Improvements in Differential Speed and Reversing Gears for Motor Cars, Tramcars, Velocipedes and other Road Carriages.
Year: 1896

page_text: Date of Application, 8th Dec., 1896
Complete Specification Left, 8th Sept., 1897-Accepted, 27th Nov., 1897
Improvements in Differential Speed and Reversing Gears for Motor
Cars, Tramcars, Velocipedes and other Road Carriages.
I, GEORGE GATTON MELHUISH HARDINGHAM, of 191, Fleet Street, in the City
and County of London, Civil Engineer, do hereby declare the nature of this in-
vention to be as follows:-
This invention relates to differential speed-gears of the kind described in the
specification to my Letters Patent, dated 24th April, 1894, No. 8150, and consists,
first, in an improved construction of duplex gear securing greater simplicity and
compactness; secondly, in triplex gear arranged on the same principle and afford-
ing two different speeds in one direction and one speed in the opposite direction;
and thirdly, in compound gear capable of effecting a large variation in speed, and
adapted for use, either in duplex or triplex gears, such as herein referred to, or
for enabling the speed between the motor and the change-gear to be largely
reduced.
A duplex differential speed-gear constructed according to my improved method,
and adapted for application, by way of example, in the wheel-hub of a motor-cycle,
comprises two trains of spur-gear, the one for the high speed and the other for the
low speed and each consisting of a central pinion, a surrounding toothed wheel
and one or more intermediate wheels, the latter gearing with the central pinion
and with the outer wheel. In the high-speed gear, the contral pinion is held
stationary by means of a friction strap arranged about a drum, or by equivalent
holding and releasing mechanism, the carrier on which the intermediate wheels
are mounted is keyed to the shaft whence motion is derived, and the circumscrib-
ing toothed wheel forms part of, or is secured to, the hub of the road- or other
wheel or part to be driven. In the low-speed gear, the central pinion is keyed
to the shaft whence motion is derived, the body carrying the intermediate wheel
or wheels is secured to the hub of the road- or other wheel to which motion is
to be imparted, and the outer toothed wheel is held stationary by means of a
friction strap or releasable device.
According to an alternative mode of constructing duplex differential speed-
gear, the several elements of the respective gear-trains are connected in the
following manner:-In the high-speed gear, the central pinion is secured to the
hub of the road or other wheel or part to be driven, the body carrying the inter-
mediate wheel or wheels is keyed to the shaft whence motion is derived, and the
outer wheel is held stationary by a friction strap or releasable device. In the
low-speed gear, the central pinion is held stationary by a friction strap or
releasable device, the body carrying the intermediate wheel or wheels is fast upon
the shaft whence motion is derived, and the outer wheel is secured to the hub of
the road or other wheel or part to be driven.
According to another alternative mode of construction, the several elements of
the respective gear-trains are so connected that in the high-speed gear, the central
pinion is held stationary by a friction strap or releasable device, the body carrying

page_text: the intermediate wheel or wheels is keyed to the shaft whence motion is derived,
and the outer wheel is secured to the hub of the road or other wheel or part to
be driven. In the low-speed gear, the central pinion is held stationary by a fric-
tion strap or releasable device, the body carrying the intermediate wheel or wheels
is secured to the hub of the road or other wheel or part to be driven, and the outer
wheel is fast upon the shaft whence motion is derived.
According to another variation, both central pinions are fast upon the shaft
whence motion is derived, both intermediate-wheel-carriers are secured to the hub
of the road or other wheel or part to be driven, and each of the outer wheels is
held by means of a friction strap or releasable device. Or both central pinions
may be secured to the hub of the road or other wheel or part to be driven and
both intermediate-wheel-carriers may be fast upon the shaft whence motion is
derived. In either case, the difference between the speeds yielded by the respec-
tive gears is but moderate, and is due to the toothed wheels constituting each
gear-train being differently proportioned.
In cases where it is necessary to provide means for enabling a motorcar or other
road-carriage to be driven in a hackward as well as a forward direction, I employ
three gear-trains, each consisting of the three elements before referred to; that
is to say, a central pinion, an intermediate wheel or a pair or set of intermediate
wheels carried on an axially mounted hody, and a surrounding internally toothed
wheel. One of the elements of each gear-train is moreover capable of being held
stationary or of being released, according to whether each gear-train is required.
to he operative or inoperative.
The manner in which the several elements of the respective gear-trains are con-
nected with the source of power and with the shaft or other part to which motion
is to be imparted is of the following character:--
In the low-speed gear, the central pinion is connected with the source of motive
power, the body carrying the intermediate wheel or wheels is fast upon the shaft,
wheel-hub or other part to which motion is to imparted, and the outer wheel is
held stationary by a friction strap or other releasable 'device. In the high-speed
gear, the central pinion is fast upon the shaft, wheel-hub or other part to which
motion is to be imparted, the body carrying the intermediate wheel or wheels is
connected with the source of motive power, and the outer wheel is held stationary
by a friction strap or other releasable device. In the gear for driving in the
reverse direction and at a low speed, the central pinion is connected with the
source of motive power, the intermediate-wheel-carrier is fast upon the shaft,
wheel-hub or other part to which motion is to be imparted, and the outer wheel
is held stationary by a friction strap or other releasable device. In this latter
case, instead of each intermediate wheel meshing with the central pinion and with
the outer wheel, a pair of wheels is substituted therefor, one of these being
mounted at a greater distance from the centre than the other. Whilst the former
meshes with the outer wheel, the latter meshes wih the central pinion, and the two
mesh together.
According to an alternative modú of constructing triplex differential speed-
gears, the several elements of the respective gear-trains are connected in the
following manner:-In the bow-speed gear, the central pinion is connected with
the source of motive power, the body carrying the intermediate wheel or wheels
is fast upon the shaft, wheel-hub or other part to which motion is to be imparted,
and the outer wheel is held stationary by a friction strap or other releasable
device. In the high-speed gear, the central pinion is held stationary by a friction
strap or other releasable device, the body carrying the intermediate wheel or
wheels is fast upon the shaft, wheel-hub or other part to which motion is to be
imparted, and the outer wheel is connected with the source of motive power. In
the gear for driving in the reverse direction and at a low speed, the central pinion
is in connection with the source of motive power, the intermediate-wheel-carrier
is fast upon the shaft, wheel-hub or other part to which motion is to be imparted,
and, the outer wheel is held stationary by a friction strap or other releasable

page_text: device. In this latter case, the intermediate wheels are arranged in pairs which
mesh together and with the central pinion and outer wheel respectively, as des-
cribed with reference to the triplex gear previously mentioned.
Either of the triplex speed-gears hereinbefore described may be modified and
converted into a duplex speed-gear by omitting the gear-train designed to drive
in the reverse direction.
Where a differential gear of the character hereinbefore referred to is required
to effect a large increase or decrease in speed, I duplicate the same in the following
manner: The intermediate-wheel-carrier of the first gear is connected with the
central pinion of the second, and the outer wheel of the first gear with the inter-
mediate-wheel-carrier or with the outer wheel of the second, according to whether
a reversal of the direction of rotation is or is not required. The outer wheel of
the first gear and the intermediate-wheel-carrier (or the outer wheel of the second
gear, as the case may be) are held stationary by the drum and friction strap, whilst
the central pinion of the first gear and the outer wheel of the second are respec-
tively connected to the actuating shaft and to the shaft or wheel to be actuated or
vice versa, according to whether the gear is required to yield a largely diminished
speed or a largely increased speed. If, however, the direction of rotation is not
to be reversed, the intermediate-wheel-carrier, instead of the outer wheel of the
second gear, is connected to the shaft or wheel to be actuated, whilst the surround-
ing toothed wheel is held by the drum and friction strap.
A compound differential gear of the kind last referred to is adapted for use in
effecting a large reduction of speed between the motor and the change-gear where
a high-speed motor is employed and the power applied indirectly or through gear-
ing. For such a purpose, the parts described as being held stationary by means
of friction-straps may be fixtures.
Where the power of a high-speed engine is applied centrally and a considerable
reduction of the speed is desired, instead of constructing each gear-train to afford
a large reduction, I provide the shaft with a sleeve, and mount the several gear
trains thereon; the shaft being connected with the sleeve through reducing gear
on the epicyclic system. Under such circumstances, the increase or decrease of
speed (as the case may be) accomplished by each gear-train may be kept within.
moderate limits.
It will be readily understood that in all these gears, what is referred to as the
driving part may become the part driven and vice versa; the effects as regards
increase or decrease in the speed yielded being reversed.
Dated this 8th day of December 1896
G. G. M. HARDINGHAM.
Improvements in Differential Speed and Reversing Gears for Motor
Cars, Tramcars, Velocipedes and other Road Carriages.
I, GEORGE GATTON MELHUISH HARDINGHAM, of 191, Fleet Street, in the City
and County of London, Civil Engineer, do hereby declare the nature of this in-.
vention and in what manner the same is to be performed to be particularly des-
cribed and ascertained in and by the following statement:-
This invention relates to differential speed-gears of the kind described in the
specification to my Letters Patent, dated 24th April, 1894, No. 8150, and consists,
first, in improved modes of constructing duplex gear securing greater simplicity

page_text: and compactness; secondly, in triplex gear arranged on the same principle and
affording two different speeds in one direction and one speed in the opposite direc-
tion; and, thirdly, in combination with duplex or triplex gears of the kind
referred to, of means for effecting a large variation in speed between the motor
or other driving shaft and the change-gear.
A duplex differential speed-gear constructed according to my improved method,
and adapted for application, by way of example, in the wheel-hub of a motor-
cycle, is illustrated in Fig. 1 of the accompanying drawings, and comprises two
trains of spur-gear, the one for the high speed and the other for the low speed,
and each consisting of a central pinion, a surrounding toothed wheel and one or
more intermediate wheels, the latter gearing with the central pinion and with the
outer wheel. In the high-speed gear, the central pinion A is held stationary
by means of a friction strap E arranged about a drum F, or by equivalent holding
and releasing mechanism, the carrier B on which the intermediate wheels bare
mounted is keyed to the shaft 1) whence motion is derived, and the
circumscribing toothed wheel C forms
part of,
of, or is secured to,
the hub of the road- or other wheel H or part to be driven. In the
low-speed gear, the central pinion A is keyed to the shaft D whence motion is
derived, the body B carrying the intermediate wheel or wheels b' is secured to
the hub of the road- or other wheel H to which motion is to be imparted, and
the outer toothed wheel C is held stationary by means of a friction strap E
arranged about a drum F, or by equivalent releasable mechanism.
According to an alternative mode of constructing duplex differential speed-
gear, illustrated in Fig. 2, the several elements of the respective gear-trains are
connected in the following manner:-In the high-speed gear, the central pinion A
is secured to the hub of the road- or other wheel H or part to be driven, the
body B carrying the intermediate wheel b, or wheels, is keyed to the shaft D
whence motion is derived, and the outer wheel C is held stationary by a friction
strap E or equivalent releasable device. In the low-speed gear, the central
pinion A is held stationary by a friction strap E or other releasable device, the
body B carrying the intermediate wheel b', or wheels, is fast upon the shaft D
whence motion is derived, and the outer wheel C is secured to the hub of the
road- or other wheel H or part to be driven.
According to another alternative mode of construction, illustrated in Fig. 3
the several elements of the respective gear-trains are so connected that, in tho
high-speed gear, the central pinion A is held stationary by a friction strap E or
other releasable device, the body B carrying the intermediate wheel b, or wheels,
is keyed to the shaft D whence motion is derived, and the outer wheel C
is secured to the hub H of the road- or other wheel or part to be driven. In
the low-speed gear, the central pinion A is held stationary by a friction strap E
or other releasable device, the body B' carrying the intermediate wheel b, or
wheels, is secured to the hub H of the road- or other wheel or part to be driven
and the outer wheel C¹ is fast upon the shaft D) whence motion is derived.
According to another variation, illustrated in Fig. 4, both central pinions A A
are fast upon the shaft D whence motion is derived, both intermediate wheel-
carriers BB are secured to the hub H of the road- or other wheel or part to be
driven, and each of the outer wheels C or C is held by means of a friction
strap E or E or other releasable device. Or both central pinions A A¹
may, as shewn in Fig. 5, be secured to the hub H of the road-or other wheel or
part to be driven, and both intermediate wheel-carriers BB may be fast upon
the shaft D whence motion is derived. In either of these cases, the difference
between the speeds yielded by the respective gears is but moderate, and is due
to the toothed wheels constituting each gear-train being differently proportioned.
In cases where it is necessary to provide means for enabling a motorcar or other
road-carriage to be driven in a backward as well as a forward direction, I employ
three gear-trains, each consisting of the three elements before referred to; that
is to say, a central pinion, an intermediate wheel or a pair or set of intermediate

page_text: wheels carried on an axially mounted body, and a surrounding internally toothed
wheel. One of the elements of each gear-train is moreover capable of being held
stationary or of being released, according to whether such gear-train is required
to be operative or inoperative.
The manner in which the several elements of the respective gear-trains are
connected with the source of power and with the shaft or other part to which
motion is to be imparted is of the following character:-
According to the mode of construction illustrated in Figs. 6, 7 and 8, the
central pinion A¹ of the low-speed gear is connected with the source of motive
power in the present instance the spur-wheel H-the body B₁ carrying the inter-
mediate wheel or wheels bb is fast upon the shaft D, wheel-hub or other part
to which motion is to be imparted, and the outer wheel C is held stationary by
a friction strap or other releasable device. In the high-speed gear, the central
pinion A is fast upon the shaft D, wheel-hub or other part to
which motion is to be imparted, the body B carrying the inter-
mediate wheel or wheels 23 is connected with the source of motive
power H, and the outer wheel C is held stationary by a friction strap E
or other releasable device. In the gear for driving in the reverse direction and
at a low speed, the central pinion A2 is connected with the source of motive
power H¹, the intermediate wheel-carrier B³ is fast upon the shaft D, wheel-
hub or other part to which motion is to be imparted, and the outer wheel C2 is
held stationary by a friction strap E2 or other releasable device. In this latter
case, instead of each intermediate wheel meshing with the central pinion and
with the outer wheel, a pair of wheels 64 65 is substituted therefor, one of these, 4,
being mounted at a greater distance from the centre than the other. Whilst the
former, 64, meshes with the outer wheel C2, the latter, 65, meshes. with the central
pinion A2, and the two wheels, 665, mesh together.
In the high-speed gear, it will be observed that the two intermediate
wheels are of different diameters and are keyed to shaft common to both,
the two working in unison. The larger wheel 62 meshes with the circumscribing
wheel C and imparts rotative motion to the smaller wheel 63, which in turn meshes
with the central pinion A. By these means, a smaller increase of speed is im-
parted to the central pinion.
According to an alternative mode of constructing triplex differential speed-
gears, illustrated in Figs. 9, 10, 11, 12 and 13 the several elements of the
respective gear-trains are connected in the following manner:-In the low-speed
gear the central pinion A is connected with the spur-wheel H', or source of
motive power, the body 131 carrying the intermediate wheel or wheels b₁₁is
secured to the shaft D by means of the auxiliary carrier B2 (hereinafter further
referred to), and the outer wheel C is held stationary by a friction strap E' or
other releasable device. In the high-speed gear, the central pinion A is held sta-
tionary by a friction strap E or other releasable device, the body B carrying the
intermediate wheel or wheels bb is fast upon the shaft D, wheel-hub or
other part to which motion is to be imparted, and the outer wheel C is connected
with the spur-wheel H', whence motion is derived. In the gear for driving in
the reverse direction and at a low speed, the central pinion A2 is in connection
with the source of motive power Hi, the intermediate wheel-carrier B2 is fast
upon the shaft D, wheel-hub or other part to which motion is to be imparted,
and the outer wheel C is held stationary by a friction strap E2 or other releasable
device. In this latter case, the intermediate wheels 64 65 are supported on oppo-
site sides by the carriers 131 132 which are bolted together. The wheels 665 are
arranged in pairs as shewn in Fig. 11 and mesh not only with one another but
with the central pinion A3 and the outer wheel. C respectively, as previously
described with reference to Fig. 8.
Either of the triplex speed-gears herein before described may be modified and
converted into a duplex speed-gear by omitting the gear-train designed to drive
in the reverse direction.

page_text: Where a high-speed engine is employed, it is preferable to reduce the speed
of rotation before applying the power to the change-gear, as compared with
effecting a large reduction in the change-gear itself. For this purpose, an epi-
cyclic gear may be employed for transmitting the power from the motor-shaft
to the change-gear, as shewn in Fig. 9; De being the motor or other driving
shaft to which is secured the pinion A The intermediate wheels are carried on
spindles in the disc 133, which also carries a toothed ring or wheel H2 for engaging
with the spur-wheel H The surrounding toothed wheel C may either be fixed
or may be temporarily held by means of a friction strap E3 as before described,
In the latter case, upon the strap being slackened and the drum F³ released 'the
transmission of power from the motor to the change-gear is entirely interrupted.
When the power of a high-speed engine is applied centrally and a considerable
reduction of the speed is desired, instead of constructing each gear-train to afford
a large reduction, I provide the shaft with a sleeve and mount the several gear-
trains thereon as illustrated in Fig. 14; the shaft being connected with the sleeve
through reducing gear of the epicyclic type. Power is applied to the shaft D
and transmitted through the central pinion A3 to the intermediate wheel-
carrier B³ the outer wheel C3 being fixed or held by means of the friction
strap E. The motion imparted to the intermediate wheel-carrier 133 is com-
municated to the sleeve D and thus to all three speed-gears. In the high-speed
gear, the central pinion A is held stationary by means of the friction strap E,
the intermediate wheel-carrier B is connected with or forms part of the road-
wheel H, and the circumscribing toothed wheel C is secured to the sleeve D¹.
In the low-speed gear, the central pinion A¹ is secured to the sleeve D)¹, the inter-
mediate wheel-carrier B is connected with or forms part of the road-wheel H,
and the outer wheel C is held stationary by means of a friction strap E'. In
the gear for driving in the reverse direction, the central pinion A3 is connected
with the sleeve D', the intermediate wheel-carrier B3 is in connection, through
the intermediate wheel-carrier B, with the road-wheel H, and the outer wheel C
is held stationary by means of the friction strap E. Fig. 14 is a face view
shewing the mode of mounting the friction strap levers and of connecting the
friction strap. e is the lever pivoted at e. Upon the outer extremity
lever being raised, the strap is tightened about the drum it encircles.
of the
It will be observed that, under the conditions above described, the increase or
decrease of speed (as the case may be) accomplished by each gear-train may be
kept within moderate limits, although the speed of the motor or other operating
shaft may be relatively high.
In Fig. 15 is illustrated the combination of a reducing gear and sleeve as em-
ployed in the construction last described with high and low change-speed-gears
such as described with reference to Fig. 9. The sleeve derives its motion,
however, from a spur-wheel instead of from the central shaft.
In Fig. 16 is represented a combination of a reducing gear with a triplex
change-speed-gear; the low and reverse speed-gears being alone mounted upon the
sleeve and the reducing gear being applied thereto, whilst the high speed gear is
operated from the spur-wheel direct. The spur driving wheel H¹ operates the
reducing gear W and the high-speed gear X. Through the reducing gear W the
sleeve D is driven, and upon this sleeve are mounted the low-speed gear Y and
the reverse speed gear Z. The introduction of the speed reducing gear between
the high-speed gear and the low-speed gear results in the more direct driving
of the high-speed gear, but, in comparison with the mode of construction illus-
trated in Fig. 14, is less advantageous as regards the arrest of transmission of
motion to all the speed-gears when the friction strap pertaining to the reducing
gear is released.
It will be readily understood that in all these gears what is referred to as the
driving part may become the part driven and vice versa; the effects as regards
increase or decrease in the speed yielded being reversed.

page_text: Having now particularly described and ascertained the nature of this in-
vention and in what manner the same is to be performed, I claim:--
1. The improved duplex differential driving gear, comprising two gear-trains,
each consisting of three elements, namely, a central pinion, an intermediate
wheel or set of intermediate wheels carried on an axially mounted body, and a
surrounding internally toothed wheel; the central pinion of the one gear and
the intermediate wheel-carrier of the other gear being connected with the driving
[or driven] part, and the intermediate wheel-carried of the one gear and the outer
wheel of the other gear being connected with the driven [or driving] part, whilst
the outer wheel of the one gear and the central pinion of the other gear are
respectively furnished with friction straps or other releasable devices whereby
either the one gear-train or the other may be rendered operative, substantially
as herein described.
2. The improved duplex differential driving gear of the general character of
that referred to in the preceding claiming clause, but having the intermediate
wheel-carriers of both gears connected with the driving [or driven] part, and the
central pinion of the one gear and the outer wheel of the other gear connected
with the driven [or driving] part, whilst the outer wheel of the one gear and the
central pinion of the other gear are respectively furnished with friction straps or
equivalent holding devices whereby either the one gear-train or the other may
be rendered operative, substantially as herein described.
3. The improved duplex differential driving gear of the general character of
that referred to in the first claiming clause, but having the outer wheel of the
one gear and the intermediate wheel-carrier of the other gear connected with the
driving [or driven] part, and the intermediate wheel-carrier of the one gear and
the outer wheel of the other gear connected with the driven [or driving] part,
whilst the central pinions of both gears are respectively furnished with friction
straps or equivalent holding devices whereby either the one gear-train or the other
may be rendered operative, substantially as herein described.
4. The improved duplex differential driving gear of the general character of
that referred to in the first claiming clause, but having the central pinions of
both gears connected with the driving [or driven] part, and the intermediate
wheel-carriers of both gears connected with the driven [or driving] part, whilst
the outer wheels of both gears are respectively furnished with friction straps or
equivalent holding devices whereby either the one gear-train or the other may
be rendered operative, substantially as herein described.
5. The improved duplex differential driving gear of the general character of
that referred to in the first claiming clause, but having the central pinion of the
one gear and the intermediate wheel-carrier of the other gear connected with the
driving [or driven] part, and the intermediate wheel-carrier of the one gear and
the central pinion of the other gear connected with the driven [or driving] part,
whilst the outer wheels of both gears are respectively furnished with friction
straps or equivalent holding devices whereby either the one gear-train or the
other may be rendered operative, substantially as herein described.
6. The improved triplex (duplex and reverse) driving gear, comprising three
gear-trains, each consisting of three elements, namely, a central pinion, an inter-
mediate wheel or set of intermediate wheels carried on an axially mounted body,
and
a surrounding internally toothed wheel, the central pinion of the
first (high-speed) gear and the intermediate wheel-carrier of the second
(low-speed) gear being connected with the driven [or driving] part,
and the intermediate wheel-carrier of the first gear and the central pinion
of the second pinion being connected with the driving [or driven] part, whilst the
outer wheels of both gears are respectively furnished with friction straps or
equivalent holding devices, in conjunction with a third (reverse) gear having its
elements connected in the same manner as the low-speed gear, the intermediate
wheels of the third gear being duplicated and meshing with the central pinion

page_text: and the outer wheel respectively and with one another so as to reverse the direc-
tion of rotation, substantially as herein described.
7. The improved triplex (duplex and reverse) driving gear, comprising three
gear-trains, each consisting of three elements, namely, a central pinion, an inter-
mediate wheel or set of intermediate wheels carried on an axially mounted body,
and a surrounding internally toothed wheel, the intermediate wheel-carriers of
the first (high-speed) and of the second (low-speed) gears being connected with
the driven for driving] part, the outer wheel of the first gear and the central
pinion of the second gear being connected with the driving [or driven] part,
whilst the central pinion of the first gear and the outer wheel of the second gear
are respectively furnished with friction straps or equivalent holding devices, in
conjunction with a third (reverse) gear having its elements connected in the
same manner as the low-speed gear, the intermediate wheels of the third gear
being duplicated and meshing with the central pinion and the outer wheel respec-
tively and with one another, so as to reverse the direction of rotation, substantially
as herein described.
8. The employment between a high-speed motor-shaft and a duplex or triplex
change-gear, of speed-reducing mechanism provided with a friction strap or
equivalent holding device, substantially as described with réference to Fig. 9 of
the accompanying drawings, and whereby the transmission of power from the
motor to the change-gear may be entirely intercepted.
9. The combination, with duplex or triplex change speed driving gear, of
speed-reducing mechanism comprising a central panion, connected with the
motor-shaft, an intermediate wheel or set of intermediate wheels carried on an
axially mounted body which also serves to transmit motion to the change-gear,
and a surrounding internally toothed wheel permanently fixed or capable of being
temporarily held stationary, the intermediate wheel or wheels meshing with the
central pinion and with the surrounding internally toothed wheel, substantially
as herein described.
10. The combination with change gear mechanism, of speed-reducing gear
comprising a central pinion, connected with the driving shaft [or other source
of power], an intermediate wheel or set of intermediate wheels carried on an
axially mounted body keyed on a sleeve in which the driving [or driven] shaft
rotates and whereon the change-gear trains or some of them are mounted, and a
surrounding internally toothed wheel permanently fixed or capable of being
temporarily held stationary; the intermediate wheel or wheels meshing with the
central pinion and with the surrounding internally toothed wheel, substantially
as described with reference to Figs. 14, 15 or 16 of the accompanying drawings.
Dated this 7th day of September. 1897.