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U.S.C.G. Merchant Marine Exam - Motor Plants (1) 2024/2025 Entry, Exams of Marine Engineering

United States Merchant Marine Academy (USMMA )Marine Engineering

1. If the piston stroke in a four-stroke cycle diesel engine is 10 1/2 inches and the speed of rotation of the crankshaft is 720 RPM, what is the average piston speed? (A) 1200 feet/minute (B) 1260 feet/minute (C) 1320 feet/minute (D) 1380 feet/minute - Correct Ans: โœ”โœ”B 2. Which of the following conditions would NOT be considered a valid reason for the diesel engine to operate in the area indicated by letter "B" shown in the illustration? Illustration MO-0126 (A) Operating the vessel against high winds and current (B) Operating with a fouled or damaged propeller (C) Operating the vessel in shallow water (D) Operating with minimal hull drag and under light draft - Correct Ans: โœ”โœ”D

Typology: Exams

2024/2025

Available from 11/24/2024

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U.S.C.G. Merchant Marine Exam - Motor
Plants (1) 2024 Entry
1. If the piston stroke in a four-stroke cycle diesel engine is 10 1/2
inches and the speed of rotation of the crankshaft is 720 RPM, what
is the average piston speed?
(A) 1200 feet/minute
(B) 1260 feet/minute
(C) 1320 feet/minute
(D) 1380 feet/minute - Correct Ans: โœ”โœ”B
2. Which of the following conditions would NOT be considered a valid
reason for the diesel engine to operate in the area indicated by
letter "B" shown in the illustration? Illustration MO-0126
(A) Operating the vessel against high winds and current
(B) Operating with a fouled or damaged propeller
(C) Operating the vessel in shallow water
(D) Operating with minimal hull drag and under light draft -
Correct Ans: โœ”โœ”D
3. The indicator card shown in the illustration is produced with a/an
__________. Illustration MO-0108
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff
pf12
pf13
pf14
pf15
pf16
pf17
pf18
pf19
pf1a
pf1b
pf1c
pf1d
pf1e
pf1f

Partial preview of the text

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U.S.C.G. Merchant Marine Exam - Motor

Plants (1) 2024 Entry

  1. If the piston stroke in a four-stroke cycle diesel engine is 10 1/ inches and the speed of rotation of the crankshaft is 720 RPM, what is the average piston speed? (A) 1200 feet/minute (B) 1260 feet/minute (C) 1320 feet/minute (D) 1380 feet/minute - Correct Ans: โœ”โœ”B
  2. Which of the following conditions would NOT be considered a valid reason for the diesel engine to operate in the area indicated by letter "B" shown in the illustration? Illustration MO- 0126 (A) Operating the vessel against high winds and current (B) Operating with a fouled or damaged propeller (C) Operating the vessel in shallow water (D) Operating with minimal hull drag and under light draft - Correct Ans: โœ”โœ”D
  3. The indicator card shown in the illustration is produced with a/an __________. Illustration MO- 0108

(A) oscillating drum (B) sliding camshaft (C) rotating drum (D) balanced-diaphragm indicator - Correct Ans: โœ”โœ”C

  1. Which of the indicator diagrams illustrated depicts the condition that should be corrected by retardingonly the timing? Illustration MO- 0029 (A) A (B) B (C) C (D) D - Correct Ans: โœ”โœ”A
  2. The greatest turbulence in a diesel engine cylinder is created by the __________. (A) shape of the combustion chamber (B) fuel injection spray pattern (C) cylinder swept volume

(A) positive seating of the bearings in their housings (B) above normal operating temperatures (C) damage to the journals (D) damage to the bearings - Correct Ans: โœ”โœ”A

  1. Connecting rods in a diesel engine are used to connect the __________. (A) piston to the crankshaft (B) engine to the bed (C) crankshaft to the gear train (D) rocker arm to the camshaft - Correct Ans: โœ”โœ”A
  2. In the diesel engine shown in the illustration, the space below the cylinder liner lower seals is subjected to __________. Illustration MO- 0005 (A) lube oil pressure (B) cooling water pressure (C) crankcase pressure (D) scavenge air pressure - Correct Ans: โœ”โœ”C
  1. Barrel face, taper face, grooved, and chrome plated are all types of diesel engine __________. (A) pistons (B) piston rings (C) piston skirts (D) cylinder liners - Correct Ans: โœ”โœ”B
  2. 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) flywheel (B) crankshaft (C) journal bearings (D) camshaft - Correct Ans: โœ”โœ”B
  3. One method of constructing large marine diesel engines and reducing the total engine frame weight is through __________. (A) casting interlocking components (B) welding plates to form sections for assembly

(A) A

(B) B

(C) P

(D) U - Correct Ans: โœ”โœ”D

  1. The fuel injector for the diesel engine shown in the illustration, is identified as _________.Illustration MO- 0122 (A) "19" (B) "H" (C) "M" (D) "Z" - Correct Ans: โœ”โœ”A
  2. The diesel engine connecting rods shown in the illustration are distinctively named __________.Illustration MO- 0122 (A) hook and nail (B) male and female (C) fork and blade (D) left hand and right hand - Correct Ans: โœ”โœ”C
  1. Which of the following procedures should be carried out when a large, low-speed, diesel engine is operated with one cylinder secured? (A) Lubrication to the defective cylinder should be increased. (B) Cooling water temperature to the engine should be increased. (C) Only the turbocharger speed should be reduced. (D) Engine speed should be reduced. - Correct Ans: โœ”โœ”D
  2. The insertion of shims between the foot of a marine type connecting rod and a bearing box would result in __________. (A) increased compression ratio (B) decreased compression ratio (C) increased bearing clearance (D) decreased bearing clearance - Correct Ans: โœ”โœ”A
  3. After a long period of operation, a wear ridge, caused by piston ring action, will develop near the top of the cylinder liner. This ridge must be removed during maintenance in order to prevent__________.

(A) The valve guides and the valve seats are both replaceable inserts. (B) The valve guides and the valve seats are both integral (non- replaceable). (C) The valve guides are integral (non-replaceable), and the valve seats are replaceable inserts. (D) The valve guides are replaceable inserts, and the valve seats are integral (non-replaceable). - Correct Ans: โœ”โœ”A

  1. The vessel to which you are assigned is fitted with a diesel driven generator engine as shown in the illustration. What statement is true in terms of the combustion chamber design? Illustration MP-HS (A) The engine uses turbulence chambers with a hemispherical fire-deck. (B) The engine uses an open type combustion chamber with a hemispherical fire-deck. (C) The engine uses an open type combustion chamber with a flat fire-deck. (D) The engine uses pre-combustion chambers with a flat fire- deck. - Correct Ans: โœ”โœ”C
  2. When starting an auxiliary diesel engine in preparation for operation, what parameter must be checked FIRST upon start-up to avoid immediate engine damage?

(A) Fuel oil supply header pressure. (B) Cylinder jacket water pump discharge pressure. (C) Winch gear oil pump discharge pressure. (D) Engine lubricating oil supply header pressure. - Correct Ans: โœ”โœ”D

  1. The diesel generator set drive engines on your vessel are protected with heavy-duty oil bath air cleaners. The oil within these air cleaners should be periodically replaced in accordance with manufacturer recommendations. What statement best describes when it would be appropriate to deviate from the recommended frequency? (A) Replace the oil more frequently when the engine is exposed to dusty conditions (such as arc welding in the engine room), and replace the oil less frequently when the oil is unusually dirty or when it thickens. (B) Replace the oil less frequently when the engine is exposed to dusty conditions (such as arc welding in the engine room), and replace the oil more frequently when the oil is unusually dirty or when it thickens. (C) Replace the oil less frequently when the engine is exposed to dusty conditions (such as arc

(A) The filter element is slightly restricted with dust but does not yet require replacement. (B) The filter element is being severely bypassed due to an improper seal and should be immediately re-seated. (C) The filter element is being slightly bypassed due to an improper seal and can be ignored until time is available for re-seating. (D) The filter element is severely - Correct Ans: โœ”โœ”D

  1. The turbocharged, four-stroke, diesel engines on your vessel are protected with dry-type air intake filters. The engines are fitted with dial-type restriction indicators measuring the pressure in the air duct between the air intake filter and the turbocharger blower inlet. Under what conditions should the air intake filters be evaluated using the restriction indicators? (A) The engine should be running at idle RPM with no load (propulsion clutch disengaged). (B) The engine should be running at rated RPM with no load (propulsion clutch disengaged). (C) The engine should be running at rated RPM with full load (propulsion clutch engaged). (D) The engine should be running at idle RPM with minimal load (propulsion clutch engaged). - Correct Ans: โœ”โœ”C
  1. An accumulator used in a hydraulic starting system is generally located between the __________. (A) pump and the compressor (B) storage tank and the pump (C) starting motor and the reserve tank (D) pump and the starting motor - Correct Ans: โœ”โœ”D
  2. Where is the air charge for an air starting system stored? (A) Air compressor (B) Pressurized tank (C) Distributor assembly (D) Cylinder check valve - Correct Ans: โœ”โœ”B
  3. The pilot valves in an air pilot starting system for a two-stroke cycle, direct reversing, main propulsion diesel engine are operated by either a ported distributor disc or a/an __________. (A) regulator valve

(A) Engine will stop (B) Starting motor will dangerously overspeed (C) Flywheel will be damaged (D) Combustion gases will enter the air starting system - Correct Ans: โœ”โœ”B

  1. Proper lubrication of the main bearings is more easily obtained in a single acting four-stroke cycle diesel engine than in a single acting two-stroke cycle diesel engine because __________. (A) bearing pressure in a four-stroke cycle single acting diesel engine is continually reversed (B) bearing pressure in a two-stroke cycle single acting diesel engine is continually reversed (C) the maximum bearing pressure is higher in a single acting two-stroke cycle diesel engine (D) two-stroke cycle diesel engines require more complicated lubrication piping - Correct Ans: โœ”โœ”A
  2. On most modern diesel engines, the main and connecting rod bearings receive their lubricating oil by __________.

(A) banjo feed (B) splash feed (C) gravity feed (D) pressure feed - Correct Ans: โœ”โœ”D

  1. The most crucial time for any bearing with regards to diesel engine lubrication is __________. (A) during periods of low load (B) during first warm up (C) during initial starting (D) after load reversals - Correct Ans: โœ”โœ”C of 37 Q531 Motor Plants I
  1. The device shown in the illustration is a __________. Illustration MO- 0008 (A) rotary type mist detector, designed for use in four-stroke, high-speed diesel engines (B) photoelectric, explosive gas indicator, for use in high-speed, two-stroke, trunk type piston engines (C) comparator type mist detector for large low-speed, crosshead type engines (D) level type explosimeter, for small medium-speed, trunk type piston engines - Correct Ans: โœ”โœ”C
  2. A "Blotter test" is a test performed on the lube oil of a diesel engine which can determine ______. (A) the specific gravity of the oil (B) the flash point of the oil (C) a change in the oils viscosity (D) the TBN number of the oil - Correct Ans: โœ”โœ”C
  3. Which of the following problems could develop due to the accumulation of oil vapors in the crankcase of a diesel engine?

(A) Reduced lubrication (B) Poor fuel economy (C) Combustion knock (D) Crankcase explosion - Correct Ans: โœ”โœ”D

  1. Which of the following effects will excessively cold lube oil have on the operation of a diesel engine? (A) The engine will crank slowly and may fail to start. (B) The engine will overspeed when started. (C) The fuel oil supply will become diluted resulting in rough running. (D) The cooling system will overheat causing the engine to stall. - Correct Ans: โœ”โœ”A
  2. Pre-combustion chambers and energy cells in high-speed, small bore diesel engines all serve to increase ________. (A) firing pressure (B) ignition quality of fuel (C) fuel/air ratio during compression (D) turbulence - Correct Ans: โœ”โœ”D