Improvements in Reduction Gearing for Steam Turbines.
Year: 1894

page_text: Date of Application, 2nd Jan., 1894
Complete Specification Left, 1st Oct., 1894-Accepted, 10th Nov., 1894
PROVISIONAL SPECIFICATION.
Improvements in Reduction Gearing for Steam Turbines.
I, JOHN SMITH RAWORTH, of 24 Kirkstall Road, Streatham, in the County of
Surrey, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention has for its object to reduce the speed of steam turbines by gearing
in a practical and inexpensive manner and to such an extent as to render such steam
turbines applicable to ordinary industrial purposes without the intervention of
electric dynamos and motors.
For this purpose I use friction gear for effecting the first reduction of speed and
friction or toothed gear for effecting the second or further reduction of speed.
An arrangement for this purpose is as follows:-On the turbine shaft I place
a small cylindrical pulley of steel or other suitable metal or material, and
diametrically on opposite sides of it I place two larger pulleys, carried by shafts
whose axes are parallel with the axis of the turbine shaft.
The two shafts carrying the larger pulleys are arranged to be moved together by
any well-known or suitable means such as levers, springs, and weights, but in such
a manner that the larger pulleys nip the small pulley on the turbine shaft without
any unbalanced side strain.
Similarly upon the other ends of the said two shafts I fix two pulleys or pinions
arranged both to gear with one larger pulley or spur wheel on the power shaft
placed in a straight line axially with the turbine shaft.
The three wheels in which is included the pulley on the turbine shaft, I call the
first motion gear, and the three wheels in which is included the spur wheel or pulley
on the power shaft I call the second motion gear.
It is obvious that in the second motion gear, the number of pinions acting on the
central wheel may be more than two, depending on the relative diameters of the
wheels and the pinion, but in the first motion gear, the driven pulleys being much
larger than the driving pulley, usually only two wheels can gear with the latter
pulley in the same plane. In cases therefore where the power to be transmitted is
too large for a single pair of wheels and a friction pulley of moderate and
convenient size, I use several pairs of wheels arranged in different planes but in
gear with the same friction pulley, the said pulley for this purpose being made of
increased length. Thus for instance, if there be two pairs of wheels, the friction
pulley must be fully twice as long, or if there be three pairs of wheels, the
friction pulley must be fully three times as long as it would be for only one pair
of wheels.
In some cases however instead of using only two large friction wheels arranged
in the same plane at diametrically opposite sides of the friction pulley on the turbine
shaft, three friction wheels may be employed arranged in the same plane around
the central pulley on the said shaft, and held in place by any suitable means such
as by a spring ring.
By constructing the reducing gear in the manner above described, I am able to
reduce, if desired, say, in the ratio of 100 to 1, within a small space and with
a minimum of friction, which may be further reduced by the use of roller or ball
bearings.
Dated this lot dof T
1004

page_text: Improvements in Reduction Gearing for Steam Turbines.
I, JOHN SMITH RAWORTH, of 24 Kirkstall Road, Streatham, 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 has for its object to reduce the speed of steam turbines by gearing
in a practical and inexpensive manner and to such an extent as to render such steam
turbines applicable to ordinary industrial purposes without the intervention of
electric dynamos and motors.
For this purpose 1 use friction gear for effecting the first reduction of speed, and
friction or toothed gear for effecting the second or further reduction of speed,
as I will now proceed to explain by the aid of the accompanying drawings in
which
Figs. 1 and 2 are respectively plan and end views showing one arrangement of
reduction gearing according to this invention.
On the turbine shaft 1 carried by a bearing 2 is fixed a small cylindrical pulley 3
of steel or other suitable metal or material, and diametrically on opposite sides of
it, I place two larger pulleys 3* 3b carried by shafts 4 4" whose axes are parallel
with the axis of the turbine shaft. The two shafts 4, 4" are arranged to be moved
together by any well-known or suitable means, such as levers, springs, and weights,
but in such a manner that the larger pulleys 3* 3b will nip the small pulley 3 on the
turbine shaft without any unbalanced side strain. In the example shown, the ends
of the shafts 4, 4ª are mounted in bearings in two levers 5, 5ª which at their lower
ends are pivoted at 6, 6* to a base plate 7 and at their upper ends are connected by
a bolt 8 which passes through such ends, the head 8 of the bolt bearing against the
outside of one lever, and a nut 8b on the bolt bearing through the interposition of a
spring 8 against the outer side of the other lever. As will be seen the arrangement
is such that the pressure with which the larger pulleys 3ª, 3b nip the smaller one 3
can be readily varied, or removed altogether, to suit requirement.
Upon the other ends of the said two shafts 4, 4ª are fixed two pinions 9ª, 9b that
are arranged on opposite sides of and gear with one larger spur wheel 9 on the
power shaft 10 which is placed in a straight line co-axially with the turbine shaft.
The ends of the shafts upon which the pinions are fixed, are mounted in bearings
carried by fixed pedestals but adapted to allow of the movements of the shafts, 4, 4³
necessary to enable the pulleys 3º, 3b to be thrown in and out of driving connection
with the pulley 3. When the power to be transmitted is small, the toothed
wheels 9, 9 and 9b may be replaced by friction pulleys in which case the ends of the
shafts carrying the said wheels would be mounted in movable bearings, in a
similar manner to the other ends of the shafts, to permit of the pressure between such
friction pulleys being varied to suit requirement.
The three pulleys 3, 3ª and 3 1 call the first motion gear, and the three wheels
(or pulleys) 9, 9ª, 9b, I call the second motion gear.
It will be obvious that in the second motion gear, the number of pinions 9, 9"
acting on the central wheel 9 could be more than two, depending on the relative
diameters of the wheel and the pinions, but in the first motion gear, the driven
pulleys being much larger than the driving pulley, usually only two driven pulleys
can gear with the driving pulley in the same plane. In cases therefore where the
power to be transmitted is too large for a single pair of driven friction pulleys and
a driving friction pulley of moderate and convenient size, I use several pairs of
wheels arranged in different or parallel planes on the two shafts 4, 4° but in gear
with the same friction pulley, the said pulley for this purpose being made of
increased length. Thus for instance, if there be two pairs of wheels, the friction

page_text: pulley must be fully twice as long, or if there be three pairs of wheels, the friction
pulley must be fully three times as long, as it would be for only one pair of wheels.
This arrangement will be readily understood without a drawing.
In some cases however instead of using only two large friction wheels 3*, 3b
arranged in the same plane at diametrically opposite sides of the friction pulley 3
on the turbine shaft 1, three friction wheels 3º, 3b, 3c may be employed arranged in
the same plane around the central pulley 3 on the said shaft, as shown diagram-
matically in Fig. 3, and held in place by any suitable means, such as by a spring
ring or steel band 11 that is sprung tightly over the ends of the shafts 4, 4, 4° on
which the said friction wheels are fixed, or over the bearings in which said shafts
are mounted.
By constructing the reducing gear in the manner above described, I am able to
reduce the speed of a turbine shaft, say, in the ratio of 100 to 1, within a small
space, and with a small amount of friction which may be further reduced by the use
of roller or ball bearings.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. Reducing the speed of a steam turbine by two sets of gear, namely friction
gear that effects a first reduction of speed, and friction or toothed gear that effects
a second or further reduction of speed, substantially as herein described.
2. Speed reducing gearing for steam turbines, constructed, arranged and
operating substantially as herein before described with reference to the drawings.
Dated this 1st day of October 1994.
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.