Hello Hydraulics Albany NY

Just when you thought electric was creating a hybrid monopoly, hydraulic fluid is on its way to clean up the refuse industry. Here's what it is, and why you can't afford to trash the idea.

Science Class

The science behind the regenerative hydraulic braking concept has some similarities to what is used in a hybrid electric, but instead of storing kinetic energy in a battery, regenerative hydraulic braking uses a series hybrid system which stores braking energy in fluid tanks. Bradley Bohlmann, marketing manager, advanced technology, Eaton Fluid Power Group, explains the technology behind what Eaton calls Hydraulic Launch Assist™: "How it works is that we have a hydraulic pump motor that is mechanically attached to the driveshaft of the vehicle and during a braking event, the torque that is normally used to slow the vehicle down by the friction brakes, instead is used to spin the hydraulic pump which transfers fluid from a low-pressure reservoir into a high pressure accumulator."

Then after the brake fluid is stored, it waits for a subsequent acceleration where "the process is reversed, and valves on the high pressure accumulator meter the fluid back to the hydraulic pump motor," he says. The fluid then turns the motor, rotating the driveshaft and transmitting torque to the rear tires through the tire shaft.

Cleaning Up

There's been a lot of media buzz lately surrounding the recent release of a hydraulic hybrid UPS delivery vehicle, an effort shared by Eaton and the EPA, as well as UPS, the US Army and International Truck & Engine Corp. Delivery routes are a good fit for this technology, but the most ideal application looks like it will be refuse vehicles. Because of the high number of starts and stops, this is the duty cycle that seems to allow for the highest return on energy and money.

For this reason, several companies are backing projects, trying to get the best hydraulic hybrid refuse vehicle on the market, and the fastest.

Two to Tango

One of the ways in which this technology was encouraged to flourish was through the active roles of both supply and demand. Bill Van Amburg, senior vice president of California-based WestStart-CALSTART describes the role of their Hybrid Truck Users Forum (HTUF) in the design and spec'ing stages of some of industry's newest hybrids.

"I've actually been very impressed and proud that I think HTUF has been able to shape the specs on some of the new products. Fleets made it very clear that they had a high expectation of increased fuel economy, so it really meant that the manufacturers had to look at their systems," Van Amburg says. "It was a real guider of how that system needed to be set up."

HTUF designated one of its numerous sub-groups to deal strictly with the needs of refuse industry vehicles, the Hybrid Refuse Truck Working Group (HRTWG). The group has no specific technological camp, only endorses vehicles which possess particular performance characteristics relevant to their industry. According to the HRTWG spokesman, Kevin Campbell, automotive engineer, City of Chicago fleet, the members of the group have a big incentive to collaborate:

"The people who are involved in the working group get the first option to select those (new hybrid) units, so they're kind of being snapped up by all the working group members," Campbell says.

Braking and Entering the Market

These hybrid refuse vehicles are teetering on the brink of readiness, so keep an eye out for the photo finish as several manufacturers try to elbow their way to the front of the pack.

Another partnership with a lead on this hydraulic technology is a joint effort on behalf of Parker Hannifin and Autocar. Clive Hindle, business unit manager, energy recovery, Parker Hannifin Corporation, describes their hydraulic offering, Runwise.

"We're continually building on our past successes of earlier brake energy recovery systems that were introduced in the '80's," Hindle says. "The Parker Runwise system is specifically developed for the refuse industry. We introduced Runwise at Waste Expo the first week in April and continue to receive very positive feedback from the industry."

The technology is housed in the E3, a beta stage refuse vehicle prototype. "We performed a side-by-side comparison with a standard Autocar chassis and realized fuel economy improvements of anywhere from 30-50 percent," Hindle says. "We will validate our results with our upcoming beta release scheduled for early next year." According to Hindle, actual production units are slated to be available by early 2008.

Payback is a Bunch

This may sound like a no-brainer, but the bottom line is always in return on investment. How many greenbacks is a green truck worth? Campbell sees this as a potential hurdle for manufacturers who are forced "to show that the initial cost is going to be recaptured in savings."

Vice president for Dana's intelligent hydraulic drive products, Edward Greif, is being tight-lipped about an upcoming hydraulic hybrid offering from Dana and the North American division of Australia's Permo-Drive. He is confident, however, that the value proposition is evident:

"Our target is to achieve no more than a two to three year payback on the technology. I think if you look at some of the hybrid electric technologies that are out there, that's been their problem," Greif says. "While they may actually have some performance characteristics, when you get down to the cost, there just isn't the payback in the sort of range that commercial entities require." Eaton's analysis of HLA™ shows a similar payback length, as does Parker's Runwise.

Fuel efficiency is just one of the payback benefits. Eaton, Parker and Dana all boast major fuel efficiency gains, but all also tout the benefits to other vehicle components. Because there will be less frequent use of the foundation brakes, the increase in brake life in a hydraulic hybrid has the potential to be enormous.

Another benefit? "It's very durable," Campbell says. "It's a very dirty operating environment for a refuse truck, so it might be more durable in that environment than an equal system."

Maintaining

Bohlmann eases any concerns about potential new maintenance: "One of the beauties of the HLA™ system is that it is a hydraulic system," he says. "Refuse vehicles already have a significant amount of hydraulics on them today for all their body packing, load and unloading features. So the mechanics that are taking care of those vehicles have a very good understanding of hydraulic systems, and when they look at the HLA™ system, they're going to see something very similar to what they've worked on before on other parts of the vehicle."

Dana and Permo-Drive say they will be offering a retrofit option, or "kit concept" to take advantage of this. "We've been able to design the system to take advantage of all the current mounting locations on the vehicle," Greif says. "So when the vehicle comes in for maintenance, they can drop out the old components, drop this new system in, without having to drill any holes or add any additional brackets to mount the technology to the vehicle."