physics

James Thompson Marshall

James Thompson Marshall is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand James Thompson Marshall rather than just read about it. In short: James Thompson Marshall (1854, Glanford Brigg, Lincolnshire - 1931, Knaresborough, Yorkshire) was an English railway and mechanical engineer known for inventing the 'Marshall valve gear' for steam locomotive use. James Marshall began his engineering career at the Leeds-based Steam Plough Company, and later moved to the city's Boyne Engine Works.

Key takeaways

James Thompson Marshall belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect James Thompson Marshall to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of James Thompson Marshall from memory before moving on to harder problems.

Reference excerpt

James Thompson Marshall (1854, Glanford Brigg, Lincolnshire - 1931, Knaresborough, Yorkshire) was an English railway and mechanical engineer known for inventing the 'Marshall valve gear' for steam locomotive use. James Marshall began his engineering career at the Leeds-based Steam Plough Company, and later moved to the city's Boyne Engine Works.

Marshall valve gear J. T. Marshall invented and patented several different valve gears but these should not be confused with the "Marshall valve gear" patented by Marshall, Sons & Co. in 1879. At least one of J. T. Marshall's valve gears was a rotary type and the only known application was to the Austrian BBÖ Class 114 locomotive. The better-known J. T. Marshall gear was a modified Walschaerts valve gear which was first applied to a Great Northern Railway mineral locomotive, no. 743, in 1901 and received a glowing report. Next, it was tried on GNR Class C2 No. 1520 in March 1903. There was no external change visible on the locomotive as a result of this modification. When the valve gear was in use, the motion was derived from two eccentrics, one of which gave lap and lead movement by swinging the link backwards and forwards on its suspension bracket. The other eccentric was set at 90 degrees to the crank and rocked the link by means of a bell crank on the hanging link pin. The position of the radius rod die pin in the link determined the direction of movement and the cutoff. Showing little advantage over the normal Stephenson link valve gear, it was removed from the C2 'Atlantic' in April 1907 to ease maintenance. A modified version of the gear (for outside drive) was tried on SECR N class no. 1850 in 1933-4 but, again, it was not a great success.

Patents 14242/1894 Improvements in steam engine valves and gear for working them, with Reginald Wigram. Applied 24 July 1894, published 25 August 1894 05430/1897 Improvements in speed-regulating governors, specially suitable for electric-light and other high-speed engines. Applied 1 March 1897, published 1 August 1898 06013/1897 Improvements in metallic pistons and piston rings suitable for steam and other fluid pressure engines. Applied 6 March 1897, published 29 January 1898 07294/1898 Improvements in or relating to fluid-pressure engine valves and valve-gear. Applied 25 March 1898, Published 11 March 1899 13662/1900 Improvements in valve gears for steam engines, with Reginald Wigram. Applied 30 July 1900, published 11 May 1901 03761/1901 Improvements in valve gear for fluid pressure engines. Applied 21 February 1901, published 6 July 1901 03144/1906 Improvements in valve gear for fluid pressure engines. Applied 8 February 1906, published 7 February 1907 20911/1908 Improvements in slide and piston valves for fluid pressure, steam and other engines, with Enoch Richardson. Applied 3 October 1908, published 3 January 1910 CA124691/1910 Slide valve for fluid pressure engines US962374/1910 Valve-gear for fluid-pressure engines GB256676/1926 Improvements in or relating to motive fluid engines CA272618/1927 Motive fluid engine

Death Marshall died in 1931.

References

Illustrations

Worked examples

Example 1 — a first encounter with James Thompson Marshall

Start with the simplest possible case. Write down what James Thompson Marshall claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to James Thompson Marshall before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about James Thompson Marshall ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of James Thompson Marshall

In research: James Thompson Marshall appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses James Thompson Marshall in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: James Thompson Marshall is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1854 births, 1931 deaths, English railway mechanical engineers, so understanding it makes those chapters shorter.
In everyday life: Look for James Thompson Marshall outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study James Thompson Marshall in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what James Thompson Marshall means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain James Thompson Marshall out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is James Thompson Marshall in simple terms?

Why does James Thompson Marshall matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study James Thompson Marshall?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on James Thompson Marshall.