250px, Joy Valve Gear Diagram Joy valve gear is a type of

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, Fuel oil, oil or, rarely, Wood fuel, wood) to heat ...

valve gear The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves to admit steam into the cylinder and allow exhaust steam to escape, respectively, at the correct points in the cycle. It can also serve as a reversing ...

, designed by David Joy (3 March 1825 – 1903), Locomotive and Marine engineer, and

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...

ed (no. 929) on 8 March 1879. The British patent has not been found but the US patent (US252224 of 10 January 1882) has. Joy's gear is similar to Hackworth valve gear but has a compensating mechanism which corrects for "the slight inequality in the motion of the valve arising from the arc of the lever". The drawing (right) shows the Joy gear as applied to a

London and North Western Railway The London and North Western Railway (LNWR, L&NWR) was a British railway company between 1846 and 1922. In the late 19th century, the LNWR was the largest joint stock company in the world. Dubbed the "Premier Line", the LNWR's main line connec ...

locomotive. The US patent shows several modifications of the gear. In figure 6 of the patent, one of the levers has been replaced by a slide. On 10 January 1882, Mr. Joy received U.S. Patent No. 252,224 for the invention.

Operation

The movement is derived from a vertical link connected to the

connecting rod A connecting rod, also called a 'con rod', is the part of a reciprocating engine, piston engine which connects the piston to the crankshaft. Together with the crank (mechanism), crank, the connecting rod converts the reciprocating motion of the p ...

. The vertical movement is translated into the horizontal movement required by the valve spindle by a die block moving in a slide which can be varied in inclination. The necessary 90 degree phase shift is obtained not from an

eccentric Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off- center, in geometry * Eccentricity (graph theory) of a ...

, as with most designs, but from both the nominal 90 degree difference of the "vertical" link with respect to the horizontal connecting rod and the 90 degree phase difference between the horizontal and vertical components of the motion of the connecting rod.

Applications

Joy's valve-gear was used extensively on

Lancashire and Yorkshire Railway The Lancashire and Yorkshire Railway (L&YR) was a major History of rail transport in Great Britain, British railway company before the Railways Act 1921, 1923 Grouping. It was Incorporation (business)#Incorporation in the United Kingdom, incorpo ...

and

locomotives, and also on the

Manning Wardle Manning Wardle was a steam locomotive manufacturer based in Hunslet, Leeds, West Yorkshire, England. Precursor companies The city of Leeds was one of the earliest centres of locomotive building; Matthew Murray built the first commercially ...

-built

narrow gauge A narrow-gauge railway (narrow-gauge railroad in the US) is a railway with a track gauge (distance between the rails) narrower than . Most narrow-gauge railways are between and . Since narrow-gauge railways are usually built with Minimum railw ...

2-6-2 Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of two leading wheels, six coupled driving wheels and two trailing wheels. This arrangement is commonly called a Prairie. Overview The maj ...

locomotives of the

Lynton and Barnstaple Railway The Lynton and Barnstaple Railway (L&B) was a single track (rail), single track, narrow gauge railway. It opened in May 1898 and ran for slightly more than through the area bordering Exmoor in North Devon, England. Although it opened afte ...

. Joy gear was also used by John Fowler & Co. and several other steam

traction engine A traction engine is a steam engine, steam-powered tractor used to move heavy loads on roads, plough ground or to provide power at a chosen location. The name derives from the Latin ''tractus'', meaning 'drawn', since the prime function of any ...

manufacturers. The most numerous locomotive class using Joy valve gear was Russian O class, in O^d and O^D variants (over 4,500 built) - a letter "d" / "D" in their designations stood for Joy (in Russian phonetically: Джой - Dzhoy). Joy's valve gear was used in the

Doble steam car The Doble steam car was an American steam car maker from 1909 to 1931. Its latter models of steam car, with fast-firing boiler and electric start, were considered the pinnacle of steam car development. The term "Doble steam car" comprises any ...

until replaced by Stephenson's valve gear.

Preservation

The last locomotives with Joy valve gear to remain in service with

British Rail British Railways (BR), which from 1965 traded as British Rail, was a state-owned company that operated most rail transport in Great Britain from 1948 to 1997. Originally a trading brand of the Railway Executive of the British Transport Comm ...

ways were the LNWR G2 and G2A Classes, of which one of the former class is preserved.

Greenly-Joy valve gear

There is a modified Joy gear designed by

Henry Greenly Henry Greenly (1876–1947) was amongst the foremost miniature railway engineers of the 20th century, remembered as a master of engineering design. Miniature railways Greenly is perhaps best remembered for his miniature locomotive designs. He wo ...

for

miniature railway A ridable miniature railway (US: riding railroad or grand scale railroad) is a large scale, usually ground-level railway that hauls passengers using locomotives that are often models of full-sized railway locomotives (powered by Diesel engine, ...

steam locomotives.Steel, E.A., ''Greenly's Model Steam Locomotive Designs and Specifications'', Cassell and Company, London, 1952, pp 16-17

References

External links

U.S. Patent 252,224
for Steam-Engine Valve-Gear
LNWR Society

at steamindex.com

at steamindex.com * A software simulation of Joy - and other common valve gear configurations - is available for download from

{{steam engine configurations Locomotive valve gear English inventions