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Home , Bore (engine), Boulton and Watt, Lap Engine, Parallel motion, Sun and planet gear, Thomas Newcomen

BOULTON ANDWATT ROTATIVE STEAM 1785 Sydney, Australia April 17, 1986

An International Historic Mechanical Landmark

The American Society of Mechanical Engineers This engine of 1785 srands known that: (1) given a ve- Newcomen’s Influence at the second beginning of tical, open-topped This was the first beam steam power; it is the moment with , atmospheric engine, a style that would carry when the chain connection be- pressure would drive the piston on for long over a century. The tween the piston and beam of down into a vacuum formed overhead beam of wood with the 73-year-old steam beneath it; (2) such a vacuum its arc ends was 24 ft (7.3 m) was replaced by two links that could be created by the con- long and centrally pivoted on formed a “.” densation of steam under the stout engine-house Wall 22 ft The piston could now add an piston. (6.7 m) above the floor. In upward push to the former (1663- 1729) of , using reality the beam was a partial down-only pull permitted by these ideas and others, put pulley, for the chains to the the chain, giving an almost together the first practical reciprocating piston rods, continuous flow of power from and pump for steam at one end, pump at the the two-fold or double action draining distressed mines or other, were always tangent to on the piston that allowed the supplying water. This event of the ares of half-beam radius, engine to be rotative and so 1712 was immortalized by thus providing rod guidance in turn the shafts of manufactur- Thomas Barney’s engraving the vertical (or perpendicular, ing industry to achieve a long- dated 1719 relating to a coa1 as was said two centuries ago) sought goal. mine in Staffordshire near as the beam oscillated. It can The steam engine’s transi- Castle. Well-executed, be read that the open-topped tion from pumping duty to its the print includes a key to the cylinder had a diameter of 21 second and more versatile form parts of the “Steam Engine” in. (533 mm) with a length of came slowly. Tracing the story and “A Scale of Feet & 7 ft 10 in. (2338 mm). of the rotative engine means Inches” enabling the deter- The -really an enor- returning to the early eigh- mination of principal dimen- mous tea kettle of 5.5-ft teenth century when it was sions. (1.67 m) diameter - was direct- ly below the open-topped cylinder and would furnish steam at atmospheric pressure to the space under the piston, the piston having been hauled to the top of its cylinder by the weight of the pump rod and its . Injection of cold water in- to the steam under the piston caused condensation with the formation of a vacuum into which atmospheric pressure, acting down, shoved the piston. This was the power with which the pump rod at the other end of the beam was hauled up. If an incomplete (poor) vacuum of say 10 psia (68 kPa) is assumed, the force on the 21-in. (533 mm) piston would have been about 3400 lb (1542 kg), giving a pivot reac- tion on the wall of twice that. to be deliberately condensed whatever profits might be Someone’s note on the engrav- for the power stroke. This con- made, went bankrupt. Great ing remarks that 10 gallons of clusion led to his first patent in good fortune brought Watt the water were raised 51 yards 1769; it might be called the engineer into partnership with “perpendicular” when run- “Keep It Hot” patent, for cen- (1728-1809) ning at 12 strokes per minute. tral idea was to keep the the astute industrialist. It was This works out at about 5.5 cylinder hot, as close to 212° F 1776 before the propositions of (4.1 kW) for the as possible, to discourage the 1769 patent were reduced water end. A calculation for that senseless steam - to successful practice. the cylinder (assuming a 6.5 - ft consuming initial condensation Public achievement came [1981 mm] stroke) yields an in- caused by a cool system. This with a mine pumping engine dicated horsepower of about “coolness” stemmed from hav- having a 50-in. (1270 mm) 8.2 (6.1 kW). There are no real ing the piston top and the diameter cylinder and a blow- data on the thermal efficiency, cylinder wall in constant con- ing engine (for an iron works) but by any guess it was appall- tact with ambient air, and a with 38-in. (965 mm) cylinder. ing, one-half percent has been cylinder bottom shockingly Their most satisfactory perfor- suggested. In fact, these pump- cooled everytime the condens- mance was in part due to the ing that did a splen- ing water was injected. accurate steam cylinders finish- did job in saving the drowning Patent No. 913, January 9, ed on ironmaster Wilkinson’s coal mines could be afforded 1769, for “a new Method of newly contrived boring mill. only there, being run on the Lessening the Consumption of Fuel consumption of these coal that was so poor that it Steam and Fuel in Fire engines was third of that nor- couldn’t be sold. Mineral Engines” featured a three- mal for the time. Word got mines (non - coal regions) could point program of direct con- around, and enquiries from the hardly take advantage of the cern: (1) reduce condensation long-suffering metal mines of engine because of the cost of at the piston by closing the top were followed by transporting coal. of the cylinder, letting the orders from there and other come through a places as well. gland, and use hot steam at at- Keep It Hot mospheric pressure instead of The Industrial Push (1736-1819) was cool ambient air to force the With the ever-increasing in- born 24 years after that first piston down; (2) arrange for a dustrial activity of the Newcomen engine went to steam jacket around the burgeoning eighteenth cen- work at . As instrument cylinder; (3) have a seperate tury, especially in , maker at the College of vessel or “external condenser” rotational power beyond that Glasgow, he was brought into connected to the cylinder bot- derived from animals, water, or contact with the steam engine tom, and carry out the conden- wind was desperately needed. in 1763 by being asked to sation in this remote vessel, Animal power was bulky and repair a model Newcomen thus keeping the cold condens- troublesome what with feeding engine used in the “Natural ing water and condensate away and stabling; wind power was Philosophy” class. The problem from the cylinder. uncertain except in favored was that the model, having Some seven years would areas and hardly suited to the large boiler and small cylinder, elapse before the merits of the regularity of industry; and would make but a few strokes patent could be demonstrated, water power could only be ex- before stopping for want of for development costs posed a ploited further by going farther steam. He recognized that the problem. Watt had his living away from the cities to tap the cylinder cooled between to earn, doing so as civil remoter portions of already strokes, that several volumes of engineer and surveyor; his pa- well-populated streams. Mine steam were therefore condens- tent sponsor, an industrialist drainage and water supply to ing idly before one remained with two-thirds interest in municipalities and canal feeders (canals constituted the the , in Patent No. 1306, main transportation system, October 25, 1781, “circular the roads being wretched) were motion round an axis.” handled by Newcomen (at- Of the several schemes the mospheric) pumping engines, sun- and- planet gear (epicyclic) but here the heavy cost of fuel was chosen and would be used for the primitive engine set until 1802, even though the limits. More and more crank patent expired in 1794. millwork and machinery, With a large , this arrange- dependent upon shaft power, ment worked well-enough for was in the making but faltering some purposes in the manner for lack of adequate drives. of the crank. After all, the The need was met, in small engine was single-acting— part, by the awkward arrange- power on only the downstroke, ment of having an engine the piston being returned to pump water over a waterwheel the top of the cylinder by iner- from a reservoir to which the tia from the wheelwork. Dou- water returned to be again ble action, or power from the pumped over the wheel. upstroke too, a notion Watt That a rotative engine would had been toying with since have unlimited industrial ap- 1775, came into view again. plication was very clear to Watt addressed the problem Boulton who began to urge with his next patent, No. With the rack-and-sector Watt to take the matter in 1321, March 12, 1782, in hookup, a rigid rack replaced hand, as by letter in 1781, June which he presented a number the flexible chain as an exten- 21: “The people in London, of “new improvements”: the sion of the piston rod. When Manchester, and expansive principle; double ac- kept in engagement with the are steam mill mad. I don’t tion to double the power and gear sector that replaced the mean to hurry you but we get a more regular motion; a arch head around which the should determine to take out a in which chain had wrapped, the rack patent for certain methods of steam used in a first cylinder held the piston rod to the same producing rotative motion would act expansively in a vertical as the chain would, from the fire engine.” second; a rack-and-sector with the advantage of being The basic problem at this relating piston rod to beam to able to transmit not only the stage was to convert the beam’s permit “push” as well as pull of the conventional single- oscillation into rotation, readily “pull” for double action; and acting piston, but also the done with a to a steam wheel or rotative push from a double-acting a crank, an idea unfortunately engine. Pertinent is the rack piston. Although a patented by someone else. piston-rod engaging a gear sec- kinematically sound idea, However, the crank arrange- tor on the beam end. The ob- workmanship and materials of ment and the single-acting vious solution of constraining the day weren’t up to it, the engine weren’t the best of the piston rod with a cast teeth of sector and rack be- partners, for it may be imag- in a vertical guide was imprac- ing troubled by the shock ined that the rotational motion tical then for manufacturing loading on reversal of the was non-uniform despite reasons: straight guides several piston’s motion. Furthermore, flywheel and often ill-suited if feet in length would have had the headroom for the rack add- not unacceptable to to be worked out by chipping ed perhaps five feet to the operations of sensitivity, as in and filing, prohibitively expen- height of the engine house. textile mills. sive for anticipated production Some other was Watt devised substitutes for engines. needed. Perpendicular Motion were protected by Patent No. ordered in 1783. A drawing of Watt puzzled mightily over 1432 dated August 24, 1784. June 1784 shows that engine the problem, and in a letter This three-bar motion was a laid out with rack and sector — of June 30, 1784, reports to bit awkward, for the radius rod but a three-bar motion sketch- Boulton that he “got a glimpse lengthened the engine by half ed over it and actually sup- of a method of causing again, thus calling for an plied. The Whitbread drawing a piston rod to move up and enlargement of the engine of a few months later shows the down perpendicularly by only house. After building two more elegant parallel motion. fixing to it a piece of iron upon engines with the three-bar mo- It has been said that when the beam, without chains or tion, Watt held the length of first installed, the single-acting perpendicular guides or on. subsequent engines down to engine did the work of 24 towardly frictions, arch heads beam length by halving the horses. This probably meant or other pieces of clumsiness.” three-bar motion (the radius the total number of animals re- About a week later (July bar was tucked under the outer quired during a day, not the 11th) he reports that he is half of the beam), and adding number in use at one time, for pleased with tests on a “very two links to form a panto- a conservative calculation leads large model of the new graph, the farthest joint of to about 17 indicated substitute for racks and which had a motion that was horsepower, (12.7 kW), assum- sectors. . . It is a perpendicular an enlargement of the perpen- ing a of motion derived from a com- dicular motion’s unique 10 psia (69 kPa) and a speed of bination of motions about straight-line point: it would 20 to 21 strokes per minute. centres.” take the piston rod. In sum- When the engine was made Early kinematicians would mary, there were two points, double-acting in 1795, the call this the “three-bar mo- the first located on the small power developed by its cylinder tion,” recognizing the three three-bar motion, with the se- was of course doubled, to an connected bars or links that cond or parallel point being IHP of perhaps 35 (26 kW) for were in play. (For “motion,” the far joint of the pantograph: the rest of its working life that one may at times read the motion of this second point extended to 1887: 102 years of “mechanism” and even was parallel to that of the first, service. The re- build in 1795 “bar,” depending upon the hence the quite proper name did not replace the original circumstances). Retaining the “parallel motion” for the pan- wood beam nor add a cen- basic beam as one of the “mo- tograph configuration. trifugal governor, for these tions about centres,” Watt It is now that “our” engine items are not shown on the of- added an outboard radius rod enters history somewhat ficial drawing of the time. The of half-beam length (another cautiously. Samuel Whitbread, present cast iron beam with “motion about centres”) and a London brewer had ordered proper counterweights appears joined the two by a link to an engine with a 24-in. to have been fitted about 1805. whose midpoint the piston rod (610 mm) cylinder, 6-ft attached. This special point (1829 mm) stroke, in 1784. Early High - Tech described a practically straight Although single-acting, it was The engine was high line in the vertical or perpen- to be rotative, and a drawing technology for its day, much dicular. Because of this, the (in the Boulton & Watt Collec- more commanding than the whole —the three-bar tion in Birmingham) dated other mechanical marvels of motion or mechasnism — was November 1784 shows a the time, the windmill and also called a “perpendicular parallel motion, almost certain- clock. King George III, a man motion.” This mechanism is ly the first application of that of plain and practical tastes the mechanical invention of mechanism. This parallel mo- and amusements, partial to which Watt would say that he tion had followed hard on the hunting and mechanical con- was proudest. It and two other three-bar motion of the Coates trivances, brought Queen linkages doing similar jobs and Jarrett oil mill engine Charlotte and their four children to the brewery in May of 1797 to inspect the “won- drous works to be seen there,” the moving and exciting engine being a key attraction. Although of modest capacity, it had set a good example, for by 1796, eleven other engines were amiably at work in London. A second engine came to Whitbread’s in 1841. In 1887 a compound engine by Messrs. Simpson & Co. fit- ted with Cowper’s inter- mediate steam reservoir replaced “our” engine. The new machine, with high and low pressure cylinders, would have operated on steam pressure a good deaal higher than the perhaps 3 psig (21 kPa) of the Boulton and Watt engine it superseded. And it would have been compact- one thinks of the old engine standing 30 ft (9.1 m) tall and swinging a 14-ft (4.2 m) flywheel, all for an IHP of maybe 35 (26 kW). At any rate, the engine was dismantled. Archibald Liversidge, Pro- fessor of Engineering at Sydney University and trustee of the Sydney Technological Museum (founded 1880), happened to be in London at this time visiting his friend the engineer of the Brewery. Samuel Whitbread kindly donated the engine to the Museum where it arrived in 1889. In course it was housed in a special building behind the Museum in Harris Street and given an electric turning motor in 1930. In 1983 the engine was removed to the Castle Hill site and with loving care was brought to steaming condition to celebrate its bicentenary in July of 1985. As mentioned earlier, the engine is 30 ft (9.14 m) tall, and has about the same length, with an overall weight of 33 tonnes. The cast iron beam, 18 ft 4 in. (5.6 m) center to center weighs about 9.2 tonnes; the wood beam of the 1795 draw- ing might have weighed about 1.5 tonnes if of oak. Built of sections of cast iron, the 14-ft (4.26 m) flywheel weighs, together with its shaft, some 8 tonnes. Finally, the connec- ting rod is 18 ft (5.5 m) center to center. Mention must be made of the next-in-age survivor, the “Lap” engine of 1788 now in the Science Museum, London, of which faithful copies have been made for museums in Munich, West Germany, and Dearborn, Michigan, U.S.A. This engine drove the laps or polishing buffs for steel or- naments in Boulton’s , delivering 70 years of service. It was the first engine to be fitted with cen- trifugal governor. Smaller than the Whitbread engine, its and stroke are 18.75 in. (476 mm) and 4 ft (1219 mm). Watt rated it at 10 horsepower (7.5 kW), but put on test when the museum acquired it in 1858, some 13.75 horsepower (10.3 kW) could be noted. Power was taken off the flywheel rim that carried 296 inserted gear teeth.

June 1986 R.S. Hartenberg F. ASME, F. I Mech E, VDI The American Society of Mechanical Engineers is most grateful to the officers and staff at the Power House Museum and the Institution of Engineers, Australia, for their assistance and support of this designation, and to Professor Richard S. Hartenberg, who wrote the text for this brochure. The Boulton and Watt Rotative Steam engine is the twentieth International Historic Mechanical Engineering landmark to be designated by ASME, and the fifth to be designated outside of the United States. The others are in Puerto Rico, Great Britain and France. For a complete list and information on the Society’s History and Heritage Program write: ASME Public Information Dept., 345 East 47th St. New York, NY 10017 The American Society of Mechanical Engineers Dr. L.S. Fletcher, President Paul F. Allmendinger Executive Director William J. Warren, International Affairs Committee ASME National History and Heritage Committee Dr. R. Carson Dalzell, Chairman Robert M. Vogel-Smithsonian Institution Dr. Richard S. Hartenberg Dr. J. Paul Hartman Dr. Euan F. C. Somerscales Joseph P. Van Overveen The Institution of Engineers, Australia W. J. Rourke, Chief Executive M. H. Thomas, Chairman, College of Mechanical Engineers Power House Museum Dr. Lindsay Sharp, Director

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