Garbage Trucks Pick Up Fuel Savings

Makers of hydraulic equipment are vying for some of the glamour and profit associated with green technology. They're starting with garbage trucks.

Eaton Corp. and Parker Hannifin Corp., both based in Cleveland, are pitching rival hydraulic systems designed to slash fuel consumption by refuse trucks, while reducing pollution and brake wear. And they are talking a bit of trash about each other's products. Bosch Rexroth, a unit of Germany's Robert Bosch GmbH, also has hopped on the garbage wagon.

The companies' systems can be built into vehicles made by such manufacturers as Volvo AB's Mack Trucks, Autocar LLC and Paccar Inc.'s Peterbilt.

The so-called hybrid-hydraulic technology makes use of the energy normally lost in the form of heat when drivers hit the brakes. Trucks equipped with it have two sources of power: the ordinary engine under the hood and a hydraulic contraption attached to the chassis.

When the driver brakes, hydraulic pumps push oil against a rubber-like "bladder" filled with nitrogen, creating pressure. When the truck accelerates, pressure is released, providing energy to turn the wheels.

The engine does less work, particularly during fuel-guzzling accelerations, when the hydraulic pumps kick in. Brakes get much less wear because the hydraulics help slow the truck.

The technology has been around for decades but is being rolled out now because fuel costs are up and modern electronics make it more effective. It works best on heavy vehicles that stop frequently, such as trash haulers, city buses and delivery trucks. The added cost wouldn't be worthwhile for passenger cars or long-haul trucks, some experts say.

The hybrid-hydraulic systems are competing with electric-hybrid technology, which uses the energy generated by braking to recharge a vehicle's battery. Hybrid-electric trucks, including delivery vans and buses, are far more common, with about 4,000 on U.S. roads, according to Bill Van Amburg, a senior vice president at Calstart Inc., a nonprofit group in Pasadena, Calif., that promotes fuel-saving technology. Hydraulics can produce a huge surge of energy quickly; batteries are better for releasing stored energy over a longer period.

Mack Trucks, a giant in the trash business, says it thinks electric hybrids—using technology from its parent, Volvo—have greater potential than hydraulics for cutting fuel use and emissions. But Mack installs hydraulic systems for clients who want them.

Parker Hannifin sees potential revenue from sales of hybrid-hydraulic systems of $300 million to $500 million a year within five years, up from a tiny sum today. Research firm Frost & Sullivan says that North American sales of garbage and other sorts of medium- and heavy-duty trucks with hybrid-hydraulic technology will reach 7,200 vehicles in 2016, up from 300 last year.

There are only about 115 garbage trucks with hybrid-hydraulic systems now operating in the U.S. But new registrations of garbage trucks have averaged nearly 7,000 annually in recent years, according to data provider R.L. Polk & Co. Hydraulic companies hope to capture a big share of those sales.

Eaton currently has about 100 of its systems in garbage trucks, Parker Hannifin 11 and Rexroth 34, mostly in Germany.

The hydraulic companies are taking different technological roads. Parker Hannifin's hydraulic system takes the place of a vehicle's transmission, so both the hydraulic pumps and the engine rely on a single mechanism to transmit energy to the wheels. Eaton and Rexroth have "parallel" systems, which use a separate transmission for the engine.

"Ours is like central air-conditioning," says Jeff Cullman, president of the hydraulics group at Parker Hannifin, "and theirs is like a window air-conditioning unit," bolted on to a more traditional structure.