Improvements in Air-pumps.
Year: 1896

page_text: Date of Application, 7th Jan., 1896-Accepted, 8th Feb., 1896
COMPLETE SPECIFICATION.
Improvements in Air-pumps.
I, CHARLES EDWARD HEARSON of No. 5 Templar Street Camberwell in the
County of Surrey Engineer do hereby declare the nature of this invention and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
My invention consists of improvements in the construction of air pumps of the
kind described and illustrated in a communication addressed by me in the name of
"Hector" to the editor of a magazine entitled "The English Mechanic" and
published in the issue thereof dated the 9th day of December 1870 which pump
may be correctly and concisely described as consisting essentially of a vertical
pump cylinder with delivery valve at top and suction inlet at some distance from
the bottom a piston working within the cylinder, a chamber for containing oil
above the top of the cylinder, a projection from the top of the piston or its rod to
come against and hold open the outlet valve at the end of the up stroke and
beginning of the down stroke so that the air escapes freely and the piston is always
kept covered with oil.
My improvements in the construction of air pumps of the said kind are herein-
after described with reference to the accompanying drawing in which a pump
embodying my said improvements is illustrated in vertical section. In the following
description the parts of the said drawing are referred to by the letters marked
thereon.
The pump barrel consists of a cylindrical tube of metal or other suitable
material a open at both ends and having a flange & formed around its upper end
which tube a is supported within a chamber consisting of a tube c screwed at its
upper end to receive a screw cap d and connected at its lower end to a foot e by-
means of a flanged cap. The support of the barrel a consists of a ring g secured
to the inner side of the tube c and having a washer h of leather or other suitable
compressible material placed thereon on which washer the flange of the barrel a
rests. The chamber for containing the oil in the upper part of the pump is
constructed as follows. The bottom of the said chamber consists of a ring i which.
partially enters the upper end of the pump barrel and has a flange formed
around it which rests on a leather washer k supported by the flange of the pump-
barrel. The sides or walls of the said chamber consist of a tube fitting within
the upper part of the tube c and resting at its lower end on the flange of the
ring which tube is retained in the position illustrated by means of another tube r
resting thereon and bearing at its upper end against a shoulder m formed within
the cap d the screwing of which in its place on the tube c forces the said tube
and ring i downward aud compresses the washers the compression of the
washer producing an air tight closure between the upper end of the pump
barrel a and the flange j of the ring i which fits therein. π is the piston
or plunger of the pump and is the cupped leather packing of the said
piston which packing is retained in place by means of a screw nut p bearing
thereon and engaged with a screw thread on the neck of the piston the
rod 9 of which passes through the central orifice of the ring i (which orifice
constitutes the means of communication between the pump barrel and the oil
chamber) and through a guide consisting of a perforated diaphragm formed
across or secured within the lower part of the tube r. The air escape valve by
which communication between the pump barrel and the oil chamber is normally

page_text: closed consists of a leather ring s backed with a metal ring and normally pressed
on the upper face of the ring by a spiral spring u one end of which bears on the
said ring t and the other against the diaphragm within the tube r. I have found
that a calf's teat is suitable and convenient for use in forming the leather face
parts of the said valve. The provision for connection of the pump to a receiver
or vessel from which air is required to be withdrawn consists of a pipe secured to
the upper part of the tube c below the ring g and communicating with the annular
space between the said tube and the pump barrel a. And the provision for passage
of air from the said annular space to the pump barrel consists of an orifice w
formed in the said barrel at such a distance from its lower end as to be
unobstructed by the piston or the packing thereof when the piston is in its lowest
position in the barrel.
By making the pump barrel open at the lower part as herein before described
compression of air below the piston is prevented and the working of the pump is in
consequence facilitated.
Before using the pump oil is placed in the chamber a portion of which oil
descends into the barrel a on the rising of the valve st by contact therewith of
the upper end of the neck of the piston when it is raised to the top of the said
barrel the oil so descending or a portion thereof remaining above the piston and
effectually preventing leakage of air between the packing and the sail barrel.
I do not consider it necessary to describe the method of using the pump or to
further describe its action as in these respects a pump constructed as hereinbefore
described is similar to pumps heretofore constructel on the principle first made
public by means of my communication to the magazine referred to in the opening
paragraph of this Specification and which are now well known.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed 1 declare that I
claim :-
First. An air pump constructed as hereinbefore described with reference to and
illustrated in the accompanying drawing.
Secondly. An air pump of the kind hereinbefore referred to having a barrel
open at the lower end.
Dated this Seventh day of January 1896.
W. T. WHITEMAN,
Agent for the Applicant.