When it opened in 1884, the meter-gauge Tramelan-Tavannes Railway procured two small tank locomotives from the SLM, which were intended to be able to cope with the line, which was then up to four percent steep. They had a 0-4-0WT wheel arrangement and used their frames as a water tank. For safety reasons, the chassis was protected on all sides with a wooden plank.
Schematic drawing with dimensions
www.le-rail.ch 
In 1891 a third, almost identical locomotive was purchased. These locomotives were actually a bit too small for the line, but they remained in use until electrification in 1913. Since other meter-gauge lines in Switzerland were subsequently electrified, the locomotives were rented out for the construction work. After some time in reserve they were scrapped in 1940 and 1943. 