The other day I was talking to one of my friends who does a lot of his own work on an old Chevelle that he's had for years. He was telling me about how he was going to have to replace the Harmonic Balancer on the engine. I was trying not to appear stupid so I just kept nodding my head with a "but of course" expression on my face. P.S. What is a Harmonic Balancer?
That's fancy terminology for a round hunk of steel mounted to the front of a crankshaft. When looking in the dictionary under "Harmonic" everything refers to music until you get to the third version of the definition which relates to physics. It reads: "of or having to do with any of the frequencies making up a wave or alternating current, that are integral multiples of the fundamental frequencies." Well, I'm sure that will clear things up for you.
It actually does make sense, but let's look at it in a more basic form. Another term for the same engine part is the "Vibration Damper", and that's exactly what it does. The Vibration Damper is a balanced cylindrical weight bolted or pressed onto the front of the crankshaft in order to minimize "torsional vibration" (The twist-untwist actions of the crankshaft caused by the cylinder firing impulses). Some vibration dampers use a rubber insert between a center hub and external metallic ring.
Yes. That strong cast iron crankshaft gets twisted around by the tremendous force being transmitted to it by the internal combustion process. If you ran an engine with its Balancer or Damper removed, believe you me, there would be a whole lot of shaking going on.