Medium speed 4-stroke engines have cylinder heads of a
complex shape because of the number of openings required for
the valves and the air and gas channels. For this reason
spheroidal graphite cast iron is used since it is relatively easy to
cast.
• Despite the high temperature and pressure during operation, the
cover must remain straight to avoid gas leakage.

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❑ Cylinder Covers
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The following example will give an impression of the forces acting
on a cover: 2-stroke diesel engine with cylinder diameter of 0.6 m.
and a combustion pressure of 130 bar.
Calculation of the force:
Force = pressure x area (F = p x A)
(to simplify the calculation we consider 1bar = 1 kg/cm2)
F = 130 kg/cm2 x 0.25 x 3.14 x 60 cm2 = 367380 kg. = ±367 tons
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This force has to be taken by the cover and by the cover studs.
The cover needs to stay straight and must therefore supported by
sufficient studs (4 to 8 studs are normally used).

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❑ Cylinder Cover Inspection
Since a cylinder cover is a heavily mechanically and thermally loaded
part, it should be inspected carefully according the maintenance
schedule and each time it is taken off from the cylinder.
Crack at corroded edge of bore for nozzle

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Cracks in Cooling Bores
Hard cooling water may also
cause a layer of scale inside the
cooling bores what will increase the
surface temperature of the cover plate
exposed to the combustion chamber.
The bores should be inspected
inside for this and if scale is detected
it must be removed by chemical
treatment. The instructions of the
supplier of the chemicals should be
followed.

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❑ Pistons and Rings
▪ Cast iron (today this would be spheroidal graphitic), forged steel
and cast steel are materials favored for the piston crowns of
large marine diesel engines.
▪ Cast steel material combines strength and wear resistance, the
thickness can be kept to a minimum improving heat transfer and
minimizing risk of thermal cracking and distortion.
▪ Where additional strength is required thin strengthening ribs are
provided.
▪ Intensive cooling of this piston is achieved by the cocktail shaker
effect of the water. With air present in the piston together with
water, the inertia effect coupled with the conically shaped inserts
leads to very effective cooling by secondary flow as the crank
goes over TDC.

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❑ Pistons and Rings

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❑ Failure of Pistons Due to Thermal Loads
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▪ When a piston crown is subjected to high thermal load, the
material at the gas side attempts to expand but is partly
prevented by the cooler metal under and around it.
▪ This leads to compressive stresses in addition to the stresses
imposed mechanically due to the variation in cylinder pressures.
▪ At very high temperatures the metal can creep to relieve this
compressive stress and when the piston cools residual tensile
stress is set up hence residual thermal stress.
▪ If this stress is sufficiently great, cracking of the piston crown
may result.

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❑ Piston Rings Properties
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1. Good mechanical strength, it must not break easily.
2. High resistance to wear and corrosion.
3. Self-lubricating.
4. Great resistance to high temperatures.
5. Must at all times retain its tension, to give a good gas seal.
6. Be compatible with cylinder liner material.

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❑ Materials used to obtain the desired properties
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1. Ordinary grey cast iron – good wear resistance, self-lubricating
but reduces strength.
2. Alloyed cast iron – give finer grained structure and good graphite
formation (Molybdenum, nickel and Copper or Vanadium and
Copper).
3. Spheroidal Graphitic iron – very good wear resistance, not self-
lubricating.
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It is possible to improve the properties by treatment. In the case of
the cast irons with suitable composition they can be heat treated
by quenching, tempering or austempering. This gives strength and
hardness without affecting the graphite.

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1. Piston Ring defects and their causes
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1. Incorrect fitted rings.
2. Fouling due to deposits on the ring sides and their inner
diameter.
1. Corrosion of the piston rings can occur due to attack from
corrosive elements in the fuel ash deposits.
1. If the bearing surfaces are in poor condition or in any way
damaged, scoring of cylinder liner may take place.

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❑ Inspection of piston, piston rings and cylinders
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1. Withdrawal of pistons, their examination, overhaul or renewal;
together with the cleaning and gauging of the cylinder liner, is a
regular feature of maintenance procedure.
2. Frequency of which depends upon numerous factors, such as:
piston size, material and method of cooling, engine speed or
rotation, type of engine (2- or 4-stroke), fuel and type cylinder
lubricant used.
3. Pistons and cylinder liners on some engines can be inspected
without having to remove the piston, thru scavenge ports.

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Engine Lubrication
➢ If the engine is a trunk type then fuel and deleterious deposits
from its combustion products may find their way into the
crankcase.
➢ The oil should therefore be one which has detergent properties
or sometimes called “Heavy Duty”.
➢ Additives in these oils deter the formation of deposits be keeping
substances, such carbon particles, in suspension.
➢ They also counteract the corrosive effect of sulphur compounds;
some of the fuels used may be low in sulphur content, in this
case the alkaline additive could be less.
➢ Straight mineral oil, generally with an anti-oxidant and corrosion
inhibitor added, is the type normally used in diesels whose
working cylinder is separate from the crankcase.

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Engine Lubrication
❑ Oxidation of the oil is one of the major causes of its deterioration
caused by high temperatures.
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1. Possible causes of oxidation
✓ Small bearing clearances (hence insufficient cooling).
✓ Not continuing to circulate the oil upon stopping the engine.
In the case of oil cooled piston types, piston temperatures
could rise and the static oil within them become overheated.
✓ Incorrect use of oil pre-heater for the purifier, e.g. shutting
off oil before the heat or running the unit part full.
✓ Metal particles of iron and copper can act as catalysts that
assist in accelerating oxidation action. Rust and varnish
products can behave in a similar fashion.

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Engine Lubrication
❑ Detection and possible remedies of the following:
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1. Rust particles – when warm oil is standing in a tank, water that
may be in it can evaporate and condenses out upon the upper
cooler surfaces of the tank not covered by oil. Rusting could
take place and vibration may cause this rust to fall into the oil.
Tanks should be given some protective type of coating to avoid
rusting.
2. Loss of oiliness – dipping fingers into the oil and rubbing the tips
together can detect reduction in oiliness.
3. Abrasive particles – may occur if a filter has been incorrectly
assembled, damaged or automatically by-passed.

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Operation and Maintenance of Marine Diesel Engines
Engine Lubrication
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4. Water – can be detected by water vapor that condenses on the
surfaces of sight glasses, thus giving indication of water
contamination.
5. Fuel – smelling the oil sample may give indication of fuel oil
contamination or if acrid, heavy oxidation. Dark color gives
indication of oil deterioration, due mainly to oxidation.
6. Sludge – an indication of increase in purifier sludge indicates
deterioration of oil. Lacquer formation on bearings and
excessive carbon formation on oil cooled pistons are other
indications of oil deterioration.

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Engine Lubrication
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➢ Regular examination and testing of the main circulating oil is
important.
➢ Oil samples should be taken and sent to laboratories for testing.
➢ Onboard testing is recommended for continuous monitoring of
oil.

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Engine Lubrication
1. 5% change in viscosity from new. Viscosity increases with
oxidation and by contamination with fuel oil, diesel oil can
reduce viscosity.
2. 0.5% contamination of the oil.
3. 0.5% emulsification of the oil, this is also an indication of
water
content. Water is generally permissible up to 2%, dangerous
if
sea water.
4. 1.0% Conradson carbon value
5. 0.01 mg KOH/g Total Acid Number (TAN). It is the total
inorganic and organic content of the oil.
1. Lubricating oil should be changed if the following limit values
are reached:

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Engine Lubrication
1. Oil Mist Detection
1. The oil mist detector is measuring the mist concentration in
the
crankcase and will stop/slow down the engine when this
concentration becomes too high.
2. It will protect the engine room personnel from a crankcase
explosion.

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Engine Lubrication
1. Mineral Oils
Lubricants whose base stocks are derived from direct
distillation and separation of crude oil.
Lubricants whose base stocks are pure chemicals. They are
not based on the simple refining of crude oil but are
manufactured by the conversion of certain chemicals into
synthetic bases with controlled structure and predictable
properties.
1. Synthetic Oils

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Engine Lubrication
1. Advantages of using synthetic oil versus mineral oil:
1. High temperature stability
2. Long life
3. Low temperature fluidity
4. High viscosity index
5. Improved wear protection
6. Low volatility
7. No wax

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Fuel Injectors
1. If sprayer holes are too short the direction can be indefinite.
2. If sprayer holes are too long impingement can occur.
3. If hole diameters are too small fuel blockage (impingement) can
take place.
4. If the hole diameters are too large, it would not allow proper
atomization.
In general, sprayer hole length: diameter ratio will be about
4:1, maximum pressure drop ratio about 12:1 and fuel velocity
through the hole about 250 m/s.
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Impingement – excess velocity of fuel spray causing contact
with metallic engine parts and resulting in flame burning.
1. Arrangement of the fuel valve tip to direct fuel in the proper
direction and correct velocity:

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Fuel Injectors
1. Procedures in Reconditioning of Fuel Injectors
1. Follow the instructions in the maintenance manual.
2. Check openings pressure and atomization performance before
disassembly.
3. Set the openings pressure till the value mentioned in the test
protocols. Move the pump lever slowly up and down, while
simultaneously tightening the spring. Check afterwards with
short fast pump jerks the condition of the atomization.
4. Check for the needle/seat tightness by pressurizing the fuel till
just under the openings pressure and check if nozzle tip stays
dry.
Testing the fuel injection valve:

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Fuel Injectors
5. Check the needle clearance by pressurizing the fuel till just
under the opening pressure and observe how fast the pressure
drops.
6. Check if atomization is equal (no clogged or partly clogged
holes) by spraying one short stroke fuel on a white paper.
7. When pumping with short jerks, the atomization should give a
loud “chatter”.
8. After closing of the needle, no fuel should dribble from the
injection nozzle.
9. When the injectors are stored for a longer period, special
testing fluid should be used.
Testing the fuel injection valve:

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Fuel Injectors
1. Follow carefully the instructions given in the maintenance
manual.
2. Work clean.
3. Pay special attention to the tightening procedure of the
cap.
Dismantling and assembling a fuel injection valve:

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Fuel Injectors
1. Follow instructions and recommendations in the maintenance
manual.
2. Renew nozzle tip when worn. To be checked by special plug
gauge.
3. Clean the holes by a drill with 0.025 smaller diameters. Clean
thoroughly by air and clean gas oil.
4. Needle may not be lapped on the seat (different angles). Only
specialized firms with the proper tools can do this. Check that
needle lift has not increased by more than 0.1 mm.
5. Should the sealing face show any damage, it may be lapped on
a special face plate.
Cleaning and overhaul of injectors:

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Fuel Injectors
P P
β
D
d
α
F
Needle LiftDetail of Nozzle

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Fuel Pumps
PORT PORT
Intake of fuel
into barrel during
downward stroke.
PORT PORT
Fuel displaced
through ports
during first part
of upward stroke.
PLUNGER LEADING EDGE
Ports closed by
plunger leading edge.
Start of injection.
LONGITUDINAL
GROOVE
Helical edge opens port.
Fuel pump pressure
drops: injection ends.
1 2
3 4
1. Bosch Jerk Pump Principle

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Fuel Pumps
1. Bosch Jerk Pump Principle
1. The principle of this type has a constant begin of the injection
and variable end.
2. This is the most common execution for plunger controlled
pumps.
3. By giving the topside of the plunger also a (small) helix it can
easily get also a varying begin of the delivery.
4. Although a plunger controlled pump will work correctly with a
helix on one side it is common practice to execute the plunger
with an identical helix on both sides.
5. The high pressure is now resting on both sides and gives a
balanced plunger. In this way wear on one side of plunger and
barrel is prevented.

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Fuel Pumps
1. Block Type Pump Principle
1. A fuel pump with valve control is a camshaft driven plunger
pump, which fuel quantity to the injectors is controlled by
valves.
2. In principle the quantity can be controlled at the beginning - at
the end - or at the beginning and the end of the plunger
stroke.
3. For economical reasons (fuel saving) the pumps nowadays are
designed with begin and end control.
4. The suction valve controls the timing while the spill valve
controls the quantity.

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Fuel Pumps
1. Block Type Pumps Principle

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Fuel Pumps
1. Adjustment of Fuel Injection Timing (Block Type)
1. Adjusting the valve stroke by turning the eccentric shafts will
alter the delivery stroke.
2. The delivery stroke determines the quantity of the injected
fuel.
3. The eccentric shafts are connected to the fuel rack, which
position is controlled by the governor or by the manual fuel
lever.
4. The suction stroke starts when the roller leaves the crown
circle of the cam.

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Fuel Pumps
5. On the downward stroke of the plunger it draws fuel from the
suction space. As a result of this the suction valve is lifted by
the suction effect of the plunger as well as the fuel pressure
from the booster pump in the suction space.
6. In the lowest part of the plunger’s downward stroke the
suction valve is also mechanically lifted by the pushrod.
7. The upward stroke of the plunger begins when the roller
leaves the base circle of the fuel cam. However, as long as the
suction valve is not yet on its seat, no fuel delivery takes place,
since the pump pressure space is still connected to the suction
space.

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Fuel Pumps
8. Only when the suction valve push rod has lowered to the point
where the suction valve closes, the delivery of fuel to the fuel
injector begins. This point is known as “start of delivery”.
9. As the upward stroke continues, the plunger delivers fuel, via
the now open delivery valve, to the fuel injectors until the spill
valve is opened by the pushrod. This means the end of delivery
stroke, “end of delivery”.
10.The beginning of the stroke, between the point where the
roller leaves the base circle and the point where the effective
delivery begins is known as the “idle stroke”.

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Fuel Pumps
11.The delivery valve works as a non-return valve and stays open
only as long as the pressure under the valve is higher than in
the high-pressure pipe.
12.As soon as the spill valve opens the pressure drops in the
pressure space and the valve will close. If the pressure in the
pipe reduces too slowly, the last fuel will be injected at a low
pressure and a low velocity and may become irregular.
Together with a risk of a secondary injection, what will cause
incomplete combustion, a stagnation valve is sometimes used.

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Fuel Pumps
Delivery valve
injection nozzle
suction valvespill valve
SPCV
Spill valve opens1
Injection valve closes2
3 Pressure wave created by the
closing shock of inj. valve is
being released by SPCV
1. Stagnation Control Valve
This is a spring loaded non-
return valve by-passing the
delivery valve.
It will open when the pressure
in the injection pipe is higher
than the spring load and
releases the pressure in the
pipe till the spring pressure is
reached, after which the valve
will close.
This pressure will be sufficient
lower than the closing pressure
of the injector needle.

!
!
NMLC-EF1-Module 1
63
Fuel Pumps
1. Functions of Variable Injection Timing (VIT) Device
1. When the fuel prices were rising, the ship owners were
using
the engines very often at reduced loads to save fuel. Since
the engines are designed and adjusted for 100% load, they
are in this situation not running under optimal conditions.
!
❖ The engines are nowadays equipped with a special execution
of the begin and end control of the fuel. In the load range
between 100% and 75% the timing will be advanced in such a
way that the combustion pressure will remain the maximum
value.

!
!
NMLC-EF1-Module 1
64
Fuel Pumps
1. The reason for using this so-called Variable Injection System
is
an economic one, to save fuel.
!
❖ The control of this system can be completely mechanical or
electronically. In the mechanical situation a profiled segment in
the fuel rack is provided, in the electronically version a
position unit is controlling the position of the fuel rack.

!
!
NMLC-EF1-Module 1
65
Fuel Pumps
B
A
80% 90% 100%
D
80% 90% 100%
Engine Output Engine Output
Combustion pressure with V.I.T.
Combustion pressure without V.I.T.
Normal combustion pressure
Combustion pressure with fuel of
lower ignition quality
B
A
C
C
D

!
!
NMLC-EF1-Module 1
66
Fuel Pumps
1. Operational faults and corrective/preventive measures
The mean indicated pressure gives an impression of the engine load.
This pi for each cylinder should not deviate more than 0.5 bar from
the average value for all cylinder. The load balance must not be
adjusted on the basis of the exhaust gas temperatures after each
exhaust valve.
!
1. Mean draught - for any particular engine speed, draught will
effect the load.
2. Engine speed. If the pi at a certain speed is greater than at the
sea trial it should be judged if this is due to:
- Changes in the draught
- An increase in propulsion resistance, for instance due to fouling
of the hull, shallow water, damaged propeller etc.
Parameters related to the mean indicated pressure (pi):

!
!
NMLC-EF1-Module 1
67
Fuel Pumps
3. Maximum combustion pressure. At loads lower than 85 – 90%
of the specified MCR, the pmax will increase proportional to the
fuel index. At loads higher than that, the pmax is kept constant.
If an individual pmax value deviates more than 3 bar from the
average value, the reason should be found and the fault
corrected.
- compression pressure
- fuel pump index

!
!
NMLC-EF1-Module 1
68
Fuel Pumps
4. Fuel pump index. If this is changed, it can be due to:
- the condition of the fuel pump, worn pumps and leaking
suction valves will give an increased fuel index in relation
to the mean pressure.
- fuel. Low viscosity will cause larger leakages in the pump
and thereby necessitate higher indexes for injecting the
same volume. The LCV and the specific gravity of the fuel
oil will effect the energy content per unit volume and
therefore the index. All other parameters that effect the
fuel consumption like ambient conditions etc.
It is recommended to overhaul the fuel pumps when the index
has increased by about 10%. Excessively worn fuel pumps will
seriously affect the starting performance of the engine.

!
!
NMLC-EF1-Module 1
69
Fuel Pumps
1. The compression pressure. The higher the output the higher
the scavenge air pressure will be. This will cause a higher
compression pressure.
1. The exhaust gas temperature after the valves. The exhaust gas
temperature is an important parameter, because the majority of
faults in the air supply, combustion and gas systems manifest
themselves as an increase in the exhaust gas temperature.
Parameters related to the effective power (Pe):

!
!
NMLC-EF1-Module 1
70
Fuel Pumps
Possible Cause Diagnosing
a. Fuel Injection Equipment: These faults occur in
individual cylinders:
compare
- Leaking or incorrectly working - Fuel indexes
fuel valves
- Worn fuel pumps - Indicator and draw
diagrams
NOTE: Inadequate cleaning of fuel Check the fuel valves:
oil can cause defective fuel valves - visually and by
pressure test
and fuel pumps.
Increased Exhaust Temperature Level

!
!
NMLC-EF1-Module 1
71
Fuel Pumps
b. Cylinder condition: These faults occur in
individual cyl:
- Blow-by, piston rings - compare the compression pressure
from the indicator draw diagrams
- Leaking exhaust valves During engine standstill:
- carry-out port inspection/check
exhaust valves
c. Air coolers:
- Fouled air/water side Check the cooling capability.

!
!
NMLC-EF1-Module 1
72
Fuel Pumps
d. Climatic conditions:
- extreme conditions Check cooling water/ER temperatures
e. Turbocharger: Use turbocharger synopsis method.
- fouled turbine and
compressor side.
f. Fuel Oil: Using heavy fuel oil will normally
- Type increase temperature by appr. 15°C,
compared to DO.
- Quality Further increase will occur when using
fuel with poor combustion properties,
in this case a reduction in Pmax.

!
!
NMLC-EF1-Module 1
73
Scavenging and Supercharging
1. If maximum performance and economy, etc. are to be
maintained it is essential during the gas exchange process that
the cylinder is completely purged of residual gases at
completion of exhaust and a fresh charge of air is introduced
into the cylinder for the following compression stroke.
!
2. In the case of 4-stroke engines this is easily carried out by
careful timing of inlet and exhaust valves, where because of the
time required to fully open the valves from the closed position
and conversely to return to the closed position from fully open,
it becomes necessary for opening and closing to begin before
and after dead center positions if maximum gas flow is to be
ensured during exhaust and induction periods.

!
!
NMLC-EF1-Module 1
74
1. By increasing the density of the air charge in the cylinder at
the
beginning of compression a correspondingly greater mass of
fuel can be burned giving a substantial increase in power
developed.
!
2. The degree of pressure charging required, which determines
the increase in air density, is achieved by the use of free
running turbochargers.

!
!
NMLC-EF1-Module 1
75
- airflow will decrease
- charge air pressure will decrease
- firing pressure will decrease
- exhaust gas temperature will rise
- fuel consumption will increase.
1. If the blower inlet temperature will rise the following
parameters
will change:

!
!
NMLC-EF1-Module 1
76
-30 -20 -10 0 10 20 25oC
0
+10%
+20%
+30%
-10%
-20%
Air flow
Firing pressure
Charge air pressure
Fuel consumption
Exhaust temp. after cylinder
Inlet air
temperature
Influence of Air Inlet Temp to Engine Operating Data

!
!
NMLC-EF1-Module 1
77
1. External conditions:
Sufficient air to the engine is essential for a good performance of
the engine. Less air will cause a worse combustion resulting in
smoke, higher exhaust gas temperatures, higher fuel consumption
and fouling.
!
1. Possible reasons for this air reduction may be:
2. Dirty air filter turbo charger/Fouled or damaged turbocharger
3. Dirty air cooler on suction side/Dirty air cooler on water side
4. Insufficient/too high temperature cooling water for air cooler.
5. Partly blocked scavenging ports
6. Dirty pipes in the economizer (exhaust gas boiler)
7. Too low pressure (too less overpressure) in the engine room

!
!
NMLC-EF1-Module 1
78
1. Mechanical defects which influence the Compression Pressure
!
Possible Causes Diagnosis/Remedy
a. Piston rings leaking Increased exhaust gas temperature.
b. Piston crown burned Check crown by means of template.
c. Cylinder liner worn Check liner by measuring tool.
d. Exhaust valve leaking Increased in exhaust gas temp.
Hissing sound heard at reduced load
Timing Check cam lead, hydraulic leakages,
damper arrangement for exhaust
valve closing.
e. Piston rod stuffing Small leakages may occur due to
box leaking corrosion of the air is emitted from
the check funnel. Bronze segments,
normally considered cosmetic
phenomenon.

!
!
NMLC-EF1-Module 1
79
1. Scavenge Fires
!
Cylinder oil can collect in the scavenge space of an engine.
Unburned fuel and carbon may also be blown into the scavenge
space as a result of the following:
- defective piston rings
- faulty timing
- a defective injector, etc.
A build-up of this flammable mixture presents a danger as a blow
past of hot gases from the cylinder may ignite the mixture and
cause a scavenge fire.
!
A loss of engine power will result, with high exhaust temperature
at the affected cylinders. The affected turbochargers may surge
and spark will be seen at the scavenge drains.

!
!
NMLC-EF1-Module 1
80
1. Procedures to do if fire occurs:
- engine should be slowed down,
- fuel shut off,
- cylinder lubrication increased, and
- scavenge drains should be closed
!
1. To avoid scavenge fires occurring the engine timing and
equipment maintenance should be correctly carried out.
1. The scavenge trunks should be regularly inspected and cleaned
2. Where carbon or oil build up is found in the scavenge spaces,
its source should be detected and fault remedied.
1. Scavenge drains should be regularly blown and any oil
discharges investigated at first opportunity.

!
!
NMLC-EF1-Module 1
81
1. Scavenge Belt Relief Door
!
Fitted to both ends of the scavenge belt and set to lift slightly
above the maximum normal working scavenge air pressure.

!
!
NMLC-EF1-Module 1
82
Turbo Chargers
1. Principle of Turbocharger
!
1. These are essentially a single axial flow turbine driving a single
stage centrifugal air compressor via a common rotor shaft to
form a self-contained free running unit.
1. Expansion of the exhaust gas through the nozzles results in a
high velocity gas stream entering the moving blade assembly.
1. Because of the high rotational speeds perfect dynamic balance
is essential if trouble-some vibrations are to be avoided.

!
!
NMLC-EF1-Module 1
83
Turbo Chargers
1. Principle of Turbocharger

!
!
NMLC-EF1-Module 1
84
Turbo Chargers
❑ Effects of Corrosion on Gas Side of Turbocharger
!
❖ With water cooled casing experience under light load conditions
when low exhaust temperatures are encountered it is possible
that precipitation of corrosive forming products ‘mainly sulphur’
will occur on the gas side of the casing.
❖ This result in serious attack which is more marked at the outlet
casing because of lower temperatures.
❖ Methods of prevention such as enamellings and plastic coatings,
etc. have been tried to alleviate this problem with varying
degrees of success.
❖ A particularly effective approach of the problem is the use of air
as the cooling media with the result that this particular instance
of corrosive attack is virtually eliminated.

!
!
NMLC-EF1-Module 1
85
Turbo Chargers
❑ Blower Efficiency on Engine Performance
!
❖ To obtain efficient and stable operation of the charging system it
is essential that the combined characteristics of the engine and
blower are carefully matched.
❖ Engine operating zone is a function of these characteristics and
taking into account the fact that blower efficiency decreases as
the distance between surges and operating zones increases, the
matching of blower to engine becomes a compromise between
acceptable blower efficiency and a reasonable safety margin
against surge.

!
!
NMLC-EF1-Module 1
86
Turbo Chargers
❑ Blower Efficiency on Engine Performance
!
❖ An accepted practice is to provide a safety margin of around 15
to 20% to allow for deterioration of service conditions such as:
- fouling and contamination of turbo chargers
- increasing resistance of ship’s hull, etc.
- apart from fouling other contributory factors to surging
are contamination of exhaust and scavenge ducting,
ports and filters.

!
!
NMLC-EF1-Module 1
87
Turbo Chargers
❑ Possible Reasons for Air Reduction or Blower Efficiency
!
- Dirty air filter on the turbo charger
- Fouled or damaged turbocharger
- Dirty air cooler on air side/Dirty air cooler on water
side
- Insufficient or too high temperature cooling water for
the air cooler
- Partly blocked scavenging ports
- Dirty pipes in the economizer (exhaust gas boiler)
- Too low pressure (too less overpressure) in the ER.

!
!
NMLC-EF1-Module 1
88
Turbo Chargers
❑ Actions Against Surging
!
❖ During normal service, build up of contaminants at the
turbocharger can be attributed to deposits of air-borne
contaminants at the compressor which in general are easily
removed by water washing on a regular basis.
❖ At the turbine however, more active contaminants resulting
from vanadium and sodium in the fuel together with the
products of incomplete combustion deposit at a higher rate
which increases with rising temperatures.
❖ A further problem arises with the use of alkaline cylinder
lubricants with the formation of calcium sulphates deposits
originating from the alkaline additives in the lubricant.

!
!
NMLC-EF1-Module 1
89
Turbo Chargers
❑ Running the Engine with Immobilized Turbocharger
!
❖ With only a single turbocharger out of a number inoperative
the power developed by the engine will obviously depend upon
charge air pressure attainable.
❖ At the same time a careful watch must be kept upon exhaust
condition and temperature to ensure efficient engine operation
with good fuel combustion.
❖ In the event of all turbochargers becoming defective it is
possible to remove blank covers from the scavenge air receiver
so that natural aspiration supplemented by under piston effect,
etc. or parallel auxiliary blower operation is possible – if this
method is carried out protective gratings must be fitted in
place of blind covers at the scavenge air receiver.

!
!
NMLC-EF1-Module 1
90
Starting and Reversing Air System
❑ Starting Air Distributor
!
❖ They are designed to admit air to the pistons of cylinder relay
valves in the correct sequence for engine starting.
❖ Valves not being supplied with air would be vented to the
atmosphere via the distributor.
❖ Some overlap of timing is required.
!
❑ Control Systems
!
Electric-Pneumatic - in case of malfunction of this system the
engine can be started and operated from a local control stand on
the engine.

!
!
NMLC-EF1-Module 1
91
❑ Safety Interlocks
3.0 MN/m2 P
A
P
B
K
C
G
DE
F
H
J
Turning Gear
OUT IN
The system consists of the air
bottle A, the automatic main
starting air valve B with venting
valve C, the starting control
valve D with lever E, the air
blocking valve F, the starting air
distributor valve G with cam H
and the starting air valve J.
The valve on the air bottle has
to be opened, so the air will
flow to the automatic valve B.
The valve spindle must be
turned in the open position.

!
!
NMLC-EF1-Module 1
92
❑ Safety Interlocks
1. Starting air from the starting receiver flows to the pre-starting
valve via the open turning gear blocking valve, and directly to
the automatic valve.
2. At the automatic valve air passes through the small drilled
passages to the back of the piston and this together with the
spring keeps this valve shut as the pilot valve is shut with air
pressure on top and atmospheric vent below.
3. If the starting lever is operated with control interlocks free, the
opening of the pre-starting valve allows air to lift the pilot valve,
vent the bottom of the automatic valve and cause it to open.

!
!
NMLC-EF1-Module 1
93
1. Safety Interlocks
4. This allows air to pass to the cylinder valve via non-return and
relief valves and also to the distributor.
5. The distributor will allow air to pass to the appropriate cylinder
valve causing it to air pressure on the piston top.

!
!
NMLC-EF1-Module 1
94
1. Control Gear Interlocks

!
!
NMLC-EF1-Module 1
95
There are many types of safety interlocks on modern IC engine
maneuvering systems. The previous few pages have picked out a
number relating to the Sulzer RD engine and these will be
adequate to cover most engine type designs as principles are all
very similar.
!
Consider the interlock systems illustrated in Figs. 65 and 66.
The telegraph and turning gear interlocks are straight mechanical
linkages. In the former case rotation of the paragraph lever from
stop position causes the pin to travel in the scroll and unlock the air
start lever as well as reposition the reversing valve. The turning
gear blocking valve can be seen to close when the pinion is placed
in line with the toothed turning gear wheel of the engine.

!
!
NMLC-EF1-Module 1
96
The interlock exerted on the block piston (fuel) is also a fairly
simple principle working in the relay valve A from the pressure trips
and is as discussed previously. Similarly the block valve (air) operates
mechanically via a lever lock on air start lever and horizontal operating
lever which rises to unlock under the oil pressure acting through relay
valve B on the block valve (air) after the clutch reversal have taken
place. (The pressure trips are merely spring loaded pistons moving
against low oil or water pressure to relieve control oil pressure just like
conventional relief valves.) It is perhaps appropriate to describe one
trip in detail and the direction safety lock will now be considered
briefly. The function is to withhold fuel supply during maneuvering if
the running direction of the engine is not coincident with the setting of
the engine telegraph lever. Refer now to fig.66

!
!
NMLC-EF1-Module 1
97
At the camshaft forward end the shaft is coupled to the
camshaft and carries round with it, due to the key, a flanged bush
and spring plates which cause an adjustable friction pressure
axially due to the spring and nut. This pressure acts on the
coupling disc which rotates through an angular travel T until the
stop pin prevents further rotation. This causes angular rotation of a
fork lever and the repositioning of a control valve plug in a new
position within the sleeve. Oil pressure from the reversing valve can
only pass to the block valve (air) and unlock the air start lever and
the fuel control if the rotation of the direction interlock is correct. If
the stop pin were to break the fork lever would swing to position M
and the fuel supply would be blocked.

!
!
NMLC-EF1-Module 1
98
1. Safety Interlocks

!
!
NMLC-EF1-Module 1
99
1. Operating Faults
1. Should a fault occur just the same, do not search for faults at
random but investigate possible causes systematically.
1. This applies in particular to difficulties in starting, reversing and
stopping the engine.
1. Many of the valves in the pneumatic control system are
equipped with pressure indicators which permit determination
of the switch position of the valves, which is indicated by
means of a red pin.
1. With the aid of the schematic control diagram, this permit
establishing which of the valves is possibly not functioning.

!
!
NMLC-EF1-Module 1
100
1. Normal Stopping
From the local maneuvering stand:
!
1. As long as the engine is under governor control, the engine is
stopped by reducing the speed setting until it comes to a
standstill.
2. If the stop lever is set to STOP, the engine is stopped by the
WOODWARD governor or the electronic actuator.
3. When the engine is no longer under governor control, but
having its speed regulated by means of the local maneuvering
stand fuel lever (emergency operation), the engine speed is
reduced until it comes to a standstill by putting the fuel lever
back to position '0'.

!
!
NMLC-EF1-Module 1
101
1. Emergency Stopping
The engine can be stopped immediately by the safety cut-out
device on fuel injection pumps by pressing the EMERGENCY STOP
button in the control room (control desk) or at the local
maneuvering stand on the engine.

!
!
NMLC-EF1-Module 1
102
1. Further possible ways of stopping the engine:
The engine can also be brought to a standstill by the following
methods which, however, take more time and, to a certain extent,
take effect only slowly.
!
1. Operating the manual cut-outs of all the fuel injection pumps.
2. Closing the shut-off valves in the fuel supply and return pipes
of the fuel injection pumps.

!
!
NMLC-EF1-Module 1
103
Governor
1. It governs or controls the engine speed at some fixed value
while power output changes to meet demand.
1. This is achieved by the governor automatically adjusting the
engine fuel pump settings to meet the desired load at the set
speed.
1. Governor for diesel engines are usually made up of two
systems:
- Speed sensing arrangement
- Hydraulic unit which operates on the fuel pumps to
change the engine power output.

!
!
NMLC-EF1-Module 1
104
Governor
1. Mechanical Governor
!
1. A flyweight assembly is used to detect engine speed.
2. Two flyweights are fitted to a plate or ball head which rotates
about a vertical axis driven by a gear wheel.
1. The action of centrifugal force throws the weights outwards;
this lifts the vertical spindle and compresses the spring until an
equilibrium situation is reached.
1. The equilibrium position or set speed may be changed by the
speed selector which alters the spring compression.
1. As the engine speed increases the weights moved outwards
and the raise the spindle; a speed decrease will lower the
spindle.

!
!
NMLC-EF1-Module 1
105
Governor
!
1. The hydraulic unit is connected to this vertical spindle and acts
as a power source to move the engine fuel controls.
1. A piston valve connected to the vertical spindle supplies or
drains oil from the power piston which moves the fuel controls
depending upon the flyweight movement.
1. If the engine speed increases the vertical spindle rises, the
piston valve rises and oil is drained from the power piston
which results in a fuel control movement.
1. This reduces the fuel supply to the engine and slows it down.
It is, in effect, a proportional controller.

!
!
NMLC-EF1-Module 1
106
Governor
THE SPEEDER SPRING
!
!
THRUST BEARING
!
!
FLY WEIGHTS
!
!
PILOT VALVE PLUNGER AND
BUSHING
!
!
OIL PUMPS

!
!
NMLC-EF1-Module 1
107
Governor
1. Electric Governor
!
1. This governor has proportional and reset action with the
addition of load sensing.
1. A small permanent magnet alternator is used to obtain the
speed signal; the advantage to be gained is that there will be
no slip rings or brushes with their attendant wear.
1. The speed signal obtained from the frequency of the generated
AC voltage impulses is converted into DC voltage which is
proportional to the speed.
1. A reference DC voltage of opposite polarity, which is
representative of the desired operating speed, is fed into the
controller from the speed setting unit.

!
!
NMLC-EF1-Module 1
108
Governor
1. Electric Governor
!
1. These two voltages are connected to the input of an electronic
amplifier.
1. If the two voltages are equal and opposite, they cancel and
there will be no change in amplifier voltage output.
1. If they are different, then the amplifier will send a signal
through the controller to the electro-hydraulic converter which
in turn, via the servo-motor, reposition the fuel rack.
1. In order that the system be isochronous the amplifier-controller
has internal feedback.

!
!
NMLC-EF1-Module 1
109
Governor
1. Governor Types

!
!
NMLC-EF1-Module 1
110
Governor
1. Governor Types

!
!
NMLC-EF1-Module 1
111
Governor
1. Governor Types

!
!
NMLC-EF1-Module 1
112
Governor
1. Overspeed Safety Devices
!
1. Mechanical overspeed trips depend upon the centrifugal forces
developed by the engine and must be maintained in good
working condition.
1. A faulty overspeed device can endanger not only the engine
but also the personnel.
1. The engine could explode or fly apart because of the
uncontrolled speed.

!
!
NMLC-EF1-Module 1
113
Governor
!
1. Hydraulic overspeed trips are extremely sensitive to dirt.
2. Dirt or lacquer like deposits may cause the trip to bind
internally.
1. The speed-sensitive element and all parts of the linkage and
mechanisms incorporated with the speed-sensitive element
must be kept clean.
1. When painting around the engine, you must avoid allowing
paint to fall on joints, springs, pins, or other critical points in
the linkage.

!
!
NMLC-EF1-Module 1
114
Governor
!
1. The overspeed trip will not function properly if parts are bent,
badly worn, improperly installed, or dirty, or if their motion is
restricted by some other part of the engine.
1. In some situations the driveshaft of the overspeed trip may be
broken; this would prevent rotation of the flyweight and the
overspeed trip.
1. Insufficient oil in the hydraulic trip may be another source of
trouble.
1. You should maintain a proper oil level as specified by the
instruction manual.

!
!
NMLC-EF1-Module 1
115
Governor
!
The following are some general procedures you should follow to
keep the overspeed safety devices in proper operation:
- Keep the overspeed trip and its linkage clean.
- Remove the source of binding.
- Replace faulty parts.
- Maintain a proper oil level in the hydraulic overspeed trip.
- Adjust the speed-sensitive element according to the instruction
manual.
- If the trip has been damaged, replace it with a spare and
completely rebuild or overhaul the damaged one according to
the instruction manual.

!
!
NMLC-EF1-Module 1
116
Governor
Speed Droop
!
Or just the term droop, is used to define the change in speed
between no load and full load conditions.
If speed droop did not exist then there would be one speed
only for any position of the governor flyweights and this in turn
means any fuel supply rate.
In this case the diesel would hunt (isochronous condition).
SPEED DROOP
ENGINE LOAD
FULL LOAD
NO LOAD
SPEED

!
!
NMLC-EF1-Module 1
117
Governor
Speed Droop
!
Forces involved in the flyweight governor movement are:
inertia, friction and spring.
Considerable effort may therefore be required to cause
movement; this would necessitate a change in speed without
alteration in governor position.
This is bad control, the system is insensitive and various
equilibrium speeds are possible.
For simple systems these various equilibrium speeds are not an
embarrassment, but if we require a better controlled system
the two functions that the flyweight governor has to perform
would be separated into (1) a speed measuring device and (2)
a servo-power amplifier.

!
!
NMLC-EF1-Module 1
118
Governor
1. Troubleshooting Guide
Check settings for actuator and control unit.C. Different direction of action in control unit and actuator.
Check and adjust.B. Speed setting coil in actuator wrong position.
Check speed pick-ups.A. No speed signal.Prime mover over speeds at start
(electrical speed control).
Check and adjust.C. Load limits setting incorrect.
Adjust droop setting.B. Droop setting incorrect on one or more units.
Check, adjust speed setting.A. Speed setting incorrect.Load does not divide correctly
between parallel units.
Check oil pressure.D. Governor oil pressure low.
Check fuel filters and fuel line.C. Fuel supply restricted.
Reduce the load.B. Prime mover may be overloaded.
Readjust needle valve.A. Needle valve adjustment incorrect.Prime mover is slow to respond to a
speed or load change.
Check oil specification.C. Cold or wrong oil viscosity.
Check oil pressure.B. Low oil pressure in governor due to worn internal parts.
Check action of automatic air starting valve.A. Booster servo motor (if used) not functioning properly.Fuel pump racks do not open quickly
when cranking prime mover.
Repair linkage, fuel pumps or valve.D. Lost motion or binding in prime mover linkage, fuel pumps or valves.
Adjust needle valve.C. Needle valve adjustment incorrect.
Drain, refill as necessary. Check suitability of oil
type and viscosity.
B. Foamy or dirty oil.
Add oil if necessary.A. Low oil levelPrime mover hunts or surges
REMEDYCAUSESYMPTOMS

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