Hybrid school bus tested
Thomas Built’s Hybrid diesel-electric engine system was given an interested visual inspection by Kern County Superintendent of Schools’ mechanics (from left) Scott Monroe, John Hopkins, Abelardo Leal and mechanics helper Ruth Heath.
Kern County Superintendent of Schools Transportation Services Director Paul Linder gave his reactions to Thomas Built representatives as he test drove the Hybrid Saf-T-Liner C2 school bus.
The bus runs on a combination diesel fuel engine and electric motor powered by a lithium-ion battery pack. Thomas Built, located in High Point, N.C., currently has two prototypes out on the road for demonstration purposes and has orders to build six others. One prototype was making the rounds to school districts and transportation facilities in California this week to generate interest in its emission-reducing features and to promote sales.
“Thomas Built felt KCSOS was a hub for school bus technology and know-how for the county and wanted us to host a demonstration for any of the districts that might be interested in learning about the hybrid,” said Transportation Services Director Paul Linder.
Approximately a dozen mechanics and school transportation officials attended the half day session that included a PowerPoint presentation, vehicle inspection on the hydraulic lift and an extensive test drive by those interested in seeing it in action. Why the interest? Well, the hybrid has many features that could benefit a county with environmental complexities, such as Kern.
As the group was taking its test drive, KCSOS mechanic Scott Monroe was taking it all in with his eyes and ears. “It’s even quieter than the CNG buses we operate, and they are quiet,” Monroe said. “The CNG engines are in the back. This one’s in the front, and I would say it is still more quiet.”
When Linder took his turn behind the wheel, he was impressed by the six-speed Eaton Automated Manual Transmission. That is right — no stick-shifting on this hybrid.
“Step on the accelerator, and it does all the shifting for you,” Linder said. “And not rough, jerking shifts, but it builds up to speed smoothly and makes the shifts between gears just as smoothly.”
What is the hybrid’s major selling point in Bakersfield is also a stumbling block for the rural parts of Kern. According to Thomas Built Manager of Sales Education David Nethercut, the vehicle is at its emissions-reducing best when operating at between 0-20 miles per hour. At that speed, only the electric motor is kicking in. Above that speed, the diesel engine takes over. Simply put, it is most efficient in stop-and-go city driving, but on rural roads or highways at speeds approaching 45-50 mph that advantage disappears.
Still, the hybrid had lots of other pluses. Nethercut said the wider, higher front windshield translates into greater visibility for the driver, making for a safer ride for students.
“The hybrid is not an emission solution. It is an emission reducer,” Nethercut said. “Its fuel economy makes it easier for school districts to reduce operating and maintenance costs. It has a good turning radius, reducing the need for backing up. And for children’s safety, it is durable — constructed by bonding parts with stronger, aerospace adhesives instead of fasteners.”
Thomas Built says in its literature that the hybrid’s diesel/electric combination can “improve fuel economy by up to 30 percent or more.” As far as gas mileage goes, the literature says current tests reveal a fuel savings of 300-450 gallons a year, based on 10,000 miles driven.
Bus West Sales Representative Darren Salo, who has been driving the hybrid to demonstration locations in California, was asked about the gas mileage by a mechanic.
“Driving the bus down here from Gilroy, then Fresno and around the city, it used half a tank, and it is only a 60 gallon tank,” Salo said.
School bus drivers having trouble climbing Kern County’s steep, mountain grades can push the accelerator to the floor to kick in the electric motor again, adding a 60 horse power boost. And, slowing down, going down the grades, causes the regenerative batteries to charge.
Good news — the batteries last between seven-to-10 years. Bad news — the replacement cost is $10,000, which will come down once more hybrids are on the road. Good news — the federal government is awarding grants to buy cleaner burning school buses.
“If we could get one of these hybrids for next to nothing through a federal grant and get better fuel economy, then the cost of replacing the battery would really be a comparatively minor expense down the road,” Linder said.
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