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Waste Not

More than 300,000 refuse vehicles collect North America's trash and recyclables, with each of them consuming an average of 170 litres of diesel per day. That's a waste - particularly when you consider...

More than 300,000 refuse vehicles collect North America’s trash and recyclables, with each of them consuming an average of 170 litres of diesel per day. That’s a waste – particularly when you consider that much of the fuel is consumed by idling vehicles that need to power auxiliary functions such as sweep and pack cycles.

The wheels may not be turning, but an idling engine may need to rev up to 1,500 RPM to power a single hydraulic pump.

The operators of specialty vehicles, however, are finding a number of solutions that will limit idling requirements, either through the use of refined hydraulic systems or hybrid equipment.

Quebec’s Labrie Environmental Group, for example, has introduced the combination of a full-flow and variable displacement piston pump to power various PTO functions, says Walter Peterson, a market specialist with Parker Hannifin. The system will deliver the 25 gallons per minute to lift a bin of trash, or combine both pumps to offer the 40 gallons per minute to operate a packer while the engine operates at speeds below 900 RPM. The power is also delivered in a package that’s smaller than a completely variable-displacement piston pump.

“The thrower (the employee who loads the trash) can initiate the hopper cycle at any time,” Peterson says, noting how the vehicle can remain in motion during the action.

Since they require lower engine speeds, the systems are also quieter, introducing the opportunity to begin shifts earlier in the day, he adds. Transmission shifters will also last longer because vehicles don’t have to shift in and out of neutral for each function.

Other fleets are seeing the value of hybrid technology to drive PTO functions.

Aerial devices can be powered by electricity that’s generated by the diesel engine, notes Bart Bradley, chassis technical liaison with Altech Industries.

“It’s pretty much the same to the operator as it’s always been,” he explains. Electric motors can be engaged from lower controls, timing out after about 20 seconds of inactivity, while upper controls can be operated through fiber optic connections; tools can be engaged with a simple flick of a switch.

An added benefit for utility companies would be a hybrid vehicle’s ability to generate up to 5 kW of power with the engine turned off, and up to 25 kW of power with a running engine, he says.

“They could provide enough power to a business when trying to restore power to it.”

FedEx Express, meanwhile, is already introducing hybrid vehicles to its urban fleets through the Opti-Fleet Program developed in conjunction with Environmental Defense. And five of the vehicles are operating on the streets of Toronto.

With a 158-inch wheelbase and 16,000 Gross Vehicle Weight Rating, the E700 Hybrid P&D trucks are designed to carry up to 6,000-lb. payloads in 681 cubic feet of cargo space. A Hybrid Drive Unit incorporates a 60-hp motor-generator, automated manual transmission and auto clutch. And a Power Electronics Carrier (battery box) contains lithium-ion, 340V DC battery modules with a motor inverter/controller.

In addition to that, the company is testing a hybrid DaimlerChrysler Sprinter van in Paris, and is developing a gasoline-electric vehicle with Ford and Azure Dynamics that will leverage a 5.4-litre V8 – promising a lower purchase cost, lighter weight, and cheaper aftertreatment than a design that relies on diesel.

“Combined with a gasoline engine, available torque would be closer to diesel engines at low-to-mid RPMs,” he says of the latter designs.

A growing number of fleets are beginning to examine hybrid technologies because of rising fuel costs and increasing electrical power needs. Recent product announcements have included a Class 7 hybrid utility truck from Peterbilt, a hybrid refuse truck from Oshkosh, and a Class 6/7 hybrid utility truck from Freightliner. At the heavier end of the scale, Eaton and Peterbilt have identified a Class 8 hybrid concept, while ArvinMeritor and Wal-Mart have agreed to develop a dual-mode, diesel-electric drivetrain for Class 8 tractors.

Despite the advances, however, there are still barriers to the widespread introduction of hybrid fleets, says Richard Parish of WestStart-CALSTART, a non-profit organization looking to advance the transportation technologies.

“Hybrids are expensive,” he admits. “The business case for them is not quite good enough, so we need some incentives.”

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