A New or Improved Pump for Pneumatic Tyres.
Year: 1899

page_text: Date of Application, 22nd June, 1899-Accepted, 22nd July, 1899
COMPLETE SPECIFICATION.
A New or Improved Pump for Pneumatic Tyres.
I. CARL HOFMANN, of Klosterstrasse 66, Breslau, in the German Empire, Mer-
chant, 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:-
―
This invention relates to a pneumatic tyre pump which is operated by the wheel
to which the tyre is attached.
The new pump consists of a movable cylinder and a fixed piston, the latter
being capable of being held in either of two positions. The cylinder is formed
with two different internal diameters, the pump being operative when the piston
is contained within the smaller diameter and inoperative when it is contained
within the larger.
The accompanying drawings illustrate the construction of the improved pump
and its application to the wheel of a bicycle.
Figure 1 represents a section through the hub of a machine and the attached
cylinder and piston.
Figure 2 shews a similar view of the same parts taken at right angles to the
view shewn in Figure 1.
Figure 3 illustrates a section of the cylinder and piston on a larger scale.
Figure 4 shews the application of the improved device to a bicycle wheel.
The cylinder a is attached to and rotates with the hub of the wheel and is caused
to reciprocate, when the wheel is rotated, by means of straps which encircle the
excentrics b, b, secured to the fixed axle c. The outer end of the cylinder has a
larger internal diameter than the inner end, and the piston c¹ is of a size to
properly fit the smaller diameter. The piston is furnished with a tubular rod d
which passes through the cylinder end and is provided with openings or perfora-
tions gf is a second tube or hollow rod one end of which passes within the hol-
low piston rod d while the other is in communication with the tyre valve. By
means of the screw or other clamp e the piston may be fixed upon the rod f either
in the operative position shown in Figure 1, or in the inoperative position illus-
trated in Figure 2. The rod f is provided with two limiting collars or stops so
that the piston may be accurately set. When in the position shown in Figure 1
holes in the rod f coincide with the holes g in the rod d and communication is
established between the interior of the cylinder and the valve of the tyre, and,
upon the wheel being rotated, air will be compressed between the piston and the
outer cylinder end and forced through the rod f into the tyre.
To put the pump out of action the clamp c is loosened, the rod d and its piston
are moved outwards along the rod f until they are stopped by the collar or stop
thereon, and the clamp is again screwed down. In this position, as will be seen
by referring to Figure 2, there is no communication between the tyre and the
cylinder, and the cylinder reciprocates idly.
Air enters the cylinder through the openings h which are fitted with non-return
valves, and passes through similar valves formed in the piston c. Upon the in-¨

page_text: ward stroke of the cylinder air is compressed and passes into the tyre when the
component parts of the device are in the relative positions indicated in Figure 1.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
1. A pump for pneumatic tyres, consisting essentially of a movable cylinder
operated by the rotation of the wheel and formed with two different internal
diameters, a fixed piston capable of being held in either of two positions, and a
tube or hollow rod for establishing communication between the cylinder and the
tyre, all constructed arranged and operating substantially as described and as
illustrated by the accompanying drawings.
2. A pump for pneumatic tyres, constructed arranged and operated substantially
as hereinbefore described and as illustrated by the accompanying drawings.
Dated this 21st day of June AD 1899.
W. E. HEYS & SON,
Agents for the Applicant.