Mixed-traffic locomotive
Encyclopedia
A mixed-traffic locomotive is one designed to be capable of hauling both passenger trains and freight train
s. The term is mostly used in the United Kingdom
and those nations following British practice. Mixed-traffic locomotives were common in the early years of railway development, but changing traffic patterns meant that later designs would tend to be more specialised, to haul the fastest passenger trains and the heaviest freight trains. Driving wheel
sizes were generally intermediate: larger than the small wheels of most freight locomotives, required to produce a high tractive effort
at low speeds, but smaller than the large wheels express passenger locomotives required to reach high speeds.
The term was generally only used for steam locomotive
s, since most of the first generations of British mainline diesel locomotive
s were equally capable of hauling both passenger and freight trains, specialised designs not appearing for many years.
Freight train
A freight train or goods train is a group of freight cars or goods wagons hauled by one or more locomotives on a railway, ultimately transporting cargo between two points as part of the logistics chain...
s. The term is mostly used in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
and those nations following British practice. Mixed-traffic locomotives were common in the early years of railway development, but changing traffic patterns meant that later designs would tend to be more specialised, to haul the fastest passenger trains and the heaviest freight trains. Driving wheel
Driving wheel
On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons...
sizes were generally intermediate: larger than the small wheels of most freight locomotives, required to produce a high tractive effort
Tractive effort
As used in mechanical engineering, the term tractive force is the pulling or pushing force exerted by a vehicle on another vehicle or object. The term tractive effort is synonymous with tractive force, and is often used in railway engineering to describe the pulling or pushing capability of a...
at low speeds, but smaller than the large wheels express passenger locomotives required to reach high speeds.
The term was generally only used for steam locomotive
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...
s, since most of the first generations of British mainline diesel locomotive
Diesel locomotive
A diesel locomotive is a type of railroad locomotive in which the prime mover is a diesel engine, a reciprocating engine operating on the Diesel cycle as invented by Dr. Rudolf Diesel...
s were equally capable of hauling both passenger and freight trains, specialised designs not appearing for many years.