Geared steam locomotive
A geared steam locomotive is a type of steam locomotive
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

 which uses reduction gearing in the drivetrain, as opposed to the common directly driven design.
The locomotives use conventional adhesion
Rail adhesion
The term adhesion railway or adhesion traction describes the most common type of railway, where power is applied by driving some or all of the wheels of the locomotive. Thus, it relies on the friction between a steel wheel and a steel rail. Note that steam locomotives of old were driven only by...

 to provide traction and therefore should not be confused with rack railway
Rack railway
A rack-and-pinion railway is a railway with a toothed rack rail, usually between the running rails. The trains are fitted with one or more cog wheels or pinions that mesh with this rack rail...

 locomotives which drive a cog along a rack to provide traction.

Explanation and rationale

The steam locomotive
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...

, as commonly employed, has its piston
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from...

s directly attached to crank
Crank (mechanism)
A crank is an arm attached at right angles to a rotating shaft by which reciprocating motion is imparted to or received from the shaft. It is used to change circular into reciprocating motion, or reciprocating into circular motion. The arm may be a bent portion of the shaft, or a separate arm...

s on the driving wheel
Driving wheel
On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons...

s; thus, there is no gearing, one revolution of the driving wheels is equivalent to one revolution of the crank and thus two power strokes per piston (steam locomotives are almost universally double-acting
Double-acting cylinder
A double-acting cylinder in a reciprocating engine is a cylinder in which the working fluid acts alternately on both sides of the piston. This is in contrast to a single-acting cylinder, in which the working fluid acts in one direction only....

, unlike the more familiar internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...


The maximum rotational speed is fairly fixed for a given engine technology. Given the lack of any variable-ratio transmission
Transmission (mechanics)
A machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...

 between the piston engine and the wheels, the designer is forced to compromise between desired torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....

 and desired maximum speed; the radius of the driving wheels determines this. The radius of the crank affixed to the wheel is of course less than this; its radius determines the length of the piston stroke. This cannot be too large, for the locomotive will be unable to generate enough steam to supply those large cylinders at speed; it cannot be too small, or the starting torque and thus tractive effort
Tractive effort
As used in mechanical engineering, the term tractive force is the pulling or pushing force exerted by a vehicle on another vehicle or object. The term tractive effort is synonymous with tractive force, and is often used in railway engineering to describe the pulling or pushing capability of a...

 will be too small, and the locomotive will not be able to start a train.

Many applications required a low speed locomotive with ample starting tractive effort – industrial use, mines and quarries and logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...

 operations, steeply graded lines and the like – especially when the track is cheaply built and not suited to high speeds anyway. Unfortunately, although the trade-off of speed versus torque can be adjusted in favour of torque and tractive effort by reducing the size of the driving wheels, there is a practical limit below which this cannot be done without making the piston stroke too short on a directly driven locomotive.

The solution is to separate the crank from the wheels, firstly allowing for a reasonable piston stroke and crank radius without requiring larger than desired driving wheels, and secondly allowing for reduction in rotational speed via gearing. Such a locomotive is a geared locomotive. Most were and are still single speed, but some did employ a variable-ratio gearbox and multiple ratios.

Types of geared locomotive

The vast majority of geared locomotives in the world were built to one of three distinct designs, whether licensed and official, or clones built after the expiration of key patents. Of the types, the Shay locomotive
Shay locomotive
The Shay locomotive was the most widely used geared steam locomotive. The locomotives were built to the patents of Ephraim Shay, who has been credited with the popularization of the concept of a geared steam locomotive...

was the most numerous and best known. The overwhelming majority operated on the North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

n continent, but with a number in use in various parts of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 and a fair number in Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, including home-developed types.

The Shay locomotive

The Shay locomotive
Shay locomotive
The Shay locomotive was the most widely used geared steam locomotive. The locomotives were built to the patents of Ephraim Shay, who has been credited with the popularization of the concept of a geared steam locomotive...

, features an offset boiler with a multiple-cylinder engine affixed to it on the opposite side, driving a longitudinal shaft geared to the axles via bevel gears (see also Ephraim Shay
Ephraim Shay
Ephraim Shay designed the first Shay locomotive and patented the type.He was born on July 17, 1839, in Sherman Township, Huron County, Ohio. His parents were James and Phoebe Shay....

, inventor).

The Climax locomotive

The Class B Climax locomotive
Climax locomotive
A Climax locomotive is a type of geared steam locomotive in which the two steam cylinders were attached to a transmission located under the center of the boiler. This transmits power to driveshafts running to the front and rear trucks....

, has two inclined cylinders driving a transverse crankshaft, geared to a longitudinal driveshaft placed centrally on the locomotive and driving the powered trucks via internal gearing.

There was also an earlier Class A Climax with a vertically mounted marine-type steam engine, working through a similar drive-line, via a two-speed gearbox.

The Heisler locomotive

The Heisler locomotive
Heisler locomotive
The Heisler locomotive was the last variant of the three major types of geared steam locomotive, Charles L. Heisler receiving a patent for the design in 1892 following the construction of a prototype in 1891. Somewhat similar to a Climax locomotive, Heisler's design featured two cylinders canted...

, has a 'Vee-Twin' style steam engine, one cylinder each side of the boiler, affixed to a centrally located longitudinal driveshaft, again geared to the wheels.

Clones and Variants

Besides the three main designs mentioned, there were other designs and clones:
  • The Willamette locomotive
    Willamette locomotive
    The Willamette locomotive was a geared locomotive of the Shay locomotive type, built by the Willamette Iron and Steel Works of Portland, Oregon...

     was an improved-upon clone of the Shay locomotive produced in limited number by Willamette Iron & Steel
    Willamette Iron and Steel Works
    Willamette Iron Works was a general foundry and machine business established in 1865 in Portland, Oregon, originally specializing in the manufacture of steamboat boilers and engines...

     (better known for their steam donkey engines) after key patents expired. West coast logging customers were clamoring for improvements in detail design and the application of more modern locomotive technology to the geared locomotive; Lima (manufacturers of the Shay) were dragging their heels. The Willamette was the response to that.
  • The Kitson-Still locomotive
    Steam diesel hybrid locomotive
    A steam diesel hybrid locomotive was a railway locomotive with a piston engine which could run on either steam from a boiler or diesel fuel. Examples were built in the United Kingdom, Russia and Italy but the relatively high cost of fuel oil meant that the designs were not pursued.-Kitson-Still...

     used different ends of the same cylinders for steam or diesel propulsion. The crank was above the frame and a gear train of fixed reduction linked it to the centre axle.
  • Aveling and Porter
    Aveling and Porter
    Aveling and Porter was a British agricultural engine and steam roller manufacturer. Thomas Aveling and Richard Thomas Porter entered into partnership in 1862, developed a steam engine three years later in 1865 and produced more steam rollers than all the other British manufacturers combined.-The...

     built some geared locomotives which were, essentially, traction engine
    Traction engine
    A traction engine is a self-propelled steam engine 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 traction engine is to draw a load behind it...

    s with flange
    A flange is an external or internal ridge, or rim , for strength, as the flange of an iron beam such as an I-beam or a T-beam; or for attachment to another object, as the flange on the end of a pipe, steam cylinder, etc., or on the lens mount of a camera; or for a flange of a rail car or tram wheel...

    d wheels. The early ones used sprocket
    A sprocket or sprocket-wheel is a profiled wheel with teeth, cogs, or even sprockets that mesh with a chain, track or other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which are radial projections that engage a chain passing over it...

     chain drive but later versions had spur gears.
  • The Avonside Engine Company
    Avonside Engine Company
    The Avonside Engine Company was a locomotive manufacturer in Avon Street, St. Philip's, Bristol, England between 1864 and 1934. However the business originated with an earlier enterprise Henry Stothert and Company.-Origins:...

     produced a small number of narrow gauge geared steam locomotives for sugar cane plantations in Natal
    Colony of Natal
    The Colony of Natal was a British colony in south-eastern Africa. It was proclaimed a British colony on May 4, 1843 after the British government had annexed the Boer Republic of Natalia, and on 31 May 1910 combined with three other colonies to form the Union of South Africa, as one of its...

    . These were similar in design to Heislers.
  • The Sentinel Waggon Works
    Sentinel Waggon Works
    Sentinel Waggon Works Ltd was a British company based in Shrewsbury, Shropshire that made steam-powered lorries, railway locomotives, and later, diesel engined lorries and locomotives.-Alley & MacLellan, Sentinel Works, Jessie Street Glasgow:...

     built numerous geared shunting locomotives
    A switcher or shunter is a small railroad locomotive intended not for moving trains over long distances but rather for assembling trains ready for a road locomotive to take over, disassembling a train that has been...

     to several designs. These combined high-pressure boilers with high-reduction gearing to provide high torque at low speeds.
  • A & G Price of Thames, New Zealand built a number of geared locomotives, often home-grown variants of the Climax A, Climax B or Heisler types. They did however produce a type that is known as the "16-wheeler" (an 0-4-4-4-4-0 type
    A 4-4-4-4 steam locomotive, in the Whyte notation for describing locomotive wheel arrangements, has a four-wheel leading truck, two sets of four driving wheels, and a four-wheel trailing truck.Other equivalent classifications are:...

    ) that was also produced by another NZ manufacturer, Johnson Brothers of Invercargill.


With the decline of the commercial use of steam traction, the commercial use of geared locomotives has similarly reduced.

Some geared steam locomotives are still at work in the sugar plantations of Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

, and no doubt elsewhere too, but in most countries they may now be seen only on tourist lines, preservation sites and museums. The particular advantage in cane sugar operations is the ability to use the dried solid residue of pressing the cane (see bagasse
Bagasse is the fibrous matter that remains after sugarcane or sorghum stalks are crushed to extract their juice. It is currently used as a biofuel and as a renewable resource in the manufacture of pulp and paper products and building materials....

) as a fuel of trivial cost, providing that low cost technical labor is available to maintain the locomotives.


  • Puffing Billy Railway
    Puffing Billy Railway, Melbourne
    The Puffing Billy Railway is a narrow gauge gauge heritage railway in the Dandenong Ranges near Melbourne, Australia. The primary starting point, operations and administration centre, main refreshment room and ticket purchasing are located at Belgrave station...

     in Victoria, Australia:
    • Class B Climax, originally used on the Tyers Valley timber tramway which branched off the Moe-Walhalla railway east of Melbourne.
    • Lima-built Shay locomotive from the Ali-shan railway in Taiwan
      Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

      , although it has not yet been restored.


The Canada Science and Technology Museum
Canada Science and Technology Museum
The Canada Science and Technology Museum is located in Ottawa, Ontario, on St. Laurent Boulevard, to the south of the Queensway .-Mission:...

 in Ottawa, Ontario has an operational 50 ton class B Shay Locomotive, that is in operation Sundays and Wednesdays in July and August.


Wide variety of types still in use at sugar mills. Most are long wheelbase 0-8-0
Under the Whyte notation for the classification of steam locomotives, 0-8-0 represents the wheel arrangement of no leading wheels, eight powered and coupled driving wheels on four axles, and no trailing wheels...

 locomotives that use an articulation technique incorporating a geared drive to the outer-most axles, the inner pair being direct-drive.

New Zealand

  • Shantytown
    Shantytown, New Zealand
    Shantytown is a tourist attraction in the West Coast Region of the South Island of New Zealand. Located ten kilometres south of Greymouth, the town was constructed and opened in the early 1970s and consists of some thirty re-created historic buildings making up a 19th century gold-mining town...

    , West Coast:
    • Heisler, makers no.1494 (unrestored)
    • Climax, makers no.1203 (under overhaul)

  • The Pukemiro Line, Pukemiro:
    • Heisler, makers no.1063 (unrestored, parts supply)
    • Heisler, makers no.1082 (awaiting overhaul)
    • Climax, makers no.1650 (unrestored)
    • Price Cb 117 (Class A Climax clone, restored)
    • Price E 111 (Class B Climax clone, unrestored)

  • "Steam Scene", Christchurch:
    • Price V 148 (Heisler clone, under overhaul)

  • "Ferrymead Heritage Park", Christchurch:
    • Heisler, makers no.1450 (unrestored)
    • Price Cb 113 (Class A Climax clone, restored)

United Kingdom

About 30 Sentinels have been preserved. A few examples are shown below:
  • Buckinghamshire Railway Centre
    Buckinghamshire Railway Centre
    Buckinghamshire Railway Centre is a railway museum operated by the Quainton Railway Society Ltd. at Quainton Road railway station, in the far depths of "Metro-land", about 5 miles west of Aylesbury in Buckinghamshire. The site is divided into two halves which are joined by two foot-bridges, one of...

    • two Aveling & Porters
    • two Sentinels

  • Embsay and Bolton Abbey Steam Railway
    Embsay and Bolton Abbey Steam Railway
    The Embsay & Bolton Abbey Steam Railway is a heritage railway in North Yorkshire, England, . It is part of the former Midland Railway branch from Skipton to Ilkley . The E&BASR currently runs from Embsay via Draughton and Holywell to Bolton Abbey station, a distance of...

    • one Sentinel

  • Northamptonshire Ironstone Railway Trust
    Northamptonshire Ironstone Railway Trust
    The Northamptonshire Ironstone Railway Trust operates a mile long heritage railway line at Hunsbury Hill, south-west of Northampton. The line is mainly dedicated to freight working, featuring many sharp curves and steep gradients which were typical of the industrial railway, but rides are...

    • two Sentinels

United States

No geared steam locomotives remain in commercial use in America. However, several are in operation on tourist lines.

The Cass Scenic Railroad State Park
Cass Scenic Railroad State Park
Cass Scenic Railroad State Park is a State Park located in Cass, Pocahontas County, West Virginia.It consists of the Cass Scenic Railroad, an long heritage railroad that is owned by the state of West Virginia...

 in West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...

 uses only geared locomotives, and featuring the largest remaining Shay locomotive, the 162-ton former Western Maryland Railway
Western Maryland Railway
The Western Maryland Railway was an American Class I railroad which operated in Maryland, West Virginia, and Pennsylvania. It was primarily a coal hauling and freight railroad, with a small passenger train operation. The WM became part of the Chessie System in 1973 and ceased operating its lines...

 #6. The railroad also owns a Climax locomotive and a Heisler enabling all three types to be seen.

The Roaring Camp and Big Trees Narrow Gauge Railroad
Roaring Camp and Big Trees Narrow Gauge Railroad
The Roaring Camp & Big Trees Railroad is a narrow gauge tourist railroad in California that starts from the Roaring Camp depot in Felton, California and runs up steep grades to the top of nearby Bear Mountain, a distance of 3.25 miles The travel is through a redwood forest.The steam engines date...

 in Felton, California
Felton, California
-2010:The 2010 United States Census reported that Felton had a population of 4,057. The population density was 891.2 people per square mile . The racial makeup of Felton was 3,691 White, 25 African American, 29 Native American, 69 Asian, 11 Pacific Islander, 60 from other races, and 172 from...

 has several operational Shays, a seldom–operated Heisler and a Climax awaiting restoration.

The White Mountain Central Railroad at Clarks Trading Post in Lincoln, New Hampshire operates Climax #6 built in 1920 (builder number 1603) on its tourist line. Clarks also has the last remaining Shay in New England. The Shay is non-operational but in storage. Clark's also has a 32 ton Heisler Locomotive that is awaiting staybolt replacement.

A 65-ton 1922 Lima locomotive with 3 truck Shay design is on static display at the Traveltown open air museum in Los Angeles.

The Mt. Rainier Scenic Railroad
Mt. Rainier Scenic Railroad
The Mt. Rainier Scenic Railroad is a steam-powered heritage railroad operating in Washington State between Elbe and Mineral. The railroad travels on tracks that pass through thick forest just south of Mount Rainier. The depot, gift shop and ticket office are located in Elbe...

 A 99 ton West Fork Logging Heisler #91 is operational, a 70 ton Hillcrest Lumber Climax #10 is operational, a 95 ton Pickering Lumber Shay #11 is awaiting boiler work, and a 75 ton Rayonier Company Willamette #2 is operational and is the only Willamette operating

See also

  • Cass Scenic Railroad
    Cass Scenic Railroad State Park
    Cass Scenic Railroad State Park is a State Park located in Cass, Pocahontas County, West Virginia.It consists of the Cass Scenic Railroad, an long heritage railroad that is owned by the state of West Virginia...

  • Steam donkey
    Steam donkey
    Steam donkey, or donkey engine is the common nickname for a steam-powered winch, or logging engine widely used in past logging operations, though not limited to logging...

  • Steam locomotive nomenclature

External links

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