Hjalmar G. Carlson
Hjalmar Gotfried Carlson (1879–c. 1930s) was an American sheet metal worker, expert in metal drawing, superintendent, and inventor who worked in Worcester, Massachusetts. Born in Östergötland, Sweden, he came to the United States in 1900 and settled in Worcester. He spent most of his career at the Rockwood Sprinkler Company, rising from sheet metal worker to general superintendent and mechanical engineer. Many of his patents were assigned to Rockwood.
In 1921 he received the first ASME Medal for his part in producing 20,000,000 Mark III drawn steel booster casings, used mainly in 75‑mm high-explosive shells and bombs. In 1924 he earned the first Holley Medal for inventions and processes in ordnance that aided World War I. An ASME committee noted his development of a cold-drawing process and its sale to the U.S. Ordnance Department, with the method later refined for practical manufacture. The 20 million casings were used in shells, bombs, gas shells, and other munitions.
In 1930, when Rockwood Sprinkler Co. was absorbed by Gamewell Co., Carlson resigned as superintendent. His great-grandson Evan Carlson (2017) recalls that Carlson’s inventions changed lives, such as the overhead sprinkler system seen in buildings around the world, and an early version of today’s bottle cap.
This page was last edited on 2 February 2026, at 23:16 (CET).