Home Automotive Vibration’s Tradition and Effects

Vibration’s Tradition and Effects


Kevin Cameron has been writing about motorcycles for nearly 50 years, first for <em>Cycle magazine</em> and, since 1992, for <em>Cycle World</em>. (Robert Martin/)

Because I’ve heard a fair amount of nonsense uttered about motorcycle engine vibration over the years, I want to present some viewpoints and some anecdotes.

First, we are accustomed to a degree of motorcycle engine vibration and may even like it because it tells us the engine’s running and everything is normal. The people on ocean liners in 1900 were aware that something was wrong when their engines stopped making a steady (and even reassuring?) thump. The steady (and even reassuring?) What’s happening? When I stop at a red light in a car with the start-stop function, I get the same feeling. Mm, something’s wrong. Then I remembered.

It was designed to have a small amount of vibration, but it is still very quiet. When “switched on” but still at rest, its electric traction motor is made to oscillate, reminding the rider it’s ready to go.

LiveWire engineered a slight vibration into the electric motorcycle while stationary to let the ride know it is ready to go.

LiveWire engineers designed a vibration that is felt by the rider when the motorcycle is stationary. This lets them know the motorbike is ready for action. (Jeff Allen /)

Engineers make sure to avoid removing balance shafts from a design when they include them. The following are some of the most effective ways to improve your own personal effectiveness. vibration. Customers have complained about vibration.

On the other hand, there’s a reason why so few riders traveled long distances on the many air-cooled Harley Sportsters produced: vibration described by some as near the double-vision level. Even rubber engine mounts couldn’t stop the mighty shaking.

A world of broken pieces lies beyond the ordinary discomfort that people experience. Kawasaki’s original 1975 KR250 tandem twin (two crankshafts, geared together, one ahead of the other) had such a tremendous fore-and-aft rocking couple that it chronically broke its front cylinder’s exhaust pipe and California racer Harry Klinzmann’s ride broke four of the six frame tubes supporting the steering head.

Later bikes (250s) were able to achieve a perfect balance when the engine was changed so that both pistons moved together. The following are some examples of how to get started: Kork Ballington, Anton Mang and 350s were smooth and won 8 world championships.

Kawasaki’s KR250. <i>PekePON (Own work), via Wikimedia Commons</i>

Kawasaki’s KR250. <i>PekePON (Own work), via Wikimedia Commons</i>

The lightweight KR3 500 two-stroke triple built by King Kenny’s team near the end of the ‘90s had nothing to deal with such engines’ strong side-to-side rocking couple. Parts breakage required parts to be reinforced, increasing weight, but that didn’t stop erratic carburetion resulting from the shaking (what do you call a milkshake made from hydrocarbons?). Yoichi Oguma, a retired Honda Engineer, offered to redesign an engine with a new balance shaft. It was a great success, and the machine just began to show its potential when the two stroke era ended in 2002.

Outstanding in the annals of vibration-driven problems was the development of Wright’s wartime R-3350 18-cylinder radial, which powered the B-29 bomber. Troubles such as badly galled propeller centering cones, repeated cracking of nose case, carburetor mounting adapter, and supercharger housing, plus failures of such details as magneto drives, starter mounting flanges, and carburetor control linkage were attributed to “normal developmental problems” and no doubt some of them were. But when improved engines were finally supplied to Boeing to enable flight test to begin, that company’s independent vibration measurements showed the presence of substantial secondary torsional vibes.

That couldn’t be ignored because it presented the possibility of vibration-fatigued steel propeller blades throwing high-velocity pieces in flight. B-29 testing was delayed by six months Eight gear-driven balancers could be fitted into each engine. They were type-tested and then put into production.

Consider vibration early in your design process to save time and money.

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