The B3.3 engine from Cummins Inc. powered the Mecalac 12MTX Hybrid wheeled excavator to dual-award-winning success at the INTERMAT show in Paris, France. The machine won the Gold Award for Innovation as well as the Special Environmental Prize. The 68-hp (51 kW) rated 4-cylinder B3.3 engine drives an electrical generator and lithium-ion battery system to achieve 25 percent lower fuel consumption with reduced CO2 emissions and quieter operation.
The 9-ton (8.1 t) 12MTX Hybrid has the ability to operate as excavator, loader, materials handler and other functions with a quick change of tool attachments. Based on the compact and agile 12MTX, the hybrid version is the latest machine from the Mecalac Ahlmann Group, who specialize in equipment ideally suited for city center construction sites with limited operating space.
The B3.3 engine incorporated within the diesel-electric system operates at an engine rpm speed optimized for fuel efficiency. The 68-hp mechanical power of the engine output is rated to match the average power requirement of the machine. When less than 68 hp is needed, the batteries are charged; when more than 68 hp is needed, the electric motor provides additional power up to 99 hp (74 kW). A power loop electronic control system ensures a seamless power adjustment between diesel engine and electric motor.
“We are extremely pleased to be working with Mecalac Ahlmann on the 12MTX Hybrid concept and congratulate them on their award-winning success at INTERMAT,” commented Rainer Wissmanns, managing director of Cummins France S.A.
“The 12MTX Hybrid demonstrates how higher fuel efficiency and lower emissions can be achieved with innovative engineering. Our application engineers worked closely with the Mecalac Ahlmann design team and the generator supplier Heinzmann. This ensured that the B3.3 engine was fully integrated within the diesel-electric powertrain to realize the full potential of this impressive technology.
“As a result, the 12MTX Hybrid with a 68-hp engine offers the same power output and torque performance as the conventional diesel-powered 12MTX equipped with a Cummins engine rated at 98 hp,” added Wissmanns.
With a compact engine envelope, the B3.3 offers a useful space-saving advantage for the diesel-electric installation. The B3.3 is directly coupled to a 20/40-hp (15/30 kW) Heinzmann electric motor generator that is attached to the hydraulic pump as a common drive. The engine requires no starter or alternator.
The diesel-electric system charges the 400V lithium-ion batteries that store the electric power. During machine braking, energy is recovered and transferred to the batteries. The diesel-electric hybrid architecture is designed to be simple and easy to maintain.
The 68-hp-rated B3.3 further enhances the environmental credentials of the 12MTX Hybrid by meeting EU Stage IIIA emissions as well as the lower 0.30 g/kW-hr particulate matter option of U.S. EPA Tier IV Interim. The engine utilizes a clean combustion formula with the simplicity of mechanically controlled fuel injection and a wastegated turbocharger.
The 3.3-L engine is built with a cast-iron bore block and deep, stiff crankcase with structural ribs. This enhanced engine strength enables the B3.3 to achieve in-service durability levels typically associated with much larger Cummins engines, according to the manufacturer.
For more information, visit www.cummins.com.
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