Improvements in Rotary Pumps, Blowers, and Exhausters.
Year: 1893

page_text: Date of Application, 13th Mar., 1893-Accepted, 13th May, 1893
COMPLETE SPECIFICATION.
Improvements in Rotary Pumps, Blowers, and Exhausters.
I, ALEXANDER STEWART of 3 Southbrook Terrace Bradford in the County of
York, 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 in certain improvements in the form of the revolving
pistons of rotary pumps, blowers, and exhausters, in the arrangement of or method
of fixing and operating such pistons upon their spindles, in order to dispense with
external driving gear, and of the bearings, packing, and casing.
In my improved form of pistons I employ three teeth or wings to each piston,
which number I find, when operated in the manner to be hereafter described, to be
the smallest which will engage with a piston of similar form and number of teeth,
whereby two opposing pistons are enabled to drive one another, and the employment
of outside gearing is rendered unnecessary, and in the construction of these pistons
I employ specially formed teeth or wings which instead of (in a transverse sectional
view) tapering outwardly towards the periphery of the circle of revolution, are
made of greater breadth as they approach that periphery, in order to avoid slip,
and to increase their holding power of the air or water upon which they are
operating.
These pistons are mounted in pairs, two pistons so fixed upon each shaft that the
centres of the teeth (transversely) of one piston, are midway between the centres of
the teeth of the adjoining one.
Two pairs of pistons thus mounted, opposing and engaging one another, are set
in a suitable casing, and a central partition divides the two sets of pistons.
In order that my invention may be fully understood, I will proceed to describe
the same with reference to the accompanying drawings in which :-
Figure 1 represents a transverse sectional elevation of my improved form of
blower.
Figure 2 represents a longitudinal elevation of the same, partly in section, and
with a portion of the casing removed.
Figure 3 represents a transverse sectional elevation of my improved form of
rotary pump, and Figure 4 the same shown in longitudinal elevation, partly in
section, and with a portion of the casing removed.
Figure 5 represents a transverse sectional elevation of my improved form of
rotary piston, constructed of suitably bent plates of iron or steel, fixed upon a cast
iron boss or foundation.
Similar letters indicate similar parts in all the drawings.
Two sets of pistons are shown at A A' and B B' axed upon the shafts C C, the
centres of the teeth of the two pistons upon the same shaft, it will be seen, do not
coincide, but those of the teeth B and B are placed midway between the centres
of the teeth A and A', in order that a more equally sustained flow of air or water
may be produced, than would be the case if both sets of teeth revolved abreast
of one another, and were both performing the heaviest part of their duty
simultaneously.
One set of pistons helps to drive the other set, thereby avoiding dead centres and
the like.
The partition which divides the interior of the easing into two equal portions,
and separates the two sets of pistons, is represented at H H, and in this partition
the bearings JJ are fixed, which support and steady the central necks of the pistor
shafts CC.

page_text: The inlet and outlet for air and water are shown at E and F respectively, the
pulley for driving at G and the outer casing at D.
The improved bearings are represented at Figure 4 as applied to a rotary pump,
K being a thimble of hard steel fixed upon the end of the shaft C which rotates in
a bush of antifriction metal, run into the space L formed to receive it. This bush
is prevented from revolving with the shaft by means of a key or screw bolt, which
fixes it to the casing.
In Figure 3 the packing N forms an approximately water-tight joint between the
piston and the casing within which it revolves.
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. In rotary pumps, blowers, or exhausters, the specially formed pistons, each
having three teeth of the non-tapering form, herein described, and represented in
the accompanying drawings.
2. In rotary pumps, blowers, or exhausters, the construction and use of pistons of
the form described, combined with the method of fixing the pairs of pistons upon
the same shafts, and engaging them with other similar pairs of pistons, all
operating in one casing, in the manner described, and as represented in the
accompanying drawings.
3. For rotary pumps, blowers, or exhausters, the piston represented at Figure 5
formed of suitably bent plates of iron or steel, rivetted, bolted, or welded together
and fixed upon a cast iron or other boss.
4. In rotary pumps, blowers, or exhausters, the arrangement and combination of
the specially formed pistons, with the run-in bearings L L, and the outwardly
pressing packing N, all substantially as described and represented in the accom-
panying drawings, more especially in Figures 3 and 4.
Dated this Eleventh day of March 1893.
WILLIAM J. BAKER,
Peasholme House, Scarborough, Agent for the Applicant.