Freightliner's Business Class M2e Hybrid is part of a powertrain and fuels road map devised by Freightliner Trucks' parent company, Daimler AG, to reduce fuel consumption and emissions.
“Some people have asked, ‘Why are you bringing the hybrid to the M2?’ ” said vocational sales manager David Bryant. “The M2 is used in a wide variety of applications: towing, tankers, fire rescue, bucket trucks, delivery vehicles. Hybrid technology really brings value in those markets.”
Five reasons:
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Fuel economy. It reduces fuel consumption compared to non-hybrid drive systems. Testing shows a savings of up to 1500 gallons of fuel per year for a typical urban delivery vehicle — nearly $5000 back to the bottom line.
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Lower emissions. Reduces carbon dioxide, nitrous oxide, and particulate emissions significantly.
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Extended wear. The engine and brakes last longer. The hybrid system has been proven to increase brake life by over 100% in urban delivery service.
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Noise reduction. Mounted equipment such as buckets and lifts run from an electric power take-off (ePTO), without noisy idling.
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Reduced idle-time. With the Business Class M2e Hybrid utility truck, idle time is reduced by as much as 87%. Less idle means less fuel, exhaust, heat, noise, and vibration.
The Eaton hybrid electric drivetrain system is the result of more than four years of development and over two million miles of successful field-testing. It features a parallel electric hybrid system that enables the truck to operate using the diesel engine alone, or in combination with the hybrid electric motor. The hybrid motor provides additional power to launch the vehicle and improves fuel economy in stop-and-go operations. The system recovers the energy normally lost during braking and stores that energy in its batteries. Stored energy also powers electric-only operation for electric Power take-off (ePTO) and Auxiliary power generation.
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Regenerative Braking. During braking, the vehicle's kinetic energy is captured and regenerated to charge the hybrid battery. Regenerative braking captures about 70% of the kinetic energy produced. It saves fuel, extends brake wear, and allows for continual battery recharge.
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Electric power take-off (ePTO) and auxiliary power generation. While in ePTO, the engine shuts off and the electric motor powers the tools and hydraulic lift. It saves fuel, reduces emissions and idle time, may replace the need for a tow-behind generator, and is particularly helpful in utility applications.
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Hybrid drive power. It provides an added power boost for hills or rapid acceleration, saves fuel, reduces emissions, increases reliability, and extends brake wear.
The Cummins ISB engine accommodates up to 20% bio-diesel, making it even more environmentally sound. The Cummins ISB engine is also lightweight, weighing approximately 400 pounds less than competitive engines.
The power electronics carrier (PEC) contains high-voltage lithium ion batteries, a controller, cooling fan, and relays, with a reinforced steel frame featuring a two-piece plastic shell. Batteries and PEC internal components are air-cooled. An inertia switch shuts off the unit in a heavy accident. The approximate dimensions are 52“×24“×15“ and it weighs 200 lb. It can be mounted in the body or on the frame rail — the cable is limited to 9' in order to minimize voltage drop.
The hybrid system uses a separate liquid cooling system for the hybrid drive unit (HDU), inverter, DC/DC converter (if ePTO-equipped), and APG (if equipped). There is a 50/50 mix of extended-life coolant and water. The service flush interval is the same as with the diesel engine.
The fuel tank's optimized design fits under the cab on the left-hand side with a 42-gallon tank. Fuel-economy gains offset a 16% reduction in capacity.
The inverter is located back of cab, connected to the HDU, PEC, and hybrid cooling system, and controls the entire high-voltage system through the CAN. It converts DC from the PEC to AC voltage power through the HDU.
The guidelines for the PTO: ePTO and mPTO are available; one PTO port is available, not two; ePTO is limited to 13 hp continuous/26 hp peak at 1100 rpm; ePTO is programmable from 1100 to 1500 rpm; and the combination could be programmed depending on the operation, pending application approval from Eaton.
The benefits to ePTO: engine-off operation; fuel savings; it's quiet; reduction in emissions; and the engine starts to recharge the hybrid battery as needed.
The benefits to mPTO: a higher PTO power output; it runs like a normal truck PTO; there's a hybrid benefit in the driving cycle only; and the hybrid system costs less.
New options
Vocational product manager Ivan Neblett listed the new options for the M2:
Wired Rite pre-wire provision. It is cab/chassis pre-wiring to accommodate the Wired Rite Flex-Panel system and provides power/ground into the cab and a power/communication harness between the dash and overhead switches and power modules. It does not pre-empt multiplexed solutions, but offers additional flexibility to bodybuilders who do not use multiplexing in their installations. The customized switch panel and power module are ordered directly from Wired Rite and are available in day, extended, and crew cabs.
Work brake with return to gear. It is specifically for curb-side refuse applications and employs an Allison 3000 series transmission and service brakes for frequent stop-and-go. On activation, for trucks stopped with service brakes, the work brake is applied, the transmission goes to neutral, the rear service brakes hold the truck, and the stop light turns on. On release, the service brake pedal is depressed, the rear service brakes are released, the transmission returns to gear, and the stop light turns off.
Primaax EX. It provides improved roll stability and steering responsiveness with revised geometry — a 38% increase in steady-state roll gradient, 24% increase in steering responsiveness, 12% increase in steady-state rollover threshold, and 6% increase in transient rollover threshold. It provides the same ride quality as standard Primaax. There is vocational air suspension for dump, mixer, tanker, fire truck, and high CG applications.
Bendix ADB22X-V disc brakes. Advantages: less fade then standard drum brakes; superior stopping performance during repeated high-speed stops, most notably during mountain descents; and service life and maintenance intervals are better than with standard drum brakes. They're available with 22.5“ and 24.5“ wheels.
Michelin X One wide-based tires. Neblett said that although they're known mostly for long-haul applications, “they do have their place not only in urban but vocational applications. In trying to optimize the cost of fuel, this can be one place where you can see savings.” He said lower rolling resistance means more fuel efficiency. There is weight savings for tandem drives (660 lb less than duals with steel wheels, 384 lb less than duals with aluminum wheels). A wider track improves stability on drive axles.