Motor Engineering – MEO CLASS 4 MMD PAPER

81) Diesel engine main and connecting rod precision bearings are made in halves. Each half exceeds one-half the bearing circumference by a small amount. The small amount is termed

1. clearance 
2. crush
3. pitch
4. thrust

ANS.: B

82) The piston rod scraper box incorporated in a single acting two-stroke/cycle, crosshead diesel engine serves to

1. eliminate the necessity for an oil scraper ring
2. prevent side thrust and cylinder scoring
3. prevent sludge and dirty oil from entering the crankcase
4. scrape oil and carbon deposits off the cylinder walls

ANS.: C

 83)   The proper location for journal bearing oil grooves isuscg91

1. in the region of the load bearing surface
2. as a side relief where the two shells meet
3. at the bottom of the bearing
4. halfway between bottom and where shells meet

ANS.: B

84)   How are hydraulic valve lash adjusters on diesel engine rocker arm assemblies lubricated?uscg93

1. Cup-fed grease
2. Sealed self-lubricators
3. Metered hydraulic oil supply
4. Forced lube oil supply

ANS.: D

85) Main propulsion diesel engines having a bore exceeding 300 mm are to have at least

1. two independent means of starting the engine
2. five air starting valves to permit the admission of starting air at any crank angle
3. one (explosion relief) valve at the position of each main crank throw
4. two engine driven lube oil pumps capable of parallel operation

ANS.: C

86) Integral water jacket liners use O-rings near the bottom of the liner, these O-rings serve to

1. form a water seal between the liner and engine block
2. allow for slight misalignment of the liner
3. prevent the escape of lubricating oil from the crankcase
4. ensure proper temperature flow between the liner and engine block

ANS.: C

88) A characteristic of a bearing material which permits small dirt particles to become embedded in the surface &is

1. desirable, as it will prevent damage to the journal surface
2. desirable, as it will assist in keeping the lube oil filters clean
3. undesirable, since the embedded particles will score the journal
4. undesirable, since the particles will interfere with lube oil flow

ANS.: A

89)   Most fuel injection nozzles are opened by

1. fuel oil pressure
2. a cam operated follower
3. a spring-loaded pressure plate
4. timing gears keyed to the crankshaft

ANS.: A

90)   Which of the following devices controls the discharge flow rate of an attached, positive displacement, rotary gear, diesel engine, lube oil pump?

1. A pressure regulating valve
2. A pressure relief valve
3. The engine speed
4. An orifice

ANS.: C

91)  The expansion tank for a diesel engine closed cooling system is designed to maintain a constant head on the system and

1. reduce water temperature
2. reduce water turbulence
3. provide an air cushion
4. allow for an increase in water volume as the engine warms up

ANS.: D

92)   To minimize corrosion, fuel oil strainer disks, spacers and scraper blades are made of

1. brass
2. copper
3. iron
4. monel metal or stainless steel

ANS.: D

93)   Which of the following statements describes the function of an expansion tank in a diesel engine cooling system?

1. Maintains a constant head on the system
2. Reduces the air cock when fires are lighted
3. Provides a low pressure point for the addition of makeup cooling water
4. All of the above

ANS.: D

94)   On a large diesel engine installation, crankshaft axial alignment is maintained by the

1. piston rod guides
2. engine thrust bearing
3. crosshead bearing
4. main shaft flexible coupling

ANS.: B

95)   Scavenging in a four-stroke/cycle diesel engine occurs during the

1. last part of the exhaust stroke, and the first part of the intake stroke
2. last part of the intake stroke only
3. early part of the injection stroke only
4. early part of the power stroke

ANS.: A

96)   In two-stroke/cycle diesel engine, the process of scavenging begins as the

1. piston nears and passes TDC
2. early part of the upstroke latter part of downstroke
3. piston passes BDC             
4. early part of the downstroke

ANS.: B

97) W res. to  flow of lubricating oil through a diesel engine, the lube oil coolers are located after filters in order to

1. allow filtration of less viscous oil
2. decrease the pressure drop across the filter
3. improve overall filtration
4. all of the above

ANS.: D

98)   Passages are drilled in the crankshafts of diesel engines to provide lubricating oil to the

1. main bearings
2. connecting rod bearings
3. piston pin bushings
4. All of the above

ANS.: D

99)   The outlet from an expansion tank of a closed freshwater cooling system should be piped to the

1. cylinder head water outlet header
2. cylinder jacket inlet main
3. heat exchanger inlet connection
4. jacket water pump suction line

ANS.: D

100)   The intake valves in diesel engine are reseated by

1. cam followers
2. push rods
3. combustion gases
4. valve springs

ANS.: D

101) Small amounts of moisture are necessary to trigger the growth of microbiological organisms found in some marine fuels. Some sources of water contamination are

1. tank surface leakage
2. humidity and condensation
3. improper tank washing procedures
4. All of the above

ANS.: D

102) On most modern diesel engines, the main and connecting rod bearings receive their lubricating oil by –

1. banjo feed
2. splash feed
3. gravity feed
4. pressure feed

ANS.: D

103)  Lubricating system for diesel engines are usually designed to initially provide lube oil to the engine-

1. camshaft bearings
2. main bearings
3. piston crowns
4. cylinder walls

ANS.: B

104) Mechanical lubricators for diesel engine cylinders are usually small reciprocating pumps which are-

1. operated manually once each hour
2. operated until the engine has started
3. placed into operation only at maximum load
4. adjustable to meet lubrication requirements

ANS.: D

 105)  Shacker, circulation, and spray are the three general methods used in

1. pre-injection fuel oil treatment
2. lube oil filtration
3. fuel oil purification
4. piston cooling

ANS.: D

106)   Fuel injector nozzles are usually of the multi-orifice type with the number and placement of the holes arranged according to the

1. type of piston rings
2. pressure of the fuel system
3. size of the pump plunger spring
4. design of the combustion chamber

ANS.: D

107) What is the crank angle between any two crank throws in the firing order of a four-stroke/cycle, in line, eight cylinder diesel engine?

1. 45°
2. 60°
3. 90°
4. 100°

ANS.: C

108)   The main reason counterweights are added to crankshafts is to

1. reduce piston side thrust 
2. reduce crankshaft end thrust
3. provide uniform loading and wear of main bearings
4. increase the strength of the crank webs

ANS.: C

109) A viscous damper, as used on a marine diesel, is a sealed precision built device which dampens the torsional vibrations in the

1. camshaft
2. flywheel
3. crankshaft
4. thrust shaft

ANS.: C

110)  A crankshaft whose center of gravity coincides with its center line is said to be

1. dynamically balanced
2. statically balanced
3. counter balanced
4. resonantly balanced

ANS.: B

111) The possibility of damage from operating a diesel engine at critical speeds is reduced by the use of

1. an isochronous governor
2. elastic engine mounts
3. a vibration damper 
4. a cast iron bed plate with good flexible qualities

ANS.: C

112)   When fuel oil heaters are required for engine operation,

1. each heater shall have the capacity to supply the main engine at full power
2. at least two heaters of approximately equal size are to be installed
3. the system shall be designed to permit series or parallel operation
4. none of the above

ANS.: B

113)   An advantage of aluminium pistons compared to cast iron pistons is:

1. greater high temperature strength
2. better heat conductivity
3. greater weight per cubic cm
4. increased resistance to wear

ANS.: B

114) Which engine component increases air density and helps to improve engine operating efficiency?-

1. impeller
2. compressor
3. aftercooler
4. exhaust diffuser

ANS.: C

115)   An electric heater built into the cylinder water jacket would be used to

1. raise lube oil viscosity for easier starting in cold weather
2. increase air inlet temperature
3. increase compression ratio
4. increase water temperature for easier starting in cold weather

ANS.: D

116)  Which is found with both mechanical and hydraulic governors?

1. direct linkage between the ball head and fuel rack
2. a servomotor
3. a compensating device
4. flyweights

ANS.: D

117) Which of the following design features will reduce the possibility of overheating the top compression rings of a cast iron piston?

1. The top ring is located as close to the piston as possible
2. The inside surface of the piston head is rounded into the ring belt
3. A nickel-bearing insert is cast into the top ring groove
4. A heat dam design is sometimes used in the piston head

ANS.: D

118)   The purpose of heat dam used in some diesel engine cast iron pistons is to

1. concentrate all heat in the piston crown
2. increase the distance of travel for heat from the crown to the top ring groove
3. ensure that all heat in the piston crowns is conducted to the top ring
4. provide a short direct path for heat to flow from the crown to the top ring

ANS.: B

119)   Valves used in diesel engine fuel oil pressure piping are to be

1. installed to close against flow or so constructed as to permit packing under pressure.
2. solenoid released upon the failure of engine lubrication
3. either of the gate or globe valve type
4. forge constructed under the approval of the Marine Inspector

ANS.: A

120) Cast iron pistons used in large propulsion engines are constructed with

1. no taper whatsoever 
2. the skirt being tapered and smaller than the crown
3. the skirt being tapered and larger than the crown
4. the crown being tapered and smaller than the skirt

ANS.: D