STATIONARY ENGINES.
153
ping. The pump rods of timber bend to the versed sine described,but being of great length the motion is but little feit.
The pumps are of two kinds—lifting or bücket pumps and for-
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Fig. 89.—Pump Rod of Cornish Engine.
a, Wooden rod. b b, Wrought-ironstraps, with jib and cotter. c, Side plates.d, Beam gudgeon.
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a, Suction pipe. B, Suction-valve ehest.
C, Working barrel. d, Delivery-valve ehest.e, Wrought-iron strap shrunk on.
cing or plunger pumps; and in some instances a combination of thesolid bücket and plunger pump is adopted.
In the former of these, as indeed in all pumps, the water is forcedup the pipe by the pressure of the atmosphere, when a fewstrokes of the pump bücket have caused a partial vaeuum in thepump barrel. The suction valve should be placed somewhat less