The driving wheels (boxed) on a 4-6-2 locomotive. Under the Whyte notation for the classification of Steam locomotives, a 4-6-2 Locomotive has four Leading wheels (generally arranged in a

On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons (or turbine, in the case of a steam turbine locomotive). A steam locomotive is a Locomotive powered by Steam. The term usually refers to its use on Railways but can also refer to a "road locomotive" A wheel is a circular device that is capable of rotating on its axis facilitating movement or transportation whilst supporting a load ( Mass) or performing labour in machines A locomotive is a railway Vehicle that provides the motive power for a Train. A piston is a component of Reciprocating engines Pumps and Gas compressors It is located in a cylinder and is made gas-tight by Piston A turbine is a rotary Engine that extracts Energy from a Fluid flow A steam turbine locomotive is a Steam locomotive which transmits steam power to the wheels via a Steam turbine. On a conventional, non-articulated locomotive, the driving wheels are all coupled together with side rods (also known as coupling rods); normally one pair is directly driven by the main rod (or connecting rod) which is connected to the end of the piston rod; power is transmitted to the others through the side rods. A coupling rod or side rod connects the Driving wheels of a Locomotive. A coupling rod or side rod connects the Driving wheels of a Locomotive. In a reciprocating Piston engine, the connecting rod or conrod connects the Piston to the crank or Crankshaft. In a reciprocating Piston engine, the connecting rod or conrod connects the Piston to the crank or Crankshaft. In a Piston engine, a piston rod joins a Piston to a Connecting rod.

On Diesel and Electric locomotives the driving wheels may be directly driven by the traction motors. A Diesel locomotive is a type of Railroad Locomotive in which the prime mover is a Diesel engine. "Electric Trains" redirects here For the 1995 Squeeze single see Electric Trains (song. See also Electric vehicle, Electric motor A traction motor is a type of Electric motor used to power the driving wheels of a vehicle such as Coupling rods are not usually used, and it is quite common for each axle to have its own motor. Jackshaft drive and coupling rods were used in the past (e. A jackshaft is a device for turning the wheels of a Locomotive. g. in the Swiss Crocodile locomotive) but their use is now confined to shunting locomotives. Crocodile Electric locomotives are so called because they have long "noses" at each end reminiscent of the snout of a Crocodile. A switcher or shunter ( Great Britain: shunter; Australia: shunter or yard pilot; USA: switcher (or

On an articulated locomotive or a duplex locomotive driving wheels are grouped into sets which are linked together within the set. Articulated locomotive usually means a Steam locomotive with one or more engine units which can move relative to the main frame A duplex locomotive is a Steam locomotive that divides the driving force on its wheels by using two pairs of cylinders rigidly mounted to a single Locomotive frame

Diameter

Driving wheels are generally larger than leading or trailing wheels. The leading wheel or leading axle of a Steam locomotive is an unpowered Wheel or Axle located in front of the driving wheels On a Steam locomotive, a trailing wheel or trailing axle is an unpowered Wheel or Axle located behind the driving wheels Since a conventional steam locomotive is directly driven, one of the few ways to 'gear' a locomotive for a particular performance goal is to size the driving wheels appropriately. The gear ratio is the relationship between the number of teeth on two Gears that are meshed or two Sprockets connected with a common Roller chain, or the Freight locomotives generally had driving wheels between 40 and 60 inches (1016 to 1524 mm) in diameter; dual-purpose locomotives generally between 60 and 70 inches (1524 to 1778 mm), and passenger locomotives between 70 and 100 inches (1778 to 2540 mm) or so. Inches redirects here To see the Les Savy Fav album see Inches. The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to Some long wheelbase locomotives (four or more coupled axles) were equipped with blind drivers. These were driving wheels without the usual flanges, which allowed them to negotiate tighter curves without binding. A flange is an external or internal Rib, or Rim (lip for strength, as the flange of an Iron beam or I-beam

The driving wheels on express passenger locomotives have come down in diameter over the years, e. g. from 8' 1" (2464 mm) on the GNR Stirling 4-2-2 of 1870 to 6' 2" (1880 mm) on the SR Merchant Navy Class of 1941. The Great Northern Railway (GNR G class Stirling Single is a class of steam locomotive designed for express passenger work The SR Merchant Navy Class, also known as Bulleid Pacifics, Spam Cans or Packets, was a class of air-smoothed This is because improvements in valve design allowed for higher piston speeds.

Balancing

Main article: Engine balance

A driving wheel on a steam locomotive. Engine balance is the design construction and tuning of an Engine to run smoothly A steam locomotive is a Locomotive powered by Steam. The term usually refers to its use on Railways but can also refer to a "road locomotive"

On steam locomotives the driving wheels have balance weights to balance the weight of the coupling and connecting rods. The crescent-shaped balance weight is clearly visible in the picture on the right.

Whyte notation

In the Whyte notation, driving wheels are designated by the middle number or numbers in the set. The Whyte notation for classifying Steam locomotives by Wheel arrangement was devised by Frederick Methvan Whyte Other classification schemes like The UIC classification system counts the number of axles rather than the number of wheels and driving wheels are designated by letters rather than numbers. The UIC classification is a comprehensive system for describing the Wheel arrangement of Locomotives Multiple units and Trams It is The suffix 'o' is used to indicate independently powered axles.

The number of driving wheels on locomotives varied quite a bit. Some early locomotives had as few as two driving wheels (one axle). The largest number of total driving wheels was 24 (twelve axles) on the 2-8-8-8-2 and 2-8-8-8-4 locomotives. the Whyte notation for the classification of Steam locomotives a 2-8-8-8-2 has two Leading wheels three sets of eight Driving wheels and two Under the Whyte notation for the classification of Steam locomotives a 2-8-8-8-4 has two Leading wheels three sets of eight Driving wheels and The largest number of coupled driving wheels was 14 (seven axles) on the ill-fated AA20 4-14-4 locomotive. A 4-14-4, in the Whyte notation for the classification of Steam locomotives by Wheel arrangement, is a locomotive with four Leading wheels fourteen

Other uses of the term driving wheel

The term driving wheel is sometimes used to denote the drive sprocket which moves the track on tracked vehicles such as tanks and bulldozers. A sprocket is a profiled Wheel with teeth that meshes with a chain, track or other perforated or indented material Continuous tracks are large (modular tracks used on the so-called caterpillar Tanks construction equipment and certain other off-road vehicles A tank is a tracked, Armoured fighting vehicle designed for Front-line combat which combines Operational mobility and tactical ----A bulldozer is a crawler ( Caterpillar tracked Tractor) equipped with a substantial metal plate (known as a blade) used to push large quantities

See also

• AAR wheel arrangement
• UIC classification
• Whyte notation
• Drive axles in the article Axle