Motor questions & answers

A labyrinth seal fitted on the back surface of a compressor wheel of a turbocharger:
A. Prevents bearing lube oil contamination B. Prevents bearing lube oil being sucked into the air stream C. Helps to keep the shaft cool by controlled leakage of air D. None of the above
In the latest concept of Variable Geometry Turbocharging , ______________ angle can be varied to match the turbocharger at varying engine loads
A. Compressor vane B. Turbine blade C. Nozzle ring blade D. Diffuser ring blade
The primary function of a flame safeguard system, as used on an automatically fired auxiliary boiler, is to prevent
A. accidental dry firing and overpressure B. uncontrolled fires in the furnace C. explosions in the boiler furnace D. explosions in the boiler furnace
Directional intake ports in diesel engines are used to
A. reduce air charge turbulence B. induce air swirl C. deflect hot combustion gas away from the valves D. oppose the effects of piston induced squish
Why does a chain stretch in service ?
A. Due to plastic elongation B. Due to high temperature expansion C. Due to wear on rollers and bushes D. Due to the phenomenon of creep
Which of the following methods is normally used to lubricate bearings in a small high-speed diesel engine?
A. Splash lubrication B. Pressure lubrication C. Sight feed lubricators D. Mechanical lubricators
External fouling of boiler tubes can lead to :
A. Greater steam generation B. Tube corrosion C. Tube Erosion D. Protection of tube against corrosion
What is the purpose of the inlet grid provided within the exhaust gas casing in the gas flow path ,prior entry to turbocharger ?
A. To filter out any unburnt carbon B. To absorb and dampen the pressure fluctuation C. To reduce noise in the constant pressure exhaust piping D. To prevent any broken piston rings finding their way to turbine
The main function of tie rods in the construction of large, low speed diesel engines is to
A. stiffen the bedplate in way of the main bearings to increase the engine's longitudinal strength B. accept most of the tensile loading that results from the firing forces developed during operation C. mount the engine frame securely to the hull to prevent shaft coupling misalignment D. connect the crosshead solidly to the piston rod
10 The fall in speed that occurs in a diesel engine equipped with governor, on increase of load is called:
A. Offset B. Speed drop C. Speed droop D. Speed offset
Which of the following factors governs the lower limit of thrust bearing clearance ?
A. To allow some oil leakage to prevent overheating B. Reduction of oil viscosity C. Alignment of crankshaft D. To allow the thrust pads to tilt and generate the oil wedge
Which of the following can result in cracking of piston crown?
A. Deposits in cooling spaces B. Impingement of fuel due to faulty injection C. Insufficient piston cooling oil flow D. All of the above
The boiler water alkalinity in a coil-type auxiliary boiler should be maintained at the pH recommended by the boiler manufacturer to
A. precipitate silica from solution B. reduce corrosion in the heating coil C. prevent clogging and erosion in the coil D. maintain zero water hardness
What does the NLGI number of a grease indicate?
A. The oxidation resistance of the grease B. The consistency of the grease i.e how fluid or non fluid C. Demulsibility of the grease D. The shelf life of the grease
Which of the following layers of a thin shell bearing gives it its fatigue strength?
A. The overlay B. The interlay C. The backing D. The barrier layer
Which of the bearings listed is most widely used for main and connecting rod bearings of modern diesel engines?
A. Steel-lined B. Poured babbitt, self-aligning C. Split roller D. Precision insert
Which of the following statements is false ?
A. The fuel oil sulfur level is one of the important criteria for choice of TBN level of cylinder oil. B. The use of anti-polishing rings or flame rings increases the consumption of cylinder oil C. Excessive cylinder oil feed can lead to harmful deposits in piston top land area D. None of the above
When preparing to light off a cold boiler equipped with a return flow fuel oil system, the recirculating valve directs the flow of oil
A. directly to the fuel oil heater inlet for further warm-up B. back to the fuel oil settler for further filtration C. back to the suction side of the service pump D. directly to the deep tanks
Prompt correction of speed of diesel engines driving alternators, without having massive fluctuations is ensured by incorporating:
A. Load limiting devices B. Load sharing devices C. Load sensing devices D. Load shedding devices
n a uniflow scavenged marine 2-stroke diesel engine, the scavenge ports in a cylinder liner are machined:
A. Only for a part of the circumference, at an angle almost tangential to the circumference of the liner B. All around the circumference at right angles to the circumference of the liner C. only for a part of the circumference, at right angles to the circumference of the liner D. All around the circumference at an angle almost tangential to the circumference of the liner
If the tappet clearance between the rocker arm tappet and exhaust valve stem is excessive then:
A. The valve will open early and close later B. The valve will open later and close early C. The valve will open and close later D. The valve will open and close early
In order to reduce thermal loading on the upper part of the liner and increase the effectiveness of cylinder lubrication, modern 2-stroke marine diesel engines are designed to have:
A. Cermet coated piston rings, bore cooled liners and uniflow scavenging B. High top land of piston crown and deeper cylinder cover with top land of crown extending into cylinder cover at TDC C. Low top land of the piston crown with bore cooled cylinder liner D. Bore cooled cylinder liner and bore cooled piston crown with toroidal shape combustion chamber
Which of the following conditions can lead to reduced power developed by a main engine?
A. High scavenge air temperature B. Choked air suction filter of a turbocharger C. Blow past in one or more units D. All of the above.
If the boiler tubes are scaled on the water side then :-
A. Heat conduction through the tubes will be very high leading to rapid evaporation B. The boiler furnace can get damaged due to excessive temperatures C. The surface of the tube will be overheated as heat transfer is impaired D. The natural circulation of water within the boiler will be more efficient
Which of the following types of diagrams would give an indication of effectiveness of exhaust and scavenge processes?
A. Power card B. Draw card C. Light spring diagram D. All of the above.
he arrangement used to protect overheating of the superheaters under fluctuating loads is called :
A. De-superheater B. Attemperator C. Steam dumping valve D. Feed heater
Piston rod stuffing box scraper rings butt clearances should:
A. Not be allowed to fall below 50% of original clearance B. Not be allowed to increase above 50% of original clearance C. Not be allowed to fall below manufacturer recommended value D. Not be allowed to increase above manufacturer recommended value
In a 2-stroke engine a ________________ separates the underpiston space from the crankcase.
A. A-frame B. Crosshead C. Diaphragm D. Scavenge space
Fusible plugs are installed in fire-tube boilers to
A. provide a means of draining the boiler B. warn the engineer of low water level C. cool the crown sheet at high firing rates D. open the burners' electrical firing circuits
The purpose of an air cooler in a supercharging system is to :
A. Reduce temperature of supercharged air in order to condense and remove maximum possible moisture from the air prior entry to the engine B. Reduce the temperature of the supercharged air in order to increase the density & also to cool down below dew point to remove moisture from air prior entry to the engine C. Cool supercharged air to increase its density such that the dew point is not reached to avoid entry of moisture into the engine D. Cool supercharged air to increase it???s density and also to keep the peak temperature and exhaust gas temperature within limits
Which of the following gauges are generally used to evaluate main bearing clearances?
A. Poker gauge B. Feeler gauge C. Telescopic feeler gauge D. Dial gauge
In a coil-type auxiliary water-tube circulation boiler
A. Unevaporated feedwater collects in the bottom of the flash chamber B. all generated steam is recirculated through heating coils in the boiler C. heated water flashes to steam in the boiler heating coils D. response to steam demand is slower than in a fire-tube boiler
For a continuous operation diesel engine, a duplex filter unit would be the best arrangement because
A. changing filter elements would not interrupt engine operation B. filtering occurs twice in each pass of oil through the system C. clogging will not occur D. dropping pressure is half of that through a single filter unit
Mark: 2
As per regulations, within how many hours before each departure, satisfactory working of the steering gear must be checked?
A. 2 B. 12 C. 24 D. None of the above
Modern 4-stroke medium speed, marine diesel engine exhaust valve spindles are rotated by providing
A. Nozzle rings B. Tappet clearance C. Spinners or vanes D. Rotocaps
It is a known fact that centrifugal pumps require priming for pumping liquids , as they cannot handle air and will lose suction due to air entry . But on the other hand T/Cs use centrifugal compressors for supercharging . Which of the following do you think makes a centrifugal compressors to pump air and behave differently than the centrifugal pumps?
A. Presence of air cooler B. Presence of Labyrinth seal C. High speed of rotation , very fine internal clearences and large impeller diameters D. Difference in principle of operation
The purpose of economiser is to:
A. Decrease the capacity and size of the auxiliary boiler B. Cooling down the exhaust gases in order to reduce NOx emission C. Allowing Sox to react at low temperatures with water to form acids thus reducing Sox emission D. Increasing the overall efficiency of the main propulsion plant
Microbiological growths in marine fuel are a common occurrence that can be
A. extremely detrimental to equipment and operating processes B. prevented by maintaining proper storage temperatures C. removed from emulsified fuel oil during the centrifuging processes D. All of the above .
The function of the tie rods is to:
A. Keep the engine components under tension at all the times B. Just secure the engine parts together C. Act as holding down bolts for the bedplate and keeps all the engine components together D. Keep engine components under high compression, so that tensile stresses acting during firing stroke do not exceed this pre-compression to avoid fatigue failure
Which of the following types of crankshafts is much lighter at similar power requirements?
A. Fully built type B. Semi built, all welded type C. Semi built type D. Solid forged type
After an engine has been started using a Bendix drive unit,the drive gear, or pinion disengages from the flywheel dueto
A. the action of a spring B. rotation of the starting cam C. the higher rotating speed of the flywheel D. accumulator pressure
Fuels as produced in a refinery are generally sterile, however, contamination can occur as fuels are
A. stored at the refinery B. stored on the vessel C. transported to the distribution sites D. All of the above are correct.
Which of the following statements is false?
A. Excessive cylinder liner lubrication can aggravate scuffing. B. Use of anti polishing ring reduces scuffing. C. Deep honing of liner fails to give an ideal liner surface. D. None of the above
In a fully built or semi built type crankshaft, how can any slippage at shrink fit be identified?
A. By inspecting the locking arrangement provided B. By checking the dowel provided. C. By checking the witness mark provided for reference . D. By checking the performance of the engine
Which of the following is one of the major advantages of resin choking over cast iron choking, in holding down arrangements of modern diesel engines?
A. Better vibration damping properties. B. Better compressive strength C. 100% contact, no need for surface preparation D. None of the above
In a 2-stroke crosshead type of engine, the side thurst generated due to rolling and connecting rod and fore-aft thrust due to pitching motion of the ship is taken care of by the:
A. Piston and the liner B. Connecting rod and the piston rod C. Crosshead shoes and guides D. Crankpin and thrust bearing
In a VIT equipped jerk type fuel pump:
A. Raising the barrel delays beginning of injection B. Lowering the barrel delays beginning of injection C. Raising the barrel delays end of injection D. Lowering the barrel delays end of injection
The overspeeding of the diesel engine driving an electric generator could cause
A. low voltage trip to trip B. reverse power trip to trip C. damage to windings D. excessive exhaust temperatures
In a large, slow-speed, main propulsion diesel engine, which of the parts listed is under tension when the engine is running?
A. Bed plate B. Column C. Entablature D. Tie rod
Use of Halon as fire extinguishing medium has been discontinued because________________
A. It is highly toxic B. It is expensive C. It has high Ozone depleting potential D. It leads to acid rains