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.