61.Besides the use of piston cooling fins to assist in cooling,they also provide extra strength for the piston ___________.
62.The minimum fuel oil delivery pressure required for efficient injection depends primarily on the ______________.
A.degree of cylinder air turbulence
B.maximum pressure in the engine cylinders during injection
C.quantity of the fuel to be injected
D.duration of the ignition delay period.
63A thrust bearing is used with a propulsion diesel engine to _____________.
A.control axial movement of the crankshaft
B.transmit engine thrust to the propeller shaft
C.absorb vibrations in the propeller shafting
D.prevent propeller thrust from being transmitted to the hull
64The two strokes of a two-stroke/cycle diesel engine are ____________.
A.power and intake
B.intake and exhaust
C.exhaust and compression
D.compression and power
65Which of the following statements pertains to propulsion engines with bores exceeding 200 mm?
A.There shall be a means to display the cooling water outlet temperature of each cylinder.
B.All engines connected to controllable pitch propellers shall be of the direct reversible type.
C.The engines will be fitted with a means to display the exhaust gas temperature of each cylinder.
D.All of the above are correct.
66Where engine bores exceed 230 mm, a bursting disc or flame arrestor is fitted ____________.
A.at the supply inlet to the starting air manifold for non-reversing engines
B.on the exhaust manifold prior to the inlet of the turbocharger
C.on all devices subject to the by-products of combustion or lubrication system vapors
D.in way of the control valve of each cylinder for direct reversing engines having a main starting manifoldAns:CAns:A
67What is the function of the main thrust bearing?
A.Prevents lateral movement of the slow speed gear.
B.Transmits propeller thrust to the hull.
C.Keeps spring bearings in line.
D.Prevents main reduction gear axial movement.
68The main function of piston compression rings is to _______.
A.prevent excessive cylinder liner wear
B.reduce friction losses in the engine
C.seal the space between the piston and the liner
D.limit upward flow of lube oil into the combustion spaceAns:BAns:C
69The function of diesel engine piston compression rings is to ____________.
A.prevent piston side thrust
B.prevent engine friction losses.
C.transmit heat from the piston to the cylinder liner.
D.remove oil from the cylinder combustion space.
70.Diesel engine piston ring gaps can be straight or angle cut. In comparison, the angle cut ring ____________.
A.allows piston ring expansion
B.controls piston ring tension
C.increases ring wearing quality
D.decreases combustion gas leakageAns:CAns:D
71.Modern marine diesel engines equipped with mechanical fuel injection operate on a combustion phase within the cycle which is _________.
A.entirely constant pressure
B.entirely constant temperature
C.a combination of constant volume and constant pressure
D.a combination of constant temperature and constant pressure
72.Which of the listed designs is effectively used to provide the turbulence necessary for proper combustion in a diesel engine cylinder?
A.Masked exhaust valves
B.Special piston rings