founded Union Switch & Signal in 1881, consolidating the assets of the Union Electric Signal Company and the Interlocking Switch & Signal Company. In 1925 US&S acquired the Hall Signal Company, primarily to obtain the latter company's patents for searchlight signals.
Corporate management
US&S operated as an independent company until 1917, when it became a subsidiary of the Westinghouse Air Brake Company. In 1968, American Standard purchased WABCO and reorganized US&S as a separate division. In 1988, Ansaldo purchased US&S from American Standard. In November 1993, US&S became a publicly traded company with shares listed on Nasdaq. In December 1996, US&S merged with the other signaling investments of Ansaldo. As a result of that merger, US&S is now a wholly owned subsidiary of Ansaldo STS, a global supplier of signaling, control and automation systems. The company was renamed Ansaldo STS – USA in January 2009. Throughout its history, US&S had manufacturing facilities in the borough of Swissvale, Pennsylvania, near Pittsburgh. The Swissvale plant was closed in 1985 and demolished in 1986. US&S moved manufacturing operations to a facility in Batesburg-Leesville, South Carolina. It maintained a research facility in Pittsburgh. Other facilities include a service and repair shop in Kingston, Ontario.
US&S first patented the Model 15A Highway crossing bell on February 20, 1917. The bell has been commonly referred to as the "Teardrop" bell by railroaders and signal fans alike because of its unique shape and thus the name has stuck. This bell has appeared on advertising literature for railroad signals as far back as the 1920s as far abroad as Chile and Italy on early wig wag crossings and flashers. There have been subtle variations in the Teardrop bell over the years ranging from different sized electric coils, inclusion of the patent date on the rain hood, as well as a very early version with a less characteristic rain hood that simply read "UNION, patent pending." This is the least commonly seen variation of the Teardrop. This bell is treasured by many signal collectors for its slow, low pitched ring at an irregular cadence. The production of this bell was discontinued sometime by the 1960s, but WABCO carried replacement castings and service manuals into the 1970s.
Wartime production
During WW1 the Le Rhône 9C 9 cylinder rotary engine was manufactured under license by Union Switch and Signal. It was one of the most common engines for fighter planes from different companies and around 10,000 were made at Swissvale. Union Switch and Signal was one of the five contractors to make M1911A1 pistols during World War II. The production blocks assigned to them in 1943 were between SN's 1,041,405 to 1096404. Colt duplicated 4,171 pistols in the 1088726-1092896 SN range. Since only 55,000 1911A1's were produced by US&S, they are highly collectible. The reason for the low production numbers is US&S was the last company awarded a government contract and as requirements were reduced in early 1943, the last contract awarded became the first to be cancelled. As a general rule, US&S produced high quality pistols. With the government-owned machine tooling already in place at US&S, they were offered a subcontract arrangement to produce M1 Carbine components. Only Singer produced fewer 1911A1's at 500 total production.
