IMPROVEMENTS IN DIFFERENTIAL GEARING
Year: 1878

page_text: LETTERS PATENT to Richard Russell Gubbins, of Wolverhampton, in the
County of Stafford, James Whitestone, of Upper Thames Street, and John
Samuel Wallis Allin, of Cannon Street, both in the City of London, for the
Invention of "IMPROVEMENTS IN DIFFERENTIAL GEARING."
Sealed the 2nd July 1878, and dated the 15th January 1878,
PROVISIONAL SPECIFICATION left by the said Richard Russell Gubbins,
James Whitestone, and John Samuel Wallis Allin at the Office of the Com-
missioners of Patents on the 15th January 1878.
RICHARD RUSSELL GUBBINS, of Wolverhampton, in the County of Stafford,
JAMES WHITESTONE, of Upper Thames Street, and JOHN SAMUEL WALLIS ALLIN, of
Cannon Street, both in the City of London. "IMPROVEMENTS IN DIFFERENTIAL
GEARING."
Our Invention consists in improved combinations of bevelled toothed wheels and
pinions, whereby great power may be obtained for lifting weights and for other
purposes, and relates more particularly to differential pulley blocks.
Our Invention consists, 1st., in the following arrangement of differential gear :-
Two bevelled toothed wheels having different numbers of teeth are mounted face to
face on the same main spindle, and upon a drum intermediate between them and
turning loose on the same spindle, two or more pairs of bevelled toothed pinions
are carried, one pinion of each pair being in gear with one of the toothed wheels,
and the other pinion in gear with the other toothed wheel, and the two pinions in
gear with each other. The rotation of the drum carrying the pinions will thus
produce a differential rotation of the two toothed wheels, and the power applied in
turning the drum which carries the pinions will thus be multiplied in a proportion
depending upon the relative numbers of teeth in the two bevelled toothed
wheels. By preference the two bevelled pinions constituting each pair are so placed
that their axes are in a plane, making as small an angle as possible with a plane
cutting the main spindle at right angles, having regard to the condition above

page_text: mentioned, viz., that each pinion is in gear with one only of the toothed wheels, and
just clear of the other toothed wheel.
In order to counteract the outward pressure on the bevelled toothed wheels where
they are acted upon by the pinions (which pressure would if not counterbalanced
cause a cross strain on the main spindle), we prefer to use two or more pairs of
pinions disposed at about equal intervals apart, which by acting in different points
in the circumference of the bevelled toothed wheels, will produce pressures.
balancing each other so as to relieve the main spindle from the cross strain above
referred to.
Another advantage in employing two or more pairs of pinions is that the strain
caused by the load to be lifted will be distributed amongst a greater number of
teeth than if only one pair of pinions were used.
We prefer that the drum carrying the pinions shall run loosely upon the main
spindle, so that there may be a certain amount of play to allow the pinions to so
adjust themselves as to take an equal share of the pressure.
In constructing differential pulley blocks a chain wheel is cast in one piece with
or firmly secured to each of the bevelled toothed wheels, and the rim of the drum
carrying the pinions is also formed to carry a chain. A chain is passed over each
of the two chain wheels first named, and the ends of these chains hanging froin
opposite sides of the two chain wheels are jointed in pairs by two cross bars, each
provided with a hook or shackle, so that a load suspended by one of the hooks or
shackles would tend to turn the two wheels in opposite directions. Over the
wheel carrying the pinions an endless chain is passed, by hauling on which the
pinions are caused to travel round the bevelled toothed wheels, and thus produce a
differential rotation which will cause a load suspended by one of the hooks or
shackles to be raised or lowered, according to the direction in which the wheel
carrying the pinions shall be rotated. The ends of the main spindle are carried by
a frame with a hook or shackle attached for suspending the pulley block.
As a modification of the above, the two main bevelled wheels may have the same
number of teeth, and have cast in one piece with each of them a subsidiary bevelled
wheel of smaller diameter. These two subsidiary wheels have different numbers of
teeth, and one or more (preferably three) bevelled pinions in gear with both of
them are carried upon pins or arms fixed to the main spindle, which spindle is
firmly fixed to the frame carrying the pulley block. There is also a chain wheel or
drum (to carry the lifting chain) running loose upon one end of the main spindle,
and having one or more radial pins or arms fixed to its rim, which pins or arms
carry one or more (preferably three) pinions in gear with the two main bevelled
wheels. The main bevelled wheel running upon the other end of the main spindle
has cast in one piece with or firmly secured to it a chain wheel to carry the hand
chain by means of which the power is to be applied. By hauling the hand chain
the two main bevelled wheels will by the action of the subsidiary differential
bevelled wheels attached thereto, and the pinions in gear with them, be turned in
opposite directions at slightly different speeds, and will thus cause the pinions
in gear with the main bevelled wheels to travel round and carry with them the
lifting chain wheel at a slow speed. To each end of the lifting chain a hook or
shackle is attached for suspending the load, and another hook or shackle is fitted to
the frame for suspending the pulley block.
As a further modification the main bevelled wheels in the arrangement lust
described may have different numbers of teeth. Very great multiplication of power
may in this way be attained with wheels of moderate diameter, having teeth of
sufficient size to resist great pressures. With this purpose the subsidiary differential
bevelled wheel would be made with such numbers of teeth respectively, that if the
main bevelled wheels had equal numbers of teeth, the lifting chain wheel would be
rotated in the one direction, and the main bevelled wheels would be made with
such numbers of teeth respectively, that if the subsidiary bevelled wheels had equal
numbers of teeth, the lifting chain wheel would be rotated in the opposite direction.
The actual angular velocity of the lifting chain wheel will therefore be equal to

page_text: the difference between the angular velocities which the two combinations of
differential gears would separately produce in the hypothetical cases above
referred to.
Our Invention may be applied to capstans, crabs, and other contrivances for
multiplying power in hauling chains or ropes, or to any machines requiring great
multiplication of power, or great differences of speed between their moving
parts.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Richard Russell Gubbins, James Whitestone, and John Samuel Wallis
Allin in the Great Seal Patent Office on the 15th July 1878.
RICHARD RUSSELL GUBBINS, of Wolverhampton, in the County of Stafford, JAMES
WHITESTONE, of Upper Thames Street, and JOHN SAMUEL WALLIS ALLIN, of Cannon
Street, both in the City of London. "IMPROVEMENTS IN DIFFERENTIAL GEARING."
Our Invention consists in improved combinations of bevelled toothed wheels and
pinions, whereby great power may be obtained for lifting weights and for multi-
plying and transmitting power, and for other purposes.
In order that our Invention may be more readily understood we will describe it
with reference to the accompanying Drawings, in which we have illustrated it as
applied to pulley blocks by way of example. Its application to other hoisting
machinery will be readily understood.
Figure 1 represents a section of the working parts of a differential pulley block
made according to our Invention, the framing being in elevation, and Figure 2
represents a side elevation of the same, the same letters of reference indicating
corresponding parts in the two Figures.
A, A', are two bevelled toothed wheels, A having one more tooth than A'. Each
is cast in one piece with or firmly secured to the chain rims or wheels B, B1,
respectively, and both run loosely upon a spindle C. Between them is a drum
capable of turning loosely upon the same spindle and provided with a circular
rim E formed to carry a chain F, and firmly attached to the boss of the drum by
means of the six pins G, G, H, H', K and K' (shown by dotted lines in Figure 2),
which are screwed into the arms D' projecting from the boss D. The rim E and
the boss D thus connected by the six pins form together the drum. M, M, N, N¹,
O and O¹ (shown by dotted lines in Figure 2), are six bevelled toothed pinions
turning loose upon the pins G, G', &c., and arranged in pairs, as indicated by their
reference letters, so that the first-named pinion of each pair may be in gear with
the bevelled toothed wheel A, and the other pinion of each pair in gear with the
other bevelled toothed wheel A', and the two pinions of each pair in gear with each
other. Thus the pinions M and M' (which form a pair) are in gear with each other,
and the pinion M is in gear with the toothed wheel A, and the pinion M' is in gear

page_text: with the toothed wheel A' similarly for the pairs N, N₁, and O, O'. This is shown
more clearly in Figure 2ª, which represents a top view of the gear, the rim E being
removed, and rims B, B', partly broken away to show the pinions.
It must be understood that there is no contact between the pinions M¹ and N,.
nor between the pinions N¹ and O, nor between the pinions O¹ and M; also that
the pinions M, N, and O (which are in gear with the toothed wheel A), are not in
contact with the toothed wheel A¹, and that the pinions M¹, N¹, and O' (which are
in gear with the toothed wheel A¹), are not in contact with the toothed wheel A.
Therefore the pins G, G, H, H', K, and K' (which carry the pinions), are not fixed
to the boss D at equal distances apart but are arranged in pairs, the pins G and G',
for example, being nearer to each other than the pins G₁ and H, or than the pins
G and K, so that each pair of pinions may be clear of the other pairs, and the pins
are also inclined alternately to the right and left of a plane, cutting the main
spindle C at right angles at the middle of its length, so. that each pinion shall be in
gear with one of the toothed wheels and clear of the other. By preference the plane
in which the axes of the two pinions of each pair are situate coincides as nearly as
possible with the plane which cuts the spindle C at right angles, having regard to
the condition above stated, viz., that each pinion is in gear with one only of the
toothed wheels, and just clear of the other toothed wheel.
Some care is required in setting out the positions of the pins in order that the
pinions and toothed wheels shall work well together.
When epicycloidal teeth (which are generally most convenient) are used only one
pair of pinions out of the three can be in gear (the pinions with each other and also
with their respective toothed wheels) with mathematical accuracy, that is to say,
with all the pitch circles touching each other. The positions of the other two pairs
of pinions must be adjusted, so as to fit their places as nearly as possible; but in
these cases the pitch circles will either not quite touch each other or will cut each
other. The amount of error in practice is very small, and as this error can be
distributed between three places of contact in each of the two pairs it does not
cause any practical inconvenience.
The adjustment of the positions of the pins will depend upon the numbers of
teeth in the several wheels and pinions. The greater the number of teeth the less
will be the mathematical error, and consequently the less will be the amount of
adjustment required. To find the amount of adjustment we fit together wheels
A, A¹, and boss D on the spindle C, and drop the pinions into their respective
places, and mark the exact places where the holes are to be bored for the reception
of the pina
P, Pi, are two chains passed over the chain rims or wheels B, B', which are formed
in the usual way to hold the chains to prevent them from slipping, and the ends of
these chains hanging from opposite sides of the two chain wheels are joined in pairs
by two cross bars Q, provided with hooks R for attaching the load. A similar book
S for suspending the block is attached to the frame T, which carries the ends of the
spindle C. By hauling the endless hand chain F, the drum D, E, is rotated
together with the pinions M, M', &c., which are thus caused to travel round the
bevelled toothed wheels A, A', and the latter having slightly different numbers of
teeth are thus caused to turn slowly in opposite directions, carrying with them the
chain wheels B, B1, a load suspended from one of the hooks R being thereby raised
or lowered, according to the direction in which the wheel carrying the pinions.is
rotated, and according to which of the hooks R it is attached, the one hook rising
while the other is descending.
The multiplication of power or purchase will depend upon the relative numbers of
teeth in the bevelled wheels A and A', and in order that the purchase shall be as
great as possible with conveniently small numbers of teeth, it is desirable that the
numbers of teeth in these two wheels should differ by one tooth only, wheel A
having for example 19 teeth, and wheel A¹ 20 teeth.
Although three pairs of pinions are shown in Figures 1 and 2, and here described,
a greater or a less number of pairs of pinions may be used, their diameteter being

page_text: modified accordingly. We prefer to use three pairs, so that the pressure upon the
teeth may be evenly distributed amongst the pinions.
To prevent confusion in the Drawings, the oblique elevations of the pinions
adjacent to M and M' are omitted at Figure 1.
As a modification of the above the pulley blocks may be constructed as shown in
Figures 3 and 4, which represent sections at right angles to each other through the
working parts. A, A¹, are two bevelled toothed wheels having the same numbers of
teeth and each respectively cast in one piece with the subsidiary bevelled wheels
B, B1, of which one, say B, has one tooth more than the other; C, C, C, are bevelled
toothed pinions, each in gear with both of the wheels B and B¹, and carried upon
pins D, D, D, screwed into the boss, which is keyed on to or otherwise firmly attached
to the main spindle F, between the bosses of wheels A, B, A¹, B¹, as shown. This
main spindle is carried by the frame G, and is secured to it by keys nt each end so
that it cannot revolve. H is a chain wheel or drum (to carry the lifting chain K).
running loose upon the main spindle F, and having a projecting rim H' with bosses
into which are screwed the radial pins or arms L, L, L, projecting inwardly towards
the centre and carrying the bevelled pinions M, M, M, each of which is in gear with
both of the main bevelled wheels A and A'. The rim A² of the main bevelled wheel
A' is formed to carry the endless hand chain N. By hauling the hand chain, the
bevelled wheels A¹ and B¹ (which are cast in one piece) are caused to rotate, and
by the action of the pinions C, C, C, which are in gear with the wheels B and B',
the wheel B will be caused to rotate in the opposite direction, carrying with it the
main bevelled wheel A which is cast in one piece with it. In consequence of the
difference between the numbers of the teeth in the wheels B and B₁, the speeds of
rotation of these, and consequently of the main wheels A and A' will be slightly
different, and the pinions M, M, M, which are in gear with both of these latter, will
therefore be caused to travel round the main pin F (besides turning on their
respective pins L, L, L,) and will carry with them the lifting chain wheel H at a
slow speed, thus raising or lowering a load attached to one of the ends of the lifting
chain, according to the direction in which the hand chain wheel A* is caused to turn.
To each end of the chain K a hook O is attached for suspending the load, and a
similar hook P is attached to the frame G for suspending the pulley block.
The multiplication of power will depend upon the numbers of the teeth in the
wheels B and B'. The numbers should differ by one tooth only, and the larger the
numbers the greater will be the multiplication of power. The exact positions of
the pins D, D, D, will depend upon the numbers of teeth in the wheels B and B¹..
These pins will not be placed at exactly equal angles to each other, but their
positions will be set out so that the pinions C, C, C, may be fairly in gear with
both the wheels B and B¹.
The same result may be obtained by making the wheels A and A' (Figures 3
and 4) with different numbers of teeth, and the wheels B and B¹ with the same
numbers of teeth. In this case however the wheels A and A¹ will rotate in opposite
directions, but at the same speed, and the pinions M, M, M, will be caused to travel
slowly round the main pin F on account of the difference in the numbers of teeth in
the wheels A and A¹ with which they are in gear.
It is not desirable to increase beyond certain limits, prescribed by the required
strength of the teeth, the number of teeth on a wheel of a given diameter, and in
cases where very great multiplication of power is needed we therefore prefer to
modify the gearing in the following manner, so that wheels of moderate diameter,
and having teeth of sufficient size to resist great pressures, may be used:-The
wheels A and A' (Figures 3 and 4) are made with different numbers of teeth, and
likewise the wheels B and B¹; and if the number of teeth in A be greater than the
number in A¹, the number in B will be less than the number in B¹, or vice versa ;
the proportion between the numbers of teeth in the pair of wheels A, A¹, must also
be different to that between the numbers of teeth in the pair of wheels B, B.
There are thus two combinations of differential gears :-
First. The differential bevelled wheels B, B¹, and the pinions C, C, C, in gear

page_text: with them, causing the wheels A and A¹ to rotate in opposite directions at slightly
different speeds, so that if the latter had equal numbers of teeth the pinions M, M, M,
would be caused to travel round the main pin F in one direction.
Secondly. The differential wheels A, A', with such respective numbers of teeth,
that if they be rotated at equal speeds the pinions M, M, M, would be caused to
travel round the main pin in the opposite direction, but at a different speed to that
which would be produced in the former hypothetical case.
The actual angular velocity at which the pinion M, M, M, will be caused to travel
round the main pin (and consequently the speed of rotation of the lifting chain
wheel H) will therefore be equal to the difference between the angular velocities
which these two combinations of differential gears would separately produce in the
hypothetical cases above referred to.
In this last-described modification the exact positions of the pins L, L, L, as well
as of the pins D, D, D, will depend upon the numbers of teeth in the respective
wheels with which the pinions they respectively carry are in gear.
Although three pinions in gear with each pair of bevelled wheels are shown in
Figures 3 and 4, and here described, a greater or less number of pinions may in
each case be used in lieu of three.
Our Invention may be applied to capstans, crabs, cranes, and other contrivances
for multiplying power for hauling chains or ropes, or to any machines requiring
great multiplication of power or great differences of speed between their moving
parts.
Our Invention may be applied to crabs as follows:-According to one arrange-
ment the spindle C (Figures 1 and 2) is extended in length, and provided with the
usual cranked handles at its ends. In this case the chain rim E is not used, the
boss D being keyed on the spindle C, so that the pinions which it carries will be
rotated with said spindle. One of the bevelled wheels (say A) is bolted to the
framing of the crab, or otherwise prevented from revolving, and the chain rim or
wheel on said wheel is not used. The spindle C is mounted parallel to the spindle
of the drum on which the lifting chain or rope is wound, and upon the latter
spindle is keyed or otherwise fixed a chain wheel or rim similar to and exactly
opposite the chain wheel B¹, which runs loosely on spindle C. These two chain
wheels are geared together by an endless chain, and the ends of the two spindles
are carried in bearings upon the side frames of the crab in the usual way.
Instead of the chain wheels or rims, spur gearing may be used for transmitting
the movement of the differential gearing to the spindle of the lifting chain drum.
According to a modified arrangement the differential gear (Figures 1 and 2) may
be on the spindle of the winding drum itself. In this case the bevelled wheel A¹,
Figure 5, is keyed to the said spindle, or bolted to the winding drum Y, whilst
the other wheel A is bolted to the frame of the crab, or otherwise prevented from
revolving. The chain rims B, B¹, are not used, but the chain rim E is used, and
the boss D runs loose on the spindle. The crank handles are on a spindle parallel
to the winding drum as usual; but in lieu of the ordinary pinion for driving the
winding drum it has a chain wheel X keyed on it opposite the chain rim E, and these
two chain wheels are geared together by an endless chain, by which the differential
gear is driven, and through it the winding drum from the crank handles. Instead
of these chain wheels or rims spur gearing may be used to transmit motion from
the crank handle spindle to the drum D, E, carrying the pinions.
Having described our Invention, and the manner of performing the same, we
declare that what we claim as our Invention to be protected by the herein-before in
part recited Letters Patent is,―
1st. The combination of a pair of differential bevelled toothed wheels, and one or
more intermediate pairs of pinions, as herein described, and shown in Figures 1 and
2, for the purposes specified.
2ndly. The combination of two pairs of bevelled toothed wheels and intermediate
pinions, as herein described and shown in Figures 3 and 4, when the numbers of

page_text: teeth in one pair of wheels are different, and the numbers in the other pair of
wheels are equal, as and for the purposes described herein.
3rdly. The combination of two pairs of differential bevelled toothed wheels and
intermediate pinions, as herein described, and shown in Figures 3 and 4, when the
wheels of both pairs have different numbers of teeth, and these two sets of
differential gears are so arranged as almost, but not quite, to neutralize one another's
effects, as and for the purposes described herein.
In witness whereof, we, the said James Whitestone and John Samuel Wallis
Allin, for ourselves and on behalf of the said Richard Russell Gubbins, have
hereunto set our hands and seals, this Fifteenth day of July, in the year
of our Lord One thousand eight hundred and seventy-eight.
JAMES
WHITESTONE
JOHN S. W. ALLIN.
(LS)
(L.S.)