WILLIAM FLETCHER'S COMPARISON OF British and American Engines

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In 1904, William Fletcher published English and American Steam Carriages and Traction Engines. A master mechanical engineer, Fletcher designed engines at various times for the British companies of Clayton & Shuttleworth and Ransomes, Sims, and Jefferies. His 428-page book (published by Longmans, Green, and Company with offices in London and New York) offers insight into how a British designer viewed American traction engines.

Fletcher believed that English engines of the late 1800s and early 1900s were built slightly heavier than most of their American counterparts. British designers wanted their traction engines to be perceived as 'all purpose 'good for hauling over relatively long distances and for belt work. Also, English threshing machines were notoriously bulky; only a sturdy engine could pull such threshers over muddy country lanes.

In Fletcher's day, the thickness of the boiler plate of the typical English engine surpassed that of an average American engine. Most of the plate used in British boilers was between seven-sixteenths and one-half of an inch thick, and the plate in those portions of the firebox exposed to the greatest heat might be even thicker. As Fletcher reported, the boiler itself was often shorter and slightly wider in diameter than was customary in an American engine. This factor might help to account for Fletcher's assumption that British engines were 'quick steamers.' Like the boilers, English fireboxes tended to be short and not too deep. The fireman (or stoker) had to hope for coal (and coke) of a high quality! In most British makes of engines, fireboxes used a sliding door, not the hinged doors common on American fireboxes.

The diameter' of the tubes in British boilers usually measured one-fourth of an inch wider than that of tubes in the average American boiler. With larger tubes, fewer were needed than was normal among American makes. According to Fletcher, British designers did not want a great many tubes because they wished to provide as much steam space above the water line as practicable. The proportionately lower water level in an English boiler might explain the property of getting steam up quickly.

British designers often employed cross-compound cylinders for plow engines, road locomotives, rollers, and showman's engines. Single-cylinder engines served agricultural and general purposes, but double-simple and tandem-compound cylinders were as rare as hen's teeth. Fletcher argued that a double-simple arrangement wasted steam. For their cross-compound cylinders, English designers preferred center-cranked engines, as a glance through Floyd Clymer's Album of Historical Steam Traction Engines will corroborate. Most British cylinders rested within a large, sturdy jacket. As steam direct from the boiler rose to fill this jacket, and as it was this steam which entered the steamchests, one could say that this jacket replaced the steamdome. Indeed, English engines seldom were equipped with a dome, while American boilers almost invariably had one. Although certain English designers placed the steamchests on the sides, thereby making it easier to gain access to the valves, most located the steamchests on top of the cylinders and well within the large jacket. This arrangement served to improve the engine's efficiency.

Fletcher points out that mechanical engineers in Britain tended to locate their cylinders next to the smokebox because they felt certain that the driest steam could be found there. They piped steam directly from the front end of the boiler into their cylinders. With the steamjacket acting as a kind of dome, the English engine had virtually no exposed steam-piping. For additional economy of operation, boilers routinely sported jackets.

Certain British builders slanted the valves downward from the top of the tall steamjacket toward the crank shaft (considerably complicating the engineering of the design). With such valves tilted above horizontal cylinders, the ports on the 'high' end had to be wider so as to prevent wire drawing of the steam on that end. 'Wire-drawing' meant that the frictional resistances in a poorly-de signed port (usually a long and constricted one) tended to throttle down the steam, thereby decreasing power.

Fletcher noted that his English colleagues staunchly favored rear-geared arrangements; that is, British designers opposed locating the driver wheels in such a way that the hubs would line up with the center of the sides of the firebox. Rather, they insisted that the best distribution of weight occurred only when the drivers were located on an axle running across the firebox at about the level of the platform. Fletcher and his con temporaries did not want the front end of their engines to lift off the ground, and they accused certain American builders of installing heavy water tanks in front of the smoke stack so as to weight down the front end of side-geared engines. Fletcher claimed that some American companies made the bottom of such front-mounted tanks from two up to five inches thickmerely to add weight!

With driver wheels on an axle be hind the firebox, British engines featured long connecting rods to reach from the steamjacket and cylinders at the smokebox end to the crankshaft at almost the opposite end of the boiler. While such a longer (and heavier!) connecting rod in a center-cranked engine smoothly applied power to the crankshaft, the extra weight in the reciprocating parts tended to slow down the engine. Also, the additional length caused the piston to run more slowly than that in an equivalent American make. The average English engine topped out at 160 revolutions per minute, while the ordinary American engine ran at 250 r.p.m.

English designers often employed a rather complicated system of levers to reverse the engine and to 'hook it up' so as to use steam expansively. Arranged in a linkage, these levers accomplished the work which eccentrics and rods did for most American engines. Occasionally, these levers attached to the sides of the connecting rod.

A high percentage of English engines adopted the practice of using four shafts: the crankshaft, the axle of the driver wheels, and two countershafts in between to spread out the gearing and to lend strength. To with stand the strains of hauling massive loads over poor roads, British driver wheels were made heavy. Preferring flat steel spokes, English designers made the diameter of their driver wheels approximately eight to ten inches larger than that of American drivers. Such wheels helped to add weight. Quite often, the compensating gear (or differential) was located on the axle, not on one of the countershafts. By employing two counter shafts, British engineers could keep more of the gearing inside heavy sideplates (which extended upward from the boiler and backward beyond the firebox), could leave room on the crankshaft for an eccentric-driven water pump or similar device, and could produce a thinner engine over all! A British law prohibited wide engines.

Numerous English engines boasted winding drums and one or more rollers for steel-wire cable. Certain builders bolted the winding drum to the compensating gear. By pulling out a pin, the person running the engine could disengage the driver wheels, and only the gears and cable-drum would turn. Cables came in handy when encountering steep grades. The engine could be parked at the top of the hill and could wind the cable to pull up a wagon, threshing machine, or other load from be low. Designers customarily attached rollers to the left side of the tender (as viewed from standing behind the engine).

In general, British builders disliked friction clutches. Instead, levers served to mesh gears. The person running an engine had to make sure that the gears were in perfect alignment before using a lever to shove them together. On the other hand, English engines (unlike their American counterparts) routinely had brakes. The device looked like either a steering wheel on a vertical shaft or a tiller located near the back of the tender. English engines nearly always included gearing for two speeds on the roadoccasionally three speeds. Such engines could pull themselves along the ground more rapidly than most American engines. Although the A. W. Stevens Company of Marinette, Wisconsin, built one of the fastest traction engines in the United States, it attained four and a half miles per hour while British makes routinely accomplished five miles per hour.

In 1870, Aveling and Porter built engines having heavy sideplates (called 'hornplates') which carried the bearings for the crankshaft, countershafts), and axle. As soon as Aveling and Porter's patent expired, other British makers adopted this system of sturdy hornplates, which, along with shields for any gears located outside the hornplates, not only prevented dust from cutting the gears but also concealed the moving parts from the eyes of nervous horses. Most English engines which were in tended for haulage on highways used a solid flywheel for the same purpose; the government had imposed restrictions on builders to prevent engines from scaring skittish horses. Fletcher thought that any moving vehicle whatsoever would frighten a nervous horse and that owners of such excitable horses had no business thrusting them into the public thoroughfares. Incidentally, early steam carriages often resembled horse-drawn carriages not because designers lacked imagination but because the builders hoped to pacify horses, which might recognize and not fear the outward appearance of a carriage.

The flywheels of British engines tended to be much larger in diameter but smaller across the face than those of American engines,. Typically, the diameter of such English flywheels exceeded that of American ones by twelve to fourteen inches. The good-sized flywheel helped to smooth out the movement of the engineespecially while in traction gear. On the road, British engines tended not to use their governors. Most were equipped with a crossarm governor, located perhaps far back from the cylinders (not on the steamchest, as was generally standard in American custom).

Almost all English engines boasted a double-formed safety valve, found on top of the steam jacket. This 'distinctively British' design was known as a Ramsbottom valve, named for its inventor. Emphasizing safety, most British engines carried two glass water-gauges.

Fletcher analyzed the 'latest types' of American traction engines; while maintaining objectivity, he permitted himself a few pointed comments. After quoting an advertisement from the Advance Thresher Company which stated that 'in beauty and simplicity of design, the Advance engine is beyond each and every one,' Fletcher remarked, 'Our readers will form their own opinion respecting the engine and the claims made for it.' Turning to a Case engine, Fletcher observed that the rear axle and countershaft were arranged 'as in English practice' and that hornplates supported the crankshaft 'again ... following English design.' Fletcher applauded Frick's decision to discard what he called the 'over-neck disc-crank' and to choose 'with advantage' a center-crank mechanism (or 'counterbalanced dip-crank,' in Fletcher's nomenclature). When Fletcher described the O. S. Kelly Manufacturing Company's engines, his objectivity waned: 'The traction engines made by this firm differ from all the American examples which we have thus far de scribed. They have advantages not possessed by the others ...' Small wonder! Kelly engines closely resembled their British counterparts.

While engines from both sides of the Atlantic enjoyed more traits in common than Fletcher or anyone had the right to expect, distinctive qualities imparted a decidedly British appearance to engines from Shake speare's 'scepter'd isle' and gave to American engines a look befitting Uncle Sam. In Great Britain and the United States, numerous enhancements awaited steam engines after Fletcher's 1904 publication date, but his book comparing English and American engines affords modern readers a keen, clear view of the remarkable industrial ingenuity of his day.

Note: This article uses 'English' and 'British' synonymously. A few builders of engines existed in Scotland, none in either Wales or Ireland.