Sidney Adolph Horstmann, OBE (July 7, 1881 - July 11, 1962) was a British automotive engineer and businessman.
In 1913, Horstmann founded an automotive company that eventually became Horstman Defence Systems Ltd.[1] He was responsible for developing a torsion bar suspension system known as the Horstmann bogie, which is used on many western tanks, including the Centurion and Chieftain. He patented this system in 1922, some nine years prior to Dr. Ferdinand Porsche's similar system which was featured in many German tanks in the Second World War.
Sidney was the son of the German clockmaker Gustav Horstmann, who designed the world's first micrometer with an accuracy greater than 1/10000 of an inch.