Description
World War II Boeing B-29 Superfortress Central Station Fire-Control Remote-Turret Elevation Drive Assembly, GRS M-8258225G5, with USAAF Motor 5BA50LJ2A
The Boeing B-29 Superfortress Remote-Turret Elevation Drive Assembly, identified as General Railway Signal model M-8258225G5, is an original World War II electromechanical component from the aircraft’s Central Station Fire-Control System.
This assembly operated the elevation axis of a remotely controlled gun turret. It includes a U.S. Army Air Forces direct-current turret drive motor, model 5BA50LJ2A, manufactured by the Electric Vacuum Cleaner Company, Inc.
This is the turret-mounted elevation drive assembly. It is not the central fire-control computer, gunner’s sighting station, complete turret, or complete aircraft fire-control system.
Historical Significance
The B-29 Superfortress used one of the most advanced defensive gun systems placed in a World War II bomber. Instead of placing a gunner inside each main turret, the aircraft used powered remote turrets controlled from sighting stations inside the pressurized fuselage.
The Central Station Fire-Control System combined optical sights, mechanical computers, electrical controls, feedback units, and powered turret drives. These parts worked together to calculate a corrected aiming point and move the selected turret toward the target.
This drive assembly supplied the mechanical movement needed to raise and lower the guns. It helped convert the gunner’s sighting commands into controlled turret elevation.
The remote system reduced exposed crew positions and allowed control to be transferred between gunner stations. It became one of the B-29’s most important technical advances and helped set the aircraft apart from earlier bombers with mostly manned gun turrets.
What This Item Is and Does
The installed direct-current motor turned the assembly’s internal gear train. The gearing reduced the motor’s high speed and produced the controlled movement needed to operate the turret.
A clutch protected the drive and allowed the mechanism to engage or release as required. The original inspection sheet also identifies 1-speed and 31-speed selsyn units. These electrical feedback devices helped the complete system compare the turret’s movement with the gunner’s sighting commands.
The documented assembly also included an interrupter drive, latch, and related mechanical parts. In the complete aircraft installation, the fire-interrupter system helped prevent the guns from firing through protected parts of the aircraft.
This assembly controlled turret elevation only. Separate equipment was required to move the turret in azimuth.
Key Features
- Product type: Remote gun-turret elevation drive and servo assembly
- Aircraft application: Boeing B-29 Superfortress
- Parent system: Central Station Fire-Control System
- Function: Raises and lowers a remote gun turret
- Drive manufacturer: General Railway Signal Company
- Manufacturer location: Rochester, New York
- Drive model: M-8258225G5
- Drive serial number: 362105
- Motor type: U.S. Army Air Forces direct-current turret drive motor
- Motor manufacturer: Electric Vacuum Cleaner Company, Inc.
- Motor model: 5BA50LJ2A
- Motor contract number: W335AC32077
- Motor drawing number: TT-8117000
- Armature rating: 60 volts
- Field rating: 27 volts
- Current rating: 8.3 amps armature and 2.3 amps field
- Rated speed: 4,000 RPM
- Rated output: 1/2 horsepower
- Documented components: Motor, gear train, clutch, 1-speed selsyn, 31-speed selsyn, interrupter drive, and latch
- Included: One elevation drive assembly with installed turret drive motor
Original Inspection Documentation
An original Bowser, Inc. inspection sheet identifies this unit as an Elevation Drive (Turret) and lists the 5BA50LJ2A drive motor.
The inspection covered:
- Starting torque
- Clockwise and counterclockwise operation
- Clutch performance
- Power-train backlash
- 1-speed selsyn backlash
- 31-speed selsyn backlash
- Interrupter-drive backlash
- Runout
- Latch operation
- Electrical operation and noise
A surviving Bowser packing label also identifies the equipment as a Drive Assembly Elevation. The visible date appears to be from 1945, placing the assembly within World War II production. The label lists a gross packed weight of 28 pounds, which should not be treated as the verified bare weight of the assembly.
Why This Item Matters
Original B-29 Central Fire-Control components are difficult to identify after they have been removed from the aircraft. This assembly retains both its General Railway Signal identification plate and the marked USAAF motor plate.
The original inspection paperwork provides additional technical history. It shows how the assembly’s motor, clutch, gear train, feedback units, interrupter drive, and latch were tested before acceptance.
This is a strong display piece for explaining how electrical commands were changed into physical turret movement. It also represents the specialized equipment required to operate the B-29’s remote defensive armament.
About This Item
The General Railway Signal identification plate is marked M-8258225G5 and SER 362105.
The motor plate is marked U.S. ARMY AIR FORCES, DIRECT CURRENT TURRET DRIVE MOTOR, MODEL 5BA50LJ2A, W335AC32077, and TT-8117000.
The assembly may show scratches, chipped finish, dust, grease, oxidation, discoloration, and other signs of age, military handling, and long-term storage.
The motor, clutch, gear train, selsyn units, wiring, and other internal parts have not been tested. Operational condition is not guaranteed.
The visible markings identify the elevation-drive function but do not name a specific forward, aft, upper, or lower turret position. This listing is for the drive assembly and installed motor only. The B-29 turret, machine guns, sight, fire-control computer, amplifiers, wiring harnesses, and aircraft mounting parts are not included.
Ideal For
- Boeing B-29 Superfortress restoration projects
- B-29 Central Fire-Control System displays
- World War II aviation collections
- U.S. Army Air Forces exhibits
- Remote gun-turret displays
- Aircraft servo and drive-system collections
- Electromechanical fire-control displays
- Military museums
- Analog-computer and feedback-control exhibits
- General Railway Signal Company collections
- Historic aircraft-component research
- Educational and technical displays
Approx length 15", Approx width 8", Approx height 10", Approx weight 20lbs.
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