Baker valve gear

Last updated

After about 1910, the Baker valve gear was the main competitor to Walschaerts valve gear for steam locomotives in the United States. Strictly speaking it was not a valve gear but a variable expansion mechanism adapted to the Walschaerts layout replacing the expansion link and sliding die block. The Baker arrangement used more pivot bearings or pin joints, but avoided the die slip inherent to the expansion link, with the aim of lessening wear and the need for service; it could also facilitate longer valve travel.

Contents

Baker valve gear assembly Baker valve gear.jpg
Baker valve gear assembly

History

In the early 1900s there were many efforts to create a new valve gear to replace the by-then-standard Walschaerts valve gear. In the United States the Young, Southern, Caprotti and Franklin patterns were used on a few classes, but only the Baker pattern won more than limited acceptance.

The design originated in the A.D. Baker Company, of Swanton, Ohio; a builder of steam traction engines. The idea came from an employee called Gifford but was developed by the Baker company with the first patents being issued in 1903. [1]

The Baker Locomotive Valve Gear was produced by the Pilliod Co. of Swanton, Ohio. Subsequent versions were produced up to the end of steam service. It was particularly popular on the Norfolk and Western Railway, and almost all later N&W engines used it. Other extensive users included the Chesapeake and Ohio Railroad, the Nickel Plate Road, the New York Central Railroad and the Baltimore and Ohio Railroad. There was always debate about the advantages of Baker gear, the main criticism being the number of pin joints and possible lost motion. While popular with railroads on the east, western states tended to continue with the Walschaerts pattern. In Britain, Baker gear was popular amongst model engineers but in full-size practice the length of the yoke and the width of the assembly may have been difficult to accommodate within the restricted loading gauge.

Other locomotives to use Baker valve gear were the New Zealand Railways J class, Ja class, Jb class, some Ka class, and the South Australian Railways 620 class.

Operation

The Baker valve gear replaces the expansion link of the Walschaerts gear with an assembly of levers and links which produces the same effect of allowing continuous variation valve travel. The remainder of the gear is the same, so that the return crank and combination lever take the same form, although the proportions are usually modified. The Pilliod Co. sold the gear as a single assembly which was mounted on the frame in the location ordinarily occupied by the Walschaerts expansion link.

The Baker mechanism consisted of the following parts:

The parts were arranged so that when the yoke was centered, the connection of the main link to the bellcrank was in a line with the two pivots on the yoke. At this point, the back and forth motion of the lower end of the main link left the top relatively motionless as main link swung back and forth on the swing links.

In forward motion, the yoke was pushed forward, so that its upper pivot was in front of the bell crank-main link connection. Moving the eccentric arm back and forth lowered and raised the top of the main link. This motion was translated by the bellcrank into back and forth motion of the radius rod. The angle of the yoke controlled the relative motion, and therefore the cutoff; tilting the yoke backwards reversed the motion of the radius rod.

Related Research Articles

Swanton, Ohio Village in Ohio, United States

Swanton is a town in Fulton and Lucas counties in the U.S. state of Ohio. The population was 3,690 at the 2010 census.

Mason Bogie locomotive

Mason Bogie locomotives are a type of articulated steam locomotive suited for sharp curves and uneven track, once commonly used on narrow gauge railways in the United States of America. The design is a development of the Single Fairlie locomotive.

A geared steam locomotive is a type of steam locomotive which uses gearing, usually reduction gearing, in the drivetrain, as opposed to the common directly driven design.

Valve gear Mechanism for controlling steam flow in a reciprocating steam engine.

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 gear. It is sometimes referred to as the "motion".

Bellcrank

A bellcrank is a type of crank that changes motion through an angle. The angle can be any angle from 0 to 360 degrees, but 90 degrees and 180 degrees are most common. The name comes from its first use, changing the vertical pull on a rope to a horizontal pull on the striker of a bell, used for calling staff in large houses or commercial establishments.

Walschaerts valve gear

The Walschaerts valve gear is a type of valve gear invented by Belgian railway mechanical engineer Egide Walschaerts in 1844 used to regulate the flow of steam to the pistons in Steam locomotives. The gear is sometimes named without the final "s", since it was incorrectly patented under that name. It was extensively used in steam locomotives from the late 19th century until the end of the steam era.

4-12-2 Locomotive wheel arrangement

Under the Whyte notation for the classification of steam locomotives, 4-12-2 represents the wheel arrangement of four leading wheels, twelve coupled driving wheels, and two trailing wheels. This arrangement was named the Union Pacific type, after the only railroad to use it, the Union Pacific Railroad.

Gresley conjugated valve gear Type of mechanism for controlling steam flow in a reciprocating steam engine

The Gresley conjugated valve gear is a valve gear for steam locomotives designed by Sir Nigel Gresley, chief mechanical engineer of the LNER, assisted by Harold Holcroft. It enables a three-cylinder locomotive to operate with only the two sets of valve gear for the outside cylinders, and derives the valve motion for the inside cylinder from them by means of levers. The gear is sometimes known as the Gresley-Holcroft gear, acknowledging Holcroft's major contributions to its development.

Stephenson valve gear

The Stephenson valve gear or Stephenson link or shifting link is a simple design of valve gear that was widely used throughout the world for various kinds of steam engines. It is named after Robert Stephenson but was invented by his employees.

Jackshaft (locomotive)

A jackshaft is an intermediate shaft used to transfer power from a powered shaft such as the output shaft of an engine or motor to driven shafts such as the drive axles of a locomotive. As applied to railroad locomotives in the 19th and 20th centuries, jackshafts were typically in line with the drive axles of locomotives and connected to them by side rods. In general, each drive axle on a locomotive is free to move about one inch (2.5 cm) vertically relative to the frame, with the locomotive weight carried on springs. This means that if the engine, motor or transmission is rigidly attached to the locomotive frame, it cannot be rigidly connected to the axle. This problem can be solved by mounting the jackshaft on unsprung bearings and using side-rods or chain drives.

Baguley valve gear Steam locomotive motion mechanism

The Baguley valve gear is a type of steam engine valve gear invented by Ernest E. Baguley, the Chief Draughtsman of the W.G. Bagnall company of locomotive manufacturers and patented in 1893. It was used by Bagnall during Baguley's time there, then by his own company of Baguley Cars Ltd.

Southern valve gear

Southern valve gear was briefly popular on steam locomotives in the United States. It combines elements of the Walschaerts and Baker patterns.

Bagnall–Price valve gear is a type of steam engine valve gear developed at locomotive manufacturer W.G. Bagnall as an alternative to the more common Walschaerts valve gear and also to supersede the Baguley valve gear their designs had previously utilised. The gear was patented in 1903 by W.G. Bagnall and T. S. Price, the manager of the works.

Cylinder (locomotive) Power-producing element of a steam locomotive

The cylinder is the power-producing element of the steam engine powering a steam locomotive. The cylinder is made pressure-tight with end covers and a piston; a valve distributes the steam to the ends of the cylinder. Cylinders were cast in iron and later made of steel. The cylinder casting includes other features such as valve ports and mounting feet. The last big American locomotives incorporated the cylinders as part of huge one-piece steel castings that were the main frame of the locomotive. Renewable wearing surfaces were needed inside the cylinders and provided by cast-iron bushings.

Bulleid chain-driven valve gear

The Bulleid chain-driven valve gear is a type of steam locomotive valve gear designed by Oliver Bulleid during the Second World War for use on his Pacific (4-6-2) designs. It was peculiar to the Southern Railway in Britain, and borrowed from motor-vehicle practice in an attempt to create a compact and efficient design with a minimum of service requirements.

Kuhn slide

The Kuhn slide is part of a modified Walschaerts (German:Heusinger) valve gear on steam locomotives and is named after its inventor, Michael Kuhn (1851–1903). The term is also used to refer to this particular type of Walschaerts valve gear system as a whole.

Holcroft valve gear

The Holcroft valve gear was a type of conjugated valve gear designed and patented by Harold Holcroft and used on three-cylinder steam locomotives of the South Eastern & Chatham Railway (SECR). It bore many similarities to the Gresley conjugated valve gear, which it predated, as eventually used on all Gresley's three cylinder designs. It varied from the Gresley method of operation by using the combination lever assembly instead of the valve spindles to drive the middle cylinder of a three-cylinder design. This had operational advantages over Gresley's design, namely eliminating the problems of flexure, bush wear and the influence of heat in the valve spindles.

Musgrave non-dead-centre engine

Musgrave's non-dead-centre engine was a stationary steam engine of unusual design, intended to solve the problem of stopping on dead centre. It was designed in 1887 to serve as a marine engine. It used a pair of linked cylinders to prevent the engine from stopping in a position where no turning force can be applied. At least one engine is known to survive.

Duplex locomotive

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; it is not an articulated locomotive. The concept was first used in France in 1863, but was particularly developed in the early 1930s by the Baldwin Locomotive Works, the largest commercial builder of steam locomotives in North America, under the supervision of its then chief engineer, Ralph P. Johnson.

Hackworth valve gear

The Hackworth valve gear is a design of valve gear used to regulate the flow of steam to the pistons in steam engines. It is a radial gear, with an actuating lever driven from the crank. The drive may be taken directly from the crank or indirectly via a return crank. The other end of the actuating lever is attached to a die block which slides in a slotted link. When the link is vertical, the engine is in mid-gear. Forward, reverse and cut-off adjustments are made by moving the link away from the vertical. The valve rod is pivoted to a point on the actuating lever.

References

  1. Blake, LeRoy W. (May–June 1979). "Remembering the A.D. Baker Company". Farm Collector. Archived from the original on 10 May 2012. Retrieved 16 November 2011.