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...my Stuff > Turbines/ Reduction Gears and Propellers > Flashcards

Turbines/ Reduction Gears and Propellers Flashcards

1
Q

propellers are visually inspected at what periodicity?

A

semi-annualy

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2
Q

what is used to clean the prairie holes on a propeller?

A

low pressure air

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3
Q

what reference can be sued to find general information on main engine reduction gears?

A

NSTM 9420

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4
Q

what two types of reduction gear teeth are in use today on propulsion reduction gears?

A

herring bone and helical gears

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5
Q

main reduction gear pinion’s are made from what material?

A

forged steel

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6
Q

the maximum allowable bearing temperature during engine operation is?

A

180 degrees F

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7
Q

what device prevents rotation of the propeller during a casualty?

A

main engine locking device

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8
Q

what medium is used to cool the stern tube during operation?

A

seawater

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9
Q

after securing the engine, equalized cooling of the shaft is made possible by what device?

A

main engine jacking gear

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10
Q

the main engine locking device should only be engaged when?

A

the ship is dead in the water and the propeller is not turning

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11
Q

when approaching port or an anchorage, main engine lube oil temperature is reduced to what temperature?

A

100 degrees F

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12
Q

why is the main engine lube oil temperature lowered to 100 degrees F upon reaching port or an anchorage

A

to minimize moisture buildup and rust formation on the reduction gears

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13
Q

when laying up reduction gears for an extended period what is used to keep them moisture free?

A

dehumidifier

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14
Q

the main reduction gear dehumidifier system must be checked at what frequency for correct operation?

A

daily

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15
Q

permission to open any access to the main engine reduction gears must be obtained from whom?

A

engineering officer

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16
Q

backlash of main engine reduction gears refers to what?

A

the gear play between the surfaces of the teeth in mesh measure at the pitch circle

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17
Q

what increases engine backlash?

A

gear wear

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18
Q

what NSTM deals with propulsion and SSTG turbines?

A

NSTM 231

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19
Q

the high pressure turbine element is normally defined as what type of turbine?

A

impulse type

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20
Q

the low pressure turbine element is normally defined as what type of turbine?

A

reaction type

21
Q

what connects the high pressure turbine to the low pressure turbine?

A

crossover or cross under pipe

22
Q

why are extraction valves fitted on some LP and HP turbines?

A

to increase steam cycle efficiency

23
Q

what does the term impulse turbine refer to?

A

a turbine in which the steam impinges upon the rotor blades and moves the rotor by a. direct push

24
Q

what type of steam turbine moves the rotor by the force of reaction?

A

reaction turbine

25
Q

what two main factors determine whether the rotor is moved by a direct impulse or reaction?

A

by the angle at which the steam hits the moving blades

26
Q

on an impulse turbine were does the steam lose pressure and gain velocity?

A

the nozzle

27
Q

in the moving blades of an impulse turbine, steam loses velocity, and pressure does what?

A

remains constant

28
Q

what type of turbine does not have a nozzle to direct steam, but has a set of fixed blades?

A

reaction

29
Q

what is the function of the fixed blades of a reaction turbine?

A

to direct the steam flow to the moving blades

30
Q

what is considered a stage on an impulse turbine?

A

one set of nozzles and the succeeding row or rows of moving and fixed blades

31
Q

what is a single stage impulse turbine usually called?

A

rateau

32
Q

what is the definition of a Curtis stage turbine?

A

a velocity compounded impulse turbine

33
Q

what does the term radial flow mean?

A

steam flows radially either toward or away from the axis of the rotor

34
Q

the astern turbine elements are located in what turbine?

A

the low pressure turbine

35
Q

what prevents foreign material from entering the high pressure turbine steam chest?

A

the main steam strainer

36
Q

what is the purpose of gland sealing steam?

A

prevents steam from leaking out of the main engine and air from being introduced into the engine

37
Q

turbine casing drains normally drain to what piece of equipment or system?

A

low pressure drain system or main condenser

38
Q

the main engine thrust bearing is normally what type?

A

kinsgbury pivoted segmental show type

39
Q

the kingsbury thrust bearing shoes serve what purpose?

A

the shoes are free to tilt and form the hydrodynamic wedge of oil between its babbitt face and the thrust collar

40
Q

what device is installed on main engine thrust bearings to indicate flow?

A

bullseye bubblers or as properly termed sight flow indicators

41
Q

what is the minimum allowable lube oil temperature prior to jacking the main engine over?

A

90 degrees F

42
Q

a bowed rotor is caused by what?

A

improper warmup or overheating of the rotor

43
Q

information on correcting a bowed rotor casualty can be found where?

A

engineering operation casualty control (EOCC) guide or NSTM 231

44
Q

what does the term singled up refer to when dealing with propulsion turbines?

A

singled up is used as an emergency means of getting underway when a casualty accurst to either the HP or LP turbine in which one is placed out of commission. Singled up of a turbine required the operator to disconnect one of the turbine’s power driven unit

45
Q

what does the term locked train reduction gears refer to?

A

the two first reduction pinions are locked between the two first reduction gears and transmit power from the turbine equally to the two gears

46
Q

the main engine flexible coupling serves to protect the engine from?

A

longitudal and angular forces

47
Q

the propeller and shaft is supported outside the hull of the ship by?

A

strut and strut bearing

48
Q

what device is installed on the main engine to prevent the leakage of steam from the engine?

A

labyrinth seals

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