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Adv. Diesels > Quiz #1: Q. 1-50 > Flashcards

Quiz #1: Q. 1-50 Flashcards

1
Q

The process of supplying a diesel engine cylinder with air at a pressure greater than atmospheric is called __________.

A

supercharging

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2
Q

Forcing the exhaust gases from the cylinder of an operating two cycle diesel engine with the aid of a blower is known as __________.

A

scavenging

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3
Q 
Which of the listed types of superchargers will NOT have a volumetric capacity proportional to engine speed?
A	Exhaust gas turbocharger
B	Roots blower
C	Piston type blower
D	Vane type blower
A

A Exhaust gas turbocharger

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4
Q

The relative air pressure in the inlet manifold of a turbocharged diesel engine is usually __________.

A

greater than the average exhaust manifold pressure

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5
Q

The process of scavenging a two-stroke/cycle diesel engine serves to __________.

A

cool the exhaust valves

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6
Q

After cooling of a turbocharged diesel engine will result in __________.

A

higher torque and higher brake horsepower

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7
Q

Why will a turbocharged diesel engine produce black smoke if excessive additional load is applied too quickly?

A

The inertia of the turbocharger rotor causes a time lag which delays the turbocharger speed increase.

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8
Q 
Which of the following devices will increase the power output of a diesel engine without increasing its frictional load?
A	Positive displacement blower
B	Roots-type rotary blower
C	Gear-driven centrifugal blower
D	Turbine-driven centrifugal blower
A

D Turbine-driven centrifugal blower

[aka a turbocharger]

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9
Q

Some diesel engines are supercharged with a __________.

A

turbocharger

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10
Q

The device shown in the illustration is commonly used to __________. Illustration MO-0080

A

utilize the flow of exhaust gases to supercharge the engine

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11
Q

At rated engine load and RPM, the diesel engine turbocharger is powered by __________.

A

exhaust gases

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12
Q

The operating speed of a turbocharger is directly dependent upon __________.

A

engine load

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13
Q

What statement is true concerning the charge air system of a modern turbocharged slow- speed two-stroke cycle diesel engine?
A A mechanically driven auxiliary blower is usually provided because the turbocharger cannot provide enough air at low engine speeds and loads.
B An electrically driven auxiliary blower is usually provided because the turbocharger cannot provide enough air at low engine speeds and loads.
C An electrically driven auxiliary blower is usually provided because the turbocharger cannot provide enough air at high engine speeds and loads.
D A mechanically driven auxiliary blower is usually provided because the turbocharger cannot provide enough air at high engine speeds and loads.

A

B An electrically driven auxiliary blower is usually provided because the turbocharger cannot provide enough air at low engine speeds and loads.

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14
Q

What statement is true concerning the charge air system of a modern turbocharged slow- speed two-stroke cycle diesel engine?
A A charge air cooler is usually provided to increase the charge air density.
B A charge air heater is usually provided to decrease the charge air density.
C A charge air heater is usually provided to increase the charge air density.
D A charge air cooler is usually provided to decrease the charge air density.

A

A A charge air cooler is usually provided to increase the charge air density.

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15
Q

On a typical turbo-charged marine diesel engine, what type of blower/compressor is used within the turbocharger?

A

Centrifugal

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16
Q

During the valve overlap period, the exhaust pressure of a turbocharged, four- stroke/cycle diesel engine must be less than the intake manifold pressure to ensure __________.

A

effective cylinder scavenging and cooling

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17
Q

The power consumed during the scavenging process of a diesel engine is known as the __________.

A

pumping loss

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18
Q

Corrosion inhibitors and/or soluble oils are added to diesel engine cooling systems to __________.

A

form a protective film on metal surfaces

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19
Q

Ethylene glycol, when used as a coolant in a closed cooling system for a diesel engine, is more advantageous than untreated raw water because it __________.

A

has a lower freezing point and higher boiling point

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20
Q

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

A

allow for an increase in water volume as the engine warms up

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21
Q

The highest pressure in any closed diesel engine freshwater cooling system is at the __________.

A

cooling water pump outlet

22
Q

The expansion tank in a diesel engine closed freshwater cooling system is located at __________.

A

the highest point in the system

23
Q

A closed freshwater cooling system is commonly used with marine diesel engines because the __________.

A

jacket water temperature is more easily controlled

24
Q

Cooling water pumps driven by direct-reversing diesel engines are usually __________.

A

straight impeller vane with concentric housing

25
Q

Sacrificial zinc anodes are used on the saltwater side of diesel engine heat exchangers to __________.

A

reduce electrolytic action on heat exchanger metals

26
Q

When checking zincs in a saltwater cooled heat exchanger, you should __________.

A

replace the zincs if they are approximately 50% consumed

27
Q

In a diesel engine jacket water cooler, with seawater cooling the fresh water, the __________.

A

jacket water pressure should always be greater than the sea water pressure

28
Q

A three-way thermostatic control valve regulates the diesel engine cooling water temperature by passing a portion of the water __________.

A

around the cooler

29
Q

What would be considered a normal temperature increase between the inlet and outlet jacket cooling water of a medium or high-speed diesel engine operating at normal load?

A

10 to 20 degrees Fahrenheit

30
Q

An electric heater built into some smaller diesel engines is used to __________.

A

increase jacket water temperature for easier starting in cold weather

31
Q

In a diesel engine closed freshwater cooling system employing a radiator, proper water temperature can be obtained by __________.

A

adjusting the radiator louvers

32
Q

The temperature at which an adjustable bellows type thermostatic valve operates is determined by __________.

A

changing the spring compression opposing the bellows

33
Q

The theoretical minimum compression ratio necessary to ensure compression ignition in a direct injection diesel engine is __________.

A

12:1

34
Q

Which of the following reasons represents why the designed compression ratio of a gasoline engine is lower than that of a diesel engine?
A Compression must be low for smooth operation.
B The heat of compression is not used as an ignition source of the fuel.
C Compression must be low to have effective pre-ignition.
D Compression must be low for effective spark ignition.

A

B The heat of compression is not used as an ignition source of the fuel.

35
Q

In the starting process of a diesel engine, the main object is to attain the compression conditions sufficient to __________.

A

ignite the fuel

36
Q

The thermal energy produced by an internal combustion engine is transformed into __________.

A

mechanical energy

37
Q

Diesel engines are classified as reciprocating internal combustion engines because they __________.

A

burn fuel in a closed chamber which imparts linear motion to pistons

38
Q

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

A

after TDC

39
Q

The load is always placed on the lower half of the main bearings in a/an __________.

A

two-stroke/cycle engine

40
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.

41
Q

The cubic inch (or liter) displacement of a cylinder is determined by the diameter of the piston and the __________.

A

length of the stroke

42
Q

If the compression ratio is increased on any diesel engine, __________.

A

thermal efficiency will increase

43
Q

In the illustrated diesel engine, which label points to the piston? MO-0122

A

4

44
Q

The diesel engine wrist pin in the illustration is indicated by the component labeled __________. MO-0122

A

7

45
Q

Which of the following is an example of a solid bearing?

A

Piston pin bushing

46
Q

The proper location for journal bearing oil grooves is __________.

A

as a side relief where the two shells meet

47
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

Precision insert

48
Q

Component ā€œUā€ of the diesel engine shown in the illustration is called the __________. MO-0122

A

crankshaft counterweight

49
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

50
Q

Connecting rods in a diesel engine are used to connect the __________.

A

piston to the crankshaft

Adv. Diesels (7 decks)

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