The twin-cylinder G 5.1 had been designed to raise the speed of goods trains on main lines.
In addition, more powerful engines were needed for the increasingly heavy train loads.
The G 5.1 was fitted with inside Allan valve gear and the carrying wheels were of the Adams axle design.
[1] Of these, only one - 54 601 (ex Ti1-15, née Danzig 4002, built by Schichau w/n 1113/1900) was returned to Poland on 29 September 1955 and immediately scrapped.
[3] Another seven went to France to the Administration des chemins de fer d'Alsace et de Lorraine (AL) which designated them class G 5.1 and numbered them 3994—4000; they were all passed on to the William Luxembourg Railway (fr) before the AL was merged into the SNCF in 1938.