The Leningrad Electrotechnical Plant (LETZ) of the USSR Ministry of Railways was established in the 1930s on the basis of the signaling and communication service workshops of the October Railway.
In 1940, the Department of Plants of "Lentransproekt" (since 1951 - "Lengiprotrans") began work on the reconstruction of LETZ in order to increase the volume of production. It was planned to manufacture relay equipment for railways in the amount of 75 thousand relays per year.
In 1942, the design was interrupted by the war. In the 1950s, the plant was completed and equipped with modern high-performance automatic machines. The assembly of the main mass types of relays was carried out on two conveyors.
In 1956, the output of relays was increased, the projected capacity was doubled. For a long time, LETZ was the only supplier of relays for the railways of the USSR.
