37.Connecting rods in a diesel engine are used to connect the _____________.

A.engine to the bed

B.rocker arm to the camshaft

C.crankshaft to the gear train

D.piston to the crankshaft

D.piston to the crankshaft

38Movement of the pump control rack in a fuel injection system using individual plunger-type pumps _____________.
A.changes the position of the fuel inlet ports

B.changes the length of the pump stroke

C.varies the quantity of fuel delivered

D.varies the compression of the delivery valve spring


C.varies the quantity of fuel delivered

39The purpose of a heat dam used in some diesel engine cast iron pistons is to ____________.
A.concentrate all heat in the piston crown
B.increase the distance of travel for heat from the crown to the top ring groove

C.ensure that all heat in the piston crown is conducted to the top ring

D.provide a short direct path for heat to flow from the crown to the top rings

B.increase the distance of travel for heat from the crown to the top ring groove

40Diesel engines are classified as reciprocating internal combustion engines because they ______________.

A.use energy from fuel burned outside their cylinders

B.burn fuel in a combustion chamber that moves back and forth

C.burn fuel in a chamber where its energy moves a piston back and forth

D.use a continuous combustion process to impart rotary motion to the pistons

C.burn fuel in a chamber where its energy moves a piston back and forth

41.A diesel engine with a full speed of 1000 RPM drives a propeller at 300 RPM. What is the speed reduction ratio?
A.0.3 to 1
B.3.33 to 1
C.33 to 1
D.300 to 1

B.3.33 to 1

42Which of the listed design features is most common to a two-stroke/cycle low-speed main propulsion diesel engines?

A.Crosshead construction

B.Cross-scavenging air flow

C.Trunk type pistons

D.Single reduction gearing
Ans:A

A.Crosshead construction

43Why is the ring belt narrower in diameter than the skirt of a piston designed for a diesel engine?

A.To allow for greater expansion due to higher operating temperature.

B.To seal the cylinder against leakage of combustion gases.
C.To provide an additional surface for oil cooling.

D.To provide additional strength for the crown and lower structure


A.To allow for greater expansion due to higher operating temperature

44Which statement about diesel engine combustion is true?

A.Combustion does not begin until the piston starts down on the power stroke.

B.Maximum combustion pressure is reached before TDC.
C.Turbulence in the cylinder causes a delay in ignition.
D.Maximum cylinder firing pressure is not developed until the piston passes TDC.

D.Maximum cylinder firing pressure is not developed until the piston passes TDC.

45The diameter of a piston is usually less at the crown than at the skirt, in order to ______________.
A.facilitate the of piston rings

B.allow for the expansion of the piston during operation

C.prevent crankcase vapors from entering the combustion chamber
D.reduce wearing of the upper cylinder liner

B.allow for the expansion of the piston during operation

46Why are some diesel engine cylinder liners plated on the wearing surface with porous chromium?

A.The chromium will not wear out the piston rings.

B.Chromium eliminates the need for oil scraper rings.

C.The chromium strengthens the liners in the way of the scavenging air ports.

D.Pores in the plating aid in maintaining the lube oil film.

D.Pores in the plating aid in maintaining the lube oil film.

47The fuel injection pumps on a diesel engine are controlled by a linkage system attached to the _____________.
A.camshaft

B.crankshaft

C.governor

D.flywheel

C.governor

48What type of fitting is to be used on diesel engine fuel injection line piping?

A.Mild steel

B.Hardened steel

C.Extra heavy

D.Double extra heavy

C.Extra heavy

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