British United Traction (BUT) was a joint company owned by the Associated Equipment Company and Leyland Motors which produced railway equipment and trolleybus

Trolleybus

A trolleybus is an electric bus that draws its electricity from overhead wires using spring-loaded trolley poles. Two wires and poles are required to complete the electrical circuit...

es. It was established in 1946.

Products

British United Traction was a major supplier of diesel engine

Diesel engine

A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

s for British Rail

British Rail

British Railways , which from 1965 traded as British Rail, was the operator of most of the rail transport in Great Britain between 1948 and 1997. It was formed from the nationalisation of the "Big Four" British railway companies and lasted until the gradual privatisation of British Rail, in stages...

's first-generation diesel multiple units. These engines were built in 125 hp, 150 hp and 230 hp versions and were branded "AEC", "Leyland" or "Leyland-Albion".

A 275 hp version was supplied to Ulster Transport Authority

Ulster Transport Authority

The Ulster Transport Authority ran rail and bus transport in Northern Ireland from 1948 until 1966.-Formation and consolidation:The UTA was formed by the Transport Act 1948, which merged the Northern Ireland Road Transport Board and the Belfast and County Down Railway...

 for their UTA MPD

UTA MPD

The Ulster Transport Authority Multi-Purpose Diesel was a diesel powered railcar, used in Northern Ireland. It was developed by the Ulster Transport Authority as a progression of the earlier Multi-engined Diesel...

class railcar.