Henry Shaw's claim for his unusual 4-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 that much of the wheel wear and vibration on contemporary locomotives, Shaw designed a system that put 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. (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 4-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 1 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 4-cylinder engine might entail.
In 1906, Shaw was claiming that the balanced 4-cylinder engines (most of which were compounds) violated his patent claims, against which he protested to no avail. Locobase suspects that his 4-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?).
He notes with sadness (and some bitterness) that after 244,000 miles of successful demonstration runs, the Shaw wound up in suburban Philadelphia, where it was soon scrapped.
|Specifications by Steve Llanso of Sweat House Media|
|Class||Henry F Shaw|
|Railroad||Shaw 4-cylinder demonstrator|
|Number in Class||1|
|Locomotive Length and Weight|
|Ratio of driving wheelbase to overall engine wheebase||0.66|
|Overall Wheelbase (engine & tender)|
|Axle Loading (Maximum Weight per Axle)|
|Weight on Drivers||49400 lbs|
|Engine Weight||74300 lbs|
|Tender Light Weight||47500 lbs|
|Total Engine and Tender Weight||121800 lbs|
|Tender Water Capacity|
|Tender Fuel Capacity (oil/coal)||3.3 tons|
|Minimum weight of rail (calculated)||41 lb/yard|
|Geometry Relating to Tractive Effort|
|Boiler Pressure||140 psi|
|Cylinders (dia x stroke)||10.5" x 24"|
|Tractive Effort||9127 lbs|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||5.41|
|Grate Area||14.80 sq. ft|
|Evaporative Heating Surface||982 sq. ft|
|Combined Heating Surface||982 sq. ft|
|Evaporative Heating Surface/Cylinder Volume||204.13|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||2072|
|Same as above plus superheater percentage||2072|
|Same as above but substitute firebox area for grate area||0|