The rotary hook (aka rotary hook, rotating hook) is a bobbin driver design used in lockstitch sewing machines of the 19th and 20th century and beyond. It triumphed over competing designs because it can run at higher speeds with less vibration.
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The rotary hook continuously rotates in place, hooking the upper thread each time its pointed tip passes the 12 o'clock position. Enough upper thread is pulled from above to pass around the bobbin case, which sits loosely inside the hook frame such that loops of thread can pass completely over it, similar to a magician's hoop passing over a levitating subject. The excess thread, no longer needed, is then pulled back upward by the sewing machine's take-up arm.
The technology was invented by Allen B. Wilson in 1851, in steps. Wilson had just left an unsatisfactory business relationship in order to partner with Nathaniel Wheeler, who was impressed by a model of Wilson's vibrating shuttle machine. Ever since developing the aforementioned, Wilson had been ruminating on a plan for a machine that used a rotating hook combined with a traditional reciprocating bobbin. For this hybrid machine he received US patent 8296 on 12 August 1851 (reissued as RE914 on 28 February 1860). Knowing that such a machine would surely lead to patent litigation with his former partners who had bought out the patent for the vibrating shuttle, Wilson kept working, and developed a refined design which kept the bobbin stationary. He filed for patent, and the partners built their first production rotary hook machine the same year, selling it for USD35 (USD891 adjusted). US patent 9041 was awarded the next year, on 15 June 1852.[1]
The rotary hook design was then called the "Wheeler & Wilson principle" after Wilson's partnership with Wheeler.[2]
Just two years later, in 1853, Scientific American took notice:
Later, once the patents had expired, the White Sewing Machine Company used it in the popular 'White Family Rotary' machine.
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