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WorksheetsMOTORES 13-14
Total questions: 51
Worksheet time: 26mins
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
formed by the piston in relation to the piston pin
between the crank arm and crankpin
between the master and link connecting rods
What type of reduction gear would most commonly be used with twin medium-speed propulsion diesel engines driving a single shaft?
Single reduction, planetary
Single reduction, single input
Single reduction, double input
Double reduction, double input, articulated
In order to keep excess oil from the intake ports in two-stroke/cycle diesel engines, __________.
wide compression rings are used
oil rings are located above the piston pin
dense chromium plating is used on all piston rings
oil rings are located near the bottom of the piston skirt
During which of the listed piston strokes of a four-stroke/cycle diesel engine, is the piston moving downward?
Intake stroke
Compression stroke
Exhaust stroke
Pumping stroke
Item "F" shown in the illustration is called a __________.
flow limiting device
relief valve
pressure reducer
sequencing valve
At bottom dead center, the centerline of the connecting rod usually coincides with the __________.
angularity of the piston motion
inertia moment from the piston
centerline of the cylinder
centerline of the king pin
The RPM of "A" is 150 and hobbed with 82 teeth. If gears "B", "C", and "D" have 62, 20, and 38 teeth respectively, the RPM of "D" in the gear train illustration is __________.
104.41 RPM
758.68 RPM
1003.42 RPM
78.95 RPM
In a diesel engine, pistons are attached to the crankshaft by __________.
push rods
piston rods
connecting rods
piston guides
Using a diesel engine indicator P-V diagram, the cylinder mean effective pressure is calculated to be 21.3 kg/cm2. What is the scale of the spring used on the indicator if the diagram area is 18.46 cm2 with a length of 13 cm?
1.5 kg/mm
5.0 kg/mm
10 kg/mm
15.0 kg/mm
Which of the following statements is true concerning pressure limit switches and pressuretrols installed on auxiliary boilers?
They are bimetallic elements sensing temperature differentials corresponding to pressure changes.
They consist of a bellows assembly, linked with a snap action switch, through a pressure adjusting mechanism.
They automatically relieve excessive steam pressure by acting as a pilot to the safety valve.
They automatically restart the burner sequence via the high water level signal.
The diesel engine component labeled "Z", shown in the illustration is called the __________.
inlet valve bridge
EGT monitor
exhaust valve bridge
scavenging air inlet
The power loss associated with slip in a fluid coupling appears as __________.
chattering in the driving member
heat in the hydraulic fluid
vibration in the driving member
leakage around the ring valve
Increasing the load on an engine equipped with a constant speed mechanical governor, will cause the engine speed to initially __________.
increase
decrease
fluctuate
remain constant
A modern centrifuge, similar to the device shown in the illustration, is opened for periodic cleaning. The most common cause of operating failure after reassembling, is due to __________.
low drive motor RPM
excessive back pressure in the bowl and fuel oil break over
the failure of the opening and closing water supply
not replacing the bowl O-rings that have taken a permanent set
The plunger in a jerk pump is rotated until the release port is uncovered. If the port remains uncovered all of the time, which of the listed operations will occur?
No fuel will be delivered.
The maximum effective stroke will be attained.
The fuel delivered to the cylinder will be excessive.
The injection nozzle will overheat and carbonize.
Helical reduction gears, as used with main propulsion drive trains, are constructed so that several teeth are meshed at the same time to __________.
eliminate propeller shaft end thrust
translate heavy load into high speed output
provide smooth continuous power transmission
allow construction with fewer gear teeth
A change in engine speed is required before a governor is able to make a corrective movement of fuel rack. This aspect of governing is commonly expressed as a percent and is known as __________.
governor sensitivity
governor promptness
speed droop
isochronous governing
The liquid line labeled "Q" on the device shown in the illustration is used to __________.
initiate the bowl opening procedure for the self-cleaning cycle
initiate the bowl closing procedure for the self-cleaning cycle
initially prime the bowl
directly position the oil emulsion interface throughout the operation of the centrifuge
If the control unit as shown in the illustration indicates alarm A01 'abnormal water content', the operator should suspect __________.
that the operating water tank is about to overflow
that the bowl is fouled and cleaning is necessary
an extremely high percentage of water in the fuel
faulty seals between the sliding bowl bottom and the paring disc assembly
What is the function of the main thrust bearing?
Prevents lateral movement of the slow speed gear.
Transmits propeller thrust to the hull.
Keeps spring bearings in line.
Prevents main reduction gear axial movement.
When would the available energy of the exhaust gases of a two-stroke/cycle diesel engine be insufficient to drive an exhaust gas turbocharger, resulting in the incorrect amount of air for combustion?
During operation at low load and speed
During operation at rated speed, but low power output
During acceleration
All of the above
What occurs in the space labeled "G" of the device shown in the illustration?
Jacket water is heated in the boiling chamber.
The feed water enters the device and vaporizes under vacuum conditions.
The feed water is cooled prior to being pumped into section "F".
Scale accumulates at position "E".
A diesel engine is driving an alternator required to run at 1800 RPM. The overspeed governor is normally required to be set within a range of __________.
1980 to 2070 RPM
2100 to 2200 RPM
2200 to 2300 RPM
2300 to 2400 RPM2300 to 2400 RPM
The best method for determining the amount of eccentricity or offset misalignment between the disconnected propeller shaft coupling flange and the reduction gear output flange is by using a __________.
straight edge laid across the flange edges
thickness gauge between the separated flange faces
bridge gauge to check the position of each flange in relation to the other
dial indicator mounted on one flange indicating any misalignment of the other flange
The diameter of a piston is usually less at the crown than at the skirt, in order to __________.
facilitate the installation of piston rings
allow for the expansion of the piston during operation
prevent crankcase vapors from entering the combustion chamber
reduce wearing of the upper cylinder liner
The submerged electrode low water cutoff used in some automatically fired auxiliary boilers, will secure the burner fuel supply if the boiler water level __________.
touches the bottom of the electrode
drops below the electrode tip
changes from low to high level
remains constant and unvarying
Proper atomization of fuel in diesel engine combustion chambers will __________.
affect the injection pressure
improve combustion
reduce compression pressure
decrease power output
In the Otto cycle, the fuel/air mixture is ignited at what point and by what means?
At TDC by heat generated by compression.
Just before TDC by heat generated by compression.
Just before TDC by spark ignition.
At TDC by spark ignition.
A device which functions to bring a diesel engine to a full stop to protect it from damage is known as a/an __________.
torque limiter
overspeed trip
overspeed governor
load limit governor
The RPM of "A" is 100 and has 80 teeth. If gears "B", "C", and "D" have 62, 20, and 38 teeth respectively, the RPM of "D" in the gear train illustration is __________.
67.91 RPM
652.63 RPM
505.79 RPM
52.63 RPM
Which of the listed devices could be used as a substitute for a ring groove cleaning tool when needed to remove hard carbon deposits from piston ring grooves in preparation for installing new rings?
Rotary steel brush
Fine emery cloth or steel wool
A section of the removed compression ring
A case hardened scraper
For the operation of the illustrated device, what fluid flow would be expected at the connection labeled "I"?
The salt water feed.
The distillate discharge.
The sea water used for condensing the water vapor.
Main engine jacket water.
In order for the self-cleaning fuel oil centrifuge, shown in the illustration, to properly operate during the desludge cycles, the __________.
bowl locking ring alignment mark should be approximately 1/4 inch to the left of the bowl alignment mark
sliding bowl bottom and operating slide seal rings should be coated with main engine lube oil
sliding bowl bottom and operating slide seal rings should be coated with a high temperature lubricating paste
all of the above
The purpose of an interference angle in a diesel engine exhaust valve is to __________.
I. work in conjunction with valve rotators to rotate the valve
II. break up seat deposits
I only
II only
both I and II
neither I nor II
If the speed of a turbocharged diesel engine is maintained constant the turbocharger speed will __________.
decrease until the engine speed increases
increase as the load increases
decrease as the load increases
remain unchanged as the load decreases
Regarding the water level electrode assembly shown in the illustration, arrow "C" indicates the point at which the __________.
feed pump starts
feed pump stops
fuel oil solenoid is de-energized
normal water level is established
The leveling plates in a Kingsbury thrust bearing are held in position by __________.
lock wires
buttons or pivots
dowels and pins
pivoted segments
Which of the following procedures decreases the total dissolved solids concentration in the water of an auxiliary boiler?
Hydrazine treatment of condensate
Frequent compounding
Chemical cleaning
Bottom blowing
A 'low pressure in oil outlet' alarm indication, as shown in the illustration, may be caused by __________.
the proper setting of valve V4
insufficient heating of the processed liquid
the three-way valve (V1) not opening
insignificant accumulations of sludge within the bowl assembly
Sacrificial zinc anodes are used on the saltwater side of diesel engine heat exchangers to __________.
reduce electrolytic action on heat exchanger metals
keep heat transfer surfaces shiny and clean
prevent rapid accumulation of marine growth
provide a protective coating on heat exchanger surfaces
If the combustion control system of an automatically fired auxiliary boiler fails to restart from the normal shutdown mode, you should check for __________.
broken or grounded high tension leads
a faulty ignition cable connector
an incorrect electrode setting
all of the above
A schematic diagram of an isochronous hydraulic governor is shown in the illustration. When the load is removed the speed increases, and the __________.
pilot valve (piece #10) moves upward
proportioner piston (piece #25) moves upward
flyweights (piece #8 and #9) move inward and the pilot valve (piece #10) moves downward
balance piston (piece #22) moves downward
An AC diesel generator incapable of being paralleled with the main bus normally employs an isochronous governor in order to __________.
increase speed droop in proportion to load
maintain a frequency of 60 cycles per second
increase or decrease engine speed upon load demand
prevent attempts to parallel
The port labeled "H" of the device shown in the illustration, is used to __________.
prevent water from accumulating beneath the operating slide
provide water flow for closing the bowl at the end of the desludging cycle
bleed off the opening water to permit the closing sequence of the bowl at the end of the desludging cycle
directly discharge accumulated sludge from the bowl
As shown in the illustration, which of the following conditions may be the cause for the 'low pressure in oil outlet' alarm to be illuminated?
Vibration switch activated.
Faulty water solenoid valve.
Throughput too high.+-
All of the above are correct.
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?
1200 feet/minute
1260 feet/minute
1320 feet/minute
1380 feet/minute
The RPM of "A" is 150 and hobbed with 94 teeth. If gears "B", "C", and "D" have 80, 30, and 46 teeth respectively, the RPM of "D" in the gear train illustration is __________.
114.95 RPM
817.39 RPM
695.65 RPM
97.83 RPM
The schematic diagram of an isochronous hydraulic governor is shown in the illustration. If there is an increase in applied load, the speed will decrease, and the __________.
flyweights (piece #8 and #9) move outward and the pilot valve (piece #10) moves upward
balance piston (piece #22) moves upward
proportioner piston (piece #25) moves downward
pilot valve (piece #10) moves downward
A loop or cross scavenged engine utilizes the motion of its pistons and a turbocharger to provide scavenging air. Which of the listed mechanical designs prevents the air under the pistons from being pumped back through the scavenge ports during the piston power stroke?
Masked intake ports
Length of the piston skirt
Positive pressure from the blower
Lower liner seals
Which of the following statements is accurate concerning the vibration sensing device used with the separator shown in the illustration?
Vibration sensors are not used with centrifuges currently installed on diesel vessels due to excessive vibrations developed by the main propulsion units.
The vibration switch is sensitive to vibration in a direction horizontal to its mounting base and is normally installed low on the separator where movement is magnified.
The detector mechanism consists of an armature suspended on a flexure pivot and restrained from motion by a permanent magnet acting through a small air gap.
The detector is so arranged to prevent abnormal harmonic frequencies from being developed while the separator is passing through its critical speed range.
An improperly assembled centrifuge, of the type shown in the illustration, may result in which of the following operating conditions to occur?
Excessive wear of fuel injection equipment.
Increased main bearing wear.
Severe injury to engine room personnel.
All of the above.
