Motores 2

In comparison to exhaust valves, intake valves of diesel engines may be fabricated from low-alloy steels because __________.

• the beveled edges of the intake valves provide for self-centering during seating

• intake valves utilize stellite-coated valve seat inserts which reduce wear

• the effective volume of air passing through intake valves is less than the effective volume of air passing through exhaust valves

• intake valves are less affected by the corrosive action of  exhaust gases

In a bypass type filtering system for a medium or high speed diesel engine, the lube oil bypassing the filter __________.

• returns directly to the suction side of the pump

• returns directly to the sump

• flows to the engine bearings

• flows through a second-stage strainer, reheater, and returns to the sump

Maximum lube system operating pressure for a diesel engine is normally regulated by a/an __________.

• orifice in the pump suction

• special filter design

• pressure drop through the filter

• relief valve

A diesel engine crankcase ventilation system __________.

• prevents spark generation

• removes combustible gases

• determines the level of combustible gases

• provides inert gas generation in crankcase

The lower section of a piston is called the __________.

• land

• skirt

• crown

• plate

Turbulence in a diesel engine cylinder is of major  importance in providing __________.

• proper fuel metering

• complete fuel/air mixing

• minimal fuel penetration

• proper fuel timing

To determine if the lube oil filter elements need changing, __________.

• open the filter and inspect the elements

• check the lube oil pump discharge pressure

• check the lube oil header pressure

• check the pressure drop across the filter

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

The minimum speed an engine must attain before ignition can occur depends upon __________.

• the type and size of the engine

• the condition of the engine

• ambient temperature

• all of the above

The knock occurring when a cold diesel engine is started and continues while running at low speed, but stops when the engine reaches normal operating speed and temperature, is __________.

• caused by retarded injection timing

• caused by a mechanical defect in one cylinder

• caused by high fuel injection pressures

• normal for these conditions