The Ahrens-Fox Company was hard-hit by the stock market crash of 1929 and the subsequent decade-long economic Depression. In 1939, the Ahrens-Fox Company was sold to Harold LeBlond of Cincinnati. The company ceased engine production in March, 1940 and under a new name, Ahrens-Fox Corporation, started making lathes for the milling of gun barrels used on battleships during WW II. Ahrens-Fox reopened its doors for fire engine production in 1946, following the end of World War II. Fire Departments around the country had been unable to replace old equipment for years due to first the Depression and then WWII rationing with its priority for fire fighting equipment going to the military. Orders immediately flowed into Ahrens-Fox.
On March 2, 1852, Abel Shawk, a Cincinnati locksmith, Alexander Bonner "Moses" Latta, a railroad locomotive builder, and Miles Greenwood, an iron-foundry owner, joined their separate corporations to unveil the world's first successful steam-powered fire engine. The City of Cincinnati immediately contracted the inventors to build a steam fire engine. Shawk's quick-steaming boiler, which could raise water in under 10 minutes, made the steam fire engine practical, while Latta lent his locomotive expertise to the steam engine, pump, and chassis.
The Ahrens Fire Engine Company reorganized on August 9, 1910, as the Ahrens-Fox Fire Engine Company. Charles H. Fox was its president. His brother-in-law John P. Ahrens was vice president and another brother-in-law, George W. Krapp, was the treasurer. Continuing a tradition of innovation, Ahrens-Fox introduced its first gasoline-propelled fire engine in 1911. The familiar front-mount piston "pumper" (with the spherical air chamber out front) followed three years later, in 1914, and continued in production until 1952. In 1913, Ahrens introduced its first rotary pumper, but the rotary pumps did not become a standard part of the Ahrens-Fox product line until 1927, with centrifugal pumpers being introduced in 1935. 
The K-S-4 Ahrens Fox is a 700 gallon-per-minute, piston Pumping Truck with a chemical tank, booster tank, and hose car with a shaft driven, Ahrens-Fox built, K motor. Ahrens-Fox fire engines were manufactured in Cincinnati, Ohio, from 1852 to 1977.  The company was known for introducing one of the most profound innovations in world fire service history. Ahrens-Fox replaced volunteer firefighters and manually powered fire engines with paid and trained professional firefighters operating mechanically powered fire engines.
1922 K-S-4 Ahrens Fox Pumper