Improvements in and relating to Differential Screws, Chiefly Designed for Presses, Stamps, Punches, Brakes, Steering Gear, and the like.
Year: 1888

page_text: Date of Application, 23rd Jan., 1888
Complete Specification Left, 23rd Nov., 1888
Complete Specification Accepted, 22nd Jan., 1889
Improvements in and relating to Differential Screws, Chiefly Designed
for Presses, Stamps, Punches, Brakes, Steering Gear, and the like.
CARL JUNGE and WILHELM JUNGE, both of 19, Camden Street, London, Engineers,
do hereby declare the nature of this invention to be as follows:-
This invention relates to differential screws, chiefly designed for the various kinds
of presses, stamps, punches, brakes, steering gear, and the like, and in general for the
numerons purposes to which such differential screws are applicable.
It is well known that the rate of axial progression and retrogression in the Hunter
or differential screws hitherto employed depends on the invariable difference between
the pitches of the screw threads, and is, therefore, substantially the same for the
production of either great or small power. This uniformity in the rate of the axial
motion being the cause of much useless expenditure of time and power in operating
differential screws, we deem it very desirable that the effective axial motion shall as
much as possible vary inversely with the changing power to be gained so as to accord
with the gradual and sudden changes that usually occur in the resistance to be
overcome.
The construction, in conformity with the above stated view, of the improved devices
constituting the subject of the said invention is based on a new principle which we
term the variable differential screw principle. This differs fundamentally from the
principle of the Hunter or differential screws heretofore known in the differential
action being the direct result of the differing rates of the rotary or axial motions of
a screw and of a nut fitted thereon. Provision is made for the screw and nut to be
turned separately; and diverse effects can be produced by causing both parts to
revolve simultaneously in the same or in opposite directions, with equal or different
velocities, or by causing only one or the other of the two parts to rotate in one or
the other direction.
According to the purposes for which our variable differential screws are to be
employed they can be carried out in different ways. In one arrangement these
devices comprise a screw which extends through a nut fitted upon it so that their
corresponding external and internal screw threads engage with each other. The

page_text: screw and nut are adapted to be turned separately, either by hand or by mechanical
means. The former part permits of rotary as well as endwise motion, whilst the
latter part, which is held in a bearing or support of suitable shape, can only be
rotated. For actuating the mechanism by hand, the said screw is provided with a
hand wheel or the like, and another hand wheel is secured upon the nut. When the
mechanism is designed to be operated by mechanical means, use is made of toothed
wheels, pulleys, friction sheaves, or the like, constituting, or forming part of, suitable
transmitting gear, in lieu of the aforesaid hand wheels. As the screw travels
in the axial direction, the transmitting gear connected therewith must be arranged so
as to adapt itself to this motion.
By the described mechanism continuously uniform or varying differential, simple
and aggregate motions can be produced. The motion in the axial direction can thus
be varied indefinitely between an extremely slow rate for very considerable power,
and the sum of the endwise motions of two screw threaded parts when great rapidity
and very small power are required. When both the screw and nut are turned simul-
taneously in the same direction at equal velocities, no axial motion will result; when
they are turned simultaneously in the same direction at different velocities, a
continuously uniform or varying differential action can be attained; when the screw
or nut is turned alone, the velocity will be that of a simple screw; and when the
screw and nut are turned at the same time in opposite directions, the aggregate of
the two rates of motion in the axial direction will constitute the actual velocity.
Simple retrogressive motion can directly follow progressive differential motion without
reversing the rotary motion of the nut, by simply discontinuing to turn the screw.
Moreover, whereas the range of effective axial motion in the differential screws
whose action depends on differing pitches of the screw threads is very limited,
our variable differential screws, arranged as above set forth, can be operated
differentially or otherwise in a continuous manner through a distance equal or
approximately equal to any available length of screw. Possessing these numerous
important features the said variable differential screws are susceptible of a great
number of applications where the Hunter screws and the various modifications of the
same are altogether impracticable.
In a modified arrangement the mechanism constructed according to our invention
comprises a central screw and a nut that is provided with internal and external
screw threads usually differing in pitch. The screw extending through the nut
carries a hand wheel or the like; and the nut, which engages by means of its
external screw thread with a bearing or support, also carries a hand wheel at one of
its extremities. The said internal and external screw threads of the nut may be
either both right handed or both left handed; or one thread may be right handed and
the other left handed. When the screw is turned alone, the described mechanism
will act as a simple screw; and when the nut is turned alone, the mechanism will
perform uniform differential action; whilst when the screw and nut are turned at the
same time, either uniform or varying differential results, or aggregate results can be
obtained at will, according as the two screw threaded parts rotate in the same or in
opposite directions.
The principle and construction of our variable differential screws being understood,
the application of these devices to presses, stamps, punches, brakes; steering gear;
and to the many other purposes for which they can be used will not present any
difficulty to the engineer.

page_text: Improvements in and relating to Differential Screws, Chiefly Designed
for Presses, Stamps, Punches, Brakes, Steering-gear, and the like.
CARL JUNGE and WILHELM JUNGE, both of 19, Camden Street, London, N.W.,
Engineers, 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 :—
This invention relates to differential screws for use in various kinds of presses,
stamps, rivetters, punches, shears, jacks, brakes, steering-gear, and the like.
In the Hunter and other differential screws heretofore employed for pressing
purposes the rate of progression and retrogression resulting from differential action
is substantially the same for varying resistance. This uniformity of action entails
much useless expenditure of time and power in operating such devices.
The aforesaid defect is obviated in our improved mechanism which we term a
variable differential screw. This mechanism depends for its longitudinal or axial move-
ment upon the rotation of a screw and of a nut fitted thereon. The said screw and nut
are provided with suitable means whereby they can be simultaneously rotated at variable
or at constant velocities relatively to each other in the same or in opposite directions,
and whereby either part can be rotated while the other part remains stationary.
Our mechanism, as represented by way of example in the accompanying drawing,
comprises a screw (a) and a nut (b) supported in a bearing (c) in which it is free to
turn but is prevented from moving endwise. Gearing of any suitable description
by which independent rotary movements can be imparted to the screw and to the
In case the said
nut is employed for operating these parts by mechanical means.
screw and nut are designed to be actuated by hand, they are provided with hand-
wheels or the like.
°
In the arrangement shown in Fig. 1 the screw (a) and nut (b) are operated by
means of belt-pulleys (d and e). The screw has a longitudinal groove (f) formed in
it to receive a feather (9) with which the pulley (d) is provided. This pulley is held
between a bracket (h) and the second pulley (e) on the rotary nut (6) which is
supported in a bearing (c) as above described.
In the modified arrangement illustrated in Fig. 2 a disc (d) is firmly secured upon
the screw (a), and another disc (e) is carried by the rotary nut (b) held in the bearing (c),.
each of these discs being operated through the medium of a friction-roller.
Either one or both friction-rollers can be adapted to be displaced radially upon the
corresponding disc or discs and raised from the same at will, and the roller which
acts in contact with the disc on the screw is so arranged that it will follow the
movements of this disc as the latter travels with the screw in the longitudinal or
axial direction.
Both discs (d and e) upon the screw (a) and nut (6) may be held against axial
displacement, as shown in Fig. 3. With a longitudinal groove (f) formed in the
screw engages a feather (g) which is fixed in the nave of the disc on the said screw.
The naves of the two discs are connected by a sleeve (h) or other suitable means
in such a manner that the discs can be rotated independently of each other.
When the operation is to be effected by hand, we can employ arrangements which

page_text: are similar to those described with reference to Figs. 1, 2 and 3, except that, instead
of using the said actuating mechanism, hand-wheels or the like are secured upon the
screw and rotary nut supported in the bearing. Fig. 4 represents one of these
arrangements, wherein the hand-wheels (d and e) are firmly fixed upon the screw (a)
and nut (b).
In Fig. 5 our variable differential' screw is shown as it can be used in jacks.
The screw (a) carries the rotary nut (b) held in the body or casing (c). A ratchet-
wheel () provided with a feather (9) is fitted upon the screw, in which a longitudinal
groove is formed to receive the said feather. With the teeth of the ratchet-wheel (1)
engages an adjustable double pawl on a hand-lever (d). Upon the said nut is fixed
another ratchet-wheel (k) which can be actuated through the medium of a second·
hand-lever (e) and pawl.
By our variable differential screw varying and constant differential, simple and
aggregate motions can be produced, so that the resultant longitudinal or axial
movement can be optionally varied between an extremely slow rate for exerting
tremendous power and a very quick rate for small power, in accordance with the
changes which occur in the resistance to be overcome. When both the screw and
nut are simultaneously rotated in the same direction at equal velocities, no longi-
tudinal or axial motion will ensue; when they are simultaneously rotated in the
same direction at different velocities, either a varying or constant differential action
can be obtained; when the screw or nut is turned alone, the longitudinal or axial
movement will be that of a simple serew; and when the screw and nut are
simultaneously turned in opposite directions, the nut, proportionately to the speed
of its rotation, will accelerate the longitudinal or axial movement of the screw.
Retrogressive motion can directly follow progressive motion, and vice versa, without
reversing the rotary motion of the screw or nut. Futhermore, the variable differential
screw can be operated differentially or otherwise in a continuous manner through a
distance approximately equal to any available length of the screw. The mechanism
characterized by the features above mentioned is susceptible of numerous applications
to pressing purposes where the Hunter and other differential screws and the ordinary
screw have hitherto been employed, and also in cases where the use of these screws
is impracticable.
Having now particularly described and ascertained the nature of our said invention,
and in what manner the same is to be performed, we declare that what we claim is :-
First. A screw and nut arranged in combination with each other and with means
whereby they can be simultaneously rotated at varying or at constant differential
velocities, as, and for the purposes, above specified.
Second. A screw and nut arranged in combination with each other and with
means whereby they can be simultaneously rotated at unequal velocities either
in the same or in opposite directions; as, and for the purposes, above specified.
Third. A screw and nut arranged in combination with each other and with means
whereby they can be simultaneously rotated either in the same or in opposite
directions, and whereby the one part can be rotated while the other part remains
stationary, as, and for the purposes, above specified.
Fourth. The improved variable differential screw mechanism constructed substantially
as described with reference to either of the forms or modifications shown in
the accompanying drawing, and operating as, and for the purposes, above specified.
Dated this 22nd day of November 1888.
HASELTINE, LAKE & Co.,
45, Southampton Buildings,
Chancery Lane, London, W.C.