Motores 5-8

The expansion tank in a diesel engine closed freshwater cooling system is located at __________.

• the highest point in the system

• the lowest point in the system

• or near the floor plate level

• or near the tank top level

In the slow speed diesel engine shown in the illustration, the part labeled "E" is the __________.

• high pressure lube oil line

• low pressure lube oil line

• high pressure fuel line

• low pressure fuel line

Where is a fusible plug installed on a Scotch or auxiliary boiler?

• At the shell approximately 1 1/2 inches (3.8 cm) below the  normal waterline.

• At or near the center of the crown sheet of the combustion  chamber.

• In the furnace approximately 1 1/2 inches (3.8 cm) below the normal waterline.

• In the furnace not more than 1 inch (2.54 cm) below the lowest permissible water level.

The quantity of air delivered at any given speed by a Roots-type blower, as shown in the illustration, decreases as the pressure ratio increases. This is due to the __________.

• decrease in clearance between the mating lobes

• increase in air leakage past the rotors

• decrease in air leakage past the rotors

• increase in clearance between the mating lobes

If the speed of the propeller is 135 RPM, the speed of the engine camshaft shown in the illustration will be __________.

• 135 RPM

• 270 RPM

• variable depending on the camshaft gear train gear ratios

• variable depending on the ratio between engine rpm and propeller shaft rpm

As a general rule, the recommended operating water jacket outlet temperature range for medium and high speed marine diesels with closed cooling systems is __________.

• 120° to 139°F

• 140° to 169°F

• 170° to 189°F

• 190° to 219°F

The water inlet manifold for the diesel engine shown in the illustration is represented by the letter or number __________.

• "M"

• "N"

• "W"

• "13"

In reducing engine speed to an efficient propeller speed by the use of reduction gears, __________.

• speed and torque are both reduced

• speed is reduced and torque remains unchanged

• speed is reduced and torque is increased

• speed is sometimes unchanged while torque is increased

Which of the operating characteristics listed applies to the Roots-type blower shown in the illustration?

• Each set of lobes is independently driven, assuring proper timing.

• Compression of the air is accomplished between the rotors.

• Air delivery is approximately proportional to engine speed.

• All of the above

Why do most temperature control valves in diesel engine closed freshwater cooling systems vary the flow of jacket water through the cooler instead of through the engine?

• Changing the rate of flow in the jackets could cause localized hot spots.

• Emergency hand control would not be possible if water flow  through the jackets were controlled.

• Excessive cooling would take place in the heat exchangers at high loads.

• Excessive cavitation erosion would take place in the coolers.