LOCOMOTIVE ENGINE. 
453 
collar soldered upon it with a thin conical end, which is fitted into the tube 7, and 
held water-tight by the socket K, screwed on to the tube and bearing against 
the collar of the suction pipe. 
The piece M, which is bolted upon the upper pipe G, is closed at the top by a 
cap, P, screwed upon it, and has a tube cast on it like the bottom piece, 7, into 
which the end of the delivery pipe, N, is fixed by the screwed socket 0, exactly 
similar to the suction pipe, 77 The delivery pipe is bent round backwards, as shewn 
in Plate LXXXIX., extending to the fire box, where it is fixed into a valve 
box, in the same manner as the other end is fixed; the pipe has to be bent in 
this way that the ends may be turned in the same direction to allow them both to 
be screwed into the sockets instead of having the screws at the two ends pulling 
against each other. This box contains another valve like those in the pump, 
and is fixed on to the fire box, communicating with the inside. The suction pipes, 
K'K', (Plates LXXXIX., XC., XCI., and XC1I.,) pass under the fire box, and are 
connected at the end to the pipes that bring the water from the tender, being sus 
pended by stays, s' s', from the fire box. 
In the pieces L and M, are fixed the valves Q and R, which are shewn to 
double the scale in figs. 30, and 31, where T is the valve seat, made conical and 
with a groove outside to hold packing for fitting it water-tight when driven into its 
place in the pump. The valve S is a ball, turned and ground truly spherical, 
fitting water-tight into its seat in every position; it is guided by the piece U U, 
screwed upon the valve seat, and cut into four bars to allow passage for the water. A 
pin, V, is screwed through the cap P, bearing upon the guide of the valve R, and 
fixed by a set nut, W, to hold down the valve seat and prevent its being raised 
out of its place by the force of the pump; the lower valve seat does not require 
holding, as the pressure is above it. 
The plunger B, fig. 29, is worked in and out of the barrel of the pump A, a dis 
tance of 18 inches, by the piston rod at each stroke; leaving a space behind it when 
drawn out equal to its bulk, which is supplied with water through the suction pipe 
and lower valve, and the water again forced out through the upper valve and delivery 
pipe into the boiler when the plunger is pushed in. The internal diameter of the 
suction and delivery pipes, and of the water way in the valve seats, is one inch. The 
pump would force a quantity of water into the boiler at each stroke equal to the 
bulk of the plunger for 18 inches in length, if the suction pipes were kept open ; but 
the quantity is regulated according to circumstances by means of the cocks t't' 
fixed in the suction pipes, the handles of which extend upwards through the foot 
board on which the engine man stands so as to be within his reach; and the closing 
these cocks causes the plunger to leave a partial vacuum behind it, and as the