Railway Oddities

[81F]

My understanding of the Midlands decision to abolish second class was more to do with downgrading their existing second class coaches rather than upgrading their third class stock.

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@81F That would make sense - less work involved.

[What About The Bee]

Stave 1: William Brunton's Obituary 

The mention of Brunton's obituary brings me to the point of this month's Railway Oddities. There is no doubt that Brunton practiced sound engineering. This must be distinctly understood, or nothing wonderful can come of the oddity I am going to relate. 

Stave 2: Early Career.

In 1796, William Brunton became employed by Watt. That Watt, the fellow who has a unit of measurement named after him.  Watt had such confidence in Brunton, that Brunton was promoted to the position of Superintendent of the Engine Manufactory, at Watt's Soho Foundry. This position put Brunton into close proximity with Watt. I do hope that James Watt's confidence in William Brunton will dispell any notion of crackpot in what you are about to see. In 1808, Brunton left Soho and joined the Butterley Works, the place where our oddity occurs.

Stave 3: The other players.  

George Stephenson. One of the engineers who worked with Stephenson during the 1810s was a fellow named Nicholas Wood. Wood published several editions of an engineering text known as A Practical Treatise of Railway Engineering. The first edition was published in 1825, with several editions to follow, the last to my knowledge in 1854. The tome is filled with data, equations, mechanical drawings, sketches & etc. Editions of the book were translated into other languages. I have seen copies in French and German. The editions are a tour de force by an early participant in the development of railways. Highly recommended to all students of early railways.

Stave 4: The Image

This was published in the 1825 edition of Practical Treatise, Nicholas Wood, Plate 4. 

I will begin in the lower right hand corner. You may recognize that image, it is my avatar. My avatar is the yellow circle that appears at the top of my posts. The image depicts Stephenson's Dynamometer. This brilliant device was used by Nicholas Wood and Stephenson to investigate the inhibiting friction of railway wagons. I will cover this device in a future article, but you should understand that this device was instrumental in the development of the railway industry. Its importance cannot be overstated.

In the upper left hand corner, is the Blenkinsop Locomotive. Blenkinsop worked around the adhesion problem, in 1811, by making a cogged railway. The early railway industry was tortured by driving friction and the adhesion of metal wheels on metal rails. The Blenkinsop Locomotive is a very important early railway device.

In the upper right hand corner is the Killingworth Locomotive. You may know this as an early George Stephenson locomotive, a precursor of things to come.

With the importance of the items in this image established, we can finally proceed.

Stave 5: Brunton's Mechanical Traveller 

In the top center of the image, taking pride of place, is Brunton's Mechanical Traveller, or as he sometimes called it, "A Horse to go by Steam". This isn't some fanciful or outlandish contraption, look at the items in the illustration that it keeps company with. It was a practical engine that worked the Butterley Gangroad so successfully, that the Newbottle Colliery ordered an engine as well.  

This locomotive worked loads uphill, the hill with a gradient of 1 in 36¹, per Brunton. To put this in perspective, the Wapping Tunnel on the Liverpool and Manchester Railway had a shallower gradient of 1 in 48, a slope which could not be serviced by LMR locomotives, well into the 1840s.  

Stave 6: The engine that walked!!

Those odd legs in the back were the motive power. The legs propelled the steam engine by pushing it along. Brunton patented this in 1813².

(Reminder, this image, as all my images, can be zoomed.)

The boiler is a return flue type, with the firebox and chimney at the same end of the locomotive. The boiler itself was of wrought iron, 5 feet 6 inches long, 3 feet in diameter.  The weight, per Brunton was 45 cwt (4500 lbs) including water. 3 feet 6 inch gauge when at Butterley Gangroad.

The 6" diameter piston had a stroke of 24 inches. Working pressure 45 psi. The piston rod is at "a". You may observe that when the piston rod extends, the foot at "b" will be forced away from the locomotive, driving the boiler forward. When the piston rod retracts,the foot lifts and is brought forward.

The other leg is wonderful. We have, in Brunton's own hand, a description and sketch of the mechanism³.

Brunton shows us the stationary pinion gear, the piston and the two racks which move in opposite directions, attached to the legs. He has unfolded the mechanism for clarity.  

In his patent, Brunton includes a plate, showing the general mechanical arrangement. By the way, unless you manage to figure out the UK's arcane system of early patents, you will probably never see the end or plan view. You will likely only ever see them here, so enjoy!! The stationary pinion gear is fixed horizontally, at the top of the boiler, with the racks parallel to the top of that boiler. As one leg is driving the locomotive forward, the other leg is retracting for the next step, due to the rack and pinion system.  

Brunton solved the adhesion problem of metal wheels on metal rails by avoiding it. He used an alternative method. His drawings and patent include various foot arrangements.  

A singular pad. Multiple pads at each foot, each free to conform to the surface. Feet with ribbed bottoms. Feet with cogged engagement like Blenkinsop. In fact, anything that would engage the surface.  

Stave 7: Empirical tests

(1)Per Brunton, he first determined that the Mechanical Traveller required 84 pounds of linear thrust to drive forward at 2½ mph⁴.  

(2) The length of each "step" is 26 inches.  

(3) Brunton then tests the horsepower as follows: boiler at 40 to 45 psi; the Mechanical Traveller moving forward at 2½ mph; a chain attached to the rear lifted a vertical weight of 812 pounds at the same rate. From this, Brunton concludes "6 horsepower, or nearly so".

Discussion

(1) Using the standard friction equations, linear force / normal force=84 lbs/4500 lbs = 0.0187 rolling coefficient of friction. Modern steel wheels on rail have a rolling CoF as low as 0.001 up to as high as 0.0025. Brunton, with performance an order of magnitude worse than modern railways, could have benefitted from analysis with Stephenson's Dynamometer.

(2) The piston stroke is specified to be 24" but the length of step is also specified to 26"! This implies there were periods when both feet were off of the ground and the engine coasted, 1 part in 13. The cuff rate may be determined. 2½ mph is 158,400 inches per hour. A step is 26" so 6092.307 steps per hour. 3600 seconds per hour/6092.307 steps = 0.59 seconds/step. Each step is one chuff, inverting yields 1.69 chuffs/second.

(3) There are two components to compute Mechanical Traveller's total horsepower. The first component of the total is the horsepower to move Mechanical Traveller itself.

 

I obtain 0.559898 HP.

The second component is the useful work done, lifting the 812 pound load at 2½ mph.

I obtain 5.41234 HP.

Add these two components, yielding 5.972 HP. "Nearly so", says Brunton, and I agree, to within 5 parts per thousand. Sound engineering indeed⁵.

Stave 8: Mechanical Traveller No.2 

The second Horse to go by Steam was larger, made for Newbottle Colliery, after the success of the first at Butterley Gangroad was demonstrated. Unfortunately, due to the engineman's adjustment of the safety valve, the engine exploded, killing several people. Testimony exists as to the improper use of the safety valve⁶.

Brunton never brought another Mechanical Traveller forward.

Stave 9: A functional model

A few years ago, a modeler made a working model of Brunton's Horse to go by Steam, in ¹/₃₂ scale.  I will emphasize that the wheels do not drive this model forward, the legs do.  

  

Here is Adrian's entire play list.  

https://youtube.com/@adriansstuff78?si=mK0gfoThDImaQdiI  

Just click on "videos" and enjoy the marvel of Brunton's Mechanical Traveller. Adrian goes through the entire build and performs empirical adhesion tests. Well worth any modeler's time.

Stave 10: Merry Christmas!!

This Railway Oddity was presented for your Holiday Enjoyment. You may recognize the initial paragraph as paraphrased Dickens. A paragraph found on the first page of A Christmas Carol (Scrooge). The 'stave' references are in Dickens as well.

Bee

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Notes: For those who care about the tiny details, as if the details given above are not enough.

¹Butterley Gangroad (Crich Railway) had a 1 in 30 or 3.3% gradient.  

Newbottle Colliery had 1 in 36 or 2.77% gradient.

²"Method and Machinery for drawing or propelling carriages on roads or railways, by means of certain levers or legs acting alternatively or conjointly upon such roads or upon machinery attached thereto." UK patent 3700, William Brunton, May 22, 1813.

As per usual, a title entirely too long!

³Brunton's handwritten letter

The Science Museum has a handwritten letter, from Brunton to his brother, which contains the patent text and some sketches. This was obviously an attempt to preserve evidence of primacy of invention because, as per the letter, he was deeply suspicious of the individual at the patent office.  

https://collection.sciencemuseumgroup.org.uk/documents/aa110073746/autograph-letter-from-william-brunton-engineer-giving-a-description-of-his-steam-horse-butterley-iron-worksl

⁴Brunton is explicit in stating the velocity at 2½ mph, in more than one instance. Why is that??? James Watt needed to sell his engines. Watt's engines would substitute for horses. What could be a better selling point than comparing his engines directly to horses. To do so, Watt needed to measure the work output of a horse. Watt placed a 100 pound weight at the bottom of a 220 foot well. It took 1 minute, on average, for draft horses to pull it up.  Watt allowed 50% for friction. Therefore, his definition of a horse's power became 150 pounds lifted up 220 feet in 60 seconds.  220 feet/60 seconds = 3.666 feet/sec = 2½ mph. Brunton's competition was a draft horse, just as Watt's competition was. Hence the 2½ mph figure of merit.

⁵An engineering statement.

While I obtain 5.97 HP for Mechanical Traveller, this is assumes we can use Brunton's numbers verbatim. There is an essential problem with that assumption. It has to do with weights, measures, resolution, accuracy and traceability. Brunton cannot know his numbers with certainty. The entire horsepower calculation provided by Brunton is an excellent guesstimate. Mechanical Traveller had a velocity around 2½ mph. The thrust to move Mechanical Traveller was around 84 pounds. The friction in the sheave used to lift 812 pounds is ignored. The calculation yields around 6HP. His numbers align with his assessment, but the numbers themselves cannot be relied upon.

⁶Testimony about the boiler explosion. 

"…in the North, a propelling engine; it was near Sunderland [Newbottle is close to Sunderland], of a boiler driving waggons; the facts of the case I know to be these, from the engineer [brunton] who made the boiler. – In the first place, they had a smaller boiler to the same engine; that boiler did not generate steam so fast as the engine could expend it, consequently there was never an excess of steam came out of the safety valve, the engine man therefore with impunity screwed down his safety valve; it was never used. The proprietor of the engine [Newbottle Colliery] wishing to have more power, ordered a larger boiler, which had the power of generating nearly double the quantity of steam; this was sent, and a caution given by the gentleman [brunton] not to attach it to the engine till he arrived; but that was not attended to; the boiler was attached to the engine; the man [engineman Wm Sharp, per newspaper accounts] went to work as before, and he screwed down his safety valve, not knowing, that though before he had a deficiency, he now had an overplus; he said he would make a good start of it; the boiler exploded, killed several people, and him among the rest...

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Fascinating stuff, as ever, Bee. Some years ago my son and I sent a frustrating morning trying to access the site of the former Butterley works. Most of the buildings had been demolished, sadly, but site security was watertight so we failed to get in. We got a few photos but at distance. Really maddening. The works had so long and productive an history - the name "Butterley" seems to crop up on iron products all over the country.

I look forward very much to your next oddity.

[What About The Bee]

But wait! There's more! These are in the showman engine family but are still steam powered, much like a locomotive.  

1824 Gordon's Steam Carriage

David Gordon's steam carriage has 6 feet, instead of Brunton's 2. It is my estimation that this device could only be made to function on flat ground. If the ground was rough, a foot would attempt to lift the carriage, likely leading to the mechanism being bent and deformed. There is no record of commercial success, although a prototype does appear to have been constructed.

Danger was evident, it used a weighted, not spring powered, safety valve, clearly evident in the image

1827 Gurney's Steam Carriage

Sir Goldsworthy Gurney (yes, Goldsworthy was his name) also participated in the walking engine family. The primary method of propulsion was wheels on a crank axle. Yet for steep hills, Gurney added "propellers" as he called them, yellow arrow.

These were coupled to pistons, providing a linear stroke to propell the carriage when the going got tough. Regular service between London and Bath was provided, averaging 14 mph.  

Note the shape of the inside carriage and its resemblance to coaches of the period and the LMR First Class carriages. This was the accepted and expected shape.

He later coupled carriages behind the engine, when the heat of the engine became uncomfortable for passengers and the danger of explosions evident.

Sir Gurney discarded the propellers :(

And that, fellow oddity enthusiasts, ends the walking engines in early steam history.

Bee

Post Script. I do realize that the Brunton article was quite long, even by my own standards. Yet the vehicle was so strange as to defy belief and deserving of complete coverage. I do hope that you visited Adrian's page of the model, link above!

[What About The Bee]

This month's edition nearly slipped my mind. Whoops!

Dynamometer Cars have been used for quite some time on the railways, famously behind some record setting speed runs. Wonderful OO models have been made. Yet one of the first Dynamometer Cars was created by George Stephenson and Nicholas Wood to study retarding friction.

Assume a flat level track. In a frictionless environment, a small shove would set a car rolling and it would roll forever, until an opposing shove was made. But in the real world, the energy of a small shove is consumed by friction and the car comes to a stop.

Stephenson and Wood needed to reduce the retarding friction, so as to be able to haul more with the same power.

This device is extremely clever. In practice, it measures the acceleration provided to the device. If we give the dynamometer car a small shove, and watched it stop, the pendulum member would continue forward because it is not decelerated at the same rate as the car.

In practice, Stephenson and Wood kept the car moving at a steady pace by having a work crew push it along from behind the pendulum, the chaldron to the front. The amount of acceleration applied by the crew was measured by the pendulum on the semicircular scale.  

The chaldron in front was loaded with different weights, the axle bearings made wide and narrow, lubricated with this, lubricated with that, the wheels evaluated, different materials & etc and the acceleration measured. Rails themselves could be compared as well. While not an absolute measurement, it was relative to the other measurements. 

Altering the circumstances permitted them to see which configuration provided the least retarding friction, by measuring the acceleration input.

The significance of this cannot be overestimated. The ability to haul larger loads for the same unit if power facilitated the entire industry. All done in 1818.

This is an oddity because there was only ever one of these. Stephenson's Dynamometer.

Bee