A sandbox is a container on most

locomotive A locomotive or engine is a rail transport vehicle that provides the motive power for a train. If a locomotive is capable of carrying a payload, it is usually rather referred to as a multiple unit, motor coach, railcar or power car; the ...

multiple unit A multiple-unit train or simply multiple unit (MU) is a self-propelled train composed of one or more carriages joined together, which when coupled to another multiple unit can be controlled by a single driver, with multiple-unit train cont ...

s and

tram A tram (called a streetcar or trolley in North America) is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport ...

s that holds

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class ...

, which is dropped on the rail in front of the driving wheels in wet and slippery conditions and on steep grades to improve traction.

Sand delivery

The sand may be delivered by gravity, by a steam-blast (

steam locomotive A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, oil or, rarely, wood) to heat water in the loco ...

s) or by compressed air. Gravity sanding requires that the sand be dry so that it runs freely. Locomotives use multiple sandboxes, so that their delivery pipes could be short and nearly vertical. Engine sheds in the UK were equipped with sand drying stoves, so that sandboxes could be refilled each morning with dry sand. Steam locomotives in the US had a single sandbox, called a sand dome, atop the boiler where the rising heat helped to dry the sand. Even with this arrangement, sand pipes tended to clog, and by the 1880s, pneumatic sanding systems were being proposed.

Steam sanding

60009 Union of South Africa Using sanders to pull away

The development of steam sanding was influential on locomotive design. As the sand could then be blown horizontally and directly under the wheels, it was no longer blown away by cross-winds before it could be effective. This prompted a resurgence of interest in some older single-driver locomotive designs, that had previously been limited by their adhesion performance. The development of Holt's steam sanding gear on the

Midland Railway The Midland Railway (MR) was a railway company in the United Kingdom from 1844. The Midland was one of the largest railway companies in Britain in the early 20th century, and the largest employer in Derby, where it had its headquarters. It ama ...

in 1886 prompted

Johnson Johnson is a surname of Anglo-Norman origin meaning "Son of John". It is the second most common in the United States and 154th most common in the world. As a common family name in Scotland, Johnson is occasionally a variation of ''Johnston'', a ...

to design his successful '

Spinner Technology *Spinner (aeronautics), the aerodynamic cone at the hub of an aircraft propeller * Spinner (cell culture), laboratory equipment for cultivating plant or mammalian cells * Spinner (computing), a graphical widget in a GUI * Spinner (MIT Med ...

s' of 1887, twenty-one years after the previous Singles. These 'modern Singles' would continue in production for a further sixteen years on a number of British railways, including the Great Eastern, Great Western, Great Central and Great Northern, and a famous single example, number 123 on the

Caledonian Railway The Caledonian Railway (CR) was a major Scottish railway company. It was formed in the early 19th century with the objective of forming a link between English railways and Glasgow. It progressively extended its network and reached Edinburgh an ...

, which remained in main-line service until 1935.

Diesel and electric locomotives

On diesel and electric locomotives and railcars, sandboxes are fitted close to the wheels so as to achieve the shortest possible length of delivery pipe. Depots may have a sand drier installed to warm and to dry the sand before it is used.

Dangers

Braking sand scattered at a low speed can cause an isolating effect between the wheel and the rail in the case of individually driven traction vehicles. The Federal Railway Authority in Germany instructed the railway companies to avoid sanding at speeds of 25 km / h (or less) on disc-braked locomotives. In its report of 20 August 2013, the ARD magazine Report mentions near misses when the use of brake sand interfered with the electrical contact between wheel and rail, thereby overriding train control systems. For this reason, the Swiss Federal Railways do not permit sanding for braking locomotives. On August 1, 2013, there was a near-collision between two S-Bahn trains at Mainz Main Station. On September 24, 2013, the Federal Railway Authority announced that the cause was too much brake sand on the tracks. :de:Sandstreuer If too much sand is applied, it can lead to problems, especially at the track points or level crossings, where the sand cannot slip sideways. Lastly, the sand increases the friction between rail and wheel flange, which counteracts the wheel flange lubrication; the reduced wheel flange lubrication increases the danger of the wheels climbing up the rail.

References

{{Reflist Locomotive parts Steam locomotive technologies Sand

Sand delivery

Steam sanding

Diesel and electric locomotives

Dangers

See also

References