Line One
Engine brake technology: Creating the strong, silent type

by Jason Cisper

In a letter to Land Linebearlier this year, one trucker, in extolling the virtues of the engine brake said, "You haven't lived until you've come off a winding, two-lane, six percent grade with a 671 Detroit and 6-inch brakes. I still kind of pucker up just thinking about it."

Truckers know that a truck's brake lining can heat up at a rapid rate on steep downgrades (and therefore be rendered ineffective). Truckers know that an engine brake helps to supplement the slowing/stopping process. Truckers know that when traveling down a steep hill, a truck without an engine brake is at greater risk of losing its stopping power as a result of overbraking. And truckers know that today's more powerful engines, combined with higher speed limits, make engine brakes more of a necessity. Yet it would seem that this information has somehow slipped past many government officials.

Rather than pushing to make the engine brake standard equipment on all trucks, many lawmakers have chosen the opposite route. Irritated by the deep "barking" sound, (emitted when compressed air is released from the cylinder near top dead center of the compression stroke), homeowners who live near interstates or heavily traveled truck routes have gone to their elected representatives with noise complaints.

Although it remains unclear whether or not engine brakes are to blame for excessive noise problems (Jacobs Vehicle Systems, Inc. and Donaldson Company, Inc. have conducted several studies that indicate engine brakes are commonly not the cause), the result is anti-engine brake legislation. Sponsors of such legislation don't realize that the engine brake serves a valuable purpose in the safety of truck operation.

Engine and engine brake manufacturers, in response to such pressure, are answering the call. While attempting to increase effectiveness, manufacturers are keeping an eye on (or an ear to) noise levels created by their product. And many engine-specific models are being developed that have resulted in less weight, less noise, and increased braking horsepower.

Essentially, an engine brake is a hydraulically-operated device that helps a truck engine absorb power by releasing compressed air via the exhaust system, rather than forcing the piston down and releasing power into the drivetrain. Through the use of "slave pistons," potential energy is rerouted and released. Technology in recent years has built upon this principle.

Cummins, for example, has worked with Jacobs to create an engine brake that is a part of the engine, rather than an add-on. In 1997, the new product was introduced. Essentially absorbed by the engine, the Intebrake uses much less material than a traditional engine brake and, therefore, weighs less than previous brake designs. The lighter unit yields higher braking hp, while at the same time reducing brake noise.

In discussing the Intebrake, Scott Fowler, vice president of sales and marketing for Jacobs said, "We knew that the weight, height and performance of traditional engine brakes could improve."

New for 2000 is Pacbrake's P-80 engine brake for Detroit Diesel's series 60 engines. At 23 percent less weight than previous models, the product provides 480-plus braking hp. Pacbrake says the largest gains with the new technology have gone to mid-range engine speeds. At 1800 RPM, for example, the new engine brakes provides an additional 55 braking horsepower. The increased efficiency has been credited to larger pistons, seven-point mounting and a two-housing/three-power braking system.

Caterpillar has likewise joined in the trend toward a brand-specific engine brake. In 1997, the engine manufacturer announced an alliance with Jacobs to design auxiliary engine brake systems. The two have assembled brake kits and components that are specific to engine model. The popular-but-retired 3406, for example, has specific trigger and brake lash settings to correspond with specific engine horsepower. And increased modifications have resulted in increased braking power.

But engine brake technology is not limited to those buying a new truck. In 1999, Donaldson Company, Inc. introduced its Silent Partner - a muffler designed to eliminate excess noise produced by vehicles during engine braking. Acoustical technologies have been developed in the Silent Partner to produce a "mellow, pleasing tone." The muffler reportedly does not increase exhaust backpressure, nor does it require engine or engine brake modifications. And because it shares similar dimensions to conventional mufflers, they are easily retrofitted to older engines with earlier model engine brakes.

Anti-engine brake legislation looms in several states. In Colorado, the House of Representatives has recently approved HB1142, which requires commercial vehicles to have mufflers for their engine brakes. The proposed penalty is a $500 fine. In Indiana, engine brakes are on the verge of being outlawed on the Indiana Toll Road in counties with populations between 125,000 and 129,000 (Porter County, and possibly others). HB1106 was on the governor's desk in March, waiting to be signed.

With more than 70 percent of all trucks on the road using some sort of engine brake, the development of a lighter, stronger and quieter product is inevitable. Engine manufacturers, knowing that the general public is not necessarily aware of the safety aspects associated with engine brakes, have adopted somewhat of a self-regulatory policy. By working with engine brake makers, they have added sound levels to the list of important technological advances. Jacobs has said in the past that the cooperative process is intended to result in "better performance, improved packaging, reduced weight and increased control of engine valve events."

And as new products continue to emerge, it is hopeful that the call for legislation (like the engine brake) will be permanently quieted.