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Reversing Gear
On a steam locomotive, the reversing gear is used to control the direction of travel of the locomotive. It also adjusts the cutoff of the steam locomotive. Reversing lever This is the most common form of reverser. It consists of a long lever mounted, parallel to the direction of travel, on the driver’s side of the cab. It has a handle and sprung trigger at the top and is pivoted at the bottom so as to pass between two notched sector plates. The reversing rod, which connects to the valve gear, is attached to this lever, either above or below the pivot, in such a position as to give good leverage. A square pin is arranged so as to engage with the notches in the plates and hold the lever in the desired position when the trigger is released. The advantages of this design are that change between forward and reverse gear can be made very quickly as is needed in, for example, a shunting engine. Disadvantages are that, because the lever must rest at one of the notches, fine adjustment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 gear. It is sometimes referred to as the "motion". Purpose In the simple case, this can be a relatively simple task as in the internal combustion engine in which the valves always open and close at the same points. This is not the ideal arrangement for a steam engine, though, because greatest power is achieved by keeping the inlet valve open throughout the power stroke (thus having full boiler pressure, minus transmission losses, against the piston throughout the stroke) while peak efficiency is achieved by only having the inlet valve open for a short time and then letting the steam expand in the cylinder (expansive working). The point at which steam stops being admitted to the cylinder is known as the '' cutoff'', and the optimal positio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cutoff (steam Engine)
In a steam engine, cutoff is the point in the piston stroke at which the inlet valve is closed. On a steam locomotive, the cutoff is controlled by the reversing gear. The point at which the inlet valve closes and stops the entry of steam into the cylinder from the boiler plays a crucial role in the control of a steam engine. Once the valve has closed, steam trapped in the cylinder expands adiabatically. The steam pressure drops as it expands. A late cutoff delivers full steam pressure to move the piston through its entire stroke, for maximum start-up forces. But, since there will still be unexploited pressure in the cylinder at the end of the stroke, this is achieved at the expense of engine efficiency. In this situation the steam will still have considerable pressure remaining when it is exhausted resulting in the characteristic “chuff chuff” sound of a steam engine. An early cutoff has greater thermodynamic efficiency but results in a lower Mean effective pressure so less ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Southern Railway (UK)
The Southern Railway (SR), sometimes shortened to 'Southern', was a British railway company established in the 1923 Grouping. It linked London with the Channel ports, South West England, South coast resorts and Kent. The railway was formed by the amalgamation of several smaller railway companies, the largest of which were the London and South Western Railway (LSWR), the London, Brighton and South Coast Railway (LB&SCR) and the South Eastern and Chatham Railway (SE&CR).Bonavia (1987) pp. 26-28 The construction of what was to become the Southern Railway began in 1838 with the opening of the London and Southampton Railway, which was renamed the London & South Western Railway. The railway was noted for its astute use of public relations and a coherent management structure headed by Sir Herbert Walker. At , the Southern Railway was the smallest of the '' Big Four'' railway companies and, unlike the others, the majority of its revenue came from passenger traffic rather than freight ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PRR N1s
The Pennsylvania Railroad's N1s was a class of steam locomotive built for Lines West. They were of 2-10-2 "Santa Fe" wheel arrangement, ten driving wheels with a two-wheel leading truck and a two-wheel cast KW-pattern trailing truck under a giant firebox. This arrangement was well suited to the N1s' intended purpose, which was as a heavy drag freight engine for coal and iron ore traffic to and from lakeside ports. The design was developed by the PRR's Fort Wayne Shops and orders were placed with Alco (Brooks) (35 locomotives) and Baldwin (25 locomotives) for a total of 60; the first Alco locomotive was delivered in December 1918, with the remainder arriving during 1919. The N1s was a large locomotive; the boiler was the largest then used on any non-experimental PRR locomotive, with a large Belpaire firebox with of grate area and a long combustion chamber. No feedwater heater was fitted, but a mechanical stoker and power reverse were, necessities on such a large locomotive. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PRR K4s
The Pennsylvania Railroad (PRR) K4 4-6-2 "Pacific" (425 built 1914–1928, PRR Altoona, Baldwin) was its premier passenger-hauling steam locomotive from 1914 through the end of steam on the PRR in 1957. Attempts were made to replace the K4s, including the K5 and the T1 duplex locomotive, but neither was very successful. The K4s hauled the vast majority of express passenger trains until they were replaced by diesel locomotives. The K4s were not powerful enough for the heavier trains they often pulled from the mid-1930s onward, so they were often double- or even triple-headed, sometimes with atlantic class locomotives. This was effective, but expensive, and several crews were needed. The PRR did have the extra locomotives, many having been displaced by electrification east of Harrisburg. The two preserved K4s Nos. 1361 and 3750 were designated as Pennsylvania's official state steam locomotives on December 18, 1987, when Pennsylvania Governor Robert P. Casey signed into l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dover Books
Dover Publications, also known as Dover Books, is an American book publisher founded in 1941 by Hayward and Blanche Cirker. It primarily reissues books that are out of print from their original publishers. These are often, but not always, books in the public domain. The original published editions may be scarce or historically significant. Dover republishes these books, making them available at a significantly reduced cost. Classic reprints Dover reprints classic works of literature, classical sheet music, and public-domain images from the 18th and 19th centuries. Dover also publishes an extensive collection of mathematical, scientific, and engineering texts. It often targets its reprints at a niche market, such as woodworking. Starting in 2015, the company branched out into graphic novel reprints, overseen by Dover acquisitions editor and former comics writer and editor Drew Ford. Most Dover reprints are photo facsimiles of the originals, retaining the original pagination an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Garratt
A Garratt (often referred to as a Beyer Garratt) is a type of steam locomotive invented by British engineer Herbert William Garratt that is articulated into three parts. Its boiler, firebox, and cab are mounted on a centre frame or "bridge". The two other parts, one at each end, have a pivot to support the central frame; they consist of a steam engine unit – with driving wheels, trailing wheels, valve gear, and cylinders, and above it, fuel and/or water storage. Articulation permits locomotives to negotiate curves that might restrict large rigid-framed locomotives. The design also provides more driving wheels per unit of locomotive weight, permitting operation on lightly engineered track. Garratt locomotives produced as much as twice the power output of the largest conventional locomotives of railways that introduced them, reducing the need for multiple locomotives and crews. Advantages of the Garratt concept The principal benefit of the Garratt design is that the boil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baldwin Locomotive Works
The Baldwin Locomotive Works (BLW) was an American manufacturer of railroad locomotives from 1825 to 1951. Originally located in Philadelphia, it moved to nearby Eddystone, Pennsylvania, in the early 20th century. The company was for decades the world's largest producer of steam locomotives, but struggled to compete as demand switched to diesel locomotives. Baldwin produced the last of its 70,000-plus locomotives in 1951, before merging with the Lima-Hamilton Corporation on September 11, 1951, to form the Baldwin-Lima-Hamilton Corporation. The company has no relation to the E.M. Baldwin and Sons of New South Wales, Australia, a builder of small diesel locomotives for sugar cane railroads. History: 19th century Beginning The Baldwin Locomotive Works had a humble beginning. Matthias W. Baldwin, the founder, was a jeweler and whitesmith, who, in 1825, formed a partnership with machinist David H. Mason, and engaged in the manufacture of bookbinders' tools and cylinders for cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Articulated Locomotive
An articulated locomotive is a steam locomotive (rarely, an electric locomotive) with one or more engine units that can move independent of the main frame. Articulation allows the operation of locomotives that would otherwise be too large to negotiate a railroad's curves, whether mainlines or special lines with extreme curvature such as logging, industrial, or mountain railways. Articulated locomotives saw service in many nations, but were very popular on narrow-gauge railways in Europe. The largest examples were developed in the United States, where the Union Pacific Big Boy 4-8-8-4s and the Allegheny H-8 2-6-6-6s were some of the largest steam locomotives ever built. Many schemes for articulation were developed over the years. Of these, the Mallet locomotive and its simple-expansion derivative were the most popular, followed by the Garratt type (mostly built in the United Kingdom, popular throughout Europe, Africa and European colonies), and the various geared steam locomot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Servomechanism
In control engineering a servomechanism, usually shortened to servo, is an automatic device that uses error-sensing negative feedback to correct the action of a mechanism. On displacement-controlled applications, it usually includes a built-in encoder or other position feedback mechanism to ensure the output is achieving the desired effect. The term correctly applies only to systems where the feedback or error-correction signals help control mechanical position, speed, attitude or any other measurable variables. For example, an automotive power window control is not a servomechanism, as there is no automatic feedback that controls position—the operator does this by observation. By contrast a car's cruise control uses closed-loop feedback, which classifies it as a servomechanism. Applications Position control A common type of servo provides ''position control''. Commonly, servos are electric, hydraulic, or pneumatic. They operate on the principle of negative feedback, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Feedback
Feedback occurs when outputs of a system are routed back as inputs as part of a chain of cause-and-effect that forms a circuit or loop. The system can then be said to ''feed back'' into itself. The notion of cause-and-effect has to be handled carefully when applied to feedback systems: History Self-regulating mechanisms have existed since antiquity, and the idea of feedback had started to enter economic theory in Britain by the 18th century, but it was not at that time recognized as a universal abstraction and so did not have a name. The first ever known artificial feedback device was a float valve, for maintaining water at a constant level, invented in 270 BC in Alexandria, Egypt. This device illustrated the principle of feedback: a low water level opens the valve, the rising water then provides feedback into the system, closing the valve when the required level is reached. This then reoccurs in a circular fashion as the water level fluctuates. Centrifugal governors were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
