Powering up: inside the new engine that could drive next-generation US Army combat vehicles
Cummins has installed its latest Advanced Combat Engine (ACE) for installation in a tracked testbed for extensive trials.
The diesel ACE has been developed under US Army Combat Capabilities Development Command and is currently at Technology Readiness Level 6. It is intended for potential installation in the army’s future XM30 Mechanized Infantry Combat Vehicle which is the intended replacement for the currently deployed BAE Systems M2 Bradley IFV... Continues below
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Above: The MICV design chosen to replace the M2 Bradley fleet could use the Cummins ACE diesel. (Photo: US Army)
Some 30 ACE units have been built so far and undertaken company trials. The engine also has commercial applications where the end user requires a high power output with limited available space in the chassis.
The four-cylinder ACE weighs 1,620kg and it features an opposed piston architecture with a two-stroke design. According to Cummins, this provides for a higher power density, improved power-to-volume ratio, higher fuel efficiency and low heat rejection.
Other features include an integrated sump lubrication system with remote filtration, which has helped to reduce the profile of the engine.
The cooling system uses integrated aluminium jacket water aftercoolers and oil coolers to optimise heat transfer, while the air intake combines a Cummins HE500 variable-geometry turbocharger with an integrated gear-driven supercharger.
Using thermally insulated exhaust manifolds and elbows has reduced surface temperatures and also improves safety.
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The current power output of the ACE is 1,000bhp at 2,600rpm, and for US Army trials it was coupled to a SAPA automatic transmission.
By eliminating hydraulics from the power path for both propulsion and steering, SAPA transmissions are claimed to deliver the highest power to the tracks.
The 32-speed power transmission is electro-hydraulically controlled and steering is activated by a system that ‘allows optimum control of the vehicle at high speeds and during sharp turns’. This system provides differential steering, pivot and neutral pivot.
SAPA transmissions were developed in Spain for tracked and wheeled armoured vehicle applications but in anticipation of future US Army requirements a production facility has been completed in Shelby Township, Michigan.
Above: The latest ACE has been installed for trials in a tracked testbed. (Photo: author)
A Cummins ACE, rated at 850hp and coupled to a SAPA ACT 850 automatic transmission and 250kW Honeywell generator was also fitted the GDLS AbramsX main battle tank shown at AUSA in 2022.
Furthermore, Cummins has taken over Meritor, a leading contractor for suspension and mobility solutions, enabling it to offer customers integrated drive packages for tactical,
logistic and ground combat vehicles in the future.
Cummins also has an environmental sustainment strategy called PLANET 2050 which includes ‘powering customer success through carbon neutral technologies that address air quality and designing out waste products and services’.
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