A radial axle is an axle on a railway locomotive or carriage which has been designed to move laterally, along the arc of a circle, when entering a curve in order to reduce the flange and rail wear. William Bridges Adams was an early developer of radial axles.
Radial axles were widely used on carriages in the late 19th century before the adoption of
bogie
A bogie ( ) (in some senses called a truck in North American English) is a chassis or framework that carries a wheelset, attached to a vehicle—a modular subassembly of wheels and axles. Bogies take various forms in various modes of tr ...
s. They were also used on the leading or trailing carrying axles of locomotives, particularly tank locomotives. The idea was tried successfully by
William Adams on the
London and South Western Railway
The London and South Western Railway (LSWR, sometimes written L&SWR) was a railway company in England from 1838 to 1922. Originating as the London and Southampton Railway, its network extended to Dorchester and Weymouth, to Salisbury, Exete ...
in 1882 in a class now known as
"Adams Radials".
Radial axles were also used in locomotives designed by
F.W. Webb of the
London and North Western Railway
The London and North Western Railway (LNWR, L&NWR) was a British railway company between 1846 and 1922. In the late 19th century, the L&NWR was the largest joint stock company in the United Kingdom.
In 1923, it became a constituent of the ...
, and by
William Stroudley and
R. J. Billinton of the
London Brighton and South Coast Railway. Webb's form of radial axle used a
cannon box bearing where the two axle bearings are carried in a single curved casting, the 'cannon box', which can slide sideways in a circular track.
David Joy, designer of
the eponymous valvegear, described encountering these axleboxes on Webb's
Precedent class.
The earlier Adams design had relied on the axle and thrust-faces within the axle bearings to keep the hornblocks in position.
Sources
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{{Locomotive running gear
Steam locomotive technologies
Train axles