Improvements in Screw-cutting Lathes.
Year: 1893

page_text: Date of Application, 12th Apr., 1893
Complete Specification Left, 8th Aug., 1893-Accepted, 16th Sept., 1893
PROVISIONAL SPECIFICATION.
Improvements in Screw-cutting Lathes.
1, HENRY JERMY of Atlas Works Levenshulme Manchester in the County of
Lancaster, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to screw-cutting lathes and consists firstly in improvements
by which screw-threads of various different pitches may be cut in a lathe without
it being necessary to remove any change-wheels from the lathe in changing from
one of such pitches to another.
66
"
"
"
"
According to this part of my invention I mount upon one shaft a suitable number
of "driving gear-wheels and mount upon another shaft parallel to that first named
a corresponding number of "driven" gear-wheels which are severally caused to
gear into or engage with the corresponding "driving" gear-wheels or in cases in
which it may be desirable or necessary carrier-wheels may be employed to connect
the "driving" gear-wheels with the "driven" gear-wheels. The different " pairs
or couples of "driving" and "driven gear-wheels are so proportioned in
relation to each other that by the employment of one or another of such "pairs
or "couples" of gear-wheels the lathe to which this part of my invention is applied
may be enabled to cut screw-threads of the several pitches which are most
frequently required in the work in the production of which such lathe is to be used.
Either the driving" gear-wheels are fast upon the shaft on which they are
mounted while the "driven" gear-wheels are loose but capable of being severally
locked or clutched to the shaft upon which they are mounted by means of suitable
clutches or a suitable key or suitable keys which may be placed in or out of action
as may be necessary from time to time or the "driving" gear-wheels are loose but
capable of being severally locked or clutched to the shaft upon which they are
mounted while the "driven" gear-wheels are fast upon the shaft upon which they
are mounted. Motion is transmitted from the mandrel or spindle of the lathe by
means of suitable gearing to the shaft upon which the "driving" gear-wheels are
mounted and by means of suitable gearing motion is transmitted from the shaft
upon which the "driven" gear-wheels are mounted to the leading or guide screw
of the lathe. When the lathe is to be employed for cutting a screw-thread of one
of the pitches which may be produced by the use of the "pairs" or "couples" of
gear-wheels above mentioned notion is caused to be transmitted from the mandrel
or spindle of the lathe through the gearing employed for the purpose to the shaft
upon which the driving gear-wheels are mounted and from the driving gear-wheel
proper for the purpose to the corresponding "driven" gear-wheel and from the
shaft upon which the driven gear-wheels are mounted by means of the gearing
employed for the purpose to the "guide" or
leading" screw of the lathe. The
movement of one or more of the clutches or of the key or keys above mentionel,
necessary to effect a change from the use of one pair" or "couple
of gear-
wheels to the use of another "pair" or couple of gear-wheels may be
effected in any suitable manner but preferably by means of a handle or handles
arranged in a convenient position or convenient positions. The shafts above
mentioned may be mounted in any suitable part of the lathe and in cases in which
be desirable the "guide or "leading screw of the lathe may have the
"driven" gear-wheels mounted upon it. I provide a clutch or key by means of
which the arrangement of gearing provided in accordance with this part of my
invention may be placed in or put out of connection with the "guide" or “ leading
may
6:
66
وو
66
"
"

page_text: screw of the lathe and placed in or put out of connection with the ordinary change-
gearing of the lathe as may be desirable. In some cases I dispense with the
ordinary arrangement of change-gearing.
My invention further consists in means by which I enable the change from the
use of one pair or couple of the gear-wheels above mentioned to the use of any
other pair or couple of such gear-wheels to be very readily made and by which I
am enabled to ensure that only one pair or couple of such gear-wheels shall be
put into action at one time to transmit motion from the spindle or mandrel of the
lathe to the guide or leading screw thereof.
In accordance with this part of my invention I provide a cam or cams which is
or are arranged to operate the clutches or key or keys above mentioned either
directly or indirectly and is or are also so arranged that according as it or they is
or are moved into one or another of several different positions all the pairs or
couples of gear-wheels above mentioned shall be put out of action or the required
pair or couple of gear-wheels shall be put into action. In conjunction with the
said cam or cams I employ a suitable index plate to indicate whether any or which
of the "pairs
or "couples" of gear-wheels is in action and so facilitate the
changes from the use of one of such " pairs or couples" of gear wheels to the
use of any other of such "pairs" or "couples" of gear-wheels and 1. provide
a detent or detents by means of which accidental changes in the position or
positions of the cam or cams above mentioned may be prevented from taking
place.
"
66
A lathe to which my invention is applied may be arranged to cut both right-
hand and left-hand screw-threads and the application of my invention to a screw-
cutting lathe does not interfere in any way with the use of such lathe for any of
the other purposes for which it may be intended or adapted.
My invention may be applied with very great advantage to lathes for the use of
brass finishers and others who frequently require to cut screw-threads of different
pitches upon the same article.
Dated this Eleventh day of April 1893.
HOWARD
CHEETHAM,
Manchester, Agent to the Applicant.
COMPLETE SPECIFICATION.
Improvements in Screw-cutting Lathes.
I, HENRY JERMY of Atlas Works, Levenshulme, Manchester, in the County
of Lancaster, Engineer 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 :-
My invention relates to screw-cutting lathes and consists firstly in improvements
by which screw-threads of various different pitches may be cut in a lathe without
it being necessary to remove any change wheels from the lathe in changing from
one of such pitches to another.
37
According to this part of my invention I mount upon one shaft a suitable number
of "driving" gear wheels and mount upon another shaft parallel to that first named
a corresponding number of "driven gear-wheels which are severally caused to
gear into or engage with the corresponding "driving" gear-wheels or in cases in
which it may be desirable or necessary carrier-wheels may be employed to connect
the "driving "gear-wheels with the "driven" gear-wheels. The different "pairs'
or "couples" of " driving and "driven" gear-wheels are so proportioned in
relation to each other that by the employment of one or another of such "pairs
or "couples" of gear-wheels the lathe to which this part of my invention is applied
may be enabled to cut screw-threads of the several pitches which are most
frequently required in the work in the production of which such lathe is to be used.
Either the "driving" gear-wheels are fast upon the shaft on which they are
"
23

page_text: "
mounted while the "driven" gear-wheels are loose but capable of being severally
locked or clutched to the shaft upon which they are mounted by means of suitable
clutches or a suitable key or suitable keys which may be placed in or out of action
as may be necessary from time to time or the "driving" gear-wheels are loose but
capable of being severally locked or clutched to the shaft upon which they are
mounted while the "driven" gear-wheels are fast upon the shaft upon which they
are mounted. Motion is transmitted from the mandrel or spindle of the lathe by
means of suitable gearing to the shaft upon which the "driving" gear-wheels are
mounted and by means of suitable gearing motion is transmitted from the shaft
upon which the "driven" gear-wheels are mounted to the leading or guide screw
of the lathe. When the lathe is to be employed for cutting a screw-thread of one
of the pitches which may be produced by the use of the "pairs" or couples" of
gear-wheels above mentioned motion is caused to be transmitted from the mandrel
or spindle of the lathe through the gearing employed for the purpose to the shaft
upon which the driving gear-wheels are mounted and from the driving gear-wheel
proper for the purpose to the corresponding "driven" gear-wheel and from the
shaft upon which the driven gear-wheels are mounted by means of the gearing
employed for the purpose to the "guide" or "leading ' screw of the lathe. The
movement of one or more of the clutches or of the key or keys above mentioned
necessary to effect a change from the use of one "pair
66
or couple" of gear-
wheels to the use of another "pair" or "couple" of gear-wheels may be effected
in any suitable manner but preferably by means of a handle or handles arranged
in a convenient position or convenient positions. The shafts above mentioned may
be mounted in any suitable part of the lathe and in cases in which it may be
desirable the "guide" or "leading" screw of the lathe may have the "driven
gear-wheels mounted upon it. I provide a clutch or key by means of which the
arrangement of gearing provided in accordance with this part of my invention may
be placed in or put out of connection with the "guide" or "leading" screw of the
lathe and placed in or put out of connection with the ordinary change-gearing of
the lathe as may be desirable. In some cases I dispense with the ordinary
arrangement of change-gearing.
"
"
"
This part of my invention is illustrated in the accompanying drawings, which also
serve to illustrate a further part of my invention.
Fig. 1 is a side view, Fig. 2 a plan partly in section and Fig. 3 an end view of
so much of a lathe having my invention applied to it as is necessary to illustrate the
application of
my invention.
Fig. 4 is a side view partly in section, Fig. 5 a plan partly in section and
Fig. 6 a transverse section serving to illustrate certain parts more clearly than
Figs. 1, 2 and 3.
Fig. 7 is a side view partly in section and Fig. 8 an end view of so much of a
lathe with my invention applied to it as is necessary to illustrate a modification of
the first part of my invention which it is desirable to employ in some cases.
Although Figs. 4, 5 and 6 serve to show certain of the parts employed in
accordance with the first part of my invention they are more particularly intended
to illustrate the second part of my invention which will be described hereinafter.
(a), (a'), (a) and (a³) are the driving wheels employed according to my invention
and (b), (b), (62) and (63) are the driven wheels respectively employed in
conjunction with the driving wheels (a), (a'), (a²) and (a³). The shaft (c) fast upon
which the driving wheels (a), (a'), (a') and (a³) are mounted, is mounted and capable
of revolving in hearings formed in brackets (d) formed upon a part (d) secured to
the bed (e) of the lathe so that the brackets (di) are in the interior of such bed (e).
Each of the driven wheels (b), (1), (2) and (63) is mounted so as to be capable
of being revolved upon a shaft (f) mounted and capable of being revolved in
bearings formed in the brackets (d'). Fast upon the shaft (f) is mounted a
toothed wheel (g) the teeth of which gear into or engage with the teeth of a
toothed wheel (h) mounted so as to be capable of revolving upon the leading or
guide screw (i) of the lathe. Upon the leading or guide screw (i) is mounted a

page_text: clutch () which is capable of being slidden longitudinally upon the said leading or
guide screw (i) but is prevented from turning upon the said leading or guide
screw () by a key or feather (i) which is secured in such screw () and passes into
a key-way formed in the said clutch (5). The clutch (j) is formed at one end with
projections or teeth (¹) and the toothed wheel (h) is formed with projections or
teeth (¹) so that by the clutch (j) being moved in the direction indicated by the
arrow (A) or in the contrary direction the toothed wheel (h) may be secured to or
set free from the leading or guide screw (i). Fast upon the shaft (c) is mounted
a toothed wheel (m) into which gears a toothed wheel (n) mounted fast upon one
end of a shaft (o) upon the other end of which is mounted a toothed wheel (p)
into which a toothed wheel (9) mounted upon a shaft (7) which is formed with a
key or feather (r) passing into a key-way formed in the said toothed wheel (g),
may be caused to gear or engage. The toothed wheel (7) is formed with a
collar (g) provided with a groove with which engages a fork (¹) formed upon the
end of a lever (s) mounted upon a stud (2) secured in a suitable part of the
headstock (t) of the lathe which lever (s) is provided with a handle by means of
which the toothed wheel (g) may be moved into or out of engagement with the
toothed wheel (p). The shaft (r) is mounted in bearings formed in suitable parts
of the head-stock (t) and has mounted fast upon it a toothed wheel () into which
gears a toothed wheel (v) gearing into or engaging with another toothed wheel (v¹).
The toothed wheels (») (v¹) are mounted and capable of being revolved upon studs
secured in a part capable of being turned upon a collar or projection formed in the
headstock (t). Into the toothed wheel (v) or the toothed wheel (»') according to
the position of the part in which are secured the studs upon which the
wheels (v) (¹) are mounted, gears or engages a toothed wheel (c) mounted fast
upon the spindle or mandrel (x) of the lathe. When the toothed wheel (v) or the
toothed wheel (v') is placed in gear with the toothed wheel (w) rotary motion
will be transmitted from the mandrel (a) by means of the toothed wheel (w) and
one or both of the toothed wheels (v) (¹), the toothed wheel (#) and shaft (r),
toothed wheels (7) and (p), shaft (o) and toothed wheels (n) and (m), to the
shaft (c), the direction of the revolution of the shaft (c) depending upon whether
the toothed wheel (¹) or the toothed wheel (e) is placed in gear with the toothed
wheel (w). Fast upon the shaft (r) is also mounted a toothed wheel (y) by means
of which rotary motion may be imparted when it may be desirable to the ordinary
train of gearing (2) mounted upon the swing-arm (2) of the lathe. The guide or
leading screw (i) is formed in two portions (3) (4) the portion (3) being formed
with a sleeve or socket (2) into which the end (2) of the other portion (4) enters.
The portions (3) (4) of the guide or leading screw (i) are capable of being
revolved in relation to each other and the sleeve or collar (8) formed upon the
portion (3) is formed with projections or teeth (5) with which may be caused to
engage projections or teeth (2) formed on the clutch (j). A fork and handle
which are not shown in the accompanying drawings are provided in order that the
clutch (j) may be readily moved in order that the portion (4) of the leading or
guide screw (i) may be placed in connection with the portion (3) of such leading
or guide screw (i) or in connection with the toothed wheel (4) When the portion (4)
of the leading or guide screw (i) is placed in connection with the portion (3) of
such leading or guide screw () the portion (4) of the said leading or guide
screw (i) may be caused to revolve by the train of gearing (=) and when the
portion (4) of the said guide or leading screw (t) is placed in connection with the
toothed wheel (1) such guide or leading screw (1) may be caused to receive motion
from the shaft () in a manner which will be hereinafter further described. The
different "pairs" or "couples" of "driving" and "driven" gear-wheels (a) (b),
(a) (1), (a) (b2), and (a³) (3), are so proportioned in relation to each other that by
the employment of one or another of such "pairs" or "couples" of gear-wheels,
the lathe may be enabled to cut screw-threads of the four pitches which are most
frequently required in the work in the production of which the lathe illustrated in
the accompanying drawings is to be used. It is obvious that the relation between
"

page_text: the sizes of the gear-wheels (a, b), (a¹, b¹), (a² 6²) (a³, 6³) may be whatever
may be convenient and compatible with the situation of such gear-wheels.
"
The
In the case of a lathe which is to be employed in the production of work in
which screw-threads of the kinds or pitches known as "gas threads are frequently
required it is convenient that the diameter of the "driving" and "driven" wheels
of the four "pairs" or **
couples" of "driving" and "driven wheels (a, b),
(a, b), (a², b²) and (a³, 63) shall be so proportioned to each other that the
employment of the wheels (a) and (b) to transmit motion to the guide or leading
screw (i) may result in the production of a screw of a pitch of eleven threads
per inch upon the object being operated upon in the lathe, that the employment
of the wheels (a) and (b) to transmit motion to the said guide or leading screw (i)
may result in the production of a screw of fourteen threads per inch
upon the
object being operated upon, that the employment of the wheels (a2) and (62) to
transmit motion to the said guide or leading screw (i) may result in the production
of a screw of a pitch of nineteen threads per inch upon the object being operated
upon, and that by the employment of the wheels (a³) and (63) to transmit motion to
the said guide or leading screw (i) may result in the production of a screw of a
pitch of twenty-six threads per inch upon the object being operated upon.
driven wheels (b), (¹), (2) and (68) are respectively provided with teeth or
projections (64). (3) is a clutch mounted so as to be capable of being slidden
longitudinally upon the shaft (f) but prevented from being turned upon such
shaft (f) by means of a key or feather ("") which is secured in the shaft (f) and
passes into a keyway or groove formed in the clutch (3). (4) is also a clutch mounted
so as to be capable of being slidden longitudinally upon the shaft (f) but prevented
from being turned thereon by means of a key or feather (f) which is secured in
the shaft (f) and passes into a key-way or groove formed in the clutch (4). The
clutch (3) is provided at one end with projections or teeth (3) adapted to engage
with corresponding projections or teeth (6) formed upon the "driven
"wheel (b)
and at the other end with projections or teeth (3) adapted to engage with
corresponding projections or teeth (64) formed upon the "driven" wheel (61).
The clutch (4) is provided at one end with projections or teeth (4) adapted to
engage with corresponding projections or teeth (64) formed upon the "driven "
wheel (62), and at the other end with projections or teeth (4") adapted to gear into
or engage with corresponding projections or teeth (64) formed on the "driven "
wheel (63). Means either such as are shown in the accompanying drawings and
will be further described hereinafter or of any other suitable kind are provided in
order to enable the clutches (3) (4) to be moved in the direction indicated by the
arrow (B) and in the opposite direction. When the clutch (3) is moved in the
direction indicated by the arrow (B) so that the projections or teeth (3) are
brought into engagement with the projections or teeth (4) of the "driven
wheel (61) the "driven" wheel (61) will be placed in connection with the shaft (f)
and when such clutch (3) is moved in the direction opposite to that indicated by
the arrow (B) so that the projections or teeth (3") are brought into engagement
with the projections or teeth (64) of the toothed wheel (6) the "driven
wheel (b)
will be placed in connection with the shaft (f). When the clutch (4) is moved in the
direction indicated by the arrow (B) so that the projections or teeth (4b) are
brought into engagement with the projections or teeth (b) of the " " driven
wheel (6) the "driven" wheel (63) will be placed in connection with the shaft (f)
and when the said clutch (4) is moved in the direction opposite to that indicated
by the arrow (B) so that the projections or teeth (42) are made to engage with the
projections or teeth (4) of the "driven" wheel (2), the "driven " wheel (62) will be
placed in connection with the shaft (/). The means by which the clutches (3)
and (4) are moved longitudinally must be so arranged that only one of the "driven
wheels (b) (6) (62) and (63) can be placed in connection with the shaft (f) at one
time or that ordinary care on the part of the person using the lathe shall be
sufficient to prevent more than one of such driven wheels from being placed at one
time in connection with the shaft (ƒ).
"
"
"2
53

page_text: .
When the lathe illustrated in the accompanying drawings is in use and it is
desired that an object which is being turned in such lathe shall have formed upon
it one of the screw threads in the formation of which for instance the pair of
"driving" and "driven" wheels (a) and (b) is adapted to be used, the toothed
wheel (y) if not already in gear with the toothed wheel (p) is placed in gear
therewith and the teeth or projections (2) of the clutch (1) are placed in engage-
ment with the teeth or projections (h) upon the toothed wheel (h). Then the
projections or teeth (3) of the clutch (3) are placed in engagement with the teeth
or projections (64) of the "driven" wheel (). Rotary motion will then be trans-
mitted from the toothed wheel (7) through the toothed wheel (p) to the shaft (r)
and thence through the toothed wheels (n) and (m) to the shaft (c) thence by
the "driving" wheel (a) and the "driven" wheel (6) to the shaft (f) and thus by
means of the toothed wheels (g) and (4) to the guide or leading-screw (i). In a
similar manner by the projections or teeth (3) of the clutch (3) being placed in
connection with the projections or teeth (4) of the "driven" wheel (61) the driving
wheel (a) and "driven wheel (1) may be employed in the transmission of motion
from the spindle or mandrel (a) of the lathe to the guide or leading screw (i).
In a similar manner by the projections or teeth (42) of the clutch (4) being placed
in engagement with the projections or teeth (4) of the "driven" wheel (²), the
"driving" wheel (2) and the "driven" wheel (62) may be employed in the trans-
mission of motion from the spindle or mandrel (x) to the guide or leading screw (i)
and in a similar manner by the projections or teeth (45) of the clutch (4) being
placed in engagement with the teeth or projections (6) of the "driven" wheel (63)
the "driving wheel (a³) and "driven wheel (63) may be employed in the
transmission of motion from the spindle or mandrel (x) to the guide or leading
screw (). When it is desired that motion shall be again transmitted to the guide
or leading screw (i) through the toothed wheels (y) and () instead of through one
of the aforesaid " pairs or "couples" of driving and "driven" gear-wheels the
clutch () is moved in the direction opposite to that indicated by the arrow (A) so
that the projections or teeth (2) upon such clutch (j) are caused to engage with
the projections or teeth (5) upon the sleeve (8) and if it be considered desirable
that the "driving" and "driven" gear-wheels shall be put entirely out of action
the handle (s) may be moved so as to move the toothed wheel (7) out of gear or
engagement with the toothed wheel (p). As the changes from the use of the
ordinary gearing (y) (2) to the use of any one of the pairs of "driving" and
"driven gear wheels (a, b) (a¹, b'), (2, 2) and (3, 3) and from the use of any
one to any other of the pairs of "driving" and "driven" gear-wheels (a, b) (a², b¹)
(a, b) and (a³, b³) in the transmission of motion to the guide or leading screw (i)
being very easily effected the production upon the object being operated upon of
screws of the various pitches for the formation of which the various "pairs" of
driving" and "driven" gear wheels are arranged is very easily and conveniently
accomplished.
66
37
"
It is obvious that more or less than four pairs of "driving" and "driven" gear-
wheels (a, b) (a', ¹) (a, b) and (a³, 6³) may be employed and that if it be
considered desirable the "driven " gear-wheels (b) (b¹) (62) and (3) may be
mounted upon and arranged to be connected by clutches when required to the
guide or leading screw (i) of the lathe in a manner similar to that in which in the
accompanying drawings they are shown as being mounted upon and arranged to be
connected by clutches when required to, the shaft (f).
It is also obvious that instead of the "driving" gear-wheels (a) (a¹) (a²) and (a³)
being mounted fast upon the shaft (c) upon which they are placed and the
"driven" gear-wheels (b) (1) (2) and (3) being mounted so as to be capable of
being revolved upon and connected by clutches when required to the shaft (/)
upon which they are mounted the "driven" gear-wheels (6) (6) (62) and (3) may
be fast upon the shaft (f) upon which they are mounted and the "driving” gear-
wheels (a) (a) (a) and (a³) may be capable of revolving upon and of being secure
by clutches when required to the shaft (c) upon which they are mounted but the

page_text: "
and
former is the arrangement which is preferable as in such arrangement there is less
probability of the clutches employed failing to quickly pass into engagement when
required to do so. The toothed wheels forming the pairs of "driving
"driven" gear-wheels (a, b) (a', 1), (a², b²) and (3, 3) employed in accordance
with this part of my invention will require to be made of different pitches in order
that the two toothed wheels forming each pair may be of such diameter that they
may gear or engage properly with one another.
22
In some cases in order to further increase the utility of lathes to which the first
part of my invention is applied I employ the arrangement illustrated in Figs. 7
and 8 to the parts illustrated in which are applied the same letters of reference as
are applied to corresponding parts shown in Figs. 1, 2, 3, 4, 5 and 6. In the
arrangement illustrated in Figs. 7 and 8 the shaft (o) upon which is mounted the
toothed wheel () by means of which rotary motion is transmitted to the "driving'
and "driven" gear-wheels (a, b) (a). b) (a², 2) and (a³, 3) provided in accordance
with the first part of my invention has mounted upon it two toothed wheels (p) (p¹)
instead of only one toothed wheel (p) and upon the shaft () are mounted two
toothed wheels (g) (q²) instead of only one toothed wheel (7). The two toothed
wheels (g) (42) mounted upon the shaft () are secured together by the collar (q¹)
in which is formed a groove with which engages the fork (s) of the handle (s)
which in this case requires to be capable of being secured in three positions that is
to say one position in which it will hold the toothed wheel (7) in engagement with
the toothed wheel (p), one position in which it will hold both of the toothed
wheels (g) (2) out of engagement with the toothed wheels (p) (p') and one position
in which the toothed wheel (42) will be held in engagement with the toothed
wheel (p). The toothed wheels (4) (2) and the collar (g) are capable of being
slidden to and fro longitudinally upon the shaft () but are prevented from being
turned in relation to such shaft (r) by means of a key or feather () which is
secured in the shaft (r) and passes into a groove or key-way formed in the toothed
wheels (g) (2) and collar (7). The two toothed wheels (7) (42) and the two
toothed wheels (p) (') are so proportioned in relation to one another that the
change in the relation between the angular velocities of the mandrel or spindle (*)
and the leading or guide screw () brought about by the use of the toothed
wheels (2) (pl) instead of the toothed wheels (7) (p) in the transmission of rotary
motion from the shaft (r) to the shaft (o) may be suitable for the purposes for
which it is desired to use the lathe in which the arrangement of mechanism is to be
employed. If for instance when the toothed wheels (q, p) are employed the
relation between the angular velocity of the guide or leading screw (i) and the
mandrel or spindle (c) be such that screw-threads of three, six, twelve, and twenty-
four turns per inch are respectively produced by the employment of the "pairs"
or "couples" (a, b) (a², b¹) (u², b²) (a³, 13) of "driving" and "driven" gear-wheels
it would be convenient if the toothed wheels (92) (¹) were of such relative size
that employed instead of the toothed wheels (7, p) they would cause the screw-
threads produced by the employment of the " pairs" or couples" of "driving'
and "driven" gear-wheels (a, b) (a¹ b¹) (a². b²) and (a³, 3) to be respectively of
two, four, eight and sixteen turns per inch. It is obvious that the relative sizes
of the wheels (, p) (1², p') may be whatever may be convenient and compatible
with the situation of such toothed wheels.
66
"
"
66
"
It will be obvious that in case it may be desired to provide for more than two
ranges of changes of angular velocity to be produced by the employment of the
pairs or "couples" of "driving" and "driven gear-wheels (a, b), (u', b¹)
(2, 2) and (3, 3) more than two pairs or couples of toothed wheels (4) (P) (²) (p')
such as are illustrated in Figs. 7 and 8 of the accompanying drawings may be
employed as will be apparent to persons conversant with the construction of
Screw-cutting lathes.
In some cases I dispense with the ordinary arrangement of change gearing and
in such cases the leading or guide-screw (i) instead of being formed in two
parts (3) () in the manner illustrated in the accompanying drawings may be

page_text: simply mounted in bearings and have the clutch (j) which in such case need only
he provided with projections or teeth at one end, mounted upon it.
My invention further consists in means by which I enable the change from the
use of one pair or couple of the gear-wheels above mentioned to the use of any
other pair or couple of such gear-wheels to be very readily made and by which
I am enabled to ensure that only one pair or couple of such gear-wheels shall be
put into action at one time to transmit motion from the spindle or mandrel of the
lathe to the guide or leading screw thereof.
In accordance with this part of my invention I provide a cam or cams which is
or are arranged to operate the clutches or key or keys above mentioned either
directly or indirectly and is or are also so arranged that according as it or they is
or are moved into one or another of several different positions all the pairs or
couples of gear-wheels above mentioned shall be put out of action or the required
pair or couple of gear-wheels shall be put into action. In conjunction with the
said cam or cams I employ a suitable index plate to indicate whether any or
which of the "pairs" or "couples" of gear-wheels is in action and so facilitate
the changes from the use of one of such "pairs" or "couples" of gear-wheels to
the use of any other of such "pairs or "couples" of gear-wheels and I provide
a detent or detents by means of which accidental changes in the position or
positions of the cam or cams above mentioned may be prevented from taking
place.
37
One arrangement of this part of my invention is also illustrated in the accom-
panying drawings and more particularly in Figs. 4, 5 and 6.
(5) is a cam which is mounted so as to be capable of being revolved on a
stud (6) secured in the bed (e) of the lathe. In the interior of the cam (5) is
formed a groove (5) projecting into which are projections (5°) (5°) (5ª) and (5º).
which may conveniently be forined by pegs being inserted in the can (5), two of
the said projections (5), (5) being on the side of the groove (5) which is nearest
to the circumference of the cam (5) and the other of such projections (56) (5º)
being on the side of the groove (5) which is nearest to the centre of the said
cam (5). The projections (5") (5) are arranged in the cam (5) in such positions
that acting upon a stud (7") projecting from an arm (7) which is mounted upon a
stud (7) secured in the part (d) secured to the bed (e) of the lathe and is provided
with jaws from which studs (7) project into the groove (3) formed in the
clutch (3), the said studs (5b) (5) will respectively move the clutch (3) into
engagement with the toothed wheel (b) or into engagement with the toothed
wheel (1). The projections (54) (5) in a similar manner are arranged in the
cam (5) in such positions that acting upon a stud (8") projecting from an arm (8)
which is mounted upon a stud (8b) secured in the part (d) secured to the bed (e)
of the lathe and is provided with jaws from which studs (8°) project into the
groove (4) formed in the clutch (4) the said studs (5") (5°) will respectively move
the clutch (4) into engagement with the toothed wheel (62) or into engagement
with the toothed wheel (3). Recesses of suitable shape are formed in the
cam (5) at the parts of the groove (5") which are opposite to the projec-
tions (5b) (5°) (5) (5) in order to permit the studs (7") (8) to move when acted
upon by the projections (5°) (5) (5) (5°) and to move such studs (7") (8") when
the projections aforesaid are moved away from the said studs (7") (8*). The
circumference of the eam (5) is formed as a toothed wheel with which engages or
gears a toothed wheel (9) mounted fast upon a shaft (10) mounted and capable of
being rotated in a bracket, tube or collar (d2) formed upon the part (d) secured
to the bed (e) of the lathe. The shaft (10) has a handle (10) secured upon it.
In the tube or collar (²) is formed a recess (d³) with which communicates a
hole (d) also formed in the tube or collar (d). In the recess (d³) and hole (d)
is mounted a detent (11) provided with a conical head (11ª). A spring (11)
abutting at one end against the head (11) of the detent (11) and at the other
end against the end of the recess (³) tends to force the detent (11) in the direction
indicated by the arrow (C). In a collar (10) secured upon the shaft (10)

page_text: recesses (10) are formed each of such recesses (10°) being formed in such position
that when by the turning of the cam (5) one of the projections (5b) (5°) (5ª) (5º)
has acted upon one of the studs (7") (8) so as to cause the clutch (3) to be placed
in engagement with the toothed wheel (b) or the toothed wheel (6) or the
clutch (4) to be placed in engagement with the toothed wheel (62) or the toothed
wheel (63) the detent (11) will pass into one of such recesses (10) and so retain
the handle (10) in position until it is desired that such handle (10") shall be moved
into some other position when the person using the lathe may move the said
handle (10) and overcome the pressure of the spring (11).
In order that the momentary engagements of the clutches (3) (4) with the toothed
wheel (61) (2) which occur when the handle (10) is being turned past the position
which it occupies when the said clutches (3) (4) are to be placed in engagement
with such toothed wheels may not cause any injury to the object being operated
upon in the lathe it is desirable that the clutch (1) should be disengaged from the
toothed wheel (1) before the handle (10) is moved in order to bring about the
engagement of the clutches (3) (4) and toothed wheels (b) (b¹) (6²) and (63) which
may be desired.
It is obvious that in case more than four pairs of driving and driven gear-.
wheels (a) (b) (a') (6) (a²) (62) and (a³) (63) are employed it will be necessary to
modify the form of the cam (5) and to provide suitable arrangements to connect
the said cam to the additional clutch or clutches which are to be employed or to
employ more than one such cam and to arrange such cams in relation to one
another and connect them with the clutches employed in a suitable manner but such
variations in the arrangement of this part of my invention will be obvious without
further description to persons conversant with the construction of lathes.
As is illustrated in the accompanying drawings a lathe to which my invention is.
applied may be arranged to cut both right hand and left hand screw-threads and
the application of my invention to a screw-cutting lathe does not interfere in any
way with the use of such lathe for any of the other purposes for which it may be.
adapted.
My invention may be applied with very great advantage to lathes for the use of
brass finishers and others who frequently require to cut screw-threads of several
different pitches upon the same article.
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 I
claim is :-
9.
39.
1. In a screw-cutting lathe the combination of a suitable number of "driving
gear-wheels such as (a) (a'), (a²) and (a³) and a corresponding number of "driven'
gear-wheels such as (b) (6) (62) and (3) arranged in conjunction with each other
and with the mandrel or spindle and leading or guide screw of the lathe and
clutches or keys such as (3) (4) by means of which the transmission of motion
from the mandrel or spindle of the lathe to the leading or guide screw of such
lathe by any one of such "driving" gear-wheels and the corresponding "driven
gear wheel may be brought about, all arranged, employed and operating for the
purposes and substantially in the manner herein before described in reference to.
aud illustrated in and by the accompanying drawings.
22-
2. In a screw-cutting lathe the combination of a suitable number of "driving
gear-wheels such as (a) (a') (a²) and (a³) and a corresponding number of
"driven" gear-wheels such as (6) (6¹) (62) and (3) arranged in conjunction with
each other and with the mandrel or spindle and leading or guide-screw of the
lathe and clutches such as (3) and (4) by means of which the transmission of
motion from the mandrel or spindle of the lathe to the leading or guide screw
thereof by any one of such "driving " gear-wheels and the corresponding "driven "
gear-wheel may be brought about and two or more pairs or couples of toothed
wheels such as (1) (p) and (92) (p) such as are described in reference to and
illustrated in and by Figs. 7 and 8 of the accompanying drawings, all arranged,.
B

page_text: employed and operating for the purposes and substantially in the manner herein-
before described in reference to and illustrated in and by the accompanying
drawings.
"
3. In a screw-cutting lathe provided with a suitable number of "driving" gear-
wheels such as (a) (a) (a2) and (a³) and a corresponding number of "driven
gear-wheels such as (b) (¹) (62) and (63) arranged and employed substantially in
the manner hereinbefore described, the combination of a cam or cams such as (5)
and clutches such as (3) and (4), arranged employed and operating for the purposes
and substantially in the manner herein before described in reference to and illustrated
in and by the accompanying drawings.
Dated this Fifth day of August 1893.
HOWARD
CHEETHAM,
Manchester, Agent to the Applicant.