Improvements in and relating to Air Pumps.
Year: 1892

page_text: Date of Application, 15th Mar., 1892
Complete Specification Left, 14th Dec., 1892-Accepted, 14th Jan., 1893
PROVISIONAL SPECIFICATION.
Improvements in and relating to Air Pumps.
I CHARLES DAVID MARTIN of 58 Motley Street, Wandsworth Road, Clapham,
in the County of Surrey, Engineer, do hereby declare the nature of this invention
to be as follows:-
My invention relates to an improved form of air pump, specially adapted for
inflating pneumatic tyres, and it consists in so constructing the pump that it acts
in both directions, thereby increasing its efficiency and giving double the power of
compression and ejection as a single acting pump of the same size.
My improved pump is constructed in the following manner:-In each end of
the cylinder of the pump are inlets for the air, the said inlets being closed with any
suitable form of non-return valve-preferably an ordinary flap valve-which will
allow air to be drawn into the cylinder through these holes, but will not allow it
to pass out therethrough. The piston of the pump-which is fitted with the usual
leathers-is a hollow one having holes in both its ends. The chamber within the
piston is in connection with the tubular piston rod which passes out through one
end of the cylinder of the pump through a suitable stuffing box and is provided at
its free end with any suitable form of coupling for attaching it to the valve or
inflation tube of the tyre. The holes in each end of the hollow piston are closed
by a flap valve adapted to work between the two inner faces of the ends of the
piston so as to close one or other of the set of holes according to the direction in
which the piston is moving,
The action of the pump is as follows:-Supposing the piston to be at the top
end of the cylinder of the pump and to be forced downwards, air is drawn into the
cylinder through the holes in the top end thereof. The air in the pump between
the piston and the bottom of the cylinder is compressed and forced through the
holes in the underside of the hollow piston into the tubular piston rod, the flap
valve in the hollow piston closing the holes in the top side thereof. When the
motion of the piston is reversed, air is drawn in through the holes in the bottom of
the cylinder, is compressed in the top part thereof, and is forced into the tubular
piston rod through the holes in the top end of the piston.
Dated this 15th day of March 1892.
ROBT. ED. PHILLIPS, M.I.M.E.,
Consulting Engineer and Pateut Agent,
70, Chancery Lane, London, W.C., Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in and relating to Air Pumps.
I CHARLES DAVID MARTIN, of 58 Motley Street, Wandsworth Road, Clapham,
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 relates to an improved form of air-pump specially adapted for
inflating pneumatic tyres and it consists in so constructing the pump that it acts in
both directions thereby increasing its efficiency and giving double the power of
compression and ejection as a single acting pump of the same size.
My improved pump is constructed in the manner illustrated in the accompanying
drawing in which

page_text: Figures 2 and 3 are views in cross section thereof on lines x, x, and y, y,
respectively.
Figure 4 is a broken sectional view showing a modification of the double valve
in the piston.
Figure 5 is a view in transverse section thereof on line z, z, and
Figure 6 is a broken sectional view showing a modification in the valve at the
back end of the cylinder.
Throughout these views similar parts are marked with like letters of reference.
In each end of the cylinder A. of the pump are inlets a, a, for the air, the said
inlets being closed with any suitable form of non-return valve which will allow air
to be drawn into the cylinder through these inlets but will not allow it to pass out
therethrough. The inlet at the forward end of the cylinder is preferably made by
making the piston rod a loose fit in the cap closing the forward end of the
cylinder, in which case the valve at this end of the cylinder preferably takes the
form of a cup leather a¹ as shown by Figure 1. The inlet a at the back end of
the cylinder is closed by a valve a³ preferably of the type generally used in these
pumps as illustrated by Figure 1, but it may be of any other construction such for
instance as that illustrated by Figure 6. The piston B of the pump which is
fitted with the usual cup leathers b, b, is a hollow one having one or more holes 6',
• in its forward end, and one or more holes, in its rear end. The hollow piston is
in connection with the tubular piston rod C by a hole or passage a³. The piston
rod C passes out through the forward end of the cylinder A and is adapted at its
free end to receive any suitable form of coupling for attaching it to the valve or
inflation tube of a tyre. The holes 6', and b, in the hollow piston are closed by
suitable valves and 6 adapted to close one or other of the set of holes according
to the direction in which the piston is moving. These valves may be of the type
generally used in these pumps as shown by Figure 4, or of the flap type as shown
by Figure 1.
The action of the pump is as follows:-Supposing the piston C to be at the
forward end of the cylinder A of the pump and to be forced downwards, air is
drawn into the cylinder through the inlet a in the forward end thereof. The air
in the cylinder of the pump between the piston B and the bottom of the cylinder A
is compressed and forced through the holes 63, 63, into the hollow piston B when it
passes through the hole or passage aª into the tubular piston rod Ĉ, the valve 6* in
the hollow piston closing the holes 6', 6', in the top side thereof. When the motion
of the piston is reversed, air is drawn in through the inlet a at the back end of the
cylinder, is compressed in the forward part thereof, and is forced into the hollow
piston B through the holes 6', 6', in the top end thereof whence it passes through
the hole or passage a into the tubular piston rod C, the valve 6* closing the
holes 63, 63, in the underside of the hollow piston.
I wish it to be particularly understood that I do not limit myself to the use of
any particular construction of valve for use in my double acting pump as any type
of valve used for similar devices may be used, neither do I limit myself to the
precise construction and arrangements of the several parts as hereinbefore
described and illustrated by the accompanying drawing, but that I hold myself at
liberty to make such changes and alterations as fairly fall within the spirit and
scope of my invention.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed I declare that what I
claim is :-
1. The improvements in air pumps as hereinbefore described and illustrated by
the accompanying drawing.
2. A pump or inflator adapted to compress and eject air by both the forward and
backward strokes, as set forth.
3. In a pump or inflator, the combination of a cylinder having air inlets at each
end closed by suitable valves or their equivalents so that the said inlets will not

page_text: act as outlets, of a hollow piston having inlets on each side closed by suitable
valves so that the said inlets will not act as outlets, and of a tubular piston rod
fixed to the hollow piston and in connection therewith by a hole or passage, all
combined, arranged and operating as and for the purpose set forth.
Dated this 13th day of December 1892.
ROBT. ED. PHILLIPS, M.I.M.E.,
Consulting Engineer and Patent Agent,
70, Chancery Lane, London, W.C., Agent for the Applicant.