OKa1
 OKa-1 at the Railway Museum in Warsaw | |||||
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OKa1 was the designation used by the PKP for light steam locomotive of the Latvian 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.[1]
History
In 1928, management of the
Usage
The locomotives were assigned to the depots in
Technical Details
The locomotives had bogies with an 1A1 axle system for use with superheated steam. The leading axle and drive axle were rigidly fixed to the underframe, the supporting rear axle was on a Bissel semi-truck (the opposite of what was the most common arrangement).[2] The Tk series locomotives were equipped with a pneumatic mechanism that allowed a load reduction on the rear running axle and thus increased the load on the driving axle by 50% when starting the locomotive.[3] The tractive weight as well as the load on the driving axle was 15.4 tons, with a maximum axle load of 17.3 tons.[2] The locomotive had a boiler with 55 tubes, a diameter of 39.5 / 44.5 mm (heating area 20.5 m2) and 26 tubes having a diameter of 100.5 / 108 mm (heating area 24.6 m2). The boiler was equipped with a superheater, having an area of 21.8 m2.[2] It also had a twin-cylinder, twin engine configuration with a cylinder bore of 320 mm and a piston stroke of 520 mm and was equipped with a Walschaerts timing gear.[2] The Tk series in Latvia also included two other locomotives (and tender): Tk-226 with a C-axel arrangement and Tk-227 with a B-axel arrangement.[5] Latvian locomotives of the Tk series should not be confused with the Lithuanian series of Tk locomotives.