PKP Ok22
Ok22-31 in Wolsztyn
Type and origin Power type Steam Builder Hanomag (5) Fablok (185) Build date 1923, 1928–1934 Total produced 190
Specifications Configuration: ​  • Whyte 4-6-0  • UIC 2′C h2 Gauge 1,435 mm (4 ft 8+1⁄2 in) standard gauge 1,524 mm (5 ft) Russian Railways Leading dia. 1,000 mm (39.37 in) Driver dia. 1,750 mm (68.90 in) Wheelbase 8.350 m (27 ft 4+3⁄4 in) Length 18.612 m (61 ft 3⁄4 in) 18.940 m (62 ft 1+5⁄8 in) Height 4.625 m (15 ft 2+1⁄8 in) Axle load 17 tonnes (17 long tons; 19 short tons) Adhesive weight 51.0 tonnes (50.2 long tons; 56.2 short tons) Loco weight 78.9 tonnes (77.7 long tons; 87.0 short tons) Tender weight 50 tonnes (49 long tons; 55 short tons) Tender cap. 10 t (9.8 long tons; 11 short tons) Firebox: ​  • Grate area 4.01 m2 (43.2 sq ft) Boiler pressure 12 kg/cm2 (1.2 MPa; 170 psi) Heating surface: ​  • Firebox 14.1 m2 (152 sq ft)  • Total surface 182.1 m2 (1,960 sq ft) Superheater: ​  • Heating area 61.6 m2 (663 sq ft) Cylinders Two, outside Cylinder size 575 mm × 630 mm (22.6 in × 24.8 in)
Performance figures Tractive effort 123 kN (27,650 lbf)
Career Operators PKP » DRB » PKP Class PKP: Ok22 DRB: 3845 Numbers PKP: Ok22-1 to Ok-22-190 DRB: 38 4501 to 38 4630 Disposition Two preserved, remainder scrapped

PKP class Ok22 is a class of ordinary passenger (O) 4-6-0 (k) steam locomotive designed in 1922 for Polskie Koleje Państwowe (Polish State Railways, PKP). It was the first locomotive designed in Poland after World War I, so the design work was done jointly with Hanomag, based on the Prussian P 8 (PKP class Ok1)

The first five engines were built in Germany by Hanomag in 1923. Polish production started in 1928 and lasted until 1934 after which 185 locomotives had been manufactured by Fablok in Chrzanów.^[1] The first Polish-built locomotive (Ok22-6) was ready on December 31, 1928. Polish versions of the locomotive bore some improvements and changes compared with German ones, and were similar to PKP class Ty23.^{[clarification needed]} Ok22 locomotives were the first on the PKP to be equipped with electric lights.^{[citation needed]}

After the German invasion of Poland in World War II, most Ok22 locomotives were taken into the Deutsche Reichsbahn fleet as 38 4501 to 38 4630.

Only two examples have survived. Ok22-23 in Jaworzyna Śląska and Ok22-31 in Wolsztyn. Ok22-31 was an operational engine. It ran until 1997, and after retirement became a stationary exhibit. In 2004 the machine was restored to working order again, and it ran until 2009. It is currently static.

• PKP classification system

• Durrant, A. E. (1972). The Steam Locomotives of Eastern Europe. Newton Abbot, Devon: David and Charles. ISBN 0-7153-4077-8.
• "Ok22". Live Machines (in Polish). Retrieved June 6, 2007.