A diesel locomotive is a teep o railwey locomotive in which the prime mover is a diesel ingine. Several teeps o diesel locomotive hae been developit, differing mainly bi transmission teep, i.e. the means bi which mechanical power is conveyed tae the drivin wheels.
A diesel-mechanical locomotive uses a mechanical transmission in a fashion seemilar tae that employed in maist road vehicles. This teep o transmission is generally leemitit tae law-powered, law speed shunting locomotives, lightweight multiple units an self-propelled railcars.
In a diesel-electric locomotive, the diesel ingine drives an electric generator the output o which provides power tae traction motors that drive the locomotive. Thare is no mechanical connection atween the diesel ingine an the wheels.