Motor Plants & Auxiliary Boilers USCG Question #1392 (Set 28)

A six-cylinder, four-stroke cycle diesel engine is fitted with a rotary distributor type air starting system. The speed of the rotating distributor disc is __________.

Official USCG Answer & Rule Citation

Correct Answer: Option A — one-half engine speed

A rotary distributor disc on a four-stroke cycle engine rotates at one-half engine speed because starting air is admitted once every two crankshaft revolutions per cylinder.

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