each of these geared steam locomotives, one end of each drive shaft was coupled to the driven truck through a universal joint while the other end was powered by the crankshaft, transmission or another truck through a second universal joint. A quill drive also has the ability to slide lengthways, effectively varying its length. This is required to allow the bogies to rotate when passing a curve. Cardan shafts are used in some diesel locomotives (mainly diesel-hydraulics, such as British Rail Class 52) and some electric locomotives (e.g. British Rail Class 91). They are also widely used in diesel multiple units. Drive shafts in bicycles The drive shaft has served as an alternative to a chain-drive in bicycles for the past century, never becoming very popular. A shaft-driven bicycle (or "Acatène", from an early maker) has several advantages and disadvantages: Advantages Drive system is less likely to become jammed. The rider cannot become dirtied from chain grease or injured by "chain bite" when clothing or a body part catches between an unguarded chain and a sprocket. Lower maintenance than a chain system when the drive shaft is enclosed in a tube. More consistent performance. Dynamic Bicycles claims that a drive shaft bicycle can deliver 94% efficiency, whereas a chain-driven bike can deliver anywhere from 75 to 97% efficiency based on condition. Disadvantages A drive shaft system weighs more than a chain system, usually heavier. Many of the advantages claimed by drive shaft's proponents can be achieved on a chain-driven bicycle, such as covering the chain and sprockets. Use of lightweight derailleur gears with a high number of ratios is impossible, although hub gears can be used. Wheel removal can be complicated in some designs (as it is for some chain-driven bicycles with hub gears). PTO drive shafts Drive shafts are one method of transferring power from an engine and PTO to vehicle-mounted accessory equipment, such as an air compressor. Drive shafts are used when there isn't enough space beside the engine for the additional accessory; the shaft bridges the gap between the engine PTO and the accessory, allowing the accessory to be mounted elsewhere on the vehicle. Drive shaft production Nowadays new possibilities exist for the production process of drive shafts. The filament winding production process is gaining popularity for the creation of composite drive shafts. Several companies in the automotive industry are looking to adopt this knowledge for their