Issue link: http://read.dmtmag.com/i/328695
P utting the driver in a quiet operating environment starts with eliminating common vehicle noises at their source, more so than merely building a better wall to fend them off, according to Peterbilt engineers. To that end, when Peterbilt engi- neers targeted best-in-class in-cab sound quality as a priority, work started from the road up. A brief primer in Sound 101 will help explain why. Sound is essentially the result of something moving or vibrat- ing, and that movement causes a result- ing disturbance in the air, which our ears recognize as sound. In the cab of a truck, minimizing or eliminating vibra- tion or movement of the chassis, there- fore, reduces a primary source of in-cab operating noise. "We spent five months analyzing sound inputs and eliminated many of these inputs in the design process," says Peterbilt Senior Assistant Chief Engineer Kevin Baney. "Textbook design is to stiffen the chassis and the cab and have softer mounts to iso- late the noise. "We did just that — made the chassis and the cab very stiff. And we adjusted mount isolation to minimize noise transfer to the cab from the chassis." Baney says the chassis design of the Peterbilt Model 579 includes use of an "overbell", a unique crossmember that strengthens the chassis at the cab mounts. The result is a cab that improves chassis stiffness by 100 percent over commonly employed chassis stiffness standards in the industry, according to Baney. Noise dampening plays a key part in quieting the cab environment, according to engineers, and new technol- ogies were a factor in driving the Model 579 to its sound quality goal. "Noise is still going to come from the road, the tires, the powertrain, up through the chassis," Baney says. "The key is to manage and control what reaches the driver's ear. The remaining noise was dampened through treatments on the engine cover, floor and cab/door panels. "But we only added it where abso- lutely required." New standard Engineers determined where best to place the materials and how much was necessary to maximize weight savings and still achieve best-in-class status. The result? A cab that set a new best- in-class standard for the industry, by nearly two decibels. "It starts with eliminating completely the source of the noises that normally reach the driver's ear," says Baney. "Those noises that survived, we dampened out with innovative treatments. So whether you're closing the door or rolling down the highway, you'll hear luxury car levels of sound quality. "It's a smart design." BEST-IN-CLASS SOUND QUALITY Achieving best-in-class sound quality starts in the chassis A Quieter Ride A tight chassis proved to be the key in achiev- ing best-in-class sound quality for the new Model 579 . 14 l FIRST CLASS