than the best single-expansion engine, and 29% more economical than the average record of 40 simple engines of the same class on the same division. Indicator-tests of a Locomotive at High Speed. (Locomotive Eng'g, June, 1893.)—Cards were taken by Mr. Angus Sinclair on the locomotive drawing the Empire State Express.

The locomotive was of the eight-wheel type, built by the Schenectady Locomotive Works, with 19 x 24 in. cylinders, 78-in. drivers, and a large boiler and fire-box. Details of important dimensions are as follows: Heating-surface of fire-box, 150.8 sq. ft.; of tubes, 1670.7 sq. ft.; of boiler, 1821.5 sq ft. Grate area, 27.3 sq. ft. Fire-box: length, 8 ft.; width, 3 ft 47% in. Tubes, 268; outside diameter, 2 in. Ports: steam, 18 x 14 in.; exhaust, 18 x 234 in. Valve-travel, 5% in. Outside lap, 1 in.; inside lap, 1/04 in. Journals: driving-axle, 81⁄2 101⁄2 in.; truck-axle, 6 x 10 in.

The

The train consisted of four coaches, weighing, with estimated load, 340,000 lbs The locomotive and tender weighed in working order 200,000 lbs,, making the total weight of the train about 270 tons. During the time that the engine was first lifting the train into speed diagram No. I was taken. It shows a mean cylinder-pressure of 59 lbs. According to this, the power exerted on the rails to move the train is 6553 lbs., or 24 lbs. per ton. speed is 37 miles an hour. When a speed of nearly 60 miles an hour was reached the average cylinder-pressure is 40.7 lbs., representing a total traction force of 4520 lbs., without making deductions for internal friction. If we deduct 10% for friction, it leaves 15 lbs. per ton to keep the train going at the speed named. Cards 6, 7, and 8 represent the work of keeping the train running 70 miles an hour. They were taken three miles apart, when the speed was almost uniform. The average cylinder-pressure for the three cards is 47.6 lbs. Deducting 10% again for friction, this leaves 17.6 lbs. per ton as the power exerted in keeping the train up to a velocity of 70 miles. Throughout the trip 7 lbs. of water were evaporated per lb. of coal. The work of pulling the train from New York to Albany was done on a coal consumption of about 31% lbs. per H.P. per hour. The highest power recorded was at the rate of 1120 H.P.

Locomotive-testing Apparatus at the Laboratory of Purdue University. (W. F. M. Goss, Trans. A. S. M. E., vol. xiv. 826.)— The locomotive is mounted with its drivers upon supporting wheels which are carried by shafts turning in fixed bearings, thus allowing the engine to be run without changing its position as a whole Load is supplied by four friction-brakes fitted to the supporting shafts and offering resistance to the turning of the supporting wheels. Traction is measured by a dynamometer attached to the draw-bar. The boiler is fired in the usual way, and an exhaust-blower above the engine, but not in pipe connection with it, carries off all that may be given out at the stack.

A Standard Method of Conducting Locomotive-tests is given in a report by a Committee of the A. S. M. E. in vol. xiv. of the Transactions, page 1312. Waste of Fuel in Locomotives.-In American practice economy of fuel is necessarily sacrificed to obtain greater economy due to heavy train-loads. D. L. Barnes, in Eng. Mag., June, 1894, gives a diagram showing the reduction of efficiency of boilers due to high rates of combustion, from which the following figures are taken:

Lbs. of coal per sq. ft. of grate per hour...... 12 40 80 120 160 200 Per cent efficiency of boiler.. 80 75 67 59 51 43

A rate of 12 lbs. is given as representing stationary-boiler practice, 40 lbs. is English locomotive practice, 120 lbs. average American, and 200 lbs. maximum American, locomotive practice.

Advantages of Compounding. Report of a Committee of the American Railway Master Mechanics' Association on Compound Locomotives (Am. Mach., July 3, 1890) gives the following summary of the advantages gained by compounding: (a) It has achieved a saving in the fuel burnt averaging 18% at reasonable boiler-pressures, with encouraging possibilities

of further improvement in pressure and in fuel and water economy. (b) It has lessened the amount of water (dead weight) to be hauled, so that (c) the tender and its load are materially reduced in weight. (d) It has increased the possibilities of speed far beyond 60 miles per hour, without unduly straining the motion, frames, axles, or axle-boxes of the engine. (e) It has increased the haulage-power at full speed, or, in other words, has increased the continuous H.P. developed, per given weight of engine and boiler. (ƒ) In some classes has increased the starting-power. (g) It has materially lessened the slide-valve friction per H.P. developed. (h) It has equalized or distributed the turning force on the crank-pin, over a longer portion of its path, which, of course, tends to lengthen the repair life of the engine. (i) In the two-cylinder type it has decreased the oil consumption, and has even done so in the Woolf four-cylinder engine. (j) Its smoother and steadier draught on the fire is favorable to the combustion of all kinds of soft coal; and the sparks thrown being smaller and less in number, it lessens the risk to property from destruction by fire. (k) These advantages and economies are gained without having to improve the man handling the engine, less being left to his discretion (or careless indifference) than in the simple engine. (i) Valve-motion, of every locomotive type, can be used in its best working and most effective position. (m) A wider elasticity in locomotive design is permitted; as, if desired, side-rods can be dispensed with, or articulated engines of 100 tons weight, with independent trucks, used for sharp curves on mountain service, as suggested by Mallet and Brunner.

Of 27 compound locomotives in use on the Phila. and Reading Railroad (in 1892), 12 are in use on heavy mountain grades, and are designed to be the equivalent of 22 × 24 in. simple consolidations; 10 are in somewhat lighter service and correspond to 20 x 24 in. consolidations; 5 are in fast passenger service. The monthly coal record shows:

Gain in Fuel
Economy.

(Report of Com. A. R. M. M. Assn. 1892.) For a description of the various types of compound locomotive, with discussion of their relative merits, see paper by A. Von Borries, of Germany, The Development of the Compound Locomotive, Trans. A. S. M. E. 1893, vol. xiv., p. 1172.

Counterbalancing Locomotives.-The following rules, adopted by different locomotive-builders, are quoted in a paper by Prof. Lanza (Trans. A. S. M. E., x. 302):

A. "For the main drivers, place opposite the crank-pin a weight equal to one half the weight of the back end of the connecting-rod plus one half the weight of the front end of the connecting-rod, piston, piston-rod, and crosshead. For balancing the coupled wheels, place a weight opposite the crankpin equal to one half the parallel rod plus one half of the weights of the front end of the main-rod, piston, piston-rod, and cross-head. The centres of gravity of the above weights must be at the same distance from the axles as the crank-pin."

B. The rule given by D. K. Clark: "Find the separate revolving weights of crank-pin boss, coupling-rods, and connecting-rods for each wheel, also the reciprocating weight of the piston and appendages, and one half the connecting-rod, divide the reciprocating weight equally between each wheel and add the part so allotted to the revolving weight on each wheel: the sums thus obtained are the weights to be placed opposite the crank-pin, and at the same distance from the axis. To find the counterweight to be used when the distance of its centre of gravity is known, multiply the above weight by the length of the crank in inches and divide by the given distance." This rule differs from the preceding in that the same weight is placed in each wheel.

G

=

C. "W= in which S = one half the stroke, G = distance from centre of wheel to centre of gravity in counterbalance, w = weight at crank-pin to be balanced, W = weight in counterbalance, ƒ coefficient of friction so called, = 5 in ordinary practice. The reciprocating weight is found by adding together the weights of the piston, piston-rod, cross-head, and one half of the main rod. The revolving weight for the main wheel is found by adding together the weights of the crank-pin hub, crank-pin, one

half of the main rod, and one half of each parallel-rod connecting to this wheel; to this add the reciprocating weight divided by the number of wheels. The revolving weight for the remainder of the wheels is found in the same manner as for the main wheel, except one half of the main rod is not added. The weight of the crank-pin hub and the counterbalance does not include the weight of the spokes, but of the metal inclosing them. This calculation is based for one cylinder and its corresponding wheels."

D. "Ascertain as nearly as possible the weights of crank-pin, additional weight of wheel boss for the same, add side rod, and main connections, piston-rod and head, with cross head on one side: the sum of these multiplied by the distance in inches of the centre of the crank-pin from the centre of the wheel, and divided by the distance from the centre of the wheel to the common centre of gravity of the counterweights, is taken for the total counterweight for that side of the locomotive which is to be divided among the wheels on that side."

E. "Balance the wheels of the locomotive with a weight equal to the weights of crank-pin, crank-pin hub, main and parallel rods, brasses, etc., plus two thirds of the weight of the reciprocating parts (cross-head, piston and rod and packing)."

F. "Balance the weights of the revolving parts which are attached to each wheel with exactness, and divide equally two thirds of the weights of the reciprocating parts between all the wheels. One half of the main rod is computed as reciprocating, and the other as revolving weight."

See also articles on Counterbalancing Locomotives, in R. R. & Eng. Jour., March and April, 1890; Trans. A. S. M. E., vol. xvi, 305; and Trans. Am. Ry. Master Mechanics' Assn., 1897. W. E. Dalby's book fon the "Balancing of Engines" (Longmans, Green & Co., 1902) contains a very full discussion of this subject.

Maximum Safe Load for Steel Tires on Steel Rails. (A. S. M. E., vii., p. 786.)-Mr. Chanute's experiments led to the deduction that 12,000 lbs. should be the limit of load for any one driving-wheel. Mr. Angus Sinclair objects to Mr. Chanute's figure of 12,000 lbs., and says that a locomotive tire which has a light load on it is more injurious to the rail than one which has a heavy load. In English practice 8 and 10 tons are safely used. Mr. Oberlin Smith has used steel castings for cam-rollers 4 in. diam. and 3 in. face, which stood well under loads of from 10,000 to 20,000 lbs. Mr. C. Shaler Smith proposed a formula for the rolls of a pivot-bridge which may be reduced to the form: Load = 1760 X face X diam., all in lbs. and inches.

See dimensions of some large American locomotives on pages 860 and 861. On the Decapod " the load on each driving-wheel is 17,000 lbs., and on "No. 999," 21.000 lbs.

Narrow-gauge Railways in Manufacturing Works.A tramway of 18 inches gauge, several miles in length, is in the works of the Lancashire and Yorkshire Railway. Curves of 13 feet radius are used. The locomotives used have the following dimensions (Proc. Inst. M. E., July, 1888): The cylinders were 5 in. diameter with 6 in. stroke, and 2 ft. 314 in. centre to centre. The wheels were 1614 in. diameter, the wheel-base 2 ft. 9 in.; the frame 7 ft. 414 in. long, and the extreme width of the engine 3 feet. The boiler, of steel, 2 ft. 3 in. outside diameter and 2 ft. long between tube-plates, containing 55 tubes of 13% in. outside diameter; the fire-box, of iron and cylindrical, 2 ft. 3 in. long and 17 in. inside diameter. The heatingsurface 10.42 sq. ft. in the fire-box and 36.12 in the tubes, total 46.54 sq. ft.; the grate-area, 1.78 sq. ft.; capacity of tank, 261⁄2 gallons; working-pressure, 170 lbs. per sq. in.; tractive power, say, 1412 lbs., or 9.22 lbs. per lb. of effective pressure per sq. in. on the piston. Weight, when empty, 2.80 tons; when full and in working order, 3.19 tons.

For description of a system of narrow-gauge railways for manufactories, see circular of the C. W. Hunt Co., New York.

Light Locomotives. For dimensions of light ocomotives used for. mining, etc., and for much valuable information concerning them, see cata. logue of H. K. Porter & Co., Pittsburgh.

Petroleum-burning Locomotives. (From Clark's Steam-engine.) The combustion of petroleum refuse in locomotives has been success fully practised by Mr. Thos. Urquhart, on the Grazi and Tsaritsin Railway, Southeast Russia. Since November, 1884, the whole stock of 143 locomotives under his superintendence has been fired with petroleum refuse. The oil is injected from a nozzle through a tubular opening in the back of the fire-box, by means of a jet of steam, with an induced current of air.

A brickwork cavity or "regenerative or accumulative combustion-chamber" is formed in the fire-box, into which the combined current breaks as spray against the rugged brickwork slope. In this arrangement the brickwork is maintained at a white heat, and combustion is complete and smokeless. The form, mass, and dimensions of the brickwork are the most important elements in such a combination.

Compressed air was tried instead of steam for injection, but no appreciable reduction in consumption of fuel was noticed.

The heating-power of petroleum refuse is given as 19,832 heat-units, equivalent to the evaporation of 20.53 lbs. of water from and at 212° F., or to 17.1 lbs. at 8% atmospheres, or 125 lbs. per sq. in., effective pressure. The highest evaporative duty was 14 lbs. of water under 81⁄2 atmospheres per lb. of the fuel, or nearly 82% efficiency.

There is no probability of any extensive use of petroleum as fuel for locomotives in the United States, on account of the unlimited supply of coal and the comparatively limited supply of petroleum. Texas oil is now (1902) used in locomotives of the Southern Pacific Railway.

Fireless Locomotive.-The principle of the Francq locomotive is that it depends for the supply of steam on its spontaneous generation from a body of heated water in a reservoir. As steam is generated and drawn off the pressure falls; but by providing a sufficiently large volume of water heated to a high temperature, at a pressure correspondingly high, a margin of surplus pressure may be secured, and means may thus be provided for supplying the required quantity of steam for the trip.

The fireless locomotive designed for the service of the Metropolitan Railway of Paris has a cylindrical reservoir having segmental ends, about 5 ft. 7 in. in diameter, 264 ft. in length, with a capacity of about 620 cubic feet. Four fifths of the capacity is occupied by water, which is heated by the aid of a powerful jet of steam supplied from stationary boilers. The water is heated until equilibrium is established between the boilers and the reservoir. The temperature is raised to about 390° F., corresponding to 225 lbs. per sq. in. The steam from the reservoir is passed through a reducingvalve, by which the steam is reduced to the required pressure. It is then passed through a tubular superheater situated within the receiver at the upper part, and thence through the ordinary regulator to the cylinders. The exhaust-steam is expanded to a low pressure, in order to obviate noise of escape. In certain cases the exhaust-steam is condensed in closed vessels, which are only in part filled with water. In the upper free space a pipe is placed, into which the steam is exhausted. Within this pipe another pipe is fixed, perforated, from which cold water is projected into the surrounding steam, so as to effect the condensation as completely as may be. The heated water falls on an inclined plane, and flows off without mixing with the cold water. The condensing water is circulated by means of a centrifugal pump driven by a small three-cylinder engine.

In working off the steam from a pressure of 225 lbs. to 67 lbs., 530 cubic feet of water at 390° F. is sufficient for the traction of the trains, for working the circulating-pump for the condensers, for the brakes, and for electriclighting of the train. At the stations the locomotive takes from 2200 to 3300 lbs. of steam-nearly the same as the weight of steam consumed during the run between two consecutive charging stations. There is 210 cubic feet of condensing water. Taking the initial temperature at 60° F., the temperature rises to about 180° F. after the longest runs underground.

The locomotive has ten wheels, on a base 24 ft. long, of which six are coupled, 4 ft. in diameter. The extreme wheels are on radial axles. The cylinders are 231⁄2 in. in diameter, with a stroke of 23% in.

The engine weighs, in working order, 53 tons, of which 36 tons are on the coupled wheels. The speed varies from 15 miles to 25 miles per hour. The trains weigh about 140 tons.

Compressed-air Locomotives.-For an account of the Mekarski system of compressed-air locomotives see page 510 ante.

SHAFTING.

(See also TORSIONAL STRENGTH; also SHAFTS OF STEAM-ENGINES.)

For diameters of shafts to resist torsional strains only, Molesworth gives /PT d = in which d = diameter in inches, P= twisting force in pounds K' applied at the end of a lever-arm whose length is 7 in inches, K = a coefficient whose values are, for cast iron 1500, wrought iron 1700, cast steel 3200, gun-bronze 460, brass 425, copper 380, tin 220, lead 170. The value given for cast steel probably applies only to high-carbon steel.

Thurston gives:

H.P. horse-power transmitted, d = diameter of shaft in inches, R = revolutions per minute.

J. B. Francis gives for turned-iron shafting d =

=

100 H.P.
R

Jones and Laughlins give the same formulæ as Prof. Thurston, with the following exceptions: For line shafting, hangers 8 ft. apart:

They also give the following notes: Receiving and transmitting pulleys should always be placed as close to earings as possible; and it is good practice to frame short "headers" between the main tie-beams of a mill so as to support the main receivers, carried by the bead shafts, with a bearing But if it is preferred, close to each side as is contemplated in the formulæ. or necessary, for the shaft to span the full width of the "bay " without in