Shaw 4-cylinder demonstrator 4-4-0 "American" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class Henry F Shaw (Locobase 11063)

Data from Angus Sinclair, "Development of the Locomotive Engine", Railway and Locomotive Engineering-September-December, 1907. See also "The Shaw Locomotive", American Machinist (18 June 1881), . Henry F "Hammer-blow" Shaw, "The Fate of an Inventor," Technical World Journal Volume 5 (1906) and Robert Grimshaw, The Steam Engine Catechism (10th ed, 1886), p. 116. (Thanks to Chris Hohl for his 2 April 2020 email giving Locobase the link to more detailed information about this design.)

NB on heating surface area: Shaw (or Hinkley) seems to have calculated tube heating surface area from each tube's inside (fire side) diameter to arrive at 881 sq ft (81.85 sq m). . Locobase follows the prevailing Anglo-American convention of using the tube's outside (water side) diameter.

Henry Shaw's claim for his unusual four-cylinder design was straightforward and greeted with skepticism: "By utilizing all the force developed upon the piston directly upon the driving wheels to rotate them, the enormous loss through friction in ordinary locomotives is entirely avoided."

Having deduced the source of much of the wheel wear and vibration on contemporary locomotives, Shaw designed a system that put individually cast cylinders side-by-side on either side of the smokebox. Each of these had a main rod, each of which was connected to crank ends outside and inside the frame. The crank ends lay at opposite ends of a forging and were driven at 180 deg from each other. In other words, as the single valve admitted steam at, say, the front end of the outside cylinder, it also admitted steam to the back end of the inside cylinder on that side.

(The view from the side must have been of more than usual interest with two rods rising and falling.)

Unlike many non-standard designs, the Shaw four-cylinder engine proved quite capable. Shaw himself proudly notes the evaporation of skepticism when the Hinkley product proved more than capable of running from Boston to Providence with an express train in less than one hour (44 miles). Regular runs on the Fitchburg and on the Camden & Atlantic showed the engine's ability to make time at reduced vibration levels and the Shaw won a gold medal at the 1883 Chicago Fair of Railway Appliances.

According to Shaw, a Franklin Institute committee charged with examining this form of counterbalancing stresses was able to "endorse unqualifiedly the correctness of the principle ...and, further, are satisfied ...that at high speed, steadiness and freedom from lateral movement are attained to a materially greater degree ..."

So what happened - why didn't this engine catch on? One clue lies in Grimshaw's observation that, at least as far as the exemplary locomotive was concerned, "...the port area being to piston area only as 1 to 11.54, the engine is manifestly choked." That is, with such small ports in the valves, there was no way to get the steam in and out easily. It's hard to see how the cylinders could have grown by very much without introducing some serious problems in geometry in directing the thrust from each of two pistons to a relatively narrow span of crank. Moreover, as Shaw admits, the cost of enduring hammer-blow could not be seen to be high enough to merit spending the extra money that a four-cylinder engine might entail.

In 1906, Shaw claimed that balanced four-cylinder engines then coming into vogue (most of which were compounds) violated his patent claims, against which he protested to no avail. Locobase suspects that his four-rod system was sufficiently unique as to forestall any patent infringement (that is, when you could drive on different axles with less hassle, why bother with infringing on Shaw's patent?).

In that samed decade in the United Kingdom, railways like the Great Western introduced four-cylinder simple-expansion locomotives.

He notes with sadness (and some bitterness) that after 244,000 miles (about 393,000 km) of successful demonstration runs, the Shaw wound up in suburban Philadelphia, where it was soon scrapped.

Principal Dimensions by Steve Llanso of Middle Run Media

ClassHenry F Shaw
Locobase ID11063
RailroadShaw 4-cylinder demonstrator
Number in Class1
Road Numbers
Number Built1
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)15 / 4.57
Engine Wheelbase (ft / m)22.67 / 6.91
Ratio of driving wheelbase to overall engine wheelbase 0.66
Overall Wheelbase (engine & tender) (ft / m)42 / 12.80
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)49,400 / 22,407
Engine Weight (lbs / kg)74,300 / 33,702
Tender Loaded Weight (lbs / kg)47,500 / 21,546
Total Engine and Tender Weight (lbs / kg)121,800 / 55,248
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 3.30 / 3
Minimum weight of rail (calculated) (lb/yd / kg/m)41 / 20.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)63 / 1753
Boiler Pressure (psi / kPa)130 / 9
High Pressure Cylinders (dia x stroke) (in / mm)10.5" x 24" / 267x610 (4)
Tractive Effort (lbs / kg)9282 / 4210.25
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.32
Heating Ability
Tubes (number - dia) (in / mm)161 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)11 / 3.35
Firebox Area (sq ft / m2)101.25 / 9.41
Grate Area (sq ft / m2)14.80 / 1.37
Evaporative Heating Surface (sq ft / m2)1029 / 95.60
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1029 / 95.60
Evaporative Heating Surface/Cylinder Volume213.93
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1924
Same as above plus superheater percentage1924
Same as above but substitute firebox area for grate area13,163
Power L14357
Power MT388.89

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