Diesel Engines Flashcards
Which of the listed design features is most common with a two-stroke cycle, low- speed main propulsion diesel engine?
piston rod and crosshead construction
In a large, slow-speed, main propulsion diesel engine, which of the parts listed is under tension when the engine is running?
tie rod
A diesel engine crankcase ventilation system __________.
removes combustible gases
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 __________ .
crush
If the chemical analysis of a lube oil sample taken from the main propulsion machinery indicates an increased neutralization number the __________ .
acidity has increased
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
B precision insert
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
D all of the above
While underway, which of the following would be the FIRST step in reversing a direct reversing large, slow-speed, main propulsion, diesel engine?
set the fuel rack to zero.
In a four-stroke/cycle diesel engine, the camshaft rotates at __________.
half the crankshaft speed
The highest pressure in a diesel engine cylinder normally occurs __________.
AFTER TDC
The linear motion of a diesel engine piston is converted into the rotary motion required to drive gears, propeller shafts, and generators by the __________.
crankshaft
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
C piston pin bushing
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
D admission of reversing start air
One method of determining crankshaft misalignment is by __________.
taking micrometer readings between the webs
The main reason counterweights are added to crankshafts is to __________ .
provide uniform loading and wear of main bearings
In a diesel engine, the main bearings are used between the __________.
crankshaft and the engine block
Which instrument is used to take crankshaft deflection readings?
dial type inside micrometer
In diesel engines designed with a crosshead, the motion of the piston rod can be described as __________.
straight reciprocation
In a large slow-speed propulsion diesel engine, the side thrust on the crosshead is the direct result of _____.
the angularity of the connecting rod against the crosshead during the power stroke
The bearings used to support the crankshaft of a diesel engine are generally called __________ .
main bearings
Integral cylinder liners constructed as part of the cylinder block, are characterized by which of the following disadvantages?
They cannot be replaced.
In large, low-speed, main propulsion diesel engines, piston ring groove wear usually occurs at the __________ .
bottom of the ring groove
Which of the listed bearing installations is subjected to swinging motion? A Crankshaft journal B Crankpin bearings C Wrist pin bearings D Thrust bearings
C Wrist pin bearings
A safety crankcase cover differs from other diesel engine access doors in that it is fitted with a __________.
spring-loaded pressure plate
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 __________.
leaky fuel injector
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
C Wrist pin bearing
Crank web deflection readings will give a positive indication of __________.
worn main bearing journals
Vibrations from diesel engines and engine driven equipment are isolated from the hull structure by __________ .
flexible engine mountings
The most practical way of detecting an overload in one cylinder of an operating large, low-speed, main propulsion diesel engine is to __________.
Check the cylinder exhaust temperature frequently
Bearing ‘crush’ as applied to diesel engine main bearings, will result in __________ .
positive seating of the bearings in their housings
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 __________.
crankshaft speed in a two-stroke cycle diesel engine
At bottom dead center, the center-line of the connecting rod usually coincides with the __________ .
center-line of the cylinder
An indication of an overloaded main propulsion diesel engine is __________ .
high exhaust gas pyrometer readings
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 __________ .
crush
In a modern internal combustion diesel engine, the load carrying part of the engine is referred to as the __________ .
bedplate or base
A main propulsion diesel engine crankshaft bearing lacking sufficient ‘crush’, will __________.
tend to rotate with the journal
What is the speed of the crankshaft in a four-stroke/cycle engine when the camshaft is turning at 750 rpm?
1500 RPM
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.
B Critical speed.
In an opposed piston engine, the term ‘crank lead’ refers to __________.
the piston in one cylinder reaching inner dead center several crankshaft degrees before the other piston
If a diesel engine were running at 20% overload with a smoky exhaust, you should __________.
Slow the engine allowing it to gradually cool
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
A Semi-floating
The flywheel reduces speed fluctuations by __________ .
Storing kinetic energy
The insertion of shims between the foot of a marine type connecting rod and a bearing box would result in __________.
Increased compression ratio
Many cast iron pistons are designed with heat dams, which serve to __________ .
reduce the possibility of overheating the top compression ring
The diameter of a piston is usually less at the crown than at the skirt, in order to __________ .
allow for the expansion of the piston during operation
Oil control rings are designed with slotted holes to __________.
permit excess oil to drain back to the sump
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
D all of the above
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.
A Machining a special ring face groove filled with anti-friction metal.
Diesel engine piston ring gaps can be straight or angle cut. In comparison, the angle cut ring __________ .
decreases combustion gas leakage
One of the most common methods in preventing a diesel engine piston pin from contacting the cylinder wall is by the use of __________ .
snap rings
The main reason for using bimetallic piston rings is to __________.
reduce the probability of ring fracture
During the power stroke, the side thrust of a trunk type piston is a result of the angle __________.
formed by the connecting rod and the cylinder center-line
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 __________ .
piston skirt
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
D all of the above
A piston is at bottom dead center when it is __________ .
farthest from the cylinder head
To reduce the weight of the reciprocating parts, pistons of high-speed engines are made considerably shorter. This results in __________ .
greater piston wear
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
B compression load during power and compression strokes
In diesel engines, hydraulic valve lifters are used to __________.
reduce valve gear pounding
What is the purpose of a hydraulic valve lash adjuster?
compensates for the expansion and contraction of the valve stem due to changes in operating temperature.
Valve lash, or clearance refers to the __________ .
clearance between the top of the valve stem and the rocker arm
During engine warm-up, the expansion of cylinder head valve stems due to the buildup of engine heat, is compensated for by the __________ .
valve lash clearance
The intake and exhaust valves used in a diesel engine are returned to their seats by __________ .
spring force
The cylinder liner forming the cylinder wall and the inside of the water jacket is called a __________ .
wet liner
