The first evidence of the nickname crocodile locomotive refers to the green Märklin model railway locomotives in gauge 0, item CCS 66/12920, as well as in gauge 1, item CCS 66/12921, which snake through the curves like a reptile when running through switch roads and counter curves, and are first referred to as such in the Märklin catalogue of 1933/1934.

These locomotives were developed for pulling heavy goods trains on the steep tracks of the Gotthardbahn from Lucerne to Chiasso, including the Gotthard Tunnel.

The electric motors available at the time were large and had to be body-mounted above the plane of the axles, but flexibility was required to negotiate the tight curves on the Alpine routes and tunnels.

[4][page needed] Nine out of 51 total produced have survived, but only three are still in operation as preserved historical locomotives in Switzerland.

This required raising the jackshaft above the plane of the axles, necessitating a more complex system of side rods.

The Bernina Railway (later merged with the RhB) also built a single Crocodile type, the Ge 4/4 No.

Two other Swiss narrow-gauge railways also have locomotives nicknamed Crocodiles; the BVZ Zermatt-Bahn (BVZ) (which merged with the Furka Oberalp Bahn (FO) in 2003 to form the Matterhorn-Gotthard-Bahn) uses series HGe 4/4I , known as the Zermatt crocodile, while the Chemin de Fer Yverdon-Ste.

These locomotives, of series WCG-1, were used from 1928 between Bombay and Pune, and were all built to the Indian broad gauge of 5 ft 6 in (1676 mm).

In the United Kingdom, the LNER Class ES1 featured a crocodile-like design and was built between 1902 and 1904, both locomotives remaining in service until 1966, when No.2 was scrapped and No.

Furthermore, some examples of locomotives similar in design to the Crocodiles, which were manufactured by Škoda can be found on the route between Borjomi and Bakuriani in Georgia.