Two of the longest-lived sewing machines, though neither were heavy-duty were the Curved Needle Wheeler & Wilson & the Singer Class 15.
The W&W was n production by 1853 & remained in Singer/Bridgeport catalogs until at least 1924 & perhaps 1925. The Singer 15 was introduced in 1889 & is I believe still in production in the far East for sale to third world countries.
Both were sold as family machines as well as for light industrial machines. Singer bought W&W in 1905 & used their Bridgeport factory for industrials. Only one family machine was ever made there, the Singer 9W which was their version of the W&W D-9
