Poland: SU 46

Railway companies: PKP Cargo, PKP - Polish National Railways

After the Class SP45 has proven itself as the first express locomotive in Poland, the Polish Federal Railways decided to procure a more powerful version to be used in heavy high-class passenger train service. Because of its reliability, the constructors fell back on the FIAT engine of the SP45 and increased its power to 2250 HP. Among the innovative features of the latest PKP diesel locomotive were the electric train heating and the optimised form of the driver’s cabin and the car-body with ribbed side walls.



Prototype SU46-001 is rolled out.



Second prototype SU46-002 is delivered.


After recognising and eliminating some teething problems with the prototype locomotives SU46-001 and SU46-002, the Poznan locomotive manufacturer Cegielski delivered 50 more SU46 locos between 1976 and 1977 with a total power of 1654 KW and a high speed of 120 km/h.

First SU46s in PKP service were used mainly with heavy express passenger trains, for which SP45s had been too weak. Modest deliveries of heavy passenger diesel locomotives never allowed for complete elimination of steam traction, which remained in regular service in Poland much longer than in other European countries. As electrification progressed, steam finally disappeared and later many SU46 were relegated to secondary lines; for a number of years a SU46 with just one or two coaches was not an uncommon view. Despite their designation, which implies a universal locomotive, they were initially seldom used with freight trains; later, however, they often appeared on the Węgliniec-Horka line between Poland and Germany, as Germans were reluctant to let ST43 locomotives in. With gradual introduction of diesel railcars, which offer much better economy on secondary lines, more and more SU46s are being shifted to freight traffic.


The program stopped as the manufacturer focused on building a new two-unit heavy electric freight locomotive, based on EU07 and delivered for the first time in 1977 as ET41. So the PKP continued to import M62 diesel locomotives from the Soviet Union (designated ST44 in Poland) despite the lack of carriage heating devices, an increased fuel consumption and huge damages to the railway tracks.

This immediately resulted in lack of spare parts for existing SU46 machines. Problems with diesel engines were particularly acute, as production of the W2112SSF was also halted. As a result, availability of SP45s and SU46s in PKP service deteriorated rapidly. Many local passenger trains had to be hauled by steam locomotives or diesel freighters with heating cars.


The Ministry of Transport wishes to order 267 slightly modified SU46s. Deep economic crisis, however, turned these plans into a mere wishful thinking. It proved impossible to maintain simultaneous production of electric and diesel locomotives and, as the former were given priority, only two more SU46s were built in December 1985. These machines – SU46-53 and SU46-54 – differed from their predecessors only in minor details and factory designation remained unchanged (externally they could be distinguished by different louvers on side walls).


The 2 prototypes were withdrawn in 1990 (both were later scrapped) and several more were written off in late 1990s, when almost 100 heavy passenger diesels were declared surplus by PKP (in fact, most of them were unserviceable examples, awaiting spares, often for several years).


PKP is split into several companies and SU46 locomotives went to PKP Cargo.


PKP Cargo still has 36 SU46 locomotives. From time to time some of them are hired to be used on passenger InterCity trains.


SU46-049 is rebuilt by PESA and fitted with the MTU 12V4000R43L 12-cylinder diesel engine, d2500 hp. Old traction engines were retained. Car heating equipment was removed and, apart from many minor improvements, cab air-conditioning system and new rectangular headlights were fitted. This "new" locomotive is designated as ST46.

Latest update on the 12th of January 2019 at 21:32

Contributor(s): Tudor C.

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