Performance, reduced weight drive design changes

Fleets are under increasing pressure to reduce operating costs, and one vehicle component that can contribute to this effort is the engine brake. By changing the exhaust valve timing, these retarders help reduce speed, saving wear and tear on the main brake system, according to Pacbrake Co. Another advantage to engine brakes is their ability to reduce tire wear. Jacobs Vehicle Systems says that the gentle retarding action of an engine brake prevents rubber-burning wheel hop and the likelihood of obtaining tire flat-spots. Engine brakes can also play a role in vehicle safety by making it easier to slow todays high-horsepower vehicles. Jacobs says that they can apply up to 100% of the engines rated horsepower for retarding at the drive wheels.

Makers of engine brakes often work very closely with engine manufacturers to build retarders that are integral to the engine. Brooks Holloway, marketing manager for Pacbrake, says that this cooperation will lead to the development of engine brakes that are lighter, more compact, and more powerful. This partnership is especially important in light of increased regulatory pressure on engine makers to reduce engine emissions, he explains. Engine brake manufacturers must ensure that their products keep pace with the changes in engines that these regulations demand.

Earlier this year, Pacbrake introduced the P-63A, a brake for Detroit Diesel Corp. Series 60 engines that offers up to 465 hp. at 2,100 rpm. Like all of Pacbrakes engine retarders, the P-63A features a Paclash timing adjuster system, in which the adjuster for the slave piston is designed to allow the exhaust valve to open sooner, greatly improving brake performance, according to the company. Pacbrake also points out that another benefit of the early timing is a reduction in engine-brake noise.

Holloway says that the benefits of lighter weight vehicles has led Pacbrake to put all of its engine brakes through a weight loss program via changes in design and materials. Without sacrificing performance and reliability, brake-weight reductions of 15-30% have been achieved, he adds. The lighter weight models are expected to be on the market by the 2nd quarter of next year.

A strategic alliance between Jacobs Vehicle Systems and Cummins Engine Co. led to the development of the Intebrake, which is standard on the Cummins Signature 600 engine. An integral part of the total engine system, this brake uses less material than a traditional unit and adds only 20 lb. to the engines weight. In addition, it adds no height to the engine. The precise timing provided by cam lobes designed specifically for braking results in 600 braking hp. In addition, the fact that the Intebrake is part of the engine itself means that the Signature 600s electronic control module can increase braking power automatically.

The Jacobs C-Brake will be an option on the new heavy-duty lightweight ISL engine from Cummins, scheduled for production in mid-1999. Designed for full integration with the ISL, the C-Brake will greatly increase stopping power while sharply reducing wear on service brakes, says Cummins.

Jacobs has also designed a brake for Mack Trucks E-Tech engine. The Jacobs 690 J-Tech engine brake is based on the companys J-Cam technology, which involves advances in valve actuation. According to Jacobs, there is a small braking bump on the exhaust valve camshaft. By leaving clearance in the system during positive power, the bump is ignored. When braking is desired, the J-Tech brake takes up the clearance. As the bump comes around on the cam, the J-Tech brake hydraulically passes the motion to the exhaust valve. In addition to producing up to 360-hp. braking effort at 2,100 rpm, the J-Tech provides enhanced performance in the 1,500-1,800 rpm range, where engine brakes are most likely to be used.

Caterpillar offers a specialty engine brake for applications such as logging, where a great deal of power is required. The BrakeSaver is available on Cats 3406E and 3406C engines.

TecBrake supplies engine brakes for Caterpillar, Cummins, and Mack engines and says that its parts and tune-up kits can also be used for Jacobs and Pacbrake models. Manufactured by Tecmur, a TecBrake affiliate located in Torreon, Mexico, the companys products are sold in North America through a network of warehouse distributors. The company has established a program that allows people to trade in used engine-brake housing assemblies for new TecBrake housings, regardless of original manufacturer.

With more and more communities banning the use of engine retarders because of the noise sometimes associated with them, at a recent meeting of The Maintenance Council, Larry Strawhorn, vp-engineering for the American Trucking Assns., called for the industry to get serious about addressing the issue.

To this end, Jacobs has been working with Donaldson to develop a silencer for engine brakes. According to Scott Fowler, vp-sales and marketing at Jacobs, theyre close to releasing a product designed with the idea of eliminating engine brake noise and positive power noise in a single muffling product. Fowler points out, however, that much of what people refer to as engine brake noise is really the result of an operator dismantling the muffler.