Diesel Engines

Question 1

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

Answer 1

piston rod and crosshead construction

Question 2

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

Answer 2

tie rod

Question 3

A diesel engine crankcase ventilation system __________.

Answer 3

removes combustible gases

Question 4

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 __________ .

Answer 4

crush

Question 5

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

Answer 5

acidity has increased

Question 6

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

Answer 6

B precision insert

Question 7

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

Answer 7

D all of the above

Question 8

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

Answer 8

set the fuel rack to zero.

Question 9

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

Answer 9

half the crankshaft speed

Question 10

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

Answer 10

AFTER TDC

Question 11

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

Answer 11

crankshaft

Question 12

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

Answer 12

C piston pin bushing

Question 13

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

Answer 13

D admission of reversing start air

Question 14

One method of determining crankshaft misalignment is by __________.

Answer 14

taking micrometer readings between the webs

Question 15

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

Answer 15

provide uniform loading and wear of main bearings

Question 16

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

Answer 16

crankshaft and the engine block

Question 17

Which instrument is used to take crankshaft deflection readings?

Answer 17

dial type inside micrometer

Question 18

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

Answer 18

straight reciprocation

Question 19

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

Answer 19

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

Question 20

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

Answer 20

main bearings

Question 21

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

Answer 21

They cannot be replaced.

Question 22

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

Answer 22

bottom of the ring groove

Question 23

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

Answer 23

C Wrist pin bearings

Question 24

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

Answer 24

spring-loaded pressure plate

Question 25

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 __________.

Answer 25

leaky fuel injector

Question 26

``` 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 ```

Answer 26

C Wrist pin bearing

Question 27

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

Answer 27

worn main bearing journals

Question 28

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

Answer 28

flexible engine mountings

Question 29

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

Answer 29

Check the cylinder exhaust temperature frequently

Question 30

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

Answer 30

positive seating of the bearings in their housings

Question 31

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 __________.

Answer 31

crankshaft speed in a two-stroke cycle diesel engine

Question 32

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

Answer 32

center-line of the cylinder

Question 33

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

Answer 33

high exhaust gas pyrometer readings

Question 34

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 __________ .

Answer 34

crush

Question 35

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

Answer 35

bedplate or base

Question 36

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

Answer 36

tend to rotate with the journal

Question 37

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

Answer 37

1500 RPM

Question 38

``` 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. ```

Answer 38

B Critical speed.

Question 39

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

Answer 39

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

Question 40

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

Answer 40

Slow the engine allowing it to gradually cool

Question 41

``` 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 ```

Answer 41

A Semi-floating

Question 42

The flywheel reduces speed fluctuations by __________ .

Answer 42

Storing kinetic energy

Question 43

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

Answer 43

Increased compression ratio

Question 44

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

Answer 44

reduce the possibility of overheating the top compression ring

Question 45

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

Answer 45

allow for the expansion of the piston during operation

Question 46

Oil control rings are designed with slotted holes to __________.

Answer 46

permit excess oil to drain back to the sump

Question 47

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

Answer 47

D all of the above

Question 48

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.

Answer 48

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

Question 49

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

Answer 49

decreases combustion gas leakage

Question 50

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

Answer 50

snap rings

Question 51

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

Answer 51

reduce the probability of ring fracture

Question 52

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

Answer 52

formed by the connecting rod and the cylinder center-line

Question 53

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 __________ .

Answer 53

piston skirt

Question 54

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

Answer 54

D all of the above

Question 55

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

Answer 55

farthest from the cylinder head

Question 56

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

Answer 56

greater piston wear

Question 57

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

Answer 57

B compression load during power and compression strokes

Question 58

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

Answer 58

reduce valve gear pounding

Question 59

What is the purpose of a hydraulic valve lash adjuster?

Answer 59

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

Question 60

Valve lash, or clearance refers to the __________ .

Answer 60

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

Question 61

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

Answer 61

valve lash clearance

Question 62

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

Answer 62

spring force

Question 63

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

Answer 63

wet liner