IMPROVEMENTS IN PUMPING OR FORCING APPARATUS FOR HYDRAULIC PRESSES AND FOR COMPRESSING OR EXHAUSTING ELASTIC FLUIDS
Year: 1870

page_text: PROVISIONAL SPECIFICATION left by Thomas Bruce at the Office of
the Commissioners of Patents, with his Petition, on the 9th July
1870.
I, THOMAS BRuce, of Monkton, in the County of Ayr, North Britain,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN PUMPING OR FORCING APPARATUS FOR HYDRAULIC PRESSES AND FOR COMPRESSING
OR EXHAUSTING ELASTIC FLUIDS," to be as follows, that is to say:-
This Invention has for one of its objects to render the working of.
hydraulic presses more convenient and more economical as regards
the power employed than heretofore by substituting for the ordinary
reciprocating pumps, the action of which is intermittent and on that
account defective, pumping or forcing apparatus of an improved kind,
and having a continuous action. The said improved pumping or
forcing apparatus is also advantageously applicable for compressing or
exhausting elastic fluids.
The Invention consists in employing a connected series or chain of
pistons for forcing water or other liquid into the cylinder of a hydraulic
press through a pipe which the pistons fit with a sufficient degree of.

page_text: tightness. The pipe, which corresponds to the barrel of an ordinary
pump, and which is herein-after termed the piston pipe, leads from a
reservoir into the hydraulic cylinder, or into a chamber in commu-
nication with the hydraulic cylinder, and the piston chain is drawn
inwards by means of an axle in the cylinder or chamber, and which
extends out through a stuffing box so as to be actuated by means of an
external hand wheel or in any other convenient way.
In one modification the axle has a toothed wheel fixed on it, and acts
on the piston chain (which is a pitch chain) as on a rack, so that the
pull is in a line passing through the axis of the piston pipe. The axle
may also be arranged to actuate the chain in various other ways.
The improved pumping or forcing apparatus may be applied in a
variety of ways in connection with hydraulic presses. Thus, for example,
two presses may be worked in connection with each other, the cylinders
or two chambers respectively communicating with each cylinder being
connected by the piston pipe; then when the piston chain is drawn in
one direction one of the rams will be forced out and the other drawn in
or relieved, and when the piston chain is drawn in the other direction
(by a suitable axle and wheel) the motions of the two rams will be
reversed. A differential action can be obtained by making one ram
of a larger area than the other. The cylinder of one ram may have
two chambers in connection with it, with a piston pipe between the
chambers, and with a reservoir in connection with the chambers or not
according to circumstances. The communications between the cylinder
and the chambers and between these and the reservoir are fitted with
valves or stop-cocks, and with these arrangements the press may be
worked in two different ways as follows:-Firstly, if a short stroke only
is wanted the piston chain will be drawn into the first chamber then in
communication with the ram, and after the stroke is completed the
valves or stop-cocks will be changed, so that the water in the cylinder
may run into the reservoir so as to lower the ram; then the valves or
stop-cocks will be changed to put the cylinder in communication with
the second chamber, and the piston chain will be drawn back into that
chamber, whereby the ram will be moved a second time; the third
stroke of the ram will be obtained by drawing the piston chain into the
first chamber, and so on, it being unnecessary to wind the piston chain
back again between each stroke. Secondly, when a longer stroke of the
ram is wanted than can be obtained by one traverse of the piston chain

page_text: the piston chain is first drawn into the first chamber, and then instead
of allowing the water to pass to the reservoir from the cylinder this is
put in communication with the second chamber, the first being then
opened to the reservoir, and on the piston chain being drawn back into
the second chamber the ram will be moved a second distance further.
This reversing of the communications may be repeated until the desired
length of stroke of the ram is attained.
By a further modification two or more chains with pistons of different
sizes may be worked in connection with the same hydraulic press
cylinder or cylinders. Thus at the early part of a pressing operation a
comparatively quick action may be obtained by working the pistons of
larger area, and subsequently a slower but more powerful one by means
of the smaller pistons. In some cases the piston pipe may be formed
through the ram of the hydraulic press.
In applying the improved pumping or forcing apparatus for com-
pressing or exhausting elastic fluids similar arrangements may be
adopted, but the air or other elastic fluid will be thereby forced into or
exhausted from a closed vessel or reservoir instead of the cylinder of a
hydraulic press.
The improved pumping, forcing, or exhausting apparatus is obviously
applicable to any purposes the same as or similar to those for which the
common hydraulic press, compressing or exhausting pump, or their
various fixed and portable modifications have been or can be applied.