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
ČKD T-669 diesel locomotive ČKD T-669 diesel locomotive T-669.0 (770) class diesel locomotives, built by ČKD are six-axle, with two bogies. The wheel pairs are set in radius arms and have a simple coil spring suspension. The body is mounted on the frame with eight anchors. The locomotive is a hood unit type with an internal, eccentrically-positioned operator's cab. Located underneath the front hood is the traction assembly – a K 6 S 310 DR diesel engine and a TD 802 traction generator – and auxiliary machinery powered by the diesel engine via a hydrodynamic transmission. Chillers and ventilators are located here as well.