On the Road with Jacobs’ HPD Engine Brake

After a successful launch of the High Power Density® (HPD®) engine brake in early 2016, the HPD demo truck continued its tour by stopping at the Ramstein Autohof, a truck stop in Ramstein, Germany. At the Autohof, truck drivers passing through Ramstein had the opportunity to get behind the wheel of the HPD truck. As during all of our demonstrations, we offered a drive in a comparison truck with the exact same specifications, and then a drive in the truck with the new HPD system. Both trucks were fully laden to 40t GCW to make it a fair comparison. For the Ramstein demo, we chose a route that consisted of a few high-speed sections to get into the higher transmission gears and a few significant slopes for real-time downhill retarding operation. The route is commonly used for demonstrations and comparison drives by Fernfahrer Magazine, who reported as well on the demonstration in its February 2017 issue.
Ramstein was also chosen because of its huge size and its popularity with all kinds of drivers from all kinds of segments of the transportation world and from many different countries. With the US military base around the corner, we bumped into several drivers that transport specific military goods such as ammunition and explosives across Europe. Safety during their daily job is something very dear to these drivers!
Unlike the Beaconsfield demo in the UK, where a driveline retarder is not as much specified, most of the heavy-duty trucks specified in Germany have a driveline retarder. The Ramstein demonstration, therefore, allowed Jacobs to get better insight into how HPD would compare to a driveline retarder, from a daily user’s perspective.

Most drivers that got onboard the HPD demo truck were astounded by the level of performance of the engine brake, especially compared to a driveline retarder. In addition to that and the obvious economical aspect that surprised them, they saw great advantages in terms of added safety and driver comfort, in itself a safety-adding aspect. 

“In any respect, the brake performance is very close to that of a retarder.”
“This thing brakes already at very low rpm. Normally I am around 2100 rpm, now we are at 1200 rpm.”
“A quarter of a retarder cost? That is really interesting.”
“If you have no retarder, then the engine brake is the most important. This system delivers enormous performance on that, I have to say.”

Other demonstrations, on an OEM level, underlined what we have heard from all of the participants, whether experienced or not, any time we had them behind the wheel of the truck: HPD really tends to a need in the market. It certainly proves that the new HPD Engine Brake indeed is the Next Generation of Engine Braking and can deliver a lot of value to the user, whether it is the fleet manager, the driver or even the service technicians whose daily work depend on reliable transportation solutions. It is therefore only logical that Jacobs is currently working on no less than nine OEM development programs concerning HPD, globally.

However, technology never stops, and certainly not at Jacobs Vehicle Systems. Since the tour with the HPD truck, Jacobs developed a less complicated and more cost-effective solution which is called 1.5 stroke HPD. Depending on the engine’s characteristics and basic design limits, 1.5 stroke HPD can deliver close to full HPD performance, while only the exhaust side of the valvetrain is manipulated (verses intake and exhaust with full HPD). Additionally, lower complexity comes from the new modular design, which turns the engine brake into a set of building blocks of which the end-user may decide what he really needs for his applications. A standard compression release brake can be designed such that it transforms very easily into either a 1.5 stroke or a full HPD engine brake. This allows for a better match for the market’s needs with ever globalizing engine platforms while keeping engineering and validation time and cost to a minimum.

This new technology, which makes use of the proven hardware has already undergone Jacobs’ harsh reliability and durability requirements validation, will make HPD easier to integrate into many more engine platforms, including engines that exist also as a compressed natural gas (CNG) or other alternative fueled version. For CNG engines, which are hardly fitted with engine brakes due to their lower compression ratio, HPD can deliver engine braking levels currently only known to be possible on Diesel-powered engines.