Gastos e Ingresos extraordinarios Desglosados
6. CONCLUSIONES
1299 Where one or more diesel driven AC generators are operating in parallel, reducing the value of the speed droop to "zero" on one unit will allow that unit to ____________.
1300 Which of the following adjustments is always required whenever the diesel engine governor oil has been drained and renewed?
A. gradually reduce its speed as load is applied A. Speed droop
B. change load without changing speed B. Compensation
C. automatically divide and balance the loads C. Idle speed setting D. effectively anticipate the amount of fuel necessary to bring the
engine up to the proper output to accept the increased load
D. Load limit control
Ans: B Ans: B
1301 If the compensating needle valve of a hydraulic governor is opened more than necessary the governor will _____________.
1302 If the load on a diesel engine equipped with an isochronous hydraulic governor is increased, after compensation is performed by the governor, the engine speed will __________.
A. have a larger than normal dead band A. remain the same
B. produce excessive speed response to a load change B. increase
C. respond slowly to any change in engine load C. decrease
D. stabilize engine speed at the new governor setting D. fluctuate
Ans: B Ans: A
1303 Trapped air was bled from the hydraulic system of a diesel engine governor while it had been operating at idle speed. Oil was added to restore the correct level and the air vent plug tightened. The compensating needle valve should then be gradually ______
1304 If a hydraulic governor has been refilled with oil, the engine should be operated until it reaches normal temperature, then the air should be purged, and the _______.
A. opened until hunting is eliminated A. rack position should be adjusted
B. closed until it is approximately 1/16 of a turn open B. compensating needle valve should be opened fully C. closed to cause the engine to hunt in order to purge trapped air
from the new oil
C. compensating needle valve should be adjusted to stabilize operation
D. closed until engine hunting is eliminated D. speed limiting device should be adjusted
Ans: D Ans: C
1305 Friction developing between the moving parts of a governor, governor linkage and control valve will cause the governor to _________.
1306 If the operating speed of a diesel engine increases without an apparent change in the engine control settings, you may suspect a ________.
A. react with insufficient speed droop A. clogged intake air intercooler
B. fail to react to small speed changes B. control air leak
C. have excessive sensitivity to small speed changes C. leaking air starting valve
D. remain in the neutral position D. malfunctioning governor
Ans: B Ans: D
1307 The major cause of trouble in a mechanical-hydraulic governor is contamination of the hydraulic fluid by _____________.
1308 Adjustments to the compensating needle valve in a hydraulic governor should be made with the engine at _____________.
A. dirt A. maximum power at a normal load
B. fuel oil B. maximum power and load under normal conditions
C. governor cooling water C. half speed and normal temperature
D. fuel oil tars D. normal operating temperature without a load
Ans: A Ans: D
1309 On a diesel engine equipped with a hydraulic speed control governor, hunting in many cases can be corrected by adjusting the _____________.
1310 A diesel generator governor is hunting. After changing the oil the governor is flushed and the compensation needle valve is adjusted; but the hunting persists. You should NOW _____________.
A. accumulator spring compression A. check air intake manifold pressure
B. balance piston B. calibrate the fuel pump rack settings
C. compensating needle valve C. set the speed droop adjustment to zero
D. proportional piston D. carefully check for binding in the governor linkage
Ans: C Ans: D
1311 Compensating needle valve adjustments to a hydraulic governor should be made with the engine _____________.
1312 If a main propulsion diesel engine hunts excessively at idle speed, you should ____________.
A. running at normal operating temperature without load A. adjust the idle speed control
B. running at half speed and at normal temperature B. drain and flush the governor and replace the oil C. running at maximum power and load under normal conditions C. adjust the compensating needle valve D. developing maximum power at normal load D. adjust the load limit
Ans: A Ans: C
1313 Which of the following methods is normally used to lubricate bearings in a small high-speed diesel engine?
1314 Clearance volume scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished ___________.
A. Spclearance lubrication A. during the valve overlap period
B. Pressure lubrication B. with only the exhaust valve open
C. Sight feed lubricators C. at a pressure below atmospheric
D. Mechanical lubricators D. without cooling the cylinders or pistons
Ans: B Ans: A
1315 Trunk-type diesel engine pistons are most effectively cooled by heat _____________.
1316 The reversing cams of some four-stroke/cycle diesel engines are brought into position by ____________.
A. conducted through the engine block A. sliding the camshaft along its axis
B. conducted to water cooled cylinder walls B. rotating the cam 180°
C. conducted through the piston crown C. rotating the cam followers 180°
D. losses to escaping exhaust gases D. moving the idler sprockets in the drive chain FOUR STROKE ENGINES - DESIGN,COMPONENTS AND OPERATION
Ans: B Ans: A 1317 Which of the following conditions can cause above normal air
temperature to develop in the intake manifold of a four-stroke/cycle, turbocharged, diesel engine?
1318 How much will the jacket water temperature normallyincrease between the inlet and outlet of medium orhigh-speed diesel engines?
A. Clogged air intake filters A. 1° to 3°C
B. Piston blow-by B. 3° to 5°C
C. A defective aftercooler C. 5° to 10°C
D. Faulty exhaust valves D. 15° to 25°C
Ans: C Ans: C
1319 Trunk type diesel engine pistons are effectively cooled when heat is ____________.
1320 Ring groove inserts are occasionally used on aluminum alloy pistons to ____________.
A. radiated through the engine block A. reduce the ring groove wear rate
B. transferred to water cooled cylinder walls B. seal against crankcase vapors
C. conducted through the piston crown C. lessen the wear on aluminum parts of the cylinder D. transferred to escaping exhaust gases D. allow for the greater expansion rate of aluminum
Ans: B Ans: A
1321 Broken intake valve springs on one cylinder of a diesel engine can cause the engine to _____________.
1322 Excessive lube oil consumption in a diesel engine can be caused by _____________.
A. overspeed A. late combustion
B. fire improperly B. plugged oil wiper rings
C. lose oil pressure C. low lube oil temperature
D. overheat rapidly D. low lube oil pressure
Ans: B Ans: B
1323 When the cold tappet clearance is less than that specified by the engine manufacturer, the diesel engine valves will _____________.
1324 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 _____________.
A. open earlier than normal A. piston skirt
B. close earlier than normal B. pinion
C. remain open for a shorter duration C. crosshead
D. fail to open when the valves are warm D. compression rings
Ans: A Ans: A
1325 Excessive lube oil consumption can result from worn or broken _____________.
1326 Excessive piston ring wear in a diesel engine will cause _____________.
A. piston rings A. high lube oil viscosity
B. valve guides B. increased lube oil consumption
C. valve seals C. low lube oil temperatures
D. all of the above D. high firing pressures
Ans: D Ans: B
1327 Excessive lubricating oil consumption in a running diesel engine can be caused by _____________.
1328 In a four-stroke/cycle diesel engine, badly worn intake valve guides can cause excessive ____________.
A. clogged lube oil piping A. exhaust pressure
B. excessive valve-guide clearance B. exhaust temperatures
C. high lube oil viscosity C. cooling water temperatures
D. low lube oil temperature D. lube oil consumption
Ans: B Ans: D
1329 The camshaft on a four-stroke/cycle diesel engine is used to operate the _____________.
1330 A diesel engine valve spring is under compression when thevalve is _________. I. open II. closed
A. fuel injectors A. I only
B. exhaust valves B. II only
C. intake valves C. both I and II
D. all of the above D. neither I nor II
Ans: D Ans: C
1331 The force exerted by a valve spring to close the diesel engine valves, is proportional to _____________.
1332 Exhaust pipes for separate diesel engines can be combined only when _____________.
A. spring compression A. space limitations prevent separately run pipes
B. engine speed B. the engines are small auxiliary units
C. the natural frequency of vibration C. they are arranged to prevent gas backflow to each engine
D. spring surge D. a waste heat boiler is installed
Ans: A Ans: C
1333 Spring surge in diesel engine valve springs can result in _____________.
1334 The satisfactory operation of diesel engine exhaust valves usually depends on ______________.
A. increasing effective spring force A. the proper back pressure
B. bouncing of the valve gear B. the cooling water temperature
C. splitting of the valve keeper collars C. correct timing and proper seating
D. failure of the valve to open D. accurate metering and the exhaust temperature
Ans: B Ans: C
1335 The angular distance a flywheel rotates between the firing of the cylinders of a V-16, four-stroke/cycle diesel engine is _____________.
1336 On a medium-speed main propulsion diesel engine, the crankpin or crank journal bearings receive lubricating oil from _____________.
A. 22.50‚ A. a spindle lubricator
B. 33.75‚ B. an oil jet
C. 45.00‚ C. internal spclearanceing
D. 90.00‚ D. drilled passages in the crankshaft
Ans: C Ans: D
1337 In comparison to exhaust valves, intake valves of diesel engines may be fabricated from low-alloy steels because _____________.
1338 Multiple concentric valve springs are often used with diesel engine valves to ____________.
A. the beveled edges of the intake valves provide for self-centering during seating
A. enable research and development of cam contour to be simplified
B. intake valves utilize stellite-coated valve seat inserts which reduce wear
B. operate the valve gear where a larger force is normally required, but space limitations restrict the use of a single large spring
C. the volume of air passing through intake valves is less than the volume of air passing through exhaust valves
C. allow for easier valve replacement
D. intake valves are less affected to the corrosive action of exhaust gases
D. enable a total smaller valve spring force to keep the valve tight on its seat
Ans: D Ans: B
1339 Before shutting off the fuel supply to stop a medium or high-speed diesel engine, why is it necessary to allow the engine to idle for a few minutes?
1340 Cooling water pumps driven by direct reversing diesel engines are usually of the straight impeller vane type pump with a concentric housing to ____________.
A. To let the waste heat boiler reduce it's rate of steam generation. A. provide cooling water flow when the engine is running either ahead or astern
B. To ensure the fuel nozzles are flushed clean. B. provide the greatest pump efficiency
C. To clear the smoke stack. C. prevent pump clogging from marine growth
D. To prevent internal damage from local overheating. D. prevent cavitation at the pump outlet
Ans: D Ans: A
1341 In a four-stroke/cycle diesel engine, the camshaft rotates at _____________.
1342 Fuel oil begins injection into the cylinder of a four-stroke/cycle diesel engine during the _____________.
A. twice the crankshaft speed A. intake stroke
B. half the crankshaft speed B. exhaust stroke
C. the same speed as the crankshaft C. power stroke
D. a speed independent of the crankshaft D. compression stroke
Ans: B Ans: D
1343 A piston in a four-stroke/cycle diesel engine makes four strokes during each __________.
1344 What is the speed of the crankshaft in a four-stroke/cycle engine when the camshaft is turning at 750 rpm?
A. crankshaft revolution A. 375 RPM
B. mechanical cycle of operation B. 500 RPM
C. period of two combustion cycles C. 750 RPM
D. cycle of two events D. 1500 RPM
Ans: B Ans: D
1345 Regarding jerk-type fuel pumps as used on some auxiliary diesel engines, the delivery cutoff point is controlled with a
_____________.
1346 What is the crank angle between any two crank throws in the firing order of a four-stroke/cycle, in line, eight cylinder diesel engine?
A. delivery valve spring A. 45°
B. spill port for leakoff B. 60°
C. check valve in the guide C. 90°
D. helical groove on the plunger D. 100°
Ans: D Ans: C
1347 The firing order of an in-line, four-stroke/cycle, six cylinder, auxiliary diesel engine is 1-5-3-6-2-4. When the #1 cylinder is firing at top dead center, the #3 piston is ____________.
1348 Precombustion chambers, air cells, and energy cells in high- speed, small bore diesel engines all serve to increase _____________.
A. on the intake stroke A. firing pressure
B. on top dead center B. ignition quality of fuel
C. on the power stroke C. fuel/air ratio during compression
D. at bottom dead center D. turbulence
Ans: A Ans: D
1349 Which of the following statements represents the advantage of a precombustion chamber used in an auxiliary diesel engine?
1350 In a full floating gudgeonpin, the pin is prevented from sliding against the cylinder walls by _____________.
A. Timing of injection does not need to be exact. A. snap rings
B. Turbulence is eliminated. B. seal welding
C. Lower mean effective pressures are developed. C. a press fitting D. Excellent control of combustion can be attained. D. a tongue-and-groove
Ans: A Ans: A
1351 The exhaust valve opens before bottom dead center in a four stroke engine to___________. I. allow for blow down II. reduce pumping losses
1352 A V-12 four-stroke/cycle 500 horsepower diesel engine is operating under a normal load, the firing pressures are low and the exhaust temperatures are high. Which of the following problems is the most probable cause of this condition?
A. I only A. Fuel pump rack setting is too far out.
B. II only B. The air intake filter is missing.
C. both I and II C. The exhaust back pressure is too high.
D. neither I nor II D. The fuel pump rack setting is too far in.
Ans: C Ans: C
1353 In order to keep excess oil from the intake ports in two-stroke/cycle diesel engines, ______________.
1354 One advantage obtained from the use of a precombustion chamber in a diesel engine is _____________.
A. wide compression rings are used A. increased engine thermal efficiency
B. oil rings are located above the piston pin B. higher peak cylinder pressures C. dense chromium plating is used on all piston rings C. higher developed BMEP D. oil rings are located near the bottom of the piston skirt D. smoother combustion
Ans: D Ans: D 1355 The use of push rods are necessary in a diesel engine when
_____________.
1356 When attempting to restart a warm high-speed engine, which of the following reactions can you expect?
A. the camshaft is located some distance below the rocker arms A. Excessive fuel use
B. the rocker arms are pivoted near their centers B. Higher than normal temperatures for start up C. two or more valves must be opened and closed at the same time C. Longer starting periods
D. hydraulic tappet clearance adjusters are used D. Higher than normal lube oil pressure
Ans: A Ans: B
1357 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 ____________.
1358 Cams used to activate mechanically operated air starting valves on four-stroke/cycle diesel engines should have which of the valve lift profiles listed?
A. bearing pressure in a four-stroke/cycle single acting diesel engine is continually reversed
A. Abrupt lift with a short open period, and abrupt valve seating.
B. bearing pressure in a two-stroke/cycle single acting diesel engine is continually reversed
B. Gradual lift with a short fully open period, and accelerated valve closing.
C. the maximum bearing pressure is higher in a single acting two-stroke/cycle diesel engine
C. Abrupt lift giving full valve opening for a long period, with gradual valve seating.
D. two-stroke/cycle diesel enginesrequire more complicated lubrication piping
D. Gradual lift giving full valve opening for a long period, with gradual valve seating.
Ans: A Ans: C
1359 In a diesel engine, with the valves set to specification, the shape of the cam determines the valve _____________.
1360 Which type of gudgeon pin uses bearings in the piston bosses, but is fixed to the small end of the connecting rod?
A. point of opening A. Semi-floating
B. speed of opening B. Full floating
C. lift from its seat C. Solid
D. all of the above D. Fixed
Ans: D Ans: A
1361 A turbocharged, four-stroke/cycle diesel engine has a larger valve overlap than a naturally aspirated, four-stroke/cycle diesel engine in order to increase the _____________.
1362 To reduce the weight of the reciprocating parts, pistons of high-speed engines are made considerably shorter. This results in _____________.
A. temperature of the exhaust gases A. less piston slap and quieter running
B. energy supplied to the turbocharger B. increased crankshaft bearing wear
C. air pressure to the intake manifold C. slightly greater piston wear
D. cooling effect on the exhaust valves D. decreased side pressures
Ans: D Ans: C
1363 Valves in the cylinder head of a diesel engine are opened by the direct action of the _____________.
1364 High-speed, multi-cylinder, diesel engines commonly use counterweights placed opposite to the crankpins to ________.
A. exhaust pressure A. prevent bearing loads
B. valve spring pressure B. provide dynamic balance by equalizing centrifugal force
C. rocker arm movement C. counteract inertia forces
D. gudgeon pin movement D. provide a balance of rocking couples around the crankshaft
Ans: C Ans: B
1365 A four-stroke/cycle six cylinder in-line diesel engine has a firing order of 153624. When cylinder #6 is firing at top dead center, piston #4 is ____________.
1366 In a diesel engine closed freshwater cooling system employing a radiator, proper water temperature can be obtained by _____________.
A. at top dead center A. adjusting the radiator louvers
B. on the compression stroke B. passing cooling water through a space heater
C. at bottom dead center C. passing cooling water through the lube oil cooler
D. on the intake stroke D. piping exhaust gases across the radiator front
Ans: D Ans: A
1367 In an auxiliary diesel engine bypass type lubricating oil system, the main lube oil pump forces _____________.
1368 If a four-stroke/cycle diesel engine is running at 1550 RPM, the speed of the camshaft will be _____________.
A. all of the oil used by the engine through a filter A. 525 RPM B. some of the oil used by the engine through a filter B. 775 RPM C. some of the oil used by the engine through a centrifuge C. 1550 RPM
D. cylinder clearance volume D. 1800 RPM
Ans: B Ans: B
1369 An inline engine having a 225mm bore and more than eight cylinders will _________.
1370 An advantage of aluminum pistons, when compared to cast iron pistons is _____________.
A. incorporate the use of two explosion relief valves A. greater high temperature strength
B. have three explosion relief valves B. better heat conductivity
C. have at least eight explosion relief valves C. greater weight per cubic cm D. not be required to have explosion relief valves D. increased resistance to wear
Ans: B Ans: B
1371 An electric heater built into some smaller diesel engines is used to _____________.
1372 In a bypass type filtering system for a medium or high speed diesel engine, the lube oil bypassing the filter __________.
A. raise lube oil viscosity for easier starting in cold weather A. returns directly to the suction side of the pump
B. increase air inlet temperature B. returns directly to the sump
C. increase compression ratio C. flows to the engine bearings
D. increase jacket water temperature for easier starting in cold weather
D. flows through a second-stage strainer, reheater, and returns to the sump
Ans: D Ans: C
1373 The camshaft on a four-stroke/cycle diesel engine provides a means to operate the _____________.
1374 In a single acting, four-stroke/cycle diesel engine, the power impulse in an individual cylinder occurs ____________.
A. fuel injectors A. once every crankshaft revolution
B. exhaust valves B. once every two crankshaft revolutions
C. intake valves C. once every piston stroke
D. all of the above D. twice every piston stroke
Ans: D Ans: B
1375 If fuel injection to a four-stroke/cycle diesel engine begins earlier than designed, ignition may be delayed because the
____________.
1376 Air motion is induced in a four-stroke/cycle diesel engine cylinder to improve air fuel mixing, and is known as _____________.
A. cylinder compression pressure may not be high enough A. supercharging B. cylinder compression temperature may be too high B. scavenging C. fuel oil injection pressure may not be high enough C. turbulence
D. scavenge and purge process is incomplete D. swept volume charging
Ans: A Ans: C
1377 One of the most common methods in preventing a diesel engine piston pin from contacting the cylinder wall is by the use of ____________.
1378 In the operating cycle of a four-stroke/cycle diesel engine, blowdown to exhaust manifold pressure must occur before the
1378 In the operating cycle of a four-stroke/cycle diesel engine, blowdown to exhaust manifold pressure must occur before the