Sisu Terminal Systems Oy (STS) was a Finnish terminal tractor producer. The production began in 1969 as a part of Suomen Autoteollisuus (SAT) and the first vehicles were based on lorry components. The portfolio grew by time. The production facilities were in Hämeenlinna until the mid 1990s, when they were moved to Tampere. The company produced terminal tractors also in Texas under the name Magnum in 1987–2005.
STS became a limited liability company in 1994 and was sold and restructured in 1997. Subsequently, the Sisu brand was replaced by Kalmar.