The world's first hybrid street sweeper promises cleaner roads and cleaner air – in addition to a top speed of 60 miles an hour.

The Allianz 4000 hybrid sweeper, currently in use in New York City, features a 6.7-liter Cummins diesel in addition to two 12-volt lithium-ion batteries and an electric-traction drive system. With the setup, Allianz estimates a 40 to 45 percent fuel savings over a diesel-only sweeper.

"A sweeper is not a typical light duty truck and therefore we need to be able to accommodate many different functions including transport, sweeping, dust control and emission compliance," said Allianz sales manager Chad Bormann. Because the sweeper needs to propel itself and spin a broom at the same time, the differential is set up to turn brooms at a constant speed regardless of how fast the sweeper travels.

"We have the ability to operate using a smaller single diesel engine running at lower RPMs," said Bormann. "This alone creates savings against any street sweeper that requires an auxiliary engine in conjunction with the chassis engine to drive and operate the sweep functions. The fuel savings are extreme and the carbon footprint minimal considering that street sweepers are operated for long shifts daily all over the world."

While the per-unit cost of the sweeper has yet to be determined, Bormann says that aside from fuel savings, emissions standards make the hybrid an attractive choice for cities whose fleets must meet certain targets set by law. "This alone helps to justify any upfront additional costs that are associated with the hybrid purchase," he said.

In order to comply with laws in certain states that require street sweepers to be able to travel at highway speeds, the 4000 has a top speed that's governed at 60 mph, though like all other sweepers we've been stuck behind, it can only clean roads between 3 and 7 mph.

Photo: Allianz