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
New Zealand DA class locomotive New Zealand DA class locomotive The New Zealand D class diesel-electric mainline locomotives operated on the New Zealand railway system between 1955 and 1989. With 146 locomotives, it was the most numerous class to ever operate in New Zealand, with five more than the A class steam locomotive. The class were A1A-A1A versions of the Electro-Motive Diesel G12 model, with the design altered slightly to run on New Zealand's rail system, and fit the small loading gauge. They were introduced between 1955 and 1967, and were the first class of diesel locomotives to seriously displace steam traction. Between 1978 and