Vibrating shuttle

A vibrating shuttle is a bobbin driver design used in home lockstitch sewing machines during the second half of the 19th century and the first half of the 20th century. It supplanted earlier transverse shuttle designs, but was itself supplanted by rotating shuttle designs.

In order to create a lockstitch a sewing machine intertwines two threads: an upper thread (descending with the needle into the workpiece from above) and a lower thread (ascending into the workpiece from the bobbin below). To intertwine them, the machine must pass its shuttle (containing the bobbin and the lower thread) through a loop temporarily created from the upper thread.

Early sewing machines of the 19th century oscillate their shuttles back and forth on horizontal tracks—an arrangement called a "transverse shuttle". A vibrating shuttle machine, by contrast, 'vibrates' its shuttle in a circular arc. This movement represents less total mechanical motion, which means less friction, less wear, higher maximum speed, and higher reliability than in a transverse shuttle system.

The shuttle itself is long and slender, shaped like a bullet, with a pointed tip that is sometimes called the hook. The tip is pointed for the purpose of intercepting the small loop temporarily created (by a brief upward needle motion) in the upper thread—see pictures below of its operation. The bobbin too is long and slender to fit inside the shuttle; in this regard it is very different than the fat rotary bobbins of later sewing machines.

Although popularized by Singer's 27/127 model series sewing machine, the vibrating shuttle was not invented at Singer.

It was actually invented by Allen B. Wilson in 1850, just one year before he would invent the rotary hook design that would eventually prevail over all other lockstitch bobbin driver designs. Wilson's original patent is US patent 7776, granted 12 November 1850, with reissues RE345 on 22 January 1856 and RE414 on 9 December 1856. The second page of his patent, showing the shuttle in its arc, is shown at left.

He was soon beset with patent litigation from the owners of the John Bradshaw patent:

His machine "had a considerable sale, but was not satisfactory to its inventor, who set himself to work to produce something more practical"—a new rotary hook design.

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