What is a BT10 bogie?

Bogies are the metal frames that sit independently beneath a railway locomotive or rolling stock to support its wheelset. The BT10 bogie is one of the most successful designs of bogie to date, it was designed in the 1970s and is still in use today.

The BT10 bogie was introduced in the 1970s for use on BR Mk3 coaching-stock. The design replaced the earlier B4 and B5 designs that had been successfully used on the Mk2s since the 1960s. The main difference on the BT10 was the introduction of dual suspension, not only did the BT10s have the coil springs that had been a massive success on both the Commonwealth bogie and the B4, but it also had a secondary airbag located on the pivot plank, combined the suspension gave an unprecedented performance and no doubt contributed to the success and longevity of the InterCity 125.