Brakes: The main wheels were equipped with dual multiple-disc hydraulic brakes with a back-up air brake system for use in the event of a complete hydraulic failure.
Hydraulics: A single high-pressure hydraulic system operated the tricycle landing gear, wing flaps, engine cowl flaps, bomb bay doors, and brakes. The system was powered by two engine-driven hydraulic pumps, one of which would run the hydraulic system with sufficient pressure should the other fail. The accumulators also retained a small amount of pressurized hydraulic fluid to permit one-way emergency operation of the wing flaps, cowl flaps, bomb bay doors, and brakes. An emergency hydraulic system with a hand-pump and a selector valve was also provided to permit operation of the system in the event of the failure of both engine-driven pumps, or if the airplane was on the ground with the engines inoperative. Schematics for the hydraulics system is provided at the following links:
Engines: Two Wright R-2600-13 Double Cyclones. The engines were fourteen-cylinder, air-cooled, staggered, twin-row radials and were equipped with two-speed superchargers. Due to the high compression ratio, the engine operated on 100-Octane fuel. Individual flame-dampening exhaust stacks reduced the glare for night flying. Under normal operating conditions, the engines developed a maximum of 1,700 brake horsepower (BHP) for take-off at 44.3 inches of mercury and 2,600 revolutions/minute (of the crankshaft, not the propeller). The cylinders were numbered in a clockwise direction when looking from the rear of the engine forward to the propeller -- Number 1 being the top cylinder of the rear row with Number 2 to its right in the front row. Thus, all odd numbered cylinders are in the rear row and all even numbered cylinders in the front row. Additional information pertaining to the Wright R-2600-13 is provided at the following link: Wright R-2600-13 Double Cyclone
Propellers: Two three-bladed Hamilton Standard Hydromatic, full-feathering propellers with a diameter of 12 feet 7 inches. The propellers were controlled by double-capacity governors and had pitch settings from 22 to 90 degrees.
Electrical System: The electrical system was a 24 volt direct current, single-wire type, with the structure of the aircraft serving as a common ground return circuit. Two engine driven generators supplied the power to the aircraft to operate various pieces of electrical equipment and recharged the batteries. The batteries were only used when the generators were not operating, and each battery had sufficient capacity to operate the aircraft's electrical system. An external power socket was located on the outboard side of the starboard engine nacelle aft of the firewall to permit an external power source to be used in starting the engines and operating the electrical system while the airplane was on the ground.
Standard Fuel Capacity: 974 US gallons in ten self-sealing tanks located in the wings.
Additional Fuel Capacity: See Bomb Bay Configurations, below.
Oil System: Each engine was provided with an independent oil system by the means of a self-sealing oil tank located in each engine nacelle. Scavenged oil flowed through two oil temperature regulators and oil coolers in each wing where it was cooled by the air-flow entering a scoop just inboard of the engine nacelle, and exiting through apertures on the upper trailing edge of the wings. The air ducts were equipped with full-closing shutters which were controlled by levers on the pilot's control pedestal. Circulating oil was also used to supply the propeller feathering system. A schematic for the oil system is provided at the following link: Oil System Schematic