[1] They were based on a design built for use in Brazil five years prior.

The first five units had a 1,035 kW (1,390 hp) engine and screw couplers.

The subsequent units fitted with a 1,145 kW (1,540 hp) engine, auto couplers and were wired for multiple unit operation.

[1][2][3] A characteristic addition to the 1250 class in 1961 was a sun visor to help reduce glare.

Two were withdrawn in the early 1980s, donating parts to the rebuild of the single 1225 class locomotive.