Suppose one of the overhead camshafts on the V-type main propulsion diesel engines on your tug are fitted on the forward end with the device shown in the illustration. In addition to serving as a counterweight, what other function does the device serve? Illustration MO-0101
• Relationship between centrifugal force and engine RPM on rotating parts • Difference between a torsional vibration damper / harmonic balancer (usually on the crankshaft) and devices that react to overspeed • How a spring-loaded flyweight mounted on a shaft behaves as speed increases
• Look closely at the moving parts in the illustration: what happens to that hinged weight and spring as the shaft spins faster and faster? • Ask yourself which of the options describes a device whose operation is based mainly on engine speed rather than engine load or twisting vibration. • Which choice normally involves a liquid or rubber element to absorb twisting, and is that present in this drawing?
• Identify whether the device is reacting to speed (RPM), to torsional twist/vibration, or to load/torque. • Check which listed devices are normally fitted to the crankshaft, not the camshaft, and which can be placed on a camshaft end. • Verify whether any external linkage or trip mechanism could be connected to that hinged weight once it moves outward against the spring.
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