Two Stroke & Four Stroke

In a singe acting four stroke/cycle diesel engine, the power impulse in an individual cylinder occurs _______________________. a. once every crankshaft revolution b. once every two crankshaft revolutions c. once every piston stroke d. twice every piston stroke

b

A piston in a 4 stroke/cycle diesel engine makes 4 strokes during each _________________. a. crankshaft revolution b. mechanical cycle of operation c. period of 2 combustion cycles d. cycle of two events

b

Directional intake ports in diesel engines are used to ____________________. a. reduce air change turbulence b. induce air swirl c. deflect hot combustion gas away from the valves d. oppose the effects of piston induced squish

b

Exhaust gases in a 2 stroke/cylinder diesel engine are discharged through_________________. a. the air valves b. a roots type blower c. exhaust ports or valves d. the after cooler and directed to the stack

c

Exhaust valves in a two cycle diesel engine cylinder head are made as large as practical to _____________________. a. increase back pressure during the exhaust process b. facilitate periodic replacement of the valves c. reduce the pumping loss associated with scavenging d. reduce tension on spring valves

c

In a single acting, two stroke/cycle, diesel engine, the power impulse in an individual cylinder occurs ________________. a. once every crankcase revolution b. once every two crankcase revolutions c. once every piston stroke d. twice every piston stroke

A

In a two stroke/cycle, opposed piston, diesel engine, one crankshaft operates several crank angles in advance of the other crankshaft to ___________________. a. allow the exhaust ports to open and close before the inlet ports close b. allow the scavenge ports to open and close simultaneously with the previous exhaust ports c. prevent the scavenge air pressure buildup in the cylinders d. prevent the exhaust piston from reaching TDC and BDC before the intake piston

A

In diesel engines, the four basic events (intake, compression, power, exhaust) are performed once in _________________. a. one complete crankshaft revolution in a two stroke/cycle engine b. two crankshaft revolutions in a two stroke/cycle engine c. two power strokes in a two stoke/cycle engine d. two piston strokes in a four stroke/cycle engine

A

Which of the listed design features is most common with a two stroke cycle, low speed main propulsion diesel engine? A. piston rod and crosshead construction B. 90 degreee "v" configuration C. Double acting trunk type pistons D. single reduction gearing

A

Which of the two events listed occurs simultaneously in a two stroke/cycle diesel engine? A. exhaust and scavenging B. scavenging and compression C. ignition and expansion D. exhaust ad compression

A

Compared to 4 stroke/cycle engines, 2 stroke/cycle diesel engines have the disadvantage of __________________________. a. less even torque b. higher cylinder head temperatures c. fewer power strokes per revolution d. greater weight/size requirements

B

If all other conditions such as bore, stroke, speed, and mean effective pressures are equal, a two stroke/cycle diesel engine will develop approximately _____________. a. the same indicated horsepower as a 4 stroke/cycle engine b. twice the indicated horsepower as a 4 stroke/cycle engine c. one half the indicated horsepower as a 4 stroke/cycle engine d. one power stroke for every 2 crankshaft revolutions

B

How many power strokes per crankshaft revolution are there in an eight cylinder, two stroke/cycle diesel engine? A. one B. two C. four D. eight

D

In diesel engines, the four basic events (intake, compression, power, and exhaust) are performed once in ____________. a. two crankshaft revolutions in a two stroke/cycle engine b. two power strokes in a two stroke/cycle engine c. one power stroke in a two stroke/cycle engine d. two piston strokes in a two stroke/cycle engine

D

The 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

D

During which of the listed piston strokes of a 4 stroke/cycle diesel engine, is the piston moving downward? a. intake stroke b. compression stroke c. exhaust stroke d. pumping stroke

a

Which of the listed design features is most common with a 2 stroke/cycle, lowspeed main propulsion diesel engine? a. piston rod and crosshead construction b. 90 degree v configuration c. double acting trunk type pistons d. single reduction gearing

a

For a given size engine, the 2 stroke/cycle diesel engine will deliver more power than a 4 stroke/cycle diesel engine because ____________________. a. it has a longer power stroke b. more air gets into the cylinder each stroke c. it develops twice as many power strokes at the same speed d. higher combustion pressure is developed

c

In a diesel engine, exhaust valves open before the intake ports are uncovered to __________________. i. reduce pumping losses ii. reduce back pressure a. i only b. ii only c. both i and ii d. neither i nor ii

c

The exhaust valve opens before bottom dead center in a 4 stroke engine to __________________________. i. allow for blowdown ii. reduce pumping losses a. i only b. ii only c. both i and ii d. neither i nor ii

c

A disadvantage of a 2 stroke/cycle diesel engine is ______________. a. more power strokes per revolution b. the use of scavenge air c. more complicated valve gear d. higher working temperatures of the piston and cylinder

d

Exhaust gases are generally removed from the cylinders of a 2 stroke/cycle diesel engine by ____________________. a. natural aspiration b. masked intake valves c. air cells d. scavenging air

d

In a 4 stroke/cycle diesel engine, after the completion of the power stroke, the piston will move _______________________. a. up and draw in a fresh air charge b. down to burn off fuel c. down to compress the fuel air charge d. up and force out the exhaust gasses

d

In the cylinder head of a 2 stroke/cycle diesel engine, valves are used for ____________________. a. air intake b. a fuel outlet c. cooling water inlets d. exhausting combustion gas

d

In the operating cycle of a 4 stroke/cycle diesel engine, blow down to exhaust manifold pressure must occur before the piston begins the exhaust stroke to minimize _______________. a. pressure losses b. exhaust pulsations c. excessive scavenging d. pumping losses

d