[Illustration: FIG. 205.]
Fig. 205 represents an approved form of steam boiler feed pump, single
acting. It has a crank shaft and a tight and loose pulley. It may be
driven direct from any line shaft, a countershaft being unnecessary.
This is a compact form of a boiler feed pump; formerly the pump crank
shaft was attached to floor beams or timbers above and connected by a
long pitman to the pump which stood upon the floor; the objections to
the older system of apparatus were found to be the vibration of the
long pitman and the springing of the floors.
To obviate these two difficulties the pump and countershaft were
attached to a post bringing them nearer together but finally resulting
in the design of pump here shown. The broad base insures great
stability in the operation of the pump especially when fixed to a rigid
floor or timber foundation.
In the Table below are given some details furnished by the makers
relating to six sizes of this style of pump, to which may be added that
_the speed_ ordinarily used varies from 100 revolutions per minute for
the small sizes, to 20 revolutions for the larger sizes.