The main wheel of wheel or the main axle or pilot wheel of the steam locomotive is a wheel or axle that is not driven in front of the drive wheel. The main wheel axle or axle is usually located in a leading truck. The main wheel is used to help the loko negotiation curve and to support the front of the boiler.
Importantly, the leading bogie does not have a simple rotational motion about the vertical axis, as perhaps first thought. It should also be free to tilt sideways slightly (otherwise the locomotive can not follow the curve accurately - the missing point on a 19th century train pioneer), and some type of spring mechanism is usually incorporated to control this movement and gives a tendency to return to the center. The bogie slid of this type was patented by William Adams in 1865. The first use of the leading wheel is generally associated with John B. Jervis who employed them in the 1832 design for locomotives with four leading wheels and two wheel drive (a type known as Jervis ). In Whyte's system describes the locomotive wheel setting, the locomotive will be classed as 4-2-0: that is, it has four main wheels, two drive wheels, and no wheels left. In the UIC classification system, which calculates the axis rather than the wheel and uses letters to denote a powerful ace, Jervis will be classified 2A.
Leading trucking locomotives are generally considered unsuitable for high-speed usage. The British Railway Inspector condemned the practice in 1895, following an accident involving two 0-4-4 at Doublebois, Cornwall, on the Great Western Railway. Other designers, however, survived with the rehearsals and passengers of the famous Gladstone 0-4-2 class revealed London, Brighton and the South Coast Railway remained in trouble-free service until 1933. A single axle (known as a horse truck) improved stability, while wheeled trucks four are almost essential for high speed operation.
The highest number of leading wheels on a single locomotive is six as seen on the Crampton 6-2-0 type and the duplex locomotive 6-4-4-6 S1 Pennsylvania Railroad and 6-8-6 S2 steam turbines. The six-wheeled main truck is not very popular. Cramptons were built in the 1840s, but it was only in 1939 that PRR used one in S1.
Video Leading wheel
See also
- AAR wheel settings
- Adams shaft
- Trailing Wheel
- UIC Classification
- Whyte Notation
Maps Leading wheel
References
Source of the article : Wikipedia
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