This cylinder is loaded with weights marked to indicate the pressure
which the accumulator will balance with those weights in use. The water
is pumped into the bottom through the pipe _C_, and fills the annular
space around the spindle. The entire weight of cylinder is raised
by the pressure of water acting only on the area of the end of brass
sleeve _D D_, which is only 1/2 inch thick all around the center
spindle, and extends down through the bottom packing in cylinder, as
shown in sectional view. Fig. 149.
A compact arrangement is thus gained and any reasonable, required
cubical capacity may be reached by lengthening the stroke.
The accumulator is supplied by two pumps having plungers 1-3/8″ diam.
by 3-1/2″ stroke, speed 100 to 120 rev. per minute.
When the loaded cylinder _B_ reaches the top of its stroke, by means of
a small chain it closes the suction cock _E_, which shuts off the water
supply of the pumps.
To put in a new bottom packing, the cylinder is let down to rest on the
wooden blocks _G_, and the spindle is lifted out of its tapered seat at
the bottom by a tackle hooked into the eye-bolt at the top. To renew
the top leather the bracket holding the top end of spindle _A_, has to
be removed.
This accumulator (having only a small area) falls quickly when the
water is withdrawn, thus producing a combined blow and squeeze, which
is of great advantage in hydraulic riveting.
_The Hydraulic Intensifier_ is a cylinder having two diameters,
in principle very like the tandem compound engine. It is used for
increasing the pressure of water in hydraulic mains, pipes, or
machines, using only the energy of the pressure water to effect the
change. But for this distinction a steam pump would be an intensifier.
An intensifier worked the reverse way is a “diminisher” as a hydraulic
pump usually is, giving a reduced pressure.
_The intensifier is in some respects analogous to the electric
transformer._
The intensifier as used in connection with hydraulic apparatus was
patented in the year 1869 by Mr. Aschroft, but the principle upon which
it works is very much older. Intensifiers are made both single and
double acting.