trains to increasing use of 'diesel railcars' (or DMUs, diesel multiple units). This led to a reduction in the demand for these locomotives on passenger services, with many falling out of use, or only finding work pulling freight trains, nevertheless, in 2000 the locomotives were still in use on mainline long-distance trains. By January 2008 there were approximately 220 copies still active. Technical information The design of the series as fundamentally the same as the rest of the V 160 family: all four axles are driven via cardan shafts by a Voith two speed hydraulic transmission which in turn is driven by a diesel engine, fuel and oil are located between the bogies under the main frame, on either side of the centrally located transmission, there are two cabs (which have slightly different windows). Externally the machines are very similar to the other members of the class, being of the longer variant at 16.4 m. The tractive and braking forces are transmitted to the main mass of the locomotive via transverse beams attached to the main longitudinal supporting beams, the superstructure is made from sheet steel, forming a shell. The framework supported on coil springs on the bogies, from 218 299 onwards flexicoil suspension was used, per bogie side and from the bogies. There are two walkways connecting the cabins inside the body. Engines Over time, several diesel engines have been used as propulsion; the first series received the MA MTU 12V 956 TB10 with Because of the available power at rail being reduced when operating at full electric heating power some machines were fitted with a French 16 Pielstick PA4 V200 engine with around built under license by KHD. MTU developed from the TB10 engine a TB11 with greater power of which was fitted to more than half the class. With the introduction of more stringent emission requirements, as well as the original engines being badly worn, or in an attempt to improve efficiency, a number of upgrades have been investigated or fitted, including: TB11 engines fitted with emission reducing kit. Electronic engine management fitted to TB11 engines. Testing of entirely new engines, leading to: Procurement of numerous 16 V R40/41 MTU engines as replacements 4 locomotives fitted with Caterpillar Inc engines Following the upgrades most of the class have either emission-improved TB11 engines or MTU 4000 engines. Since 1985, the locomotives have had additional engine exhaust devices fitted