Question 30Motor Plants - 1st Asst/Chief

70% to pass

If the speed of the propeller is 135 RPM, the speed of the engine camshaft shown in the illustration will be_______________. Illustration MO-0003

Diagram for USCG Motor Plants Chief: If the speed of the propeller is 135 RPM, the speed of the engine camshaft...
A135 RPM
B270 RPM
Cvariable depending on the camshaft gear train gear ratios
Dvariable depending on the ratio between engine rpm and propeller shaft rpm
AI Explanation

The correct answer is A) 135 RPM. In a marine engine, the speed of the camshaft is directly linked to the speed of the crankshaft, which in turn is directly linked to the speed of the propeller. Since the propeller speed is given as 135 RPM, the speed of the engine camshaft will also be 135 RPM, as they are directly connected through the engine's internal gearing. The other options are incorrect because B) 270 RPM would be twice the propeller speed, which is not the case, and C) and D) suggest the camshaft speed could be variable, when in fact it is directly proportional to the propeller speed in a fixed gear ratio.

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