Improvements in Calculating Machines.
Year: 1892

page_text: Date of Application, 17th Oct., 1892
Complete Specification Left, 17th July, 1893-Accepted, 14th Oct., 1893
PROVISIONAL SPECIFICATION.
Improvements in Calculating Machines.
MICHAEL HEARN 17 Nassington Road Hampstead Gentleman, do hereby declare
the nature of this invention to be as follows:-
This invention relates to improvements in calculating machines.
To this end on one and the same bearing I pivot a series of wheels in combination
as follows:-
To one end of a ratchet pinion having 10 teeth I attach two wheels somewhat
similar to an ordinary escapement wheel, each wheel having 10 teeth, and to the
other end of the said pinion, a wheel in the shape of a cap or cover, which I use as
the index or numeral wheel, having the numbers 0 to 9 engraved on its periphery.
Across the open side of the index wheel mounted on a bridge which is attached to
the index wheel is a small pinion having 3 or 4 teeth, the rest of its periphery
being cut away at the bottom of the tooth for a purpose explained hereinafter. Both
wheels mentioned above, similar to escapement wheels may be the same diameter-
one wheel acting as the brake or stopping wheel, the other as a carrying wheel and
hereafter I will refer to these as brake and carrying wheels. In order to permit
a pawl to actuate the carrying wheel freely, this wheel may be placed at a distance
of th of an inch or thereabouts from the brake wheel. To actuate the ratchet
pinion to which the above wheels are attached I use a long lever having its
fulcrum at the back part of the machine, the said lever being referred to hereafter
as the driving lever. To this lever is pivotted a rack, curved at the end which
forms its bearing. The said rack being kept in gear with the ratchet pinion by a
spring. Its action being to clutch and hold the ratchet pinion when the driving
lever is pressed downward, and to release and slide over the teeth of the said
pinion when returning to its normal position. Directly under the driving lever
and having its fulcrum either at the back part or front of the machine I pivot
a lever extending a little beyond the 9th hole in the driving lever. This lever,
hereafter called a stopping lever is connected with a metal band or strap to a brake
lever placed above the driving lever and pivotted on a fulcrum about midway in the
machine. To actuate the driving lever I drill in it 9 holes. Similarly in the cover
of the machine are 9 holes through which I pass vertically a series of finger keys,
each one varying in length according to the depression required. For a portion of
their length each key is rounded so as to pass freely through the holes of the
driving lever. Their shoulders resting on the driving lever and their square
ends working freely in the holes drilled in the top or lid of the machine. These
keys it will be understood work with a perpendicular plunger motion and are
all returned to their normal position by spiral springs, which are pressed in
operation by the flat part of their heads. In order to keep the keys in position
on the cover of the machine I place a series of strips of metal running parallel
with the keys and acting as guides to them on each side. Each key as above
explained is returned to position by a spiral spring, but to prevent it being jerked
out by the action of the driving lever in its return movement and also to enable
a workman or operator to readily replace a new key without taking the cover off
the machine I cut shallow slots on one side of each key and in every case on the
same side, thus forming a shoulder to each key at its upper end. On the same
side on which these slots are cut runs one of the strips of metal above referred to-
the said strip being kept in position by screws passing through slots or oval
shaped holes in the said strips. It will therefore be seen that as the keys return to
their norinal position the shoulders formed by these slots striking against the strip
of metal above referred to, prevent the keys being thrown or jerked up, while by
.

page_text: loosening the screws the metal strip may readily be drawn to one side and any key
removed and replaced by another if necessary. All these keys it will be under-
stood are properly graduated so that on depressing the unit key the index wheel
will record one and so on throughout, according to the key depressed. To
transmit motion from one set of wheels to another I use the following device. On
a bearing placed beneath the index wheels and their attached wheels I pivot a series
of circular racks having projecting arms to which are pivotted pawls controlled by
light springs. These racks run in gear with the pinions having 3 or 4 teeth above
mentioned and are kept in their normal position by springs placed on the same
bearing on which the said racks oscillate. The action of these racks hereafter
called carrying racks is explained further on. In order to correct any uncertain
motion of the wheels and also to prevent their running forward when the driving
lever is operating I may place in gear with the brake or carrying wheels a pawl
kept in position by a light spring, the said pawl dropping between the teeth of the
wheel and preventing it moving as the driving rack is returning to position. To
prevent overrunning of the wheels in carrying I suitably pivot a stop one end of
which rests on the head of the pawl connected with the carrying rack the other
end resting on a pin on the driving lever the action of this stop in combination
with the pawl being as follows:-
When the carrying rack is operated the pawl is withdrawn from under the
carrying stop. The stop at the same time dropping slightly. When the pawl
returns at the same time that it pushes forward the carrying wheel, it pushes up
the carrying stop and as the other end of the stop comes in contact with the pin on
the driving lever above referred to it locks the wheel and so prevents it rotating
beyond the required distance.
The action of these parts as above described will therefore be as follows:-
On depressing any finger key the driving lever is immediately moved downwards,
the rack pivotted to it drawing the ratchet pinion with the wheels attached thereto.
The driving lever having travelled until the key comes in contact with the stopping
lever, the brake lever is immediately drawn against one of the teeth of the brake
wheel, when the number required is shown on the index wheel, while the carrying
is effected by the pinion attached to the index wheel gearing with the carrying rack
and causing it to rotate till the blank part of the said pinion releases it, when the
carrying rack is pressed back by the spring above referred to and the pawl attached
to the said carrying rack gearing with the carrying wheel, the said wheel and those
attached to it are drawn the space of one tooth, the number carried being shown on
the index wheel as before explained. In returning to position the driving levers
rest against adjustable screws fitted on a bearing above them and which bearing
may act as a guide to the said levers and keep them in position as they work
up and down.
To return all the wheels to their normal position or zero point the bearing upon
which the said wheels rotate has a groove cut along its entire length. Inside
each cap or index wheel is fitted a spring pawl. This pawl is pressed against the
bearing in such a way that it will revolve freely with its index wheel, but when
the rod is rotated the groove comes against the pawl and meshing with it, the index
wheel may be rotated to any point of setting desired. As all the wheels will be
locked when the index wheels are at zero, it will be necessary before turning the
rod to release such wheels as may be standing at nought when the calculation is
completed by touching the keys 4 or when the rod may be actuated as before
described. A perforated plate running over the index wheels shows at the several
perforations the units, tens, hundreds and so on. It should be pointed out that as
the stop for preventing the overrunning of the carrying wheel is placed on the
driving lever, immediately this driving lever is operated the stop travels with it,
consequently the pawl which actuates the carrying wheel is released and with the
wheels attached thereto permitted to fully rotate. It will be seen from the
foregoing that owing to the simple combination of a self releasing rack pivotted to
a driving lever cach combination of wheels is solid or whole in itself, while great

page_text: simplicity of mechanism is attained with an avoidance of numerous spring detents
which always require very nice adjustment as regards the tension on their springs
to obtain absolute accuracy of motion.
number of columns of figures may be rapidly and simultaneously added by pressing
finger keys, of which the following is a detailed description
Fig. 1 is a vertical longitudinal section showing the driving and stopping
mechanism.
Fig. 2 is a side view of the carrying mechanism.
Fig. 3 is a front view of same.
Figs. 4, 5, 6, 7, 8 are hereinafter described.
Fig. 9 is a part top view of machine, showing a part of the keyboard and farthing
and pence wheels.
Fig. 10 is a vertical longitudinal section showing the brake lever placed above
the driving lever.
Fig. 11 is a front view of same.
Fig. 12 is a perspective view of the key plunger.
Each combination is made up of the following wheels:
A, carrying wheel, B brake wheel, C driving pinion, D index wheel, E carrying
pinion. All these wheels are fixed together and rotate on the shaft P.
Each combination of wheels, as above described, is driven by a self releasing
rack G pivotted to a driving lever H, the said rack G gearing with the ratchet
pinion C and drawing it a number of teeth according to the depression given to the
driving lever H by the graduated key plungers I, 1. Beneath the driving lever H
is pivotted a stopping lever J its free end resting on a brake lever K which is
thrown into gear with the brake wheel B as soon as the stopping lever J is struck
by any one of the key plungers I as will be readily understood by reference to the
illustration Fig. 1.
It should be stated that the mechanism is the same throughout. The wheels of
the farthings, pence, and decimal of shillings varying only as regards the number of
teeth in their respective wheels.
For the farthings, wheel A 1, brake wheel B 1. and driving pinion C 1. being
divided into 8 teeth carrying twice in each revolution with the carrying pinion L.
See Figs. 5 & 9.
For the pence, the carrying, brake and driving wheels A2, B2, C 2 being
divided into 12 teeth carrying once in each revolution. And in like manner the
carrying, brake and driving wheels of the decimal of shillings are divided into
6 teeth carrying 3 times in each revolution. The carrying pinion V with its sector U
being shown in Fig. 4.
The pound or decimal wheels are all divided into 10 teeth, the carrying pinions
of same having 3 teeth. See Fig. 2 E.
All the index wheels have 0 to 9 engraved on their peripheries, except in the
case of the farthings, pence and decimal of shillings. The first having 0 to 3 engraved
twice, the second 0 to 11, and the last 0 to 1 three times.
The carrying is effected in the following manner :—
When the driving pinion C is rotated all the wheels attached to it rotate at the
same time. The carrying pinion E Fig. 2 in the course of its revolution gears

page_text: with the sector M which carries the pawl N pivotted to it over a tooth of the
carrying wheel A until the sector is released by the blank part of the pinion E,
when it is retracted by the spring F, the pawl N at the same time drawing the
carrying wheel A one tooth. See Figs. 2 & 3.
The carrying wheel A is prevented from overrunning by the butt end of the
pawl N striking against the driving lever H as will be readily understood by
reference to Figs. 2 & 9. When the driving lever H is operated it releases the
pawl and permits the wheels which are being driven to rotate freely. Any
tendency to forward movement on the part of the wheels operated, by the action of
the rack G returning to its normal position being prevented by the pawls O which
gear with their respective wheels A, the said pawls being controlled by light
springs u.
In my present machine the index wheels are returned to zero by adding the
difference. That is to say should a wheel indicate 8 to this 2 will be added and so on.
But the last wheel of all; the one which is not driven, but carried by the revolu-
tion of the wheel adjacent to it and which is more particularly described further
on I return in the following manner. On a part of its length I cut a groove » in
the shaft P Fig. 6 on which all the wheels rotate. Inside the index wheel, all of
which have a flange, 1 place a pawl Q and spring R. See Fig. 6.
When the
index wheel D revolves this pawl Q will revolve freely with it, but when the shaft P
is rotated by the handle or nut S the groove meshing with the pawl will cause it
to rotate the index wheel to any point of setting desired. A bridge T is placed
on the index wheel, under which the pawl and spring may freely work.
bridge also forms a bearing for the index wheel D.
This
In Fig. 9 three strips of metal h, i, h being the guides to the key plungers are
shown in part. The slotted part of the key plungers, slides in the slots k of the
stripi, the strips h, on each side preventing the plungers being thrown out in
the manner hereinafter explained.
Springs l, m, n, suitably placed operate the different parts, p, q, r, being respec-
tively the shafts on which the driving, stopping, brake levers and sectors oscillate,
while a screw w regulates the depression of the stopping lever J another screw.c
prevents it moving upwards beyond a certain point and by passing through the said
lever, acts also as a guide. Washers y are placed between the wheels, as shown in
Figs. 3 & 9.
All the key plungers have graduated slots cut on part of their lengths to prevent
being jerked out on the driving lever returning to position as will be easily under-
stood. Fig. 7 shows the unit key with slot. To distinguish to the touch between
even and odd numbers I make the buttons of the even numbers octagonal and the
odd, round. See Fig. 9.
In using the machine as a cash register, to prevent any tampering with the record
I make the small collar Y which takes the place of the ratchet wheel C and connects
the carrying wheel A with the index wheel D, with a tooth Z. On the key
plunger a is an arm b, which comes in the path of the said tooth. When the index
wheel D is set at zero, this tooth is beneath the arm b, but as soon as the index
wheel records 9 the tooth comes against the arm which locks it against any further
movement until the machine is reset for a fresh total. This is done by unlocking
the padlock as shown at c and depressing the key plunger as will be readily
understood by reference to the drawing Fig. 8.
It should be stated that this toothed collar is placed on the last wheel in the
machine or in other words the wheel which is rotated by the carrying mechanism
only, and assuming for a cash register a total of £99 19s. 11 d. sufficient, the
toothed collar would be attached to the index wheel showing the 9 in the ten column.
It will therefore be seen that any attempt to set the machine to zero, while the
padlock was locked to the key plunger would result in the instrument recording
and remaining set at £90, 0, 0, 0, 0.
The projection d on the key plunger
driving levers shown in Fig. 2 viz.
answers the same purpose as the end of the
to lock the pawl N against overdriving.

page_text: When the key plunger is depressed, it releases the pawl and permits the index
wheel to be reset as before explained.
A perforated index plate e, see Figs. 1 & 9 in the front part of the machine
shows at the several perforations g g the numbers added, while pointers f. f serve
to mark off the different columns.
In Fig. 9 the length of the machine is not shown as this is given in Fig. 1 while the
width depends upon the number of columns required in the pounds. The driving
and stopping levers H & J are shown as made out of square drawn aluminium
tubing, the wearing surfaces being protected by thin sheets of steel.
A modification of my invention is shown on Sheet 4.
In Fig. 10, the lever 2 acts as a stopping and brake lever and is placed above
the driving lever 1. The key plungers 4, 5, 6 rest on the driving lever, their
graduated shoulders 7 striking downward the brake lever 2 and throwing it into
gear with the brake wheel B when the driving lever is depressed by them. The
upper shoulders 9 of the keys serving as stops to prevent them being jerked out on
the return of the driving lever to its normal position.
In Fig. 11. a front view of the foregoing is shown. The pin or stem 8 of the
screw which pivots the rack G 1 to the driving lever acting as a stop to the butt
end of the pawls N as herein before explained.
By using brake and driving levers as above described I am enabled to do away
with levers made of tube or channel metal. A strip of steel thick giving suffi-
cient rigidity and lightness for the purpose required. While by using keys as
shown in combination with these levers I obtain a key which can be easily stamped
and thus easily produced.
It will also be seen that by using a self releasing rack for driving a simple and
effective combination of wheels is obtained, obviating a number of spring detents
common to machines of this class, which always require a careful and accurate
adjustment in order to obtain a positive result.
In showing key plungers passing through holes in a driving lever as in Fig. 1 I
do so to illustrate the method of working my invention but I do not claim this as
I am aware the device is old.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what 1
claim is :-
1st. In an adding machine, the combination of a rack pivotted to a driving lever
substantially as and for the purpose specified, and shown in the drawings Figs. 1 & 9.
2nd. In an adding machine the combination of a stopping lever with a brake
lever substantially as and for the purpose specified and shown in the drawings
Figs. 1, 2 & 9.
3rd. In an adding machine the combination of key plungers with driving and
brake levers substantially as and for the purpose specified and shown in the drawings
Figs. 10, 11, & 12.
4th. In an adding machine the combination of the several parts comprising the
mechanisin, substantially as and for the purpose specified and shown in the drawings
with reference to Figs. 2, 3, 4, 6, 8 & 9.
1
1000