Diesel locomotive break down. Hydraulic transmission for locomotives was developed in Germany. There is still debate over the relative merits of hydraulic vs. electrical transmission systems: advantages claimed for hydraulic systems include lower weight, high reliability, and lower capital cost. By the 21st century, for diesel locomotive traction worldwide the majority of countries used diesel–electric designs, with diesel hydraulic designs not found in use outside Germany and Japan, and some neighbouring states, where it is used in designs for freight work. In Germany and Finland, diesel–hydraulic systems have achieved high reliability in operation. In the UK the diesel–hydraulic principle gained a poor
Diesel locomotive 1970s onwards diesel–electric transmission has dominated. The earliest recorded example of the use of an internal combustion engine in a railway locomotive is the prototype designed by William Dent Priestman, which was examined by Sir William Thomson in 1888 who described it as a ""[Priestman oil engine] mounted upon a truck which is worked on a temporary line of rails to show the adaptation of a petroleum engine for locomotive purposes."". In 1894, a two axle machine built by Priestman Brothers was used on the Hull Docks. In 1896 an oil-engined railway locomotive was built for the Royal Arsenal, Woolwich,