MACHINIST MATE EXAM, PRACTICE EXAM AND STUDY
GUIDE NEWEST 2024 ALL IN ONE DOCUMENT 500
QUESTIONS AND CORRECT ANSWERS (VERIFIED
ANSWERS) |ALREADY GRADED A+
What is the the purpose of reduction gears? - ANSWER: To reduce high speed to low
speed
What is the purpose of double-helical gears in reduction gears? - ANSWER: To
produce smoother action and eliminate tooth shock
In reference to reduction gears, the term axial float has what meaning? - ANSWER:
The gears are capable of free motion, neither supporting nor supported by other
gears axially.
What is the meaning of the term lock-train? - ANSWER: The two first reduction
pinions are locked between the two first reduction gears.
What means are provided to inspect the rotating pairs? - ANSWER: Inspection plates
When first and second reduction gears are fabricated for an articulated, double-
reduction, divided-power path gear set, why are the teeth cut in a temperature-
controlled room? - ANSWER: To prevent the effects of temperature and humidity
In propulsion systems, the shaft for a main reduction gear is made from what type of
material? - ANSWER: Forged steel
The type of construction for gear wheels used in reduction gear mechanisms aboard
ship is determined by which of the following factors? - ANSWER: The size of the gear
wheel
What types of flexible couplings are used in most turbine reduction gear
installations? - ANSWER: Gear tooth
The expansion and minor misalignments that occur between the main turbines and
the reduction gears are compensated by what device? - ANSWER: Sleeve
Failure to use the turning gear during turbine startup may result in which of the
following casualties? - ANSWER: Bowed rotor
Geared turbine installations are equipped with turning mechanisms for all of the
following reasons EXCEPT? - ANSWER: To prevent heat acceleration
In the type of turning gear discussed in the chapter, what component connects the
turning gear to the high-pressure pinion? - ANSWER: A manually operated jaw clutch
,What type of reduction gearing is used for turbo generators? - ANSWER: Helix
In the reduction gearing for a typical ship's turbo generator, the gear that drives the
oil pump and governor is mounted on the turbine end of what component? -
ANSWER: Turbine shaft
Before any cover, connection, or inspection plate that permits access to the gear
casing is replaced, who should make a careful inspection to ensure no foreign matter
has entered the gear casing? - ANSWER: Officer from engineering
If work is being done by a repair activity, who must inspect the gear casing? -
ANSWER: Officer from the repair activity
What type of reduction gear does a ship's service turbo generator use? - ANSWER:
Single-reduction, single-helical gear unit
Before any inspection or work on or around the reduction gears is accomplished,
who must be present? - ANSWER: Engineer officer
What is the ratio of the turbine-driven main circulating pumps? - ANSWER: 8 to 1
If properly maintained, how long should reduction gears give reliable service? -
ANSWER: Lifetime of the ship
What type of lubrication oil is used for the propulsion gears? - ANSWER: 2190 TEP
By what sign can churning be identified? - ANSWER: High bearing temperatures
What is one of the most important steps prior to getting underway? - ANSWER:
Determine if circulating water is available at the lube oil cooler
In the main engine installations, the main reduction gear bearings and other bearings
have which of the following characteristics in common? - ANSWER: They are Babbitt
lined
Reduction gear bearings are mounted rigidly in their housings by what means? -
ANSWER: Dowels or locking screws and washers
The splits in the main reduction gear bearings are mounted at an angle to the
horizontal to prevent which of the following problems? - ANSWER: Wiping
A main thrust bearing of a ship's propulsion plant located in the reduction gear
casing has which of the following purposes? - ANSWER: To absorb the axial thrust
transmitted through the shaft from the propeller
, Which of the following should you use for instructions when a turbine is first put into
service? - ANSWER: Engineering operation sequencing system
What is the first step to start a turbine that is driving an electric generator? -
ANSWER: Ensure that the turbine is free of all loose material and that all working
parts are clean and well lubricated. Test all safety devices where practical, tripping
them by hand to ensure proper functioning.
What is the last step for securing a turbine that is driving an electric generator? -
ANSWER: After all the condensate has drained out and the casing has cooled to
engine-room temperature, close all the drains. To prevent corrosion, take every
precaution to guard against steam bleeding into the turbine casing.
Which of these defects causes excessive vibration in a steam driven generator? -
ANSWER: Wiped bearings or excessive oil clearance
The shaft packing used on most turbogenerators is - ANSWER: Labyrinth type rings or
seals
Take extreme care in cleaning turbine casing joints. Carefully scrape and clean joint
surfaces, then polish them with ___ - ANSWER: Crocus cloth
What can seriously weaken a turbine generator casing? - ANSWER: Corrosion
What is the general reduction gear ratio of a turbogenerator? - ANSWER: 8 to 1
On most turbogenerators, the reduction gear casing must be ____ before you can
reach the pinion gear bearings, the main gear bearings, and the low-speed thrust
bearing. - ANSWER: Removed
The axial position of the thrust collar is determined by the ____ - ANSWER: Spacer or
shim
The axial position of the generator rotor is maintained by the ____ on the gear
bearings. - ANSWER: Thrust faces
Oil pressure to operate the constant-speed governor and lubricate the bearings and
gears is supplied by a ____ - ANSWER: Gear-type pump
All turbine-driven generators have a lube oil low-pressure alarm. The alarm
contactor is located in the ____ leading to the bearings - ANSWER: Lube oil line
The contactor is set at the factory to operate when the oil pressure drops to how
many psig? - ANSWER: 4 psig
____ is a device that automatically releases the operating oil pressure under the
throttle valve operating piston. - ANSWER: Overspeed trip
GUIDE NEWEST 2024 ALL IN ONE DOCUMENT 500
QUESTIONS AND CORRECT ANSWERS (VERIFIED
ANSWERS) |ALREADY GRADED A+
What is the the purpose of reduction gears? - ANSWER: To reduce high speed to low
speed
What is the purpose of double-helical gears in reduction gears? - ANSWER: To
produce smoother action and eliminate tooth shock
In reference to reduction gears, the term axial float has what meaning? - ANSWER:
The gears are capable of free motion, neither supporting nor supported by other
gears axially.
What is the meaning of the term lock-train? - ANSWER: The two first reduction
pinions are locked between the two first reduction gears.
What means are provided to inspect the rotating pairs? - ANSWER: Inspection plates
When first and second reduction gears are fabricated for an articulated, double-
reduction, divided-power path gear set, why are the teeth cut in a temperature-
controlled room? - ANSWER: To prevent the effects of temperature and humidity
In propulsion systems, the shaft for a main reduction gear is made from what type of
material? - ANSWER: Forged steel
The type of construction for gear wheels used in reduction gear mechanisms aboard
ship is determined by which of the following factors? - ANSWER: The size of the gear
wheel
What types of flexible couplings are used in most turbine reduction gear
installations? - ANSWER: Gear tooth
The expansion and minor misalignments that occur between the main turbines and
the reduction gears are compensated by what device? - ANSWER: Sleeve
Failure to use the turning gear during turbine startup may result in which of the
following casualties? - ANSWER: Bowed rotor
Geared turbine installations are equipped with turning mechanisms for all of the
following reasons EXCEPT? - ANSWER: To prevent heat acceleration
In the type of turning gear discussed in the chapter, what component connects the
turning gear to the high-pressure pinion? - ANSWER: A manually operated jaw clutch
,What type of reduction gearing is used for turbo generators? - ANSWER: Helix
In the reduction gearing for a typical ship's turbo generator, the gear that drives the
oil pump and governor is mounted on the turbine end of what component? -
ANSWER: Turbine shaft
Before any cover, connection, or inspection plate that permits access to the gear
casing is replaced, who should make a careful inspection to ensure no foreign matter
has entered the gear casing? - ANSWER: Officer from engineering
If work is being done by a repair activity, who must inspect the gear casing? -
ANSWER: Officer from the repair activity
What type of reduction gear does a ship's service turbo generator use? - ANSWER:
Single-reduction, single-helical gear unit
Before any inspection or work on or around the reduction gears is accomplished,
who must be present? - ANSWER: Engineer officer
What is the ratio of the turbine-driven main circulating pumps? - ANSWER: 8 to 1
If properly maintained, how long should reduction gears give reliable service? -
ANSWER: Lifetime of the ship
What type of lubrication oil is used for the propulsion gears? - ANSWER: 2190 TEP
By what sign can churning be identified? - ANSWER: High bearing temperatures
What is one of the most important steps prior to getting underway? - ANSWER:
Determine if circulating water is available at the lube oil cooler
In the main engine installations, the main reduction gear bearings and other bearings
have which of the following characteristics in common? - ANSWER: They are Babbitt
lined
Reduction gear bearings are mounted rigidly in their housings by what means? -
ANSWER: Dowels or locking screws and washers
The splits in the main reduction gear bearings are mounted at an angle to the
horizontal to prevent which of the following problems? - ANSWER: Wiping
A main thrust bearing of a ship's propulsion plant located in the reduction gear
casing has which of the following purposes? - ANSWER: To absorb the axial thrust
transmitted through the shaft from the propeller
, Which of the following should you use for instructions when a turbine is first put into
service? - ANSWER: Engineering operation sequencing system
What is the first step to start a turbine that is driving an electric generator? -
ANSWER: Ensure that the turbine is free of all loose material and that all working
parts are clean and well lubricated. Test all safety devices where practical, tripping
them by hand to ensure proper functioning.
What is the last step for securing a turbine that is driving an electric generator? -
ANSWER: After all the condensate has drained out and the casing has cooled to
engine-room temperature, close all the drains. To prevent corrosion, take every
precaution to guard against steam bleeding into the turbine casing.
Which of these defects causes excessive vibration in a steam driven generator? -
ANSWER: Wiped bearings or excessive oil clearance
The shaft packing used on most turbogenerators is - ANSWER: Labyrinth type rings or
seals
Take extreme care in cleaning turbine casing joints. Carefully scrape and clean joint
surfaces, then polish them with ___ - ANSWER: Crocus cloth
What can seriously weaken a turbine generator casing? - ANSWER: Corrosion
What is the general reduction gear ratio of a turbogenerator? - ANSWER: 8 to 1
On most turbogenerators, the reduction gear casing must be ____ before you can
reach the pinion gear bearings, the main gear bearings, and the low-speed thrust
bearing. - ANSWER: Removed
The axial position of the thrust collar is determined by the ____ - ANSWER: Spacer or
shim
The axial position of the generator rotor is maintained by the ____ on the gear
bearings. - ANSWER: Thrust faces
Oil pressure to operate the constant-speed governor and lubricate the bearings and
gears is supplied by a ____ - ANSWER: Gear-type pump
All turbine-driven generators have a lube oil low-pressure alarm. The alarm
contactor is located in the ____ leading to the bearings - ANSWER: Lube oil line
The contactor is set at the factory to operate when the oil pressure drops to how
many psig? - ANSWER: 4 psig
____ is a device that automatically releases the operating oil pressure under the
throttle valve operating piston. - ANSWER: Overspeed trip
