PKP class SM42

SM42 (factory types Ls800E and Ls800P, design type 6D along with subtypes PKP class SM42) is a Polish standard gauge shunter diesel locomotive built for midweight and heavyweight shunting and lightweight local freight traffic, built from 1963 to 1992 by Fablok in Chrzanów also offered to 2013. 1822 locomotives were built, including 1157 for PKP.

SM42 Locomotives are one of the most popular locomotive series throughout Poland (in December 2009, 1224 of them existed including 867 in PKP Cargo livery), in fact these locomotives were the first Polish-designed heavier diesel-electric locomotive.

The technical documentation for this locomotive was developed in 1958-1962 by the state Central Construction Bureau of Railway Stock Industry (CBKPTK) in Poznań, as type 6D. The production was given over to the Fablok Locomotive Factory in Chrzanów, where it was designated Ls800E. These diesel locomotives were designed for heavy and midweight shunting as well as lightweight freight traffic along branchlines and short distances on the mainlines. The most important factors were to replace steam locomotives from shunting duties and the ability to form heavy trains for the newly delivered locomotives classified ST43 and ST44 also the electric locomotives ET21. SM42 is the country's first ever diesel locomotives with a bigger amount of power output, thanks to it the dieselisation of Polish railways increased.

The prototype was ready in December 1963. It was lent to the Polish State Railways (PKP), as the SM42-001, the class designation 'SM' meaning a diesel shunter locomotive, and was tested in Warsaw in 1964. Two improved locomotives were built for the PKP in 1964, and twenty in 1965. In 1967, the locomotive entered serial production and 1,822 were built until production ceased in 1992. During the long production run, some minor improvements were incorporated into the design. The locomotives produced from 1972 onwards (so-called batch 2) had simplified chassis (starting from SM42-521, works no. 8499).

Instead of production for the state carrier, between 1969 and 1992 622 locomotives were built for industrial railways. A variant of type 6D locomotive was a type 101D locomotive, equipped with a steam generator for carriage heating. 268 locomotives of this variant were built and classified as SP42. The locomotive was offered in 6Da factory type and 6Da/R modification type until May 2013, when it was announced by a court in Kraków for bankruptcy of the company.

SM42 is a single cab 4-axle locomotive with Bo′Bo′ wheel arrangement, electric transmission and an electropneumatic control equipped with vigilance control (Czuwak aktywny). The locomotive's prime mover is the a8C22 diesel engine with compression ignition with a power of 800 HP (590 kW) and a capacity of 81,6 L built by H. Cegielski in Poznań. The engine has an unusual for a V engine cylinder bank angle of 50 degrees, which was designed to obtain the narrowest possible engine design and the entire engine compartment of the locomotive in order to maintain visibility from the cab. The engine is not balanced enough, causing the locomotive to strongly vibrate while the engine is running, thus having the nickname "Vibrator".

The locomotive has two levels of springing: the bogie frame relative to the axle bogies (wheel set bearings) using leaf springs and rubber pads, and the spring between the locomotive frame and the bogie frame. Locomotive enables in double traction (unless changes has been made to the equipment). Two units can be controlled from a single place.

Due to the creosote buildup caused by the locomotive exhaust smoke filling the Diameter line tunnel in Warsaw, the concept of making a battery electric locomotive was made at the Central Center for Railway Technology Research and Development (COBiRTK), solution for this was to decrease the amount of smoke filling the tunnel and maintenance costs.