Analog Computing Component - Limit Stop Rotary

Analog Computing Component - Limit Stop Rotary

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This mechanism was manufactured by Ford Instrument Company for use in analog computing devices such as range keepers and its computers. Called a “limit stop rotary” it limited the number of revolutions in a gearing line.
The aluminum base has two shafts mounted on it that both pass through an oval frame piece. Each shaft also carries a gear which has black arm pieces above and below it. One shaft also has a T-shaped aluminum piece atop it. A ring of ball bearings is between the edges of this shaft and this aluminum piece.
A black mark in ink on the base reads: item 12. A mark on the ball bearing holder reads: FAFNIR USA. A mark on one gear reads: 615430B. A mark on the other gear reads: 615431A. A mark on the edge of the oval frame piece reads: 615661. A mark on the underside of the top frame piece reads: 38-0043 2.
The precise date of the object is unknown but one might guess the 1930s or later.
A.B. Clymer, "The Mechanical Analog Computers of Hannibal Ford and William Newell," Annals of the History of Computing, 15, #2, 1993, 19-34.
Accession file.
Currently not on view
Object Name
analog computing component
date made
ca 1920-1955
Ford Instrument Company
place made
United States: New York, Queens, Long Island City
Physical Description
aluminum (frame material)
iron (gears, shafts material)
overall: 9 cm x 5.2 cm x 5 cm; 3 17/32 in x 2 1/16 in x 1 31/32 in
ID Number
catalog number
accession number
Credit Line
Ford Instrument Company, Division of Sperry Rand Corporation
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History
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