The MLS Auxiliary Power Unit / Environmental Control Unit (APU/ECU) is designed to provide electrical power and cooling to the Multiple Launch Rocket System (MLRS) tracked vehicle. Both the APU and ECU systems can operate independently of each other. The power plant is a Hatz 2G-40 air-cooled diesel engine with a brushless, permanent magnet generator. The generator system and engine power are controlled by a variable speed governor that optimizes the engine operating speed based on the system load. The ECU is completely electrically driven and can be operated from either the main engine alternators or the APU. The vapor cycle air conditioning system uses R-134a refrigerant and is designed to operate in severe desert conditions.

• Power Output: Provides 8.5 kW of electrical power at 28 VDC and 18,500 Btu/hr of cooling capacity.
• Engine: Features a Hatz 2G-40 air-cooled diesel engine.
• Generator: The system uses a brushless, permanent magnet alternator.
• Weight: The gross weight of the APU is under 330 pounds, while the ECU weighs 150 lbs. The combined gross weight of the system is 480 lbs.
• Fuel: It uses DF-1, DF-2, and JP-4 diesel fuels and takes fuel from the main engine’s fuel tank.