The main differences to Class 23 were the cables on the roof and the provision of wheelslip detection plus an improved starting system.

A second run of six locos produced Type 140, numbered 140.001-140.006 because their top speed was re-geared to 140 km/h (87 mph).

This did not work out too well as the locos lost tractive effort and did not accelerate as fast as the normal Series 125 version.

They continued in service pulling mostly freight trains all over the system and into Holland until their retirement in 2009.

Class 25.5 locomotives were assigned to the Benelux limited stop service between Brussels and Amsterdam hauling I4 coaches.

This idea was later applied to the Class 25 fleet so they could easily work peak hour trains on the electrified part of the network.