RunWise. The RunWise system replaces a Class 8 refuse truck’s conventional drive train with a series hybrid drive system that marries the variable features of a hydrostatic drive for urban routes during refuse collection with a mechanical drive for efficient operation at highway speeds.

The system is considered a hydrostatic drive with brake energy recovery and does not require a conventional drive shaft. The engine may be decoupled from the drive train during stop and go driving, delivering greater fuel savings, reduced emissions and engine-off operation when compared with a parallel hybrid.

The brake energy recovery system converts the vehicle’s kinetic energy into stored energy by compressing nitrogen gas in a storage device called an accumulator. This stored energy is then released during acceleration to reduce the energy required from the engine to propel the vehicle.

By combining hydraulic components, advanced control software, and brake energy recovery technology which captures more than 71% of a vehicle’s otherwise lost braking energy, RunWise reuses this stored energy, saving fuel, to power the trash truck during collection routes.

The RunWise hybrid drive system is built around the company’s proprietary Power Drive Unit (PDU); C24 Variable Displacement Bent-Axis Hydraulic Pump/Motors; and Composite Bladder Accumulators, all designed specifically for high power, high start-and-stop applications.

The hydraulic hybrid system consists of:

• Two high-pressure hydraulic pump/motors. As pumps they use mechanical energy to deliver high-pressure oil. As motors they accept high-pressure oil and deliver mechanical energy to drive the vehicle.

• Accumulators. These are the energy-storage devices for the high-pressure oil.

• Oil cooler to maintain the proper operating temperature.

• Power Drive Unit to multiply and transfer torque from the engine input and output shafts and the hydrostatic pump/motors.

• Electronic controller to manage all Power Drive Unit functions. The onboard controller coordinates pumps, hydrostatic motors and accumulators to power the vehicle when in hydrostatic mode during start-and-stop operation while collecting refuse. Instead of solely using power from the engine, accumulated energy from the vehicle’s braking system is stored and used to power the truck each time it accelerates. As the truck reaches highway speed, the PDU transfers from hydrostatic drive to mechanical drive to maximize operational efficiency.

A cradle assembly houses the major RunWise components.

The diesel combustion engine powers the hydraulic power drive unit, with power going to the primary pump and the oil cooler and lubrication pumps. The primary pump supplies the pressure to drive two hydrostatic motors.

These motors drive the output shaft through a simple two-speed gear reduction (Lo and Hi). The two-speed hydrostatic drive runs at low speed from 0-25 mph and high speed from 26-45 mph for urban driving, then combines with mechanical direct drive for more efficient operation at highway speeds (46-60+ mph).

Highway driving may limit gains due to inefficiencies caused by hydraulic losses at high rotating speeds.

The company first unveiled the technology in 2006 in cooperation with refuse truck-maker Autocar (earlier post). In 2010, Autocar and Parker began delivering hydraulic hybrid refuse vehicles to three South Florida municipalities.

Benefits of the system include a 35%-55% reduction in diesel consumption (fleet average 43%) with lower accompanying greenhouse gas emissions; reduced criteria pollutants; increased productivity, and brake savings.

CNG concept. Parker partnered with Autocar, Heil and Republic Services to develop and validate a proof of concept Compressed Natural Gas (CNG) fueled refuse truck equipped with the RunWise Advanced Series Hybrid Drive System. Parker is working with Cummins/Westport for engine calibration.

The CNG concept has already participated in demonstration in Chula Vista, California over one month on a collection route typically served by a traditional CNG truck.

As a vehicle fuel source, natural gas provides comparable amounts of power and acceleration to diesel, while producing lower levels of emissions and particulates, all at a significantly lower cost.

RunWise improves upon the typical gains achieved by using natural gas as a fuel source. As many municipalities and fleet operators look to convert to CNG, the RunWise system is attractive to those who are under pressure to meet reduced emissions mandates.

We are pleased with the initial results of the CNG powered RunWise refuse trucks. Test data shows that the RunWise system is delivering up to 20% incremental fuel savings over traditional CNG trucks and a 10% improvement in productivity, and we can anticipate that reduced brake wear and routine maintenance requirements will also contribute to the value of these clean energy vehicles.

—Shane Terblanche, General Manager, Hybrid Drive Systems Division

Parker said it will continue to develop this technology with its industry partners to commercialize a CNG option for its RunWise Advanced Series Hybrid Drive System.

OSU evaluation. The Ohio State University College of Engineering’s Center for Automotive Research (CAR) conducted testing on CNG, conventional diesel, diesel hybrid and CNG hybrid refuse trucks equipped with the RunWise technology to compare fuel economy and emissions.

The tests, carried out between December 2012 and September 2013, measured fuel economy; carbon dioxide emissions; hydrocarbon emissions (THC); carbon monoxide (CO); and oxides of nitrogen (NO_x) emissions. The tests were conducted in three separate cycles:

• Low speed based on a rear-loading refuse truck serving a densely populated neighborhood (below 20 mph)

• High speed based on a rear-loading truck traveling from a route to a transfer station (above 20 mph)

• Standard speed from a West Virginia University study (a special route cycle developed to compare performance)

Parker IVT for medium-duty applications. Click to enlarge.

Class 4-6 trucks. In 2013, Parker unveiled the hydraulic hybrid Parker IVT (infinitely variable transmission) with brake energy recovery technology for medium-duty Class 4-6 trucks. A smaller version of RunWise, the IVT has been tested for package delivery with US DOE funding by FedEx, UPS and Purolator Courier.

Futures. Parker’s actual business with RunWise and hydraulic hybrid systems is currently all on the Autocar chassis; the units are, for the most part, all automated side loaders. About 50% of the company’s customers are coming back and ordering addition trucks, McGrew said. The company’s hybrid drives unit is actively looking at other applications, both in the refuse market (front-load and rear-load) as well as transit and the medium-duty applications.

For a long time, McGrew noted, the refuse industry was predominantly rear load. Today, there is a move to greater automation, with fewer personnel on the trucks—i.e., a side-loader, where one operator controls the truck and the mechanical grabbing mechanism.

When Parker release a new version of the heavy-duty transmission, it will go after the transit bus market, McGrew said.

All of it will be global. A transit bus application is a great opportunity to tap into the Asian, European and South American markets.

—Mark McGrew

According to McGrew, the development focus right now is on ways delivering a smaller package with less weight, primarily through a focus on the software.

We’re not looking so much to optimize [the hardware]; the pumps are what they are. What we are looking to do is to develop the software—the heart behind the technology and where we get the efficiencies. We are looking to find ways to reduce weight—being able to get a smaller package with less weight, especially when it comes to the refuse industry. The more weight we can get out of the system, the more we can get to a modular design instead of a cradle.

If you take a standard diesel trash truck with a standard Allison transmission, we add about 1.5 tons to the weight of the truck. From a payload standpoint, that truck can’t collect 1.5 tons per route. Especially in states like California, that’s a big deal. From a revenue standpoint, it’s a loss. We are able to offset that loss with reduced fuel and maintenance costs, but in a perfect world we would like to get to a reasonable weight so as not to take revenue away from these guys.

—Mark McGrew

In the future, Parker would like to move to split power Infinitely Variable Transmissions (IVTs), with integration of the hydraulics and the gear box, displacing manual power shift transmissions. This approach is emerging first with the medium-duty market, where the commercial version of the system now under test will be a “simple, normal transmission, just like an Allison,” McGrew said. “We are trying to find a way to do that with the heavy-duty application as well.”

The company’s business barrier, said McGrew, is making sure that the operators can recognize some sort of return on investment in a reasonable period of time.

If I can’t get an ROI in a 4-5 year time frame, the system is of no use. This is the primary barrier for us. Our job as a transmission manufacturer is to figure out how we continue to take price out to continue to make sense for end users.

—Mark McGrew