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License Seminar > Diesel Engines > Flashcards

Diesel Engines Flashcards

1
Q

Which of the listed design features is most common with a two-stroke cycle, low- speed main propulsion diesel engine?

A

piston rod and crosshead construction

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2
Q

In a large, slow-speed, main propulsion diesel engine, which of the parts listed is under tension when the engine is running?

A

tie rod

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3
Q

A diesel engine crankcase ventilation system __________.

A

removes combustible gases

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4
Q

Precision engine bearing inserts are manufactured with a small portion of the bearing ends extending beyond the bearing housing or caps. The installation process of these bearings requires sufficient __________ .

A

crush

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5
Q

If the chemical analysis of a lube oil sample taken from the main propulsion machinery indicates an increased neutralization number the __________ .

A

acidity has increased

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6
Q 
Which of the bearings listed below is most widely used for the main and connecting rod bearings of a modern high-speed diesel engine?
A	Poured Babbitt, self-aligning
B	precision insert
C	Steel-lined
D	Split roller
A

B precision insert

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7
Q

The reversing mechanism on a large four stroke main propulsion diesel engine, can be operated by __________ .
A using double roller followers engaging individual cams lobes
B displacing the camshaft axially according to a double cam lobe design
C using a separate camshaft having a symmetrical cam lobe design and rotating the camshaft by an appropriate angle
D all of the above

A

D all of the above

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8
Q

While underway, which of the following would be the FIRST step in reversing a direct reversing large, slow-speed, main propulsion, diesel engine?

A

set the fuel rack to zero.

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9
Q

In a four-stroke/cycle diesel engine, the camshaft rotates at __________.

A

half the crankshaft speed

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10
Q

The highest pressure in a diesel engine cylinder normally occurs __________.

A

AFTER TDC

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11
Q

The linear motion of a diesel engine piston is converted into the rotary motion required to drive gears, propeller shafts, and generators by the __________.

A

crankshaft

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12
Q 
Which of the following is an example of a solid bearing?
A	Turbo-generator turbine bearing
B	Thrust bearing
C	piston pin bushing
D	Spring bearing
A

C piston pin bushing

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13
Q 
During maneuvering operations for a direct reversing large, low-speed, main propulsion diesel engine, which of the following actions is used to stop the shaft from turning prior to changing the engine rotation for a vessel with moderate headway?
A	The way of the vessel
B	Flywheel inertia
C	Securing cylinder lubricators
D	admission of reversing start air
A

D admission of reversing start air

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14
Q

One method of determining crankshaft misalignment is by __________.

A

taking micrometer readings between the webs

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15
Q

The main reason counterweights are added to crankshafts is to __________ .

A

provide uniform loading and wear of main bearings

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16
Q

In a diesel engine, the main bearings are used between the __________.

A

crankshaft and the engine block

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17
Q

Which instrument is used to take crankshaft deflection readings?

A

dial type inside micrometer

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18
Q

In diesel engines designed with a crosshead, the motion of the piston rod can be described as __________.

A

straight reciprocation

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19
Q

In a large slow-speed propulsion diesel engine, the side thrust on the crosshead is the direct result of _____.

A

the angularity of the connecting rod against the crosshead during the power stroke

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20
Q

The bearings used to support the crankshaft of a diesel engine are generally called __________ .

A

main bearings

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21
Q

Integral cylinder liners constructed as part of the cylinder block, are characterized by which of the following disadvantages?

A

They cannot be replaced.

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22
Q

In large, low-speed, main propulsion diesel engines, piston ring groove wear usually occurs at the __________ .

A

bottom of the ring groove

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23
Q 
Which of the listed bearing installations is subjected to swinging motion?
A	Crankshaft journal
B	Crankpin bearings
C	Wrist pin bearings
D	Thrust bearings
A

C Wrist pin bearings

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24
Q

A safety crankcase cover differs from other diesel engine access doors in that it is fitted with a __________.

A

spring-loaded pressure plate

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25
Q

When inspecting pistons, liners, and rings of a large two-stroke/cycle diesel engine through the cylinder ports, a wet piston crown would indicate a __________.

A

leaky fuel injector

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26
Q 
Which is the first bearing designed to absorb the load created on the piston by combustion in the engine cylinder.
A	Crankshaft journal bearing
B	Crankpin bearing
C	Wrist pin bearing
D	Thrust bearing
A

C Wrist pin bearing

27
Q

Crank web deflection readings will give a positive indication of __________.

A

worn main bearing journals

28
Q

Vibrations from diesel engines and engine driven equipment are isolated from the hull structure by __________ .

A

flexible engine mountings

29
Q

The most practical way of detecting an overload in one cylinder of an operating large, low-speed, main propulsion diesel engine is to __________.

A

Check the cylinder exhaust temperature frequently

30
Q

Bearing ‘crush’ as applied to diesel engine main bearings, will result in __________ .

A

positive seating of the bearings in their housings

31
Q

The camshaft drive is designed to maintain proper camshaft speed relative to crankshaft speed. In maintaining this relationship, the camshaft drive causes the camshaft to rotate at __________.

A

crankshaft speed in a two-stroke cycle diesel engine

32
Q

At bottom dead center, the center-line of the connecting rod usually coincides with the __________ .

A

center-line of the cylinder

33
Q

An indication of an overloaded main propulsion diesel engine is __________ .

A

high exhaust gas pyrometer readings

34
Q

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 __________ .

A

crush

35
Q

In a modern internal combustion diesel engine, the load carrying part of the engine is referred to as the __________ .

A

bedplate or base

36
Q

A main propulsion diesel engine crankshaft bearing lacking sufficient ‘crush’, will __________.

A

tend to rotate with the journal

37
Q

What is the speed of the crankshaft in a four-stroke/cycle engine when the camshaft is turning at 750 rpm?

A

1500 RPM

38
Q 
Which of the terms listed below represents the operational speed at which excessive engine vibration is created?
A	Non-harmonic speed.
B	Critical speed.
C	Maximum speed.
D	Design maximum speed.
A

B Critical speed.

39
Q

In an opposed piston engine, the term ‘crank lead’ refers to __________.

A

the piston in one cylinder reaching inner dead center several crankshaft degrees before the other piston

40
Q

If a diesel engine were running at 20% overload with a smoky exhaust, you should __________.

A

Slow the engine allowing it to gradually cool

41
Q 
In a diesel engine, which type of wrist pin uses bearings in the piston bosses, but is fixed to the small end of the connecting rod?
A	Semi-floating
B	Full floating
C	Solid
D	Fixed
A

A Semi-floating

42
Q

The flywheel reduces speed fluctuations by __________ .

A

Storing kinetic energy

43
Q

The insertion of shims between the foot of a marine type connecting rod and a bearing box would result in __________.

A

Increased compression ratio

44
Q

Many cast iron pistons are designed with heat dams, which serve to __________ .

A

reduce the possibility of overheating the top compression ring

45
Q

The diameter of a piston is usually less at the crown than at the skirt, in order to __________ .

A

allow for the expansion of the piston during operation

46
Q

Oil control rings are designed with slotted holes to __________.

A

permit excess oil to drain back to the sump

47
Q

The shape of a diesel engine cam determines the __________.
A points of opening and closing of the valve
B velocity of opening and closing of the valve
C amount of the valve lift from its seat
D all of the above

A

D all of the above

48
Q

Which of the following ring designs is commonly used on new piston rings to facilitate run-in or seating?
A Machining a special ring face groove filled with anti-friction metal.
B Increasing ring tension as high as possible.
C Machining the ring from extra soft nonferrous alloys.
D Provide a minimum gap clearance under cold conditions to prevent ring expansion.

A

A Machining a special ring face groove filled with anti-friction metal.

49
Q

Diesel engine piston ring gaps can be straight or angle cut. In comparison, the angle cut ring __________ .

A

decreases combustion gas leakage

50
Q

One of the most common methods in preventing a diesel engine piston pin from contacting the cylinder wall is by the use of __________ .

A

snap rings

51
Q

The main reason for using bimetallic piston rings is to __________.

A

reduce the probability of ring fracture

52
Q

During the power stroke, the side thrust of a trunk type piston is a result of the angle __________.

A

formed by the connecting rod and the cylinder center-line

53
Q

During the power stroke of a four-stroke/cycle diesel engine, most of the side thrust of a trunk-type piston is absorbed by the __________ .

A

piston skirt

54
Q

The function of the piston compression rings used in a diesel engine is to __________ .
A seal the space between the piston and liner
B transmit heat from the piston to the cylinder liner
C reduce the amount of combustion gas blow-by
D all of the above

A

D all of the above

55
Q

A piston is at bottom dead center when it is __________ .

A

farthest from the cylinder head

56
Q

To reduce the weight of the reciprocating parts, pistons of high-speed engines are made considerably shorter. This results in __________ .

A

greater piston wear

57
Q

A connecting rod in a four-stroke/cycle diesel engine is subject to __________ .
A tension load twice each crankshaft revolution
B compression load during power and compression strokes
C inertia load once every four crankshaft revolutions
D bending loads at bottom and top dead center

A

B compression load during power and compression strokes

58
Q

In diesel engines, hydraulic valve lifters are used to __________.

A

reduce valve gear pounding

59
Q

What is the purpose of a hydraulic valve lash adjuster?

A

compensates for the expansion and contraction of the valve stem due to changes in operating temperature.

60
Q

Valve lash, or clearance refers to the __________ .

A

clearance between the top of the valve stem and the rocker arm

61
Q

During engine warm-up, the expansion of cylinder head valve stems due to the buildup of engine heat, is compensated for by the __________ .

A

valve lash clearance

62
Q

The intake and exhaust valves used in a diesel engine are returned to their seats by __________ .

A

spring force

63
Q

The cylinder liner forming the cylinder wall and the inside of the water jacket is called a __________ .

A

wet liner

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