Description
WWII General Electric 5D48AB1 Type-D Dynamotor for M1942 60-Inch Antiaircraft Searchlight
Item Overview
This WWII-era General Electric Model 5D48AB1 Type-D dynamotor was used in the control system of the U.S. Army Model 1942 60-inch antiaircraft searchlight. A dynamotor is a combined electric motor and generator built around a shared shaft. This unit accepted 78-volt direct current and produced 115-volt single-phase alternating current for the searchlight’s position indicators and remote-control equipment.
Identification and Electrical Ratings
The permanent identification plate names General Electric as the manufacturer and identifies the unit as Model 5D48AB1. Its electrical specifications match the dynamotor documented in the Army technical manual for the General Electric Model 1942 searchlight. An attached Sperry tag carries drawing number 803840, linking the component to the related Sperry searchlight equipment system.
- Manufacturer: General Electric
- Model: 5D48AB1
- Type: D
- Frame: 48
- Input: 78 volts DC at 6 amperes
- Output: 115 volts AC at 3 amperes
- Rated output: 210 watts
- Output phase: Single-phase
- Frequency: 60 cycles
- Operating speed: 3,600 rpm
- Duty rating: Continuous
- Sperry reference: Drawing 803840
- Original application: Model 1942 60-inch antiaircraft searchlight
- Status: military electrical component
Original Service Function
The dynamotor operated as a compact electromechanical inverter. Its DC motor turned an AC generator at 3,600 rpm, producing the 60-cycle power required by the searchlight’s zero-reader indicators and Distant Electric Control system. The unit was mounted on the searchlight chassis beneath the main equipment. It did not operate the searchlight’s carbon arc or create the light beam. The carbon arc received power from the system’s separate large DC generating plant.
Zero-Reader and Remote-Control Systems
The zero-reader system helped the crew compare the searchlight’s actual position with the aiming information received from the control station. Indicators showed the operators when the light had reached the ordered elevation and direction. The Distant Electric Control system allowed the searchlight to be aimed from a remote position through electrical control signals. The dynamotor supplied AC power for these indicating and control circuits, but it did not locate aircraft or aim the light by itself.
General Electric and Sperry Markings
The permanent General Electric plate identifies the company that manufactured the dynamotor. The additional Sperry paper tag appears to show that Sperry cataloged, procured, or installed the component under drawing 803840. It should not be interpreted as evidence that Sperry manufactured the dynamotor. Army field manuals explain that General Electric and Sperry Model 1942 searchlight equipment used similar chassis dynamotors and that most major components were interchangeable. The extended hand controllers were an important exception to that general interchangeability.
Model 1942 Searchlight System
The U.S. Army Model 1942 system centered on a mobile 60-inch carbon-arc searchlight carried on a wheeled chassis. A complete field installation also included a separate generating plant, power and control cables, cable reels, a control station, an extended hand controller, tools, spare parts, and protective covers. Early crews worked with sound locators, while later units could receive direction information from radar equipment. Remote controls allowed the crew to place the bright beam on an aircraft while working away from the searchlight itself.
Historical Background
Large antiaircraft searchlights were an important part of night air defense before and during World War II. Their beams helped expose enemy aircraft for antiaircraft guns, observers, and night fighters. Searchlight battalions trained throughout the United States, guarded military bases and important industrial areas, and served with American forces overseas. U.S. Army photographs document 60-inch searchlights with stateside antiaircraft units and with the Fifth Army in Italy during 1944. Radar reduced the need to search the sky with the beam alone, but searchlights remained useful for visual tracking and illumination.
Condition and Completeness
This is a vintage military-surplus electrical component. It may show scratches, dents, worn paint, oxidation, dirt, faded labels, old grease, damaged wiring, tool marks, or other signs of age, service, and storage. The fragile paper Sperry tag may have staining, fading, tears, or missing sections. Electrical operation has not been confirmed unless specifically stated, and the unit should be inspected by an experienced technician before any attempt to apply power. This listing is for one dynamotor only; the searchlight, carbon-arc lamp, chassis, power plant, control station, cables, indicators, and other equipment are not included. Please check the pictures for the general condition of the item.
Ideal For
This General Electric dynamotor is a strong display or restoration component for collections devoted to World War II antiaircraft equipment, military searchlights, early remote-control systems, and historic electrical engineering.
- Model 1942 searchlight restoration projects
- World War II antiaircraft displays
- U.S. Army equipment collections
- General Electric military equipment collections
- Vintage motor-generator and dynamotor collections
- Military museums and educational exhibits
- Historic electrical-control displays
Approx length 13", Approx width 10", Approx height 8", Approx weight 55lbs.
Pictures are stock images of our inventory. Unless otherwise noted, you will not be receiving the exact item shown in the pictures. The pictures are representative of the item’s general condition. The item you receive might be slightly better, or worse, condition than was shown in the pictures.
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