Reciprocating Engines Maximize Efficiency When They Employ Flywheels

   Last time we had a look inside a marvelous piece of engineering machinery known as a crankshaft.   It plays a key role in converting the reciprocating linear motion of a steam driven engine into the rotary motion required to power externally mounted devices that are attached to it.   Today we’ll finish up our blog series on flywheels when we see how using one in conjunction with a crankshaft facilitates a more even transmission of energy.   Reciprocating engines maximize efficiency when they employ flywheels.

   We learned that the energy in the steam supply decreases as the piston moves in its cylinder, which means a concurrent decrease in the engine’s horsepower and its ability to power machinery.   Without an intervening action, the reciprocating steam engine would stall.   Now, let’s see how adding a flywheel to the crankshaft can solve the problem.

Reciprocating Engines Maximize Efficiency When They Employ Flywheels

Reciprocating Engines Maximize Efficiency When They Employ Flywheels


   As we’ve learned before, a flywheel stores up kinetic energy while the engine powering it is performing at full horsepower, but if that power should drop off or cease to be produced, the flywheel gives up the kinetic energy stored inside it so as to keep externally mounted machinery operating until that stored energy is exhausted.   This is all made possible because flywheels are designed to have moments of inertia sufficient to positively contribute to its storage of kinetic energy.   This inertia is a numerical representation of the flywheel’s resistance to change in motion.   Please review our past blog on the subject to refresh your memory.

   The overall effect is that while the engine is operating, there’s an even flow of energy between the engine and flywheel and horsepower is supplied to keep machinery mounted to the crankshaft operating.   Any diminishment in the power supplied will be compensated for by the flywheel’s stored kinetic energy.

   Next time we’ll introduce a new topic, a phenomenon known as cavitation.

opyright 2017 – Philip J. O’Keefe, PE

Engineering Expert Witness Blog



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