Demonstrating the Power of Jacobs’ Advanced Engine Brake

As engine manufacturers began providing high power density engines for better fuel economy and lower cost of ownership for their customers, a need for better engine brake performance at lower rpm became important. While engine manufacturers sought ways to make the engine more efficient, vehicle manufacturers focused on areas such as decreasing aerodynamic drag and reducing rolling resistance from the tires. Together, the need for higher engine brake power was even greater. With these trends in mind, Jacobs’ engineers challenged one another to come up with a new, more powerful engine brake solution.

After years of development, testing, and durability studies, the Jacobs team had full confidence in their new engine brake—High Power Density® (HPD®). With this confidence, Jacobs purchased a vehicle in Europe, installed the HPD system, and began vehicle testing by traveling across the continent in 2015. It was now time to show off this new technology and put OEMs, fleets, and drivers behind the wheel to experience the power of the advanced engine brake system.

In the spring of 2016, Jacobs hosted a week-long ride and drive event at the Millbrook Proving Ground in Bedford, UK, where OEMs around the globe had the opportunity to test drive Jacobs HPD demonstration vehicle. During the test drives at Millbrook, guests had the opportunity to first drive a comparison vehicle with the current Jacobs production engine brake before getting behind the wheel of the HPD demonstration truck. Both vehicles were the same model and fully loaded to experience the power of the new engine brake. The route consisted of twists and turns and hills with grades up to 21 percent. With the HPD engine brake, even untrained drivers were able to descend the 21 percent grade safely and under control without having to step on the brakes unlike the vehicle with the standard engine brake which required service brakes to slow the vehicle.

After driving the two vehicles, drivers exited the vehicles with smiles. Those who were skeptical of the HPD system were now believers. Even a few drivers asked to take the HPD demo truck back on the route for a few more laps. After experiencing both the standard compression release brake and the High Power Density engine brake, the Jacobs team gathered VOC to learn more about the drivers’ experience. Initially reserved about the possible differences between standard engine brake and the new HPD system, the drivers explained afterward that having so much more braking power at low engine speeds added greatly to them feeling safe and secure going down steep hills. In addition, as many of the participants stated, the fact that one does not need to downshift as much as before means a greater focus on the road and traffic, and it adds to the driver’s overall comfort level.


After the successful launch of HPD at Millbrook, Jacobs decided to take the demo truck on the road to get feedback from experienced truck drivers. The truck stopped at Extra’s Beaconsfield Service Area in Beaconsfield, UK, just off the M40. Throughout the day, drivers were able to drive the truck both on the highway and town roads using the HPD engine brake while descending hills and slowing in traffic.

The drivers who were willing to test the HPD demo truck had vast experience using engine brakes in addition to other secondary braking devices such as driveline retarders. And, all of them liked the system a lot, although they quickly noted the prototype-level integration of the system in the truck. The very high engine braking power at low speeds again won most of their awe, but the drivers were also very sensitive to the commercial aspect of the system. Their eyes lit up when hearing that the system was so much less expensive than a driveline retarder but still provided all the slowing power necessary to slow down the vehicle. As we would see in future demonstrations like these, the experienced drivers very quickly learned how to use the new level of braking efficiently and very quickly got used to that new level. We often heard them say things such as:

“I wouldn’t accept anything that performs less.”
“The power is absolutely phenomenal to be fair. Better than the Volvo or anything I’ve driven.”
“It's holding me better than my retarder does.”
“You have to have the confidence, but once you do, you don’t even need the brake pedal at all.”
“Wow, that is holding out well with 40 tons back there. Wow, that pulls back amazingly!”