The two-car variant, which was supposed to be in service in 2016, received an authorisation to place in service from the German Federal Railway Authority (EBA) at the end of May.
The new 140km/h trains being built by Pesa at its plant in Bydgoszcz, Poland, will be used from the autumn on the Sauerland network on lines RB 43, 52, 53 and 54 as well as RE 17 and 57.
The two-car class 632, which is 43.73m long with a service mass of 86.5 tonnes and a maximum axle load of 12.2 tonnes, is powered by two six-cylinder, four-stroke diesel engines each generating an output of 390kW.
The three-car class 633 will be 57.13m long with a service mass of 120.4 tonnes and maximum axle load of 18.9 tonnes. The two 12-cylinder, four-stroke diesel engines will each have an output of 625kW.
The fleet of 36 trains will replace the currently-used older DMUs by spring 2019.