gas engines has helped get more air into the engine at higher speeds, helping manufacturers maintain as flat as possible torque curve across the engine revolution range. [But] it’s important to note that diesel and gas rely on the transmissions and rear axle ratios to help the engine’s torque at the crankshaft drive the bus. Electric motors do not need them.” Arjun Nair, manager of the electric vehicle program


for Thomas Built Buses and Daimler Truck North Amer- ica, noted that commercial vehicles like school buses need torque to be high because they are moving a larger mass. “Because school bus operation is stop-and-go, EVs with almost-instant torque availability ease the driving experience,” he commented. While theoretically correct that diesel and gasoline rely


on the transmissions and rear axle ratios to help the en- gine’s torque at the crankshaft drive, Nair explained that school buses and electric motors do not need them. “The challenge with having a direct drive is that you will need a very large motor to meet the speed and torque require- ments, which is why transmissions and rear axle ratios are commonly used, especially for commercial vehicles.” Still, Nair pointed out that “harsh acceleration” wheth- er in an ESB or an internal combustion engine bus, is bound to have an impact on energy or fuel efficiency. And it’s not a safe driver behavior. “Moreover, in an ESB with quick availability of torque


at the wheels, it is not necessary to floor the pedal to achieve the necessary start-ability,” he added. Brian Alexander, a spokesperson for The Lion Electric


Company, agreed that the way torque is delivered from an electric motor differs greatly for that of diesel. “The powerbands are essentially inverse between EV and diesel. An electric motor has maximum torque from zero RPM, whereas a diesel engine has to rev to reach maximum torque, say around 4,000 RPM, just an assumption for the sake of an example,” he said. “As a result, electric buses are very responsive off the line, so to speak, whereas a diesel can feel sluggish. Overall, this creates a better, much smoother driving experience for the [electric] driver.” The main factor in driver training is teaching drivers


how to maximize regenerative braking, which occurs when lifting one’s foot off the throttle. The electric motor acts as a generator and provides resistance to slow the


vehicle and convert the kinetic energy to send energy back to the battery, said Alexander. “Stepping on the brake pedal would otherwise waste this energy as heat generated by friction from the disc brakes,” he added. “We work with drivers to help them learn to coast to a stop and maximize efficiency.” Bethlehem Central School District (CSD) is among the first non-New York City areas to receive electric bus- es. Karim Johnson, director of transportation and fleet services, pointed out that the more torque available, the better the bus can haul more students and climb hills. “Our district is mixed between suburban neighbor- hoods right outside New York state’s capital city [Albany] and hilly terrain. The five EV buses we are currently operating present an advantage with their available torque over its diesel counterpart for the hilly areas of our community,” he explained. Sandra Mortensen, Bethlehem’s assistant transporta-


tion director for safety and training, suggested that while some may believe many drivers enjoy rapid acceleration, that cannot be said of school bus drivers. “When you are in a large vehicle, the tendency is not to accelerate,” she observed. “Most new [school bus] drivers are hesitant in general. Going fast is not their priority. Most of our driving is in a school district where speed limits are 30 mph or less.” Bethlehem CSD trainers teach slow accelerating from bus stops, lights, in school lots, and maintaining speed limits of 30 mph or less, said Mortensen. “We train to recognize the nuance of these buses and


be aware of the issues of concern,” she added. “Our driv- ers get to know and practice their runs. Any driver can practice using one of these buses anytime they like to get the feel of these buses and learn how to handle their unique characteristics.” A YouTube video posted by Virginia Clean Cities offers best management practices for powering up the high voltage system on a Jouley electric bus. Daniel Droog, a certified trainer for Thomas Built Bus dealer Sonny Merryman, notes that after the key is turned to the run position, all of the lights in the instrument cluster will come on for a few seconds and then go out. The ignition key is then moved to the start position


and released until the green truck light on the dashboard comes on, indicating the high voltage is energized.


Listen to Daniel Droog, a certified trainer for Thomas Built Bus dealer Sonny Merryman in Virginia, talk about the best management practices for powering up the highvoltage system on a C2 Saf-T-Liner “Jouley” electric school bus.


28 School Transportation News • NOVEMBER 2022


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