Whether or not the sound waves emitting from mobile equipment are considered noise or music is a relative thing. The noise from a finely tuned diesel engine can be beautiful, drawing crowds of fans who pay good money to feel the ground vibrate beneath their feet. On the other hand, it can be an ear-splitting discomfort that drowns out a perfectly good FM channel as it broadcasts a classic song by Quiet Riot.
My wife's boss, Chris Feller, wrenches for a Super Farm pulling team from northern Illinois. It's more fun to watch an event when you know a participant, so we're in the stands with corn dogs and funnel cakes when the Badger State Tractor Pullers are in town and the "Wild Buck" team is pulling with its modified John Deere 4560 during the Jefferson County Fair.
The fair occurs less than 10 miles north of OEM Off-Highway's office, and there's a pretty good chance you can stand out in the parking lot in Fort Atkinson and hear the tractors when they're running. The volume level from those machines can be deafening, but to the fans in the stand, it's a pleasant by-product of the sport's main event: when an extremely powerful, highly modified engine gets pushed to its operating limit as the weight climbs up the back of the sled.
Sitting in those stands and feeling — loving —the noise is such a contrast from my experience operating a late '70s articulated tractor on a corn and soybean farm during high school. Although it had a cab, it had no air conditioning, so I had to open the windows to cool things off. The noise, vibration and harshness (NVH) coming up from the floor and in through the windows from the tractor's various operating systems made listening to the AM/FM radio and its dual speaker set up nearly impossible.
The difference is in the duration and the contrast between play and work. We were at the Jefferson County Fair to hear the engines roar, but after a little over 300 ft. the engine is shut down and the sound waves from the exhaust stack seem to reverberate through the grandstands for a few seconds afterward. The tractor's not traveling back and forth across the hundreds of acres required with tilling. On the job, today's equipment operator expects some piece and quiet so he or she can crank up the stereo system and enjoy the music. Doctors say it's healthier, too.
In this issue, Michelle EauClaire takes a look at the various ways suppliers are tackling the NVH issue at the component level. With the goal of stopping or fine-tuning noise and other environmental issues before it becomes an airborne problem, solutions are being found where you might least expect them.