Bulleid Firth Brown wheel

The BFB comprises a single disc, with teardrop-shaped indentations to give rigidity, and lightening holes to reduce weight.

Disc wheels also distribute the weight more evenly, reducing hammer blow on [citation needed] (and thus the damage to) the rail.

gives BFB as meaning Beaumont Firth Brown, referring to the engineer at the firm who oversaw the development.

In addition, the wheels were found to be prone to cracking, though this was later attributed to the poorer quality of available steel used during and after the Second World War than to some intrinsic design flaw.

The use of the BFB was discontinued in 1948 after the amalgamation of the Southern into British Railways and Bulleid's departure to work for CIE in Ireland.