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.
MISCELLANEOUS
PUMPS
Fig. 437. (See page [146].)