Pumps and Hydraulics, Part 2 (of 2) :: THE STEAM FIRE ENGINE

THE STEAM FIRE ENGINE

Fig. 388.

THE STEAM FIRE ENGINE.

The steam fire engine is practically a portable pumping engine. It is in all respects a complete water works on a small scale, hence, a modern apparatus must, within itself, and each part working harmoniously with every other part, contain several complex mechanisms. This will readily appear by a study of the several succeeding illustrations; the first, which in the figure below exhibits a “view” of a complete machine.

Fig. 389.
(See page 109.)

Modern steam fire engines are classified as to “size,” as “double extra first,” etc.; their capacities and weights are given approximately in the following

Table.

Size of Engines.	Capacity.	Weight.
Double Extra First	1,300 gallons per min.	10,800 pounds.
Extra First	1,100 gallons per min.	9,800 pounds.
First	900 gallons per min.	8,800 pounds.
Second	700 gallons per min.	7,800 pounds.
Third	600 gallons per min.	6,800 pounds.
Fourth	500 gallons per min.	5,800 pounds.
Fifth	400 gallons per min.	4,800 pounds.

The foregoing list of the sizes, capacities, etc., of the fire apparatus now in general use, affords a very good comparison between it and that which has, little by little, progressed for two thousand years to its present high plane. The application of electric power to the operation of the pumps and the propulsion of the apparatus is yet in too elementary a stage for present discussion in a work of this scope for—

It is essential that the machinery relied upon for fire protection should at all times be ready for instantaneous and effective service; this, because both life and vast property interests are at stake, hence of all machines made, the modern steam fire engine is produced with a niceness of finish and accuracy of fit equaled by no other, when size is considered; it approaches towards the perfection seen in the mechanism of a fine watch.

Figs. 390, 391.

This degree of excellence has been arrived at by successive steps. The illustration on page 92, Fig. 388 exhibits the fire-fighting tools of the early Romans and similar apparatus was used in England as late as the fifteenth century. The implements shown are a syringe, a sledge hammer, two fire hooks and three leathern buckets conveniently arranged against a wall. The owners of houses or chimneys that took fire were fined; and men were appointed to watch for fires and give the alarm. In 1472 a night bellman was employed in Exeter to alarm the inhabitants in case of fire, and in 1558, leathern buckets, ladders and crooks, were ordered to be provided for the same city; no application of the pump seems to have been then thought of.

Syringes continued to be used in London till the latter part of the 17th century, when they were superseded by more improved machines. They were usually made of brass and held from two to four quarts. The smaller ones were about two feet and a half long, and an inch and a half in diameter; the bore of the nozzles being half an inch. Three men were required to work each, which they achieved in this manner: one man on each side, grasped the cylinder with one hand and the nozzle with the other; while the third man worked the piston! Those who held the instrument plunged the nozzle into a vessel of water, the operator then drew back the piston and thus charged the cylinder, and when it was raised by the bearers into the required position, he pushed in the piston and forced, or rather endeavored to force, the contents upon the fire.A

Fig. 392.

Figs. 390 and 391 show an early form of syringe. A description of it translated from the original Greek, written by Hero of the ancient city of Alexandria, reads thus—“A hollow tube of some length is made, A, B; into this another tube, C, D, is nicely fitted, to the extremity of which is fastened a small plate or piston; at, D, is a handle, E, F. Cover the orifice, A, of the tube, A, B, with a plate in which an extremely fine tube, G, H, is fixed, its bore communicating with A, B, through the plate—as a vacuum is thus produced in A, B, something else must enter to fill it, and as there is no other passage but through the mouth of the small tube we shall of necessity draw up through this any fluid that may be near.”

A Note.—We are told that some of these syringes are preserved in one or two of the parish churches. It can excite no surprise that London should have been almost wholly destroyed in the great fire of 1666, when such were the machines upon which the inhabitants chiefly depended for protecting their property and dwellings. If the diminutive size of these instruments be considered, the number of hands required to work each, beside others to carry water and vessels for them, the difficulty and often impossibility of approaching sufficiently near so as to reach the flames with the jet, the loss of part of the stream at the beginning and end of each stroke of the piston, and the trifling effect produced—the whole act of using them, appears rather as a farce. These primitive devices were known as “hand squirts.”

Fig. 392 is a copy of an old engraving (A. D. 1568) which shows an “engine” of this type sufficiently enlarged to contain a barrel or more of water and as a matter of necessity, placed on a carriage.

Fig. 393.

To eject the water uniformly, the inventor moved the piston by a screw; and when the cylinder was emptied, it was refilled through the funnel by an attendant, as the piston was drawn back by reversing the motion of the crank. When recharged, the stop cock in the pipe of the funnel was closed and the liquid forced out as before. As flexible pipes of leather, the “ball and socket” and “goose-neck” joints had not been introduced, some mode of changing the direction of the jet of this enormous syringe was necessary. To effect this, it is represented as suspended on pivots, fastened in two upright posts: to these are secured (see figure) two semi-circular straps of iron, whose centers coincide with the axis, or pivots, on which the syringe is balanced. A number of holes are made in each, and are so arranged as to be opposite each other. A bolt is passed through two of these, and also through a similar hole, in a piece of metal, that is firmly secured to the upper part of the open end of the cylinder; and thus holds the latter in any required position. The iron frame to which the box or female part of the screw is attached, is made fast to the cylinder; and it is through a projecting piece on the end of this frame that the bolt is passed. By these means, any elevation could be given to the nozzle, and the syringe could be secured by passing the bolt through the piece just mentioned, and through the corresponding holes in the straps. When a lateral change in the jet was required, the whole machine was moved by a man at the end of the pole, as in the figure. Jointed feet were attached to the frame which were let down when the engine was at work.

Fig. 393 shows an engine for extinguishing fires, which has come down to us from the times of Hero, who thus describes it:

Note.—The siphons used in conflagrations are made as follows. Take two vessels of bronze, A B C D, E F G H (Fig. 393), having the inner surface bored in a lathe to fit a piston (like the barrels of water-organs), K L, M N, being the pistons fitted to the boxes. Let the cylinders communicate with each other by means of the tube, X O D F, and be provided with valves, P, R, such as have been explained above, within the tube, X O D F, and opening outwards from the cylinders. In the bases of the cylinders pierce circular apertures, S, T, covered with polished hemispherical cups, V Q, W Y, through which insert spindles soldered to, or in some way connected with, the bases of the cylinders, and provided with shoulders at the extremities that the cups may not be forced off the spindles. To the center of the pistons fasten the vertical rods, S E, S E, and attach to these the beam A´ A´, working, at its center, about the stationary pin, D, and about the pins, B, C, at the rods, S E, S E. Let the vertical tube, S´ E´, communicate with the tube, X O D F, branching into two arms at, S´, and provided with small pipes through which to force up water, such as were explained above in the description of the machine for producing a water-jet by means of the compressed air.

Now, if the cylinders, provided with these additions be plunged into a vessel containing water, I J U Z, and the beam, A´ A´, be made to work at its extremities, A´, A´, which move alternately about the pin, D, the pistons, as they descend, will drive out the water through the tube, E´ S, and the revolving mouth, M´. For when the piston, M N, ascends it opens the aperture, T, as the cup, W Y, rises, and shuts the valve, R; but when it descends it shuts, T, and opens, R, through which the water is driven and forced upwards. The action of the other piston, K L, is the same. Now the small pipe, M´, which waves backward and forward, ejects the water to the required height but not in the required direction, unless the whole machine be turned round; which on urgent occasions is a tedious and difficult process. In order therefore, that the water may be ejected to the spot required, let the tube, E´ S´, consist of two tubes, fitting closely together lengthwise, of which one must be attached to the tube, X O D F, and the other to the part from which the arms branch off at, S´; and thus, if the upper tube be turned round, by the inclination of the mouthpiece, M´, the stream of water can be forced to any spot we please. The upper joint of the double tube must be secured to the lower to prevent its being forced from the machine by the violence of the water. This may be effected by holdfasts in the shape of the letter L, soldered to the upper tube, and sliding on a ring which encircles the lower.

Fig. 394.
(See page 109.)

Heron or Hero was an Alexandrian mathematician of the 3d Century B. C. He was the inventor of “Hero’s Fountain” in which a jet of water was maintained by condensed air and of a machine acting upon the principle of Barker’s Mill, in which the motion was produced by steam. Fragments of his works on mechanics have been preserved for more than 2000 years.

Lack of space forbids following, as could be done, the growth of the modern steam fire engine from these primitive beginnings to its present high point of excellence and widely extended use. Wherever civilized men are gathered into towns and cities there can be found this admirable mechanism affording protection to both life and property.

The Working Parts,
The Boiler, and
Its facilities for Transportation are the three essential parts of the one mechanism which combined, form the steam fire engine. In brief reference to the last qualification, it may be said that these engines are drawn by hand, by one or more horses, or other animals and are self-propelled by both steam and electric power; again the hose carriage can be drawn by hand, by horses or can be attached to the engine.

The main working parts of the machine can be easily divided into two parts, the engine and the pump.

The boiler in all its details has been designed to meet the requirements peculiar to the fire service and needs a full explanation with illustrations.

The auxiliary appliances found necessary for the operation of the modern steam fire engine are large in number; this is owing to the fact that the machine combines within itself so complete a system for extinguishing fires. The supplies needed for its maintenance and use are also in proportion, as to quantity and variety, to its complex make up.

The boiler, which is generally of the upright semi-water tube type, is combined with the engine by means of a strong iron frame, which carries all the appliances as well as the driver’s seat, and also forms the body of the truck.

Vertical Section.
Fig. 395.

The pumps may be of the reciprocating or rotary type, and are generally placed in front of the boiler. If of the reciprocating type, two pumps are placed alongside each other, and are operated either by a double slide valve or piston valve engine.

The piston rods connect directly with the plunger rods and are also connected to a crank shaft by means of either connecting rods or yokes, the cranks being set at right angles, so that one pump is always acting, while the other passes the dead center, thus giving a practically steady stream.

The engine exhausts into the stack, which gives the necessary draft. Some engines are equipped with a boiler feed pump, others only depend upon an injector, or feed directly from the main pump. The coal box, which also forms a platform for the engineer to stand upon while under way, is placed back of the boiler.

All engines are equipped with two suctions and two discharge openings, so that either side may be connected up. The tool box and driver’s seat are in front of the engine. The frame rests upon springs, to make the machine easy running.

Fig. 396.

The Fox Boiler with which the Metropolitan and other engines are equipped deserves an extended notice. It is shown in vertical section in Fig. 395, the arrows indicating the steam and water circulation. Its design, while simple, embodies some original ideas as to the arrangement of the tube surface method of circulation, etc.; it is a steam generator of the water tube type designed to meet the requirements peculiar to the fire service. The steam take-off and sectional view of shell with the tube system removed is shown in Fig. 397.

Note.—Working pressure can be generated in this boiler in six minutes from cold water, and the provisions for expansion are so near perfect that no bad effect is noticeable from such severe treatment. The manifold tube sections are tested to 600 pounds pressure, and are put together with great care; the manifolds are counter-bored to admit the full diameter of the tube, leaving none of the threaded portion exposed.

Plan showing Steam Take-Off.—Fig. 397.

Top View of Empty Shell, showing manifold Beam.—Fig. 398.

The boiler consists primarily of a simple annular shell heavily stay-bolted throughout, and constitutes a water-legged fire-box and steam reservoir; the principal heating surface of the boiler consists of straight water tubes, manifolded in sectional form and housed within the shell, the general scheme providing arrangements to make all connections readily accessible, and permitting the withdrawal from the boiler of any one or all of the several tube sections; the shell, being practically a permanent feature, need seldom be disturbed by reason of subsequent repairs or renewals of the tube systems.

It may be noted that the lower part, or water leg, of the shell is contracted for the purpose of facilitating the rapid generation of steam, and also providing the maximum grate area; at a point somewhat below the water line of the boiler, the inner shell is flanged inward, thereby enlarging the annular space between the inner and outer sheets for the purpose of providing a more copious reservoir.

The water line being carried in this larger part of the shell, tends to prevent the rapid fluctuation of the water level, and the increased area of its surface at this point is favorable to the disengagement of the steam.

Sectional Unit
for Outer-Tube
System.
Fig. 399.

Sectional Unit for
Inner-Tube System.
Fig. 400.

When held at its normal point, the water line protects the flanged part of the inner shell; but no damage can occur, either from a willful or an accidental drawing down of the water, as the spray deflected through the nipples of the outer tubes is sufficient to protect the flange, although the actual water level is well down in the leg.

The steam in contact with the upper part of the shell is by no means dry, and the heat absorbed at this point is amply sufficient to protect it. To insure a delivery of dry steam to the cylinders, a peculiar “take-off” ring is provided at the highest part of the steam reservoir, the same encircling the inside sheet of the shell. The upper edge of the ring is perforated at a distant point from the throttle, and the steam entering the ring chamber in small streams is held in close contact with the hot shell at a point closely adjacent to the upper line of rivets; the steam by this means is dried during its passage to the throttle, and the heat thus absorbed serves as a protection to the rivets just referred to.

Note.—The life of both water tubes and fire tubes is generally found disproportionate to the heavier parts used in boiler construction, and experience shows conclusively that the cost of subsequent maintenance is measured directly by, and may be diminished by, the facility with which these indispensable parts may be replaced or repaired in an emergency.

The principal heating surface of the boiler is contained in the vertical water tube sections, which comprise and will be referred to, as an inner and an outer tube system.

The outer system, embraces the short manifold sections which completely encircle the fire-box walls. The top end of each section is screwed and suspended from the flanged part of the shell, and the lower end is stayed by direct connection with the leg of the fire-box. The tubes are “staggered” in their manifolds, thereby exposing the greatest possible surface to the fire, and filling out the space due to the difference in the width of the water-leg and steam space of the shell.

The direct application of heat to the tubes causes a natural and active upward current therein, which in turn induces a corresponding downward movement of the water in the leg of the fire-box, and promotes the flow into the feed pipes.

Top View.—Fig. 401.

Bottom View.—Fig. 402.

The inner-tube system comprises those tube sections which extend to the upper limits of the boiler, their number and arrangement being such as to completely fill the interior of the shell above the space required for the combustion of the fuel. The construction of the vertical inner-tube system is simple, and consists of the required number of manifold sections, suitably arranged to conform to the circular space occupied, the flat inner end of each upper manifold being rigidly bolted to a heavy transverse beam, which in turn is supported in suitable pockets secured to the upper part of the shell.

At the top of the boiler, each section has its own connection with the steam space, and it is easy to remove either one of the sections separately without disturbing the others; or the entire inner-tube system can be raised out of the boiler as a whole, after breaking the proper connections, all of which are accessible. The current of steam and water carried over through the top connections of the inner system is generally sufficient to keep the tubes clear of scale; and the point of discharge and disengagement is brought down low, to prevent its mixture with the drier steam contained in the highest part of the shell.

When connected to a stationary boiler, as is now the general practice in fire departments, the circulative currents of water reach all parts of the boiler, hence its contents may be kept uniformly at any desirable temperature.

A stationary heater for the fire engine consists of a small boiler, placed at some convenient point near the same when in quarters. It is connected with the engine boiler by means of suitable circulating pipes, the entire arrangement being adapted to supply hot water through pipe connections which separate automatically as the engine leaves the house.

Although the best types of fire engine boilers require but a few minutes’ time to generate a working pressure from cold water, the general adoption of many improvements has made the stationary heater an essential part of a complete equipment.

Experience proves that the life of the boiler is prolonged by being kept constantly in a state of activity, and the elevated temperature of the water insures prompt and efficient work by the steamer at the very time when a few moments’ delay may breed disaster.

The pumps fitted and adapted to steam fire engines comprise two separate and distinct double acting piston pumps united in a single body and akin in many details to the duplex pump.

Fig. 403.

Calling in mind the well-known fact, that, in drawing a water supply the only power available to bring the fluid under forcing influence of the pump’s pistons is the limited pressure of the atmosphere, therefore the importance of all details concerned in first inducing an entry of the water will be readily conceded. Easy and unrestricted “suction ways” in direct communication with properly proportioned receiving valves (and these valves suitably arranged in close proximity to the working barrels of the pump), are the conditions that must always remain paramount, and to which all other features must give way, to safely attain the desirable high piston speeds. The value of perfect, simple and direct water ways, the passages, and all which they imply, has been studied in the design of this pumping engine. See Figs. 403-407.

The facilities provided for exposing the interior mechanism permits all such parts to be quickly reached for examination, or detached for renewal or repair, and this can be done without dismounting the entire pumps or greatly disturbing their exterior attachments. It will be seen, by reference to the cuts, that all of the valves can be easily and quickly examined, and also replaced, by removing the caps that enclose the chambers; all joints required for this purpose are made between flat surfaces planed true, as shown in Fig. 404; gun metal, or other suitable composition, is used and no part of the pump body is subject to wear, either by friction or corrosion. All valve seats are screwed into place, and either these or the working barrels of the pump may be readily replaced with new ones, in case the same should become worn. All stud bolts, nuts, etc., coming in contact with water, are made of drawn phosphor or Tobin bronze; nipples, piping, etc., are of brass.

Figs. 404, 405, 406 and 407.

Suction or hydrant connection may be made at either side of the engine; and, in operation, the central core of the pump body is practically a continuation of the suction hose, and serves to establish a direct communication with the receiving pump valves, arranged on opposite sides of the chamber. This chamber, as shown in the sectional view, Fig. 408, thus becomes the distributing center, from which the incoming water flows to the suction valves. The current from the suction is not required to change its general direction, and but little friction is encountered by the water in its diversion through the pump valves.

The position of the suction or receiving valves, in relation to the water cylinders, may be understood by reference to Fig. 408, which shows the same arranged in a cluster around the open ends of the barrels. The suction valve area is large, and the proportions adopted contribute largely to the smooth running of the pump, under conditions of speed seldom attempted in ordinary practice.

Fig. 408.

The valves in this pump are controlled by improved springs, the tension of which is at all times the same; and which are made of phosphor bronze; the force chambers in opposite ends of the pumps are practically equal, and, owing to the close proximity of the valves, the clearance is reduced to a minimum The discharging outlets are elevated above the highest point of the valve chambers, and the communicating passages are designed to prevent conflicting currents, and also to permit the pump to free itself promptly of air. The pistons are of a frictionless type, and in accordance with the usual practice of working double pumps in unison, the cranks controlling the movements of the pistons are placed at 90 degrees.

Fig. 409.

A convenient and effective arrangement of suction strainers is shown in Fig. 409. Perforated cages are introduced into the suction chambers through the inlets on opposite sides of the pump. The ends of these cages are open, and a short sleeve, which is permanently secured within the pump, serves to support and also to establish communication from one cage to the other.

The surface of both cages is, therefore, available as a strainer, and any obstruction entering with the water is carried to the opposite side, to a point where it can be removed, without first detaching the suction hose.

The driving mechanism supplied with the American Pump is shown by Figs. 389 and 394, which are perspective views engraved from photographs. It may be noted that the design is practically compact and well balanced, and embodies many excellent advantages found in no other type of fire engine.

The pumps, steam cylinders and driving parts are built as a unit, and have no direct connection with the boiler other than the necessary stays and pipe connections, all of which are readily accessible and visible for inspection at any time.

The steam cylinders used in connection with the pumps are of the ordinary slide valve type. The valve chests are easily opened from either side of the engine for examination, and the valve rods are made from a special composition and can not corrode. The valve motion is simple, and there is nothing connected with the steam ends that may not be quickly understood.

Fig. 410.

Maximum Dimensions of Steam Fire Engines.

SIZE OF ENGINE.	LENGTH OVER ALL.		WIDTH OVER HUBS.	HEIGHT OVER DOME.
SIZE OF ENGINE.	WITH POLE	WITHOUT POLE	WIDTH OVER HUBS.	HEIGHT OVER DOME.
Double Extra First	25 ft. 3 in.	10 ft.	6 ft. 7 in.	10 ft.
Extra First	24 ft. 10 in.	9 ft. 10 in.	6 ft. 5 in.	9 ft. 10 in.
First	24 ft. 5 in.	9 ft. 6 in.	6 ft. 2 in.	9 ft. 6 in.
Second	23 ft. 11 in.	9 ft. 1 in.	6 ft.	9 ft. 1 in.
Third	23 ft. 2 in.	8 ft. 11 in.	5 ft. 9 in.	8 ft. 11 in.
Fourth	22 ft. 11 in.	8 ft. 7 in.	5 ft. 9 in.	8 ft. 7 in.
Fifth	22 ft. 3 in.	8 ft. 5 in.	5 ft. 6 in.	8 ft. 5 in.

Appurtenances. In addition to such special fixtures as may be necessary for their proper working, the following articles are a part of each engine:

Smooth bore rubber suction hose, carried in substantial brackets on the machine and fitted with suitable couplings, hydrant connections and interchangeable outside suction strainer.

Polished copper vacuum and air chambers.

Fuel pan of ample capacity.

Detachable footboard, for the engineer and an assistant.

Driver’s seat, for either one or two men.

Seat cushion.

Whip socket.

Blanket holders, when desired.

Foot brake, to operate from front or rear.

Horse pole, with whiffletrees.

Trace and pole chains or straps with patent snaps.

Gong attached to driver’s footboard or

Locomotive bell mounted over steam cylinders.

Steam signal whistle.

Grate bars, dumping or stationary pattern.

Stationary sprinkler, for wetting ashes under grate.

Pop safety valves.

Variable regulator for exhaust nozzles.

Auxiliary steam blast into chimney.

Nickel-plated brass chimney dome and bands around boiler.

Two steam pressure gauges.

Water pressure gauge.

Glass water gauge on boiler with extra tube.

Try cocks on boiler.

Brass feed pump for boiler.

Auxiliary feed to boiler from main pumps.

Churn valve, for feeding boiler when streams are shut off.

Necessary air, drain and pet cocks.

Surface blower from water line of boiler.

Blow-off cocks and cleaning plugs in fire-box leg.

Cleaning and “thaw” hose with connections.

Regrinding throttle valve, with drain cock attached.

Automatic or sight-feed lubricators.

Cylinder oil cups.

Necessary oil cups and lubricating devices.

Hand oil cans.

Three-pint reservoir cans for cylinder and lubricating oil.

Keepers, attached to all stuffing-box nuts.

Poker, shovel and other stoking tools.

Fire department hand lanterns, carried in brackets.

Adjustable screw wrenches.

Universal spanner for slotted nuts.

Hose spanner.

Hammer.

Tool box, with all necessary monkey-wrenches, cold chisels, and files.

Two polished play pipes and nozzles.

Stop valves next to boiler and flow and return pipes for use with stationary Fire Engine Heaters.

Fig. 411.

THE SILSBY ROTARY STEAM FIRE ENGINE.

The distinguishing feature of this engine will be found in the fact that, in both the cylinder and pump, the rotary type is substituted for the reciprocating or piston principle.

Fig. 412.

The larger sizes of these engines, Fig. 411, are hung on platform truck springs in front and on half-elliptic springs in the rear, and are braced and stayed to withstand violent shocks in the rapid driving over pavements. Although fitted to be drawn by horses only, they can be supplied with rope reel and drag rope.

Fig. 413.

The Silsby steam cylinder consists of two rotary pistons or cams, mounted on steel shafts and working together within an elliptical steam-tight case. Live steam from the boiler enters at the bottom of this case, and in its passage presses apart their long teeth or abutments, causes the two cams to rotate, and exhausts from the top into the tank and feed-water heater; these cams are provided with teeth or cogs, adapted to mesh with corresponding recesses in each other, so that a steam tight joint is maintained between them and leakage thereby prevented from passing directly upward into the exhaust.

The sides of these cams have their arcs turned to fit the heads of the case, and are so adjusted that, while being practically steam tight, allowance is made for expansion and contraction. In the ends of the longest teeth of the revolving cams are placed removable packing strips, which are forced outward into contact with the cylinder walls by means of springs. These packing strips may be removed through openings in the sides of the cylinder, and readjusted to take up the wear, which is confined to the ends of these adjustable strips. This can be done without taking the pump or cylinder apart.

Fig. 414.

Fig. 415.

The construction of the pump is similar to that of the cylinder; in this there are three long teeth in each cam instead of two. One shaft of the pump is coupled to the corresponding shaft of the cylinder, there being outside gears on both cylinder and pump to compel a uniform motion of the cams and to equalize the pressure. This construction secures a transmission of power at once direct and positive in Fig. 412.

The stuffing-boxes, used on both cylinder and pump, are self-adjusting, reduce friction and insure tightness. Valves are entirely absent from the pump and cylinder. The water ways being large, anything liable to enter the suction will pass through the pump without injury or interruption; the pump requires no priming, but when started will immediately without the aid of a check valve lift water vertically any required distance up to 29 feet.

The construction of the boiler ordinarily supplied with this engine is shown in Figs. 414-415. In the fire-box hangs a series of circulating water tubes arranged in concentric circles and securely screwed into the crown sheet. These drop tubes are closed at their lower ends by means of wrought-iron plugs welded in, and within each of them is placed a much smaller and thinner tube, which latter is open at both ends. The cooler water in the boiler descends through the inner tube and is thus brought directly into the hottest part of the furnace, whence, after being for the most part converted into steam, it ascends through the annular spaces between these inner and outer tubes.

The gases of combustion pass from the fire box to the stack through smoke flues, the lower ends of which are expanded into the crown sheet, and the upper ends into the top head of the boiler.

Fig. 416.

TABLE OF EFFECTIVE FIRE STREAMS.

USING 100 FEET OF 2¹/₂-INCH ORDINARY BEST QUALITY RUBBER-LINED HOSE BETWEEN NOZZLE AND HYDRANT, OR PUMP.

Smooth Nozzle, Size	³/₄-inch.
Pressure at Hydrant, lbs.	32	43	54	65	75	86
Pressure at Nozzle, lbs.	30	40	50	60	70	80
Pressure Lost in 100 feet, 2¹/₂-inch Hose, lbs.	2	3	4	5	5	6
Vertical Height, feet	48	60	67	72	76	79
Horizontal Distance, feet	37	44	50	54	58	62
Gallons Discharged per Minute	90	104	116	127	137	147
Smooth Nozzle, Size	⁷/₈-inch.
Pressure at Hydrant, lbs.	34	46	57	69	80	91
Pressure at Nozzle, lbs.	30	40	50	60	70	80
Pressure Lost in 100 feet, 2¹/₂-inch Hose, lbs.	4	6	7	9	10	11
Vertical Height, feet	49	62	71	77	81	85
Horizontal Distance, feet	42	49	55	61	66	70
Gallons Discharged per Minute	123	142	159	174	188	201
Smooth Nozzle, Size	1-inch.
Pressure at Hydrant, lbs.	37	50	62	75	87	100
Pressure at Nozzle, lbs.	30	40	50	60	70	80
Pressure Lost in 100 feet, 2¹/₂-inch Hose, lbs.	7	10	12	15	17	20
Vertical Height, feet	51	64	73	79	85	89
Horizontal Distance, feet	47	55	61	67	72	76
Gallons Discharged per Minute	161	186	208	228	246	263
Smooth Nozzle, Size	1¹/₈-inch.
Pressure at Hydrant, lbs.	42	56	70	84	98	112
Pressure at Nozzle, lbs.	30	40	50	60	70	80
Pressure Lost in 100 feet, 2¹/₂-inch Hose, lbs.	12	16	20	24	18	32
Vertical Height of Stream, feet	52	65	75	83	88	92
Horizontal Dist. of Stream, feet	50	59	66	72	77	81
Gallons Discharged per Minute	206	238	266	291	314	336
Smooth Nozzle, Size	1¹/₄-inch.
Pressure at Hydrant, lbs.	49	65	81	97	113	129
Pressure at Nozzle, lbs.	30	40	50	60	70	80
Pressure Lost in 100 feet, 2¹/₂-inch Hose, lbs.	9	25	31	37	43	49
Vertical Height of Stream, feet	53	67	77	85	91	95
Horizontal Dist. of Stream, feet	54	63	70	76	81	85
Gallons Discharged per Minute	256	296	331	363	392	419
Smooth Nozzle, Size	1³/₈-inch.
Pressure at Hydrant, lbs.	58	77	96	116	135	154
Pressure at Nozzle, lbs.	30	40	50	60	70	80
Pressure Lost in 100 feet, 2¹/₂-inch Hose, lbs.	28	37	46	56	65	74
Vertical Height of Stream, feet	55	69	79	87	92	97
Horizontal Dist. of Stream, feet	56	66	73	79	84	88
Gallons Discharged per Minute	315	363	406	445	480	514

N.B.—Mr. John R. Freeman, member of the New England Waterworks Association, should have the credit of this carefully arranged table.—See also page 125 for data relating to Nozzles.

The Clapp & Jones piston engine in design has features peculiar to itself; Fig. 416 represents one of six sizes, adapted particularly to city service.

Fig. 417.

The illustrations, Figs. 417 and 418, show the vertical pump as built for the larger engines: namely, the sizes known as Extra First, First, Second, Third and Fourth. The complete engine corresponding to the detailed views is shown by Fig. 416 on the preceding page.

The principal details are very clear in this engraving. The steam and water ends, together with the crank and reciprocating mechanism, are compactly arranged and the complete structure which comprises these parts is rigidly self-contained. The steam cylinders and valve chest are cast in a single piece and while this part is firmly secured to the boiler, all steam and exhaust connections are entirely independent of these fastenings.

The Clapp boiler is represented in Fig. 419. Reference to the annexed illustration makes clear the special features of this boiler, which consist chiefly of a series of spiral water-tube coils arranged within the fire-box. The coils are of copper and are produced by the seamless drawn process. Each coil is connected separately to the boiler, and the spiral form of these tubes permits freedom for expansion and contraction without strain on the terminal joints. The connections and the ends of the tubes are made by means of threaded nipples, jam nuts and corrugated copper washers, and the joints thus made insure tightness, yet admit of ready disconnection at any time.

Fig. 418.

The lower ends of the coil tubes are directly joined to the hollow fire-box walls and the upper terminals are arranged to discharge the circulated water over the crown sheet. This upward movement of the water within the spiral coils is caused by the application of heat to the outer surfaces of the tubes, and the circulation thus set up induces a corresponding downward action in the leg of the boiler. The circulation, therefore, continues without interruption so long as fire is maintained on the grate. In operating this boiler the water should be carried a few inches above the level of the crown sheet, but owing to the protection afforded by the constant distribution of water over the crown sheet, the limit of safety is not reached until the water is nearly out of the fire-box leg.

Fig. 419.

An improvement in the design of this boiler is the water-circulating deflector, which was devised to occupy the central space within the coil tubes. This deflector comprises an additional sectional unit, and its action coincides with the functions served by the coil tubes. The prime object of this device is to break up and direct the gases of combustion in a manner that adds to the heat-absorbing qualities of the coil tubes. See Figs. 420, 421.

Fig. 420.

Extending from the crown sheet to the top head are the smoke flues, which are securely expanded at both ends, and through which the gases of combustion pass from the fire box to the stack.

The Clapp & Jones Village Engine. By the illustrations, Figs. 422, 423, 424, etc., it will be noted that the cylinders and pumps are disposed horizontally and are fitted in a self-contained manner between bars, which also serve as the main frame of the engine.

The steam cylinders are 8 inches diameter; the pumps 4³/₈ inches, and the stroke common to both is 7 inches. These sizes are properly proportioned for effective work and the boiler power provided is ample to drive the pumping mechanism to its rated capacity of 400 gallons per minute.

Fig. 421.

The pumps are fitted with gates permitting two lines of hose to be worked either independently or at the same time without interference. The machine is mounted on half-elliptic springs, front and rear, and the weight of the boiler and pumps is distributed equally over both axles. The front pair of wheels turn completely under the goose necks, and the engine can therefore be turned on either hind wheel as a pivot. The arch of the main frames under which the wheels pass in turning is immediately forward of the boiler, and the advantage to be noted in this connection is the reduction in the over-all length of the entire machine. The front axle is equipped with a rope reel, and the pole is arranged for either hand or horse draft. The wheels are fitted with brakes, which are operated from the rear footboard. The engine weighs about 4,400 pounds. A detail description of the pump and valve gear follows.

Fig. 422.

The valve gear of the Clapp & Jones village engine is simple yet controls the moving mechanism of the two pumps working in unison. Each pump is driven directly by its own steam cylinder, and the steam valves are actuated by the positive movement of the opposite piston rod. The principle is substantially the same as practiced in the “Duplex” pump construction, and may be readily understood by reference to the detailed views which are given of these parts in other portions of this work.

Fig. 423.

The steam cylinders and pump are self-contained, and aside from the distinctive difference in the reciprocating gear the design of the steam and water ends does not differ from the vertical engines of the Clapp & Jones type.

On these engines intended for use in cold climates a “thaw-pipe” is attached, at the engineer’s side, inside the frame, and is used in extremely cold weather to prevent the feed-pump, as well as the main pump and connecting pipes, from freezing. It is operated by means of a small globe valve. If it is desired to warm the main pump, the two-way cock used in feeding the boiler should be turned as when feeding directly from the main pump, when steam will have access both to the main pump and the feed-pump; but care must be observed not to heat the main pump too warm. When the two-way cock is closed, and also when it is open as when feeding from the tank, the steam goes only to the feed-pump.

After using it to warm the main pump, the two-way cock, should be closed; otherwise, if the check-valve should happen to stick fast, the water would pass out of the boiler through the main pump.

Fig. 424.

Always keep the globe valve closed when not in use. It will be observed that the vacuum chamber upon the suction pipe is located within the air chamber upon the discharge passage.

The valves of this pump are formed by heavy rubber rings which surround the pump barrel, as shown in Fig. 423, therefore there can be no hammering of these valves when the pump is at work.

The rubber rings have slots cut into them at each side of each valve so that each valve can open and close without stretching the rubber bands. The steam valve is of the well-known rocker type. The plungers have no packing excepting water.

Fig. 425.—See page 122.

NOZZLES.

The sizes of nozzles named below will give the most satisfactory results, those in italics being the ones best adapted for fire duty. Also see page 93 for standard sizes of steam fire engines and page 117 for table of effective Fire Streams.

1, Extra first size engine.—1,100 to 1,150 gallons capacity. Through short lines of hose: One 1¹/₂-inch smooth-bore nozzle, for one stream; one 1³/₄-inch ring nozzle, or one 2-inch ring: nozzle; 1⁵/₁₆-inch ring nozzles for two streams. With 1,000 feet of hose, one 1⁵/₁₆-inch ring nozzle.

2, First size engine.—900 to 1,000 gallons capacity. Through short lines of hose: One 1³/₈-inch smooth-bore nozzle, for one stream; one 1¹/₂-inch ring nozzle, or one 1⁵/₈-inch ring nozzle; 1¹/₄-inch ring nozzles for two streams. With 1,000 feet of hose, one 1¹/₄-inch ring nozzle.

3, Second size engine.—700 to 800 gallons capacity. Through short lines of hose: One 1¹/₄-inch smooth-bore nozzle, for one stream; one 1³/₈-inch ring nozzle, or one 1¹/₂-inch ring nozzle; 1¹/₈-inch ring nozzles for two streams. With 1,000 feet of hose, one 1¹/₈-inch ring nozzle.

4, Third size engine.—600 to 650 gallons capacity. Through, short lines of hose: One 1¹/₈-inch smooth-bore nozzle, for one stream; one 1¹/₄-inch ring nozzle, or one 1³/₈-inch ring nozzle; 1-inch ring nozzles for two streams. With 1,000 feet of hose, one 1-inch ring nozzle.

5, Fourth size engine.—500 to 550 gallons capacity. Through short lines of hose: One 1¹/₁₆-inch smooth-bore nozzle, for one stream; one 1¹/₈-inch ring nozzle, or one 1¹/₄-inch ring nozzle; ⁷/₈-inch ring nozzles for two streams. With 1,000 feet of hose, one 1-inch ring nozzle.

6, Fifth and sixth size engines.—300 to 450 gallons capacity. Through short lines of hose: One 1-inch smooth-bore nozzle, for one stream; one 1-inch ring nozzle, or one 1¹/₈-inch ring nozzle, ⁷/₈-inch ring nozzles for two streams. With 1,000 feet of hose, one ⁷/₈-inch ring nozzle.

The Ahrens steam fire engine is not presented as a whole, but Figs. 426-428 show parts of this interesting and widely known apparatus.

Fig. 426.

The boiler, Fig. 426, is radically different from others, and the special features making it so popular in the past are the absence of a crown sheet and smoke flues, coupled with the advantageous manner in which the water-tube coil sections can be withdrawn from the containing shell of the boiler. The peculiar arrangement of the tubes compels a forced circulation of the water, and for which purpose an independent steam pump is provided. Water drawn from the fire-box leg is forced through the water tubes, and this relation between the circulating pump and the other elements of the boiler will be more readily understood by reference to the illustrations, where Fig. 426 is a sectional, 427 a top, and 428 a bottom view.

Fig. 427.

Fig. 428.

Fig. 429.—See page 141.

INSTRUCTIONS AND SUGGESTIONS.

The fire engine is essentially an apparatus adapted to emergencies, and owing to the intermittent nature of the duty performed, it is quite likely, unless the proper precautions are observed, that its several parts, more especially its interior mechanism, will suffer more deterioration while standing idle than from actual service.

It is necessary that these interior parts, as well as those more readily apparent, be cared for with a view of keeping them constantly in condition to endure the most severe and protracted strains at the shortest notice. While standing in the house, the engine should at all times be kept ready for immediate service, with shavings and kindlings in the fire-box, and as much kindlings and coal in the fuel pan as can be conveniently carried.

In winter, if no heater is attached to the engine, the room must be kept warm, to insure against frost.

The machine should be started gradually, but before doing so the engineer ought to satisfy himself that the joints and connections in the suction hose are air tight, that the discharge gate is open, the churn valve closed, that the fire has been properly attended to, the cylinder cocks open, the exhaust nearly closed, and all the bearings and journals well oiled, and the wheels properly blocked, especially if the engine is standing on a grade.

The automatic air cocks on the upper pump heads must be opened immediately after starting. They serve to promptly relieve the upper pump discharge chambers of air, and may be closed as soon as water escapes from their orifices.

When cylinder condensation has nearly ceased, the engine being warm, the drain cocks should be closed and the machine speeded up gradually until a good pressure of steam is obtained.

Until the engineer has had some experience with the machine, and is familiar with its workings, it is not advisable to use more than 90 or 100 pounds of steam, which is all that is required for ordinary fire duty; the necessity for more than 120 pounds will probably never arise.

The stuffing-boxes of the engine and pump should be carefully packed.

All of the bearings and journals, as well as the oil cans, should be well supplied with good oil. The best mineral engine oil is recommended for this purpose, as it does not gum or change its viscosity with variations in the temperature of the atmosphere, and it will endure a higher temperature than animal or fish oil without injury.

Fig. 430.—See page 141.

The engineer should keep all joints tight, the stuffing-boxes properly packed, and all bearings thoroughly oiled.

If the journal boxes or other working parts require taking up, remember that a little play is preferable to a close adjustment liable to cripple the engine at a critical moment. To insure perfect safety, always thoroughly test the apparatus after making such repairs, by subjecting the parts affected, to the strains usually encountered in actual service.

The principal requirement of the steam cylinders and slide valves is proper and constant lubrication. Let this one item be attended to, and its mechanism will practically take care of itself for many years.

The joints and connections in the suction must be perfectly tight.

Before laying the fire, see that the grate and fire-box are clean, also that the grate bars are fast, so they will not be liable to jar out, and that all the steam outlets of the boiler are tightly closed.

Lay on the grate some dry pine shavings—not too many—spread evenly over the grate, with a few hanging down between the bars; on the shavings put some finely-split pine or hemlock wood, then some a little coarser, and finally a quantity coarser still. It is well to put on the top some finely-split hard wood. These kindlings must all be dry and split—not sawed—and should be put in loosely, in layers, the layers being crossed, so that there will be a free circulation of air between them.

To light the fire: Apply torch (described in page 135) below the grate, never in the door; and while doing so move the torch around to insure thoroughly igniting the shavings.

When there is a pressure of 40 to 60 pounds of steam, begin throwing in coal, a little at a time, broken up in pieces about the size of a man’s fist. Bituminous coal should be used, the same as that from which illuminating gas is made. It should be of the very best quality, and very free burning.

Do not put the wood or coal all close to the fire door, but scatter it about and spread it evenly over the grate.

As soon as the engine is started, coal should be put on often, a little at a time, and the grate should be kept covered, but not thickly—say to a depth of three or four inches. Be particular to fire evenly and regularly, taking care to cover air holes through the fire, and to keep the fire door closed as much as possible.

The grate bars should be kept well raked out from below, and the fire and coal occasionally stirred off the grate bars inside the fire-box, using the flat side of the poker for the latter operation.

Fig. 431.—See page 138.

Fig. 432.—See page 138.

Fig. 433.—See page 139.

The water in the boiler should be carried as high as six or eight inches in the glass tube as soon as the engine gets fairly to work and a good pressure of steam is raised. The gauges will indicate more water in the boiler when the machine is running than it will with the same quantity of water if it is not at work, owing to the expansion of water by the application of heat.

If there is a tendency to foam, the feed should be increased and the surface blow-off opened quite frequently to relieve the boiler of the scum and surplus water. If the foaming is unusually violent, it may be subdued by stopping the engine for a few moments and permitting the water to settle.

During temporary stops the fire should be cleaned, by removing the clinkers and the moving parts of the machinery examined and oiled.

The boiler is usually fed by force pumps, the plungers of which are secured directly to the yokes of the main engines. Both pumps are arranged to work in unison; and the supply is generally taken from the discharging chamber of the main pumps, and is controlled by an ordinary globe valve. Should the water being delivered by the main pumps be unsuitable for feeding the boiler, this valve must remain closed, and a supply from a barrel or tank introduced through the connection provided for that purpose.

When feeding the boiler, it is a good plan to occasionally feel the pipe leading from check to boiler with the hand, as one can tell by this means whether the pump is feeding properly. If feeding all right, the pipe will be cool. If the pipe is hot, the pump is not feeding properly, try the pet cock.

Always keep a good torch, ready for use, in the fuel pan. This can be made by tying some cotton waste on one end of a stick about two feet long and saturating the waste with kerosene oil.

The kindling should be carefully prepared, and the quantity carried sufficient to generate a working pressure in the boiler before coal is added to the fire.

Care should be taken not to use too large nozzles if two or more streams are being thrown.

Owing to the contracted diameter of fire hose, the flow of the water is retarded; the loss of power due to friction increases directly with the length of the line and nearly as the square of velocity. In other words, if the loss due to a given flow be 12 pounds for 100 feet of hose, then 24 pounds will be required to maintain the same rate through an additional 100 feet. To double the velocity will require four times the pressure, or 48 pounds for 100 feet and 96 pounds for 200 feet.

From this brief explanation, it must be plain that the capacity of any engine is diminished as the length of the line of hose is increased.

For this reason, the greater the lift the smaller the stream that can be thrown effectively, and the size of nozzle used should depend upon the height the water is draughted, reducing it one-eighth inch for every five feet above a lift of ten feet. If the engine uses a 1¹/₄-inch nozzle for ordinary work, it will answer for any lift up to 10 feet. If water has to be draughted 15 feet, a 1¹/₈-inch nozzle should be used; if 20 feet, 1-inch; and if 25 feet, ⁷/₈-inch.

Never start a fire unless one full gauge cock of water appears in the boiler.

The suction basket or strainer should always be attached when draughting water, and every precaution taken to insure tight connections in the suction. The basket must be kept well under the surface, to avoid clogging if the water be foul.

When the supply is taken from a hydrant, the valve should be fully turned on; if opened before water is wanted through the hose the discharge gates on the pumps must be closed. Unless the pressure is excessive, the hydrant is usually permitted to remain open while the steamer is attached, the discharge during temporary stops being controlled by the pump gates.

The apparatus should always be halted, or placed at a proper point, with reference to the source of the water supply. When attached to a hydrant or plug, do not run the engine faster than the water will flow to supply the pump, and if the supply is not sufficient to allow the pump to work to its full capacity, avoid using too large nozzles.

The safety of life and property is very often dependent upon the skill and good judgment of the engineer, and as the maximum effect of such apparatus is generally required at the most critical time and under the most exciting circumstances, it is important that the endeavor by constant and persistent practice to acquire that confidence and proficiency that will insure a correct and decisive action in all matters pertaining to the management of the machine.

From three-fourths to one inch of water should be indicated in the glass gauge, except when there is a heater attached to the engine, then from four to five inches should be carried. The bottom of the glass tube being on a line with the crown-sheet, when one inch of water shows in the tube, the water-line in the boiler is then one inch above the crown-sheet.

It is advisable occasionally—say once a month—in towns where fires are not frequent, to fire up and take the engine out for practice and drill, and to make sure that it is in proper working order, after which the boiler should be blown off and refilled with fresh water, as hereinafter directed.

Every engine required to pump salt water, or other water unfit for the boiler supply, should be provided with a fresh-water feed tank.

The purpose of the automatic air cock (if there is one) is to prevent the rattling of the check valves when the pumps are being only partially filled; if the supply is to be drawn from a barrel or tank, the entrance of air through this cock must be prevented.

When draughting the water, bear in mind that the greater the perpendicular lift the less the quantity of water which can be pumped, remembering that it is the pressure of the atmosphere which forces the water into the pump, and not any power exerted by the pump itself, which simply produces the vacuum. Thus, the nearer the surface of the water the greater the velocity with which it enters the pump, while the higher the pump the weaker the pressure and the less the quantity of water which enters it, and at a height of about 30 feet no water at all will go into the pump.

If it is suspected that one of the joints in the suction is loose, the speed of the engine may be slackened without stopping entirely, until water is thrown eight or ten feet from the nozzle, when if the pump is taking air the stream will snap and crack instead of flowing out smoothly. If it is found that the pump is taking air through the suction, and the leak cannot be located in any other way, it may be found by removing the suction basket and turning the end of the suction up higher than the top of the pump, and then filling it with water. The water will be forced out through the joints wherever loose, and leaks can be found in this way.

The principal object of the churn valve is to permit the operation of the pumps without discharging any water through the natural channels; it controls a passage by which the discharging side of the pumps is connected with the suction chamber. In draughting water, when the pumps are first started, this valve must remain closed until the pumps are filled with water, thereby excluding the air which would find its way into the suction chamber if the same were open. It should also be closed when the pumps are at rest, to prevent the dropping of the water into the suction pipe.

When the engine is put to suction, acquire the habit of feeling this valve to assure its complete closure.

If there is anything about the engine that is not fully understood, or if it fails to do its work properly from any cause, the maker should be communicated with at once; inquiries are promptly answered, and usually required information or suggestions are cheerfully furnished.

THE AMERICAN STEAM FIRE ENGINE.

The number of appliances and special devices used on and about a steam fire engine is not large, as it is the aim of both designers and builders to simplify the machine as much as possible without diminishing its efficiency.

Fig. 434 is an appliance known as the Siamese connection. It is used for stand pipes attached to the outside of buildings, etc., and also as a detail of the fire pump. Its use is to lead off two lines of hose.

The valve shown in the figure, closes automatically in case of stoppage of one of the engines or the bursting of the hose.

Figs. 434, 435.

Fig. 435 exhibits an approved form of strainer for the bottom of the suction pipe.

The American steam fire engine pump is shown in Figs. 431 and 432.

Fig. 431 being the front view, one side of it shown in section, exposing the interior parts for explanation, and Fig. 432, representing the side elevation, also in section.

The pumps, which are double acting, are united in a gun-metal casting, which forms a single body for both, and permits them to be placed much closer as to centers than could otherwise be done. This method provides an ample suction-chamber which is common to both.

In cross section the pump somewhat resembles a box girder. This peculiarity of the pump’s combined form furnishes a rigid base for the entire structure, simplifies the driving mechanism and enables it to endure extraordinary strains without vibration.

It will be seen by reference to the cuts that any of the valves can be easily and quickly examined, and, if necessary, replaced, by simply removing the caps and heads.

The pump barrels are provided with removable linings, which can readily be replaced with new ones in case the same should become worn after years of service. These, as well as the valve seats, are made of gun metal, no cast iron or other material subject to corrosion by water being used in any part of the pumps.

Both the suction and discharge valves are supplied with improved valve springs, the tension of which is, at all times, the same; and being made of phosphor bronze, the springs retain their elasticity and will not corrode.

The steam cylinders used in connection with this pump are of the ordinary slide-valve type, with which most mechanics are familiar, and are thus easily repaired when necessary. The cylinders and pumps are detached from the boiler, and are separated therefrom sufficiently to allow every facility for getting at each and every part. All connections, both steam and water, are made outside of the boiler.

The La France steam fire engine pump is shown in outline in Fig. 433, which consists of a double plain slide-valve engine, operating a double pump.

The steam piston rod of each side connects with its pump rod, by means of square bars, two of which are on each side of the crank shaft. The crank is operated by the cross-head through a connecting rod; the arrangement of these parts can be seen in Fig. 433. The cross-head guide is entirely done away with, as the stiffness of the connection between the two piston rods takes the thrust of the connecting rod.

The pump barrel is enclosed by an outer casing. The space between barrel and casing is always kept filled with water which is supplied through the suction pipe.

Fig. 436.

When the pump barrel is being filled with water the suction valves are lifted from their seats, which allows the water to pass into the space between the valve-seat plates and thence into the pump barrel.

When the pump barrel is being emptied the suction valves are closed while the discharge valves are open, which allows the water to pass into a triangular shaped space between the front plate and valve-seat plates thence upward to the discharge pipe.

The suction and discharge valve of this pump being all grouped together, it is only necessary to remove the plates which can be seen, Fig. 433, bolted to the front of the pumps and form part of the outer casing; these plates are in front of the pump and may be quickly unscrewed by a T wrench.

The Amoskeag steam fire engine is shown in the views (Figs. 429 and 430 on pages 128 and 130). This world widely known machine is made by the Manchester Locomotive Works at Manchester, New Hampshire, U. S. A.

The former cut represents the extra first, first, second, third and fourth size double steam fire engine of this make. They have “crane-neck” frames and are arranged for horse draft and are mounted upon Endicott’s patent platform springs. The effect of this improvement is that the draft strain is transmitted directly from the horses to the axles, the springs bearing no part of this draft strain.

Fig. 430 shows the “fifth” size, also with “crane-necked” frame and made for either horse or hand draft.

The boiler used is upright and tubular in style, is made of the best quality of steel plate, with seamless copper tubes, thoroughly riveted and stayed; it is simple in its construction, and for strength, durability, accessibility for repairs, and its capacity for generating steam, has passed a most critical test. For engines of the second size and larger, the boilers expand downwards at the crown sheet of the fire-box, thus increasing the grate surface and consequently the steaming capacity of the boiler.

The connections with the steam cylinders are simple, direct and of good capacity, peculiarly accessible for repairs, and have the great advantage of being entirely unexposed to the air.

The steam cylinders of the single engines are made in one casting; they are secured to the boiler framing, and covered with a lagging of wood, with a metallic jacket on the outside. The pump for the double engines is made entirely of composition, and its main shell is also in one casting. It is vertical double acting; its valves are vertical in their action; the water-ways are free and direct, and the valves accessible, so that examination or renewal of these parts may be quickly made. The pump is arranged for receiving suction hose on either side, and has outlets also on either side for receiving the leading hose.

Self-propelled steam fire engines are well adapted for city service. In Fig. 436 is shown a double extra, first size self-propelling engine of the Amoskeag pattern. The road driving power is applied from one end of the main crank shaft, through an equalizing compound and two endless chains running over sprocket-wheels on each of the main rear wheels, permitting these rear wheels to be driven at varying speeds as when turning corners.

The driving power is made reversible, so that the engine may be driven either forward or backward on the road at will.

The steering of the engine is effected by means of a steering hand wheel at the front, adjusting the front axle through a system of bevel and worm gearing, so arranged that the constant exertion of the steersman is not required to keep the wheels in line on the road. By the removal of a key the driving power may be disconnected from the road driving gearing, when it is desired to work the pumps when the engine is standing still.

Clyx.com