A naturally aspirated diesel engine at full throttle will have an intake manifold pressure
a)slightly less than atmospheric pressure
b)approximately equal to exhaust manifold pressure at all times
c)that is widely fluctuating
d)constantly decreasing as engine load increases
Answer-A
The output pressure of a diesel engine lube oil pump is regulated by a/an
a)relief valve
b)metering valve
c)variable speed pump drive
d)orifice in the lube oil header
Answer-A
An increase in the air inlet manifold pressure of a diesel engine will result in a/an
a)decrease in maximum cylinder pressure
b)increase in ignition lag
c)decrease in fuel consumption per horsepower-hour
d)decrease in exhaust manifold pressure
Answer-C
Maximum lube oil system pressure is normally controlled by
a)the capacity of the lube oil pump
b)the speed of the lube oil pump
c)the outlet pressure of the lube oil pump
d)a relief valve
Answer-D
Which of the following statements is true concerning an oil cooler?
a)The oil temperature is less than the cooling water temperature
b)The oil pressure is less than the cooling water pressure
c)The oil pressure is greater than the cooling water pressure
d)The magnets are installed to remove metal particles
Answer-C
The highest pressure in any closed diesel engine freshwater cooling system is at the
a)jacket water outlet
b)expansion tank inlet
c)heat exchanger inlet
d)cooling water pump outlet
Answer-D
Concerning diesel propelled vessels, the astern power is to provide for continues operation astern
a)equal to that available for ahead operation
b)at 70 percent of the ahead rpm at rated speed
c)while underway and under all normal conditions
d)at 70 percent of the ahead rpm of average continious sea speed
Answer-B
Maintaining the lowest possible scavenging air temperature at all times is not recommended due to the possibility of the
a)air charge density becoming too high
b)piston crown surfaces becoming too cold
c)formation of excessive quantities of condensate
d)compression pressure being greatly reduced
Answer-C
The nuts of main bearings, connecting rod bolts and all other moving parts are to be secured by
a)hardened steel nut locks
b)cotter pins made of spring steel
c)split pins or other effective means
d)hydraulic nuts as commonly found on large low speed engines
Answer-C
If the valve tappets in a diesel engine are set at greater clearances than those specified by the engine manufacturer, those valves will
a)open late and close early
b)open late and close late
c)fail to open when the engine is cold
d)fail to open at normal operating temperature
Answer-A
Proper lubrication of the main bearings is more easily obtained in a single acting four-stroke/cycle diesel engine than 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
Answer-A
Increasing the valve clearance between a valve stem and rocker arm, will result in the valve
a)closing later
b)opening sooner
c)staying open for a shorter period of time
d)staying open for a longer period of time
Answer-C
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?
a)Clogged air intake filters
b)Piston blow-by
c)A defective after cooler
d)Faulty exhaust valves
Answer-C
Cooling the intake air supplied to a diesel engine will
a)reduce mean effective pressure
b)decrease average compression pressure
c)decrease air charge density
d)increase power output
Answer-D
Which of the following condition may need to be reduced when operating a large, low-speed, main propulsion, diesel engine at low loads?
a)Injection pressures
b)Control air supply pressure
c)Cooling water flow through after coolers
d)Lube oil temperature
Answer-C
One function of the fuel pump delivery check valve is to
a)prevent carbon deposits from forming on the injector nozzle
b)help the injector needle reseat without dribbling at the nozzle holes
c)provide a prolonged pressure drop in the high pressure steel piping to the injector
d)ensure a fuel leakoff between the plunger and barrel which provides lubrication for relative movement
Answer-B
A closed freshwater cooling system is commonly used with marine diesel engines because the
a)need for water treatment is eliminated
b)cooling water temperature differential is greater
c)cooling water pumps are directly reversible
d)jacket water temperature is more easily controlled
Answer-D
Fuel droplets injected into a diesel engine cylinder must have adequate penetration to
a)prolong the ignition delay period
b)ensure the beginning of fuel injection
c)thoroughly utilize the air charge
d)allow controlled fuel combustion
Answer-C
The valve cam slope angle determines the
a)engine torque characteristics
b)acceleration rate of valve opening and closing
c)engine fuel efficiency
d)diameter of intake and exhaust valves
Answer-B
The rate of fuel injection in a diesel engine cylinder depends primarily on
a)the size of the holes in the fuel nozzle
b)timing of the pump
c)supply pressure to the pump
d)shape of the combustion chamber
Answer-A
Which of the following devices is normally provided to prevent oil starvation in a diesel lubrication system utilizing the "full flow" principle?
a)Duplex strainer
b)Three-way valve
c)Pressure relief bypass line around the filter
d)Mechanical straining filter
Answer-C
A port-and-helix fuel injection pump having upper and lower plunger helixes is designed to
a)vary fuel delivery and return pressure
b)vary the beginning and ending of injection
c)operate with residual fuels only
d)provide maximum fuel delivery rate
Answer-B
One advantage of hydraulic clutches over mechanical clutches in diesel engine installations is
a)the power is transmitted at very high efficiency of 60%
b)the torsional vibrations are transmitted directly to the reduction gears
c)each clutch has a separate oil gland for reverse operation
d)no mechanical connection exists between the driving and driven elements
Answer-D
An individual injection pump is designed for variable beginning and constant ending of injection. For diesel engines operating at constant speeds, the start of injection will
a)advance as the load increases
b)retard as the load increases
c)remain unchanged regardless of load
d)always occur at top dead center
Answer-A
The amount of fuel injected in a particular time, or degree, of crankshaft rotation is termed
a)metering
b)timing
c)rate of injection
d)rate of distribution
Answer-C
In a normally operating diesel engine, the main source of lubricating oil contamination in the crankcase is a result of the
a)metal particles loosened by wear
b)air when no air cleaners are used
c)condensation of water wapors
d)breakdown of the lubricating oil itself
Answer-D
On small diesel engines, a noticeable decrease in the time interval between the replacement of the lube filter cartridge indicates
a)piston ring blow-by
b)dirty air filter
c)excessive oil pressure
d)excessive oil temperature
Answer-A
When the lower edge of the spiral begins to uncover the release port in a jerk pump, the
a)pumping continues until the plunger travels its full stroke
b)effective pumping stroke of the plunger ends
c)pressure drops slowly until the full stroke is attained
d)plunger rotates to the zero delivery position until the next stroke
Answer-B
Some diesel engines are fitted with a thermometer in the cooling water outlet from each cylinder. If the cooling water temperature from all cylinders begins to rise above normal, you should suspect
a)increased blow-by in all cylinders
b)incomplete combustion in all cylinders
c)overloading in all cylinders
d)insufficient fuel delivery to all cylinders
Answer-C
Proper operation of the main engine reduction gear set requires the operator to monitor
a)the sump oil level
b)oil flow sight glasses
c)bearing temperatures
d)all of the above
Answer-D
The duration of fuel injection developed by an individual port-and-helix fuel injection pump, is determined by the
a)total pump stroke
b)pump plunger diameter
c)plunger helix angle
d)effective pump stroke
Answer-D
Before starting a diesel engine using an attached lube oil pump, the engineer should
a)open the bypass line
b)cut in the lube oil cooler
c)pressurize the lube oil system
d)top off the expansion tank
Answer-C
A diesel engine using lube oil with too high a viscosity will exhibit
a)increased starting difficulty in cold weather
b)increased oil consumption
c)thickening at higher operating temperatures
d)minimal friction losses
Answer-A
If the main propulsion diesel engine governor works irregularly with a jerking motion, a possible cause can be
a)a sticking fuel control linkage
b)a malfunctioning overload cam
c)an unlocked overspeed trip
d)floating valves
Answer-A
During extremely cold weather, while starting an engine, it turns too slowly and fails to start. This problem is most likely the result of
a)high fuel oil viscosity
b)low fuel oil temperature
c)high lube oil viscosity
d)energized glow plugs
Answer-C
Prolonged operation of a diesel engine with a closed cooling water system, at lower than normal designed temperatures can
a)increase power output
b)decrease lube oil viscosity
c)eliminate fuel knock
d)cause sulfuric acid formation
Answer-D
Which of the listed governor characteristics will greatly affect the load sharing relationship between paralleled diesel generators?
a)Sensitivity
b)Power
c)Speed droop
d)Compensation
Answer-C
An emergency diesel generator cooling system is equipped with an automotive type thermostat. If the thermostat bellows loses its charge, the thermostat will
a)open, and the coolant temperature will increase
b)open, and the coolant temperature will decrease
c)close, and the engine coolant temperature will increase
d)close, and the coolant temperature will decrease
Answer-C
No comments:
Post a Comment