LVD Tk class

OKa1 was the designation used by the PKP for light steam locomotive of the former Latvian State Railways Tk series. Built in 1928–1934, the units were of German and Latvian production. After 1945, it was used by the Polish State Railways; it was the only steam locomotive in Poland with one driving axle.

==History== In 1928, management of the Latvian State Railways placed an order for the construction of light and economical locomotives to support suburban traffic. A total of 20 were purchased, of which the first three were built in Germany (Nos. 231–233) at the Hohenzollern plant in Düsseldorf. Locomotive trials were successful, so in 1931 a further six were ordered from German plants (234-236 - Krupp and 237-239 - Henschel), with final assembly and the construction of various parts (such as the driver's cab and water tanks) carried out by the Latvian Fēnikss plant in Riga. Slight improvements to the design were made over the first batch of locomotives delivered. In 1933–1934, the last 11 locomotives were built in Latvian railway workshops: 6 at TFD in Daugavpils (240-242, 248–250) and 5 at TFL in Liepāja (243-247). They were used as an alternative to diesel railcars on lesser-used passenger routes. The locomotives were normally used on 1,524 mm gauge tracks, but also had interchangeable axles for use on standard gauge tracks of 1,435 mm.