Improvements in the Method of Gearing Elliptical Pistons for Rotary Pumps and Elliptical Wheels Applicable to other Purposes.
Year: 1888

page_text: Date of Application, 27th Aug., 1888
Complete Specification Left, 27th May, 1889-Accepted, 6th July, 1889
PROVISIONAL DI ECIFICATION.
Improvements in the Method of Gearing Elliptical Pistons for Rotary
Pumps and Elliptical Wheels Applicable to other Purposes.
I CHARLES ASTON WINDER, Pitsmoor, Sheffield, in the County of York, Mechanical
Engineer, do hereby declare the nature of the said invention, for "IMPROVEMENTS IN
THE METHOD OF GEARING ELLIPTICAL PISTONS FOR ROTARY PUMPS, AND ELLIPTICAL
WHEELS APPLICABLE TO OTHER PURPOSES," to be as follows:-
My invention consists in an improved method of Gearing, i.e., of forming and
arranging the teeth of elliptical pistons for rotary pumps, and elliptical wheels, so that
the bearing surfaces of the teeth of such pistons or wheels when in gear may have a
more uniform rolling contact than is obtainable by the ordinary methods employed.
I effect this improvement by varying the form and centre lines of the teeth, having
found by experiment that such gearing works best when a certain number of the
teeth have their centre lines formed radially from the centre of gyration and certain
other teeth having their centre lines drawn at right angles to the chord of the are
formed by the pitch line at each tooth. This arrangement of centre lines gives a
certain number of the teeth uniformity of shape, the remainder being irregular in form
and having a distorted appearance.
The accompanying rough sketch illustrates such a piston or wheel in elevation with
a portion of the companion piston or wheel shewn in gear.
A B is a centre line, through the transverse diameter, and C, D, a centre line
through the conjugate diameter of the ellipse.
E, E, E, E, represent the pitch line of the teeth, and in this particular example the
pitch line is divided into eighteen equal parts commencing at point 1, on the line;
C, D, each division being marked with figures from 1, to 18, and for the convenience
of illustration each such division is made the centre line of a tooth, the teeth are
consequently of uniform pitch.
E, F, is a divisional line equi-distant between the points 1 and 2, 10, and 11, on the
pitch lino.
G, H, is also a divisional line drawn from point 5, to point 14 on the pitch line.
Both the last named divisional lines intersect, at the centre of gyration of the wheel
or piston.
The teeth on and between the lines G, F, or what may be called the right hand
upper limb of the piston or wheel, have their centre lines drawn to the centre of
gyration, and the teeth on and between the lines E, H, or what may be called the left
hand lower limb, have also their centre lines drawn to the centre of gyration.
9
The teeth on and between the lines E, G, or what may he called the left hand upper
limb, and the teeth on and between the lines F, H, or what may be called the right
hand lower limb, have their centre lines drawn at right angles to the chord of
the are formed by the pitch line of each such tooth, thus; the teeth in the upper right
hand and lower left hand limbs of the pistons or wheels are alike, and those on the
upper left hand and lower right hand limbs are also alike.
It will be seen in this illustration that the teeth on the divisions marked 1, and 10,
are common to both arrangements of centre lines, the teeth 5. 6. 7. 8. 9, 14. 15. 16.
17 and 18 have their centre lines radiating from the centre of gyration, but such lines
are not necessarily at right angles to the chord of the arc of the respective teeth,
whereas the teeth marked 2, 3, 4, 11, 12 and 13, have their centre lines at right angles
to the chord of the arc of their respective teeth, such lines, being, as is shewn out of
radius with the centre of gyration.
Teeth of a smaller or greater pitch may be arranged in a similar manner on larger
or smaller wheels as the case may be, and the proportion of the teeth which radiate

page_text: from the centre, and those which do not radiate from the centre, will be similar to the
arrangement herein described and illustrated.
I do not confine myself strictly to the arrangement of teeth shewn in the accom-
panying rough sketch. as in some wheels or pistons, according to the circumference,
and the number and pitch of the teeth, the spaces within which the teeth radiate to the
centre, and the spaces within which the teeth do not radiate to the centre, inay be
slightly varied or modified.
Neither do I confine myself to the proportion of the ellipse here shewn which may
also be varied according to circumstances.
1000
R. HEBER RADFORD,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Method of Gearing Elliptical Pistons for Rotary
Pumps and Elliptical Wheels applicable to other Purposes.
I, CHARLES ASTON WINDER, Pitsmoor, Sheffield, in the County of York, Mechanical
Engineer, do hereby declare the nature of the said invention, for "IMPROVEMENTS IN
THE METHOD OF GEARING ELLIPTICAL PISTONS FOR ROTARY PUMPS AND ELLIPTICAL
WHEELS APPLICABLE TO OTHER PURPOSES," 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 an improved method of Gearing, i.e. of forming and
arranging the teeth of elliptical pistons for rotary pumps, and elliptical wheels, so that
the bearing surfaces of the teeth of such pistons or wheels when in gear may have a
more uniform rolling contact than is obtainable by the ordinary methods employed.
I effect this improvement by varying the form and centre lines of the teeth, having
found by experiment that such gearing works best when a certain number of the teeth
have their centre lines formed radially from the centre of gyration and certain other
teeth having their centre lines drawn at right angles to the chord of the arc formed
by the pitch line at each tooth. This arrangement of centre lines gives a certain
number of the teeth uniformity of shape, the remainder being irregular in form and
having a distorted appearance..
The drawing accompanying my provisional specification illustrates such a piston or
wheel in elevation with a portion of the companion piston or wheel shewn in gear.
A. B. is a centre line, through the transverse diameter, and C. D. a centre line
through the conjugate diameter of the ellipse.
e. e. e. e. represent the pitch line of the teeth, and in this particular example the
pitch line. is divided into eighteen equal parts commencing at point 1, on the
line C. D. each division being marked with figures from 1, to 18, and for the con-
venience of illustration each such division is made the centre line of a tooth, the teeth
are consequently of uniform pitch.
E, F, is a divisional line equi-distant between the points 1 and 2, 10, and 11, on the
pitch line.
G, H, is also a divisional line drawn from point 5, to point 14 on the pitch line.
Both the last named divisional lines intersect, at the centre of gyration of the wheel
or piston.
The teeth on and between the lines G, F, or what may be called the right hand
upper limb of the piston or wheel, have their centre lines drawn to the centre of
gyration, and the teeth on and between the lines E, H or what may be called the left
hand lower limb, bave also their centre lines drawn to the centre of gyration.
The teeth on and between the lines E, G, or what may be called the left hand upper
limb, and the teeth on and between the lines F, H, or what may be called the right
hand lower limb, have their centre lines drawn at right angles to the chord of the arc
formed by the pitch line of each such tooth, thus; the teeth in the upper right hand

page_text: and lower left hand limbs of the pistons or wheels are alike, and those on the upper
left hand and lower right hand limbs are also alike.
It will be seen in this illustration that the teeth on the divisions marked 1 and 10
are common to both arrangements of centre lines, the teeth 5, 6, 7, 8, 9, 14, 15, 16 17
and 18 have their centre lines radiating from the centre of gyration, but such lines
are not necessarily at right angles to the chord of the arc of the respective teeth,
whereas the teeth marked 2, 3, 4, 11, 12 and 13, have their centre lines at right angles
to the chord of the arc of their respective teeth, such lines, being, as is shewn out of
radius with the centre of gyration.
Teeth of a smaller or greater pitch may be arranged in a similar manner on larger
or smaller wheels as the case may be, and the proportion of the teeth which radiate
from the centre, and those which do not radiate from the centre, will be similar to the
arrangement herein described and illustrated.
I do not confine myself strictly to the arrangement of teeth shewn in the accom-
panying drawings, as in some wheels or pistons, according to the circumference, and
the number and pitch of the teeth, the spaces within which the teeth radiate from the
centre, and the spaces within which the teeth do not radiate from the centre, may be
slightly varied or modified.
Neither do I confine myself to the proportions of the ellipse here shewn which may
also be varied according to circumstances.
The accompanying drawing marked Sheet 2, illustrates a pair of my improved
elliptical pistons as applied to a rotary pump. These pistons are proportioned and
geared in a manner similar to those described and illustrated in the Drawing, (say
Sheet 1,) which accompanied my Provisional Specification.
A. A. are the elliptical pistons.
B. B. the shafts by which they are driven.
C₁ is the inlet or suction pipe.
d, is the outlet or discharge pipe.
e. e, is the case or cylinder of the pump.
The arrows indicate the direction in which the pistons revolve and of the direction
of the fluid actuated by them.
Having now particularly described and ascertained the nature of my Inven-
tion and in what manner the same is to be performed, I declare that what I
claim is,
(1). In elliptical pistons, for rotary pumps and elliptical wheels applicable to other
purposes, forming, arranging and gearing the teeth of such pistons and wheels by
varying the form of the teeth and the direction of their centre lines, so that a certain
number of the teeth have their centre lines formed radially from the centre of
gyration and certain other teeth have their centre lines drawn at right angles to the
chord of the arc formed by the pitch line of each tooth, whereby a certain number of
teeth have uniformity of shape, whilst others are irregular in form and of a distorted
appearance, substantially as and for the purposes herein described and illustrated by
the accompanying drawings herein previously referred to.
(2). Improvements in the method of Gearing elliptical pistons for rotary pumps and
elliptical wheels applicable to other purposes, substantially as herein described and
illustrated.
Dated this 23rd day of May 1889.
K. HEBER RADFORD,
Agent for the Applicant.