Improvements in or relating to Differential Speed Gearing.
Year: 1899

page_text: Date of Application, 16th Jan., 1899-Accepted, 16th Jan., 1900
Improvements in or relating to Differential Speed Gearing.
I, PAUL LEMAIRE, of Gomiécourt, Department of Pas de Calais, in the French
Republic, Landed Proprietor, 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 :-
The present invention relates to an apparatus or combination of mechanism for
converting the speeds of one two or more rotating shafts into a single differential
speed for another shaft.
The characteristic feature or function of my invention is to transmit upon a single
axle the rotary motion of one or inore motors running at any speeds and in either
direction and to impart to the said single axle any number of revolutions (speed)
that may be desired and either in a forward or backward direction, even unto
stoppage.
I will now proceed to describe my invention by the aid of the accompanying draw-
ings illustrating it, and in which :-
Figure 1 is a longitudinal vertical section of the apparatus or mechanism as
arranged to be driven by two separate motors, and
Figure 2 is a longitudinal vertical section of the apparatus or mechanism as arranged
for a single motor.
The differential apparatus (Figure 1) consists of a pulley a with wooden rim in
which is situated the differential movement. Two plates p, p₁ forming cheeks are
screwed on to the edges of and make this pulley a a hermetically closed drum which is
supported by two sleeves t, t¹, integral with the plates ppl,upon axles f,f¹which are them.
selves supported in hangers or brackets s, s¹. The two crank-shafts or axles f, f¹ pass
through the sleeves t, t¹, and at their inner end carry the truncated cone wheels g, g¹
forming with the two conical gear wheels h, h¹, a closed set of bevel gearing;
the wheels h and h' being mounted respectively on axles j, j fixed in the rin of the
pulley and fitted with ball bearings. The working is as follows:
The crank shaft f remaining fixed and shaft f¹ running, say for example, at 100 revo-
lutions, the pulley a will perform 50 revolutions. In fact, let us imagine two parallel
racks, the one A-B fixed and the other C-D movable, and let us place between
these two racks a pinion E gearing with the two racks. If we pull E by its axle, this
pinion will advance between the two racks turning in the opposite direction to its
rectilineal motion, and the movable rack C-D will receive the result of the two
notions: 1st, of the translation of the pinion E between the racks, and 2nd, of the
rotation of the pinion E in the opposite direction to its motion, and at a speed equal
to that of the translation, the result of which will be to make the rack C-D advance
double the distance travelled over by the pinion E.
In this invention the equivalent of the imagined rack A-B is formed by the
conical or bevel wheel g of the shaft f; the wheel g¹ of shaft corresponding
to the rack C-D and the differential gear / corresponding to the pinion E. Therefore
when the shaft f¹ turns, the gear wheel receives a rotary and a translatory motion
Price Q77
h

page_text: equal to each other, the sum of which is the speed of the shaft f', therefore the move-
ment of translation produced will be 2.
If instead of being fixed, the shaft ƒ also turns, its speed will have to be added or
deducted from the result according as it turns in the same direction as the shaft f¹ or
in the contrary direction.
If for example f¹ performs 600 revolutions and f 500 revolutions let us consider the
system as making 600-500-100 revolutions (f fixed and f¹ 100 revolutions), the
pulley will perform 50 revolutions; but ƒ performing 500 revolutions and f¹ 600 revo-
lutions the system will be animated with a supplemental speed of 500 revolutions and
consequently the pulley will perform 50 + 500-550 revolutions.
Therefore in the case where the two shafts f and f¹ turn in the same direction at
equal or different speeds the formula will be
pulley.
If, supposing fixed and f¹ running at a speed of 100 revolutions, we apply
to f and a speed of 500 revolutions, but in the opposite direction in such a way
that turns 500 revolutions in one direction and f¹ 600 revolutions in the opposite
direction, this supplement of speed will not change the speed of the pulley a, for
these two speeds in opposite directions and equal, only transmit to the differential
gear a movement of rotation but no movement of translation. Therefore in the
case of movement in opposite direction the pulley a will revolve in the direction of
the greater speed and at a speed equal to half the difference.
The above formula applies then again, and simplified it becomes:
If the difference of speeds becomes nil, the movement of the pulley becomes almost
nil and the strain tending to move it is infinite. From this fact there is a considerable
mechanical advantage, inasmuch as it is effected without any engaging, controlling
the stoppage, starting, progressive forward or backward motion and without possible
jolts.
If the difference of speeds becomes nil, the movement of the pulley becomes almost
nil and the strain tending to move it is infinite. From this fact there is a considerable
mechanical advantage, inasmuch as it is effected without any engaging, controlling
the stoppage, starting, progressive forward or backward motion and without possible
jolts.
Figure z represents the differential apparatus driven by a single motor.
a is the pulley to be made to revolve.
b is the driving pulley.
c is a pulley which varies in speed, through the intervention of an endless
screw k.
dis an intermediary pulley.
Pulley b drives a gear-wheel g forming part of the differential gear h of the pulley c:
and a second conical gear wheel g¹, mounted on a tubular sleeve which is fixed in the
sleeve of gb and receives in consequence its movement from b.
This gearing g¹ forms part of the differential gear h¹ of the pulley a. The pulley d
by its gearing e and e¹ forms, at the same time, part of the differentials h of the
pulley c and h of the pulley a.
The pulley c being supposed to be kept stationary. by the endless screw k, acting as
a brake, its differential h will work the pulley d by the gearing e in an opposite
direction, that is to say, the pulley & will turn at the saine speed as the pulley 6 but
in the opposite direction.
But the differential of the pulley a will receive two speeds in opposite directions,
viz. that of the gearing e¹ of the pulley d and that of the gearing g₁ governed by the
pulley b; these two speeds will be equal or different according as the gearings g and g¹
have the same or a different number of cogs. The two speeds being equal, the

page_text: pulley a will remain at rest like pulley c; if, on the contrary, these two speeds are
different, the pulley will turn in the direction of the greater speed.
But since the pulleys a and c are interdependent, we can, by allowing c to turn,
make the pulley a begin to run or modify its rate of motion conformably with the
variations of speed of the pulley c. The endless screw which acts as a brake enables
us to impart to pulley cany rate of speed we desire and we shall obtain communica-
tion of these same speeds to the pulley a.
In designating the speed of each pulley by the reference letter thereof, we have :-
a formula which gives us the speeds of the pulley a resulting from the co-operation of
the speeds of g¹, 6 and e.
The movement of the pulley a is transmitted to the shaft ƒ by the lugs and the
sleeve m fast on f.
The endless screw or worm k remains at rest or submits to the influence direct or
indirect of one or the two motors b or d. If it remains at rest it acts as a brake; if it
is set in motion it works as a regulator or moderator of the speed. But instead of
working the endless screw k by means of one of the two motors b or d, we could work
it by a motor apart, running for example at a speed different from those of the motors
b and d, and in consequence we should obtain the combination of the speeds, of
necessity very various or variable, of three motors.
Furthermore we could combine the apparatus with another pulley or a similar
motor to that d, and obtain the combination in a single differential apparatus of the
rotary motions various or variable of four motors absolutely independent of each
other.
It is evident that the driving pulley b can be replaced by any motor; likewise the
intermediary pulley d might be replaced by any other movable or rotatable piece such
for example as the movable part (armature for instance) of an electro-motor.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. The apparatus or combination of mechanism for transmitting to and concentrat-
ing upon a single driving shaft or axle the rotary motion of two motors having the
same centre of revolution and running in the same or opposite direction at any speed
or speeds imparting to the said single axle any differential speed desired in either
direction even unto stoppage without the employment of clutches or other temporary
engaging and disengaging device, consisting of the combination of a closed set or sets
of bevel-gearing connected with the shafts of the driving motors and with a pulley in
which the said gearing is located, the said pulley being connected by a belt or other
transmission device with the single shaft which is to run at the differential speed,
substantially as described and as illustrated in Figure 1.
2. In an apparatus or combination of mechanism for converting the speeds of one
or two rotating shafts into a differential speed for a third shaft as claimed in Claim 1
nereof, the combination therewith of an endless screw or worm constituting a brake
or regulator for controlling the speed of the pulley (c) containing the bevel-gear (h)
and thereby vary at will the speed of the pulley (a) containing the bevel-gear (h¹).
substantially as described and as illustrated in Figure 2.
3. The apparatus or combination of mechanism constructed in detail, operated, and
working, substantially as described and illustrated.

page_text: 4. The combination with the shafts of one, two or more motors, of the apparatus or
combination of mechanism constructed in detail, operated, and working, substantially
as described and illustrated.
Dated the 16th day of January 1800
PHILLIPS & LEIGH,
No. 22, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.