IMPROVE. MENTS IN APPARATUS FOR PUMPING OR COMPRESSING AIR, WHICH IMPROVEMENTS ARE IN PART APPLICABLE FOR PUMPING PURPOSES GENERALLY
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Richard Elihu Dickinson at the Office.
of the Commissioners of Patents on the 25th June 1881.
RICHARD ELIHU DICKINSON, of Birkenhead, in the County of Chester. "IMPROVE.
MENTS IN APPARATUS FOR PUMPING OR COMPRESSING AIR, WHICH IMPROVEMENTS
ARE IN PART APPLICABLE FOR PUMPING PURPOSES GENERALLY."
The said Invention relates to improvements in apparatus for pumping or
compressing air and for other pumping purposes, and has for its object to provide
simple and efficient means which are more especially adapted for pumping air for
condensing the exhaust steam from the engines of tramway cars, but which are
applicable to other pumping purposes as hereinafter described.
The apparatus constructed according to the said Invention consists of a cylinder,
in which a piston of peculiar construction is worked to and fro in the said cylinder
by a piston rod, actuated from any suitable part of the engine of the tramway car,
or of other mechanism with which the said apparatus is used, or by an independent
motor. The outer part or ring of the said piston is packed like an ordinary piston
to slide in air tight contact with the cylinder. At the interior of the said piston
is a chamber open to the cylinder at each side of the piston, and having around
each of its circular openings a continuous seating. The piston rod is provided at
its inner end with a head piece which engages and slides for a short distance in
the chamber of the piston, having an air tight bearing at each side, which as the
stroke is reversed alternately rests against one or the other of the aforesaid
seatings at the openings of the chamber in the piston, and by this means giving
motion to the piston. The piston rod is hollow as is also its head, engaging in the
chamber in the piston as aforesaid, the opening in the piston rod forming com-
munication between the exterior of the apparatus and the opening or chamber in
the head of the said rod. This hollow head communicates with the chamber in
the piston, and alternately with the interior of the cylinder at one or other side of
the piston according to the direction in which the piston is making its stroke, and
consequently upon which seating at the opening of the said chamber the said
hollow head bears. The cylinder at either side of the piston is provided with
valves opening outwards to the outlet channel from the pump, which channel may
be provided with a relief valve for adjusting the pressure.

page_text: In action the piston is moved in one direction by the hollow head of the piston
rod bearing upon the seating around the opening at one side of the piston and
closing the said opening, and the contents of the cylinder at this side of the piston
are expelled therefrom, whilst a charge is drawn into the cylinder at the other side
of the piston, the said charge passing through the hollow piston rod into the
hollow head thereof, thence through passages or the space between the exterior of
the said head and the interior of the chamber in the piston, and out therefrom
into the cylinder. On the next stroke of the piston rod in the reverse direction,
the hollow head of the said rod is drawn away from the seating around the opening
in the piston against which it bore at the preceding stroke and comes into contact
with the other seating, closing the opening at this side of the piston and opening
the communication through the hollow piston rod and its head and the chamber in
the piston with the cylinder at the other side of the piston, so that as the piston
is reciprocated by the piston-rod head bearing alternately upon the seatings and
closing the opening at one side of the piston, leaving the opening on the other side
of the piston open, a charge is drawn into the cylinder alternately on either side of
the piston through the hollow piston-rod, hollow piston head, and hollow piston,
whilst the charge previously drawn in on the other side of the piston is expelled
by the piston-rod head closing the opposite seating.
In adapting the improvements for air pump buckets, guards or lugs are cast on
one side of the piston rod-head or bucket to prevent the closing of the opening
on the one side of the piston, so that during the inward stroke a passage is left
through the chamber in the piston proper from the underside to the top side of
said piston, the action in this case being as follows:-On the down stroke of the
piston the head on the piston rod moves in the chamber in the piston till the lugs
thereon come into contact with the lower seating of the piston, which piston it
forces along with it, the water and air passing through the chamber in the piston
from below to above the said piston. On the return or up stroke, the head of the
piston rod bears air tightly against the seating of the other opening in the piston,
and the water and air are lifted and forced into the hot well. A. vacuum is then
formed under the bucket, thus drawing the water from the condensers, which is
retained in the usual way by a foot valve. In this case both the piston rod and
the head thereof are made solid, or do not communicate with the chamber in the
piston.
The improvements under this last mentioned arrangement are adapted to act as
force and lift pumps for marine or land purposes, for feeding water to boilers, or for
grain, salt, or bilge pumps, or the like, and their adoption will render unnecessary
the valves hitherto employed, the piston itself forming the only valve that is
necessary, and a valve which is not liable to stick or "choke."