Improvements in or relating to Lathe Chucks.
Year: 1899

page_text: Date of Application, 10th Feb., 1899
Complete Specification Loft 26th Sant 1800 Accented
10th Fah
1000
PROVISIONAL SPECIFICATION.
Improvements in or relating to Lathe Chucks.
We, ALFRED HERBERT, of "Brantwood," Spencer Road, Coventry, County of
Warwick, Engineer, and OSCAR HARMER, of "Dalhousie," Spencer Park, Coventry,
in the County of Warwick, Engineer, do hereby declare the nature of this inven-
tion to be as follows:-
This invention relates to lathe chucks and has for its object to provide a chuck
which is not only capable of being opened and closed while the machine is running
but is also self-adjusting to accommodate variations in the diameters of the
bars which it is intended to grip.
The chucks of this type which are at present in use have the disadvantage
of requiring the machine to be stopped to allow the adjustment required by
variations in size of the bars to be made The improved chuck however will grip
bars varying by as much as 1/16th of an inch or even th of an inch from their true
nominal size without stopping the machine.
According to this invention the chuck comprises a cylindrical body which may
be either screwed on to the lathe spindle or may form part of the lathe spindle
This body is bored sufficiently large to admit bars of the actual diameter which
the chuck is intended to hold and its outer end is formed conical internally for
the reception of a correspondingly tapered collet which is bored parallel on its
inside to suit the nominal size of bar to be gripped and divided longitudinally
into three or four pieces When this collet is forced into the conical end of the
chuck body it will grip the bar. An annular cap fits over the body sliding freely
on a plain cylindrical portion at the end of the same, the cap having a flange
which bears against the collets. At the inner end this cap is of larger internal
diameter and provided with an internal thread of some convenient pitch say for
example seven threads per inch. A sleeve is situated between the larger portion
of the cap and the chuck body, this sleeve having an external screw thread corre-
sponding with the thread on the interior of the cap and having also an internal
screw thread of some convenient pitch say for example eight threads per inch fitting
a corresponding thread cut on the exterior of the chuck body. A pin or feather
prevents the cap from rotating in relation to the chuck body while permitting the
cap to slide freely in a longitudinal direction.
If now the above described sleeve with internal and external screw threads be
rotated in one direction it will move the cap outwards away from the collets and
if it be turned in the other direction it will move the cap so as to press upon
the collets and force them into the coned end of the chuck body, thus closing the
chuck and gripping the bar. It will be seen that with the above mentioned
arrangement the screw threads act differentially so that with threads such as those
mentioned above by way of example the cap is moved at the same rate and
with the same force as if it were actuated by a thread of 56 threads per inch.
By this means the necessary power is obtained and at the same time threads of
sufficiently coarse pitch to be durable and strong can be employed.
The mechanism for operating the screw-threaded sleeve while the lathe is in
motion is as follows:

page_text: ⋅
A spur wheel is mounted on the spindle of the lathe or on the chuck body and
gears with a pinion which carries a cone friction clutch. This pinion runs loose
in a shaft or on a hollow sleeve mounted parallel to the lathe spindle. The screw
threaded sleeve upon the chuck body has formed upon it or attached to it a
toothed wheel which gears with a pinion rigidly mounted on the shaft above
mentioned between the clutch cone on the loose pinion and a second fixed clutch
cone through which the shaft passes. This shaft can be moved endwise by means
of a lever which rotates a pinion gearing with a rack upon the end of the shaft
or by other approved means. This endwise movement enables either the fixed or
rotating conc to be frictionally engaged with conical recesses formed on either
side of the pinion mounted upon the shaft; it is understood of course that the
relative positions of the male and female cones may be reversed.
The operation is as follows:-If by means of the lever the shaft is moved
endwise say to the left the clutch connecting the shaft to the rotating pinion
which gears with the spur wheel on the lathe spindle or chuck body is brought
into action. The effect of this is to rotate the screw-threaded sleeve on the chuck
body faster than the lathe spindle by an amount due to the ratio of the gear
wheels, the result of this action through the differential screw causing the cap, to
force the collets into the conical end of the chuck body and so close the chuck
As soon as the bar is gripped sufficiently tightly the clutch slips, the angle of
the clutch cone being so arranged that it will slip when the desired amount of
pressure has been applied to the bar. In order to release the chuck the lever has
to move the shaft say to the right when the fixed clutch cone is brought into
action. By this means the screw-threaded sleeve is prevented from rotating with
the result that as the lathe spindle continues to revolve the chuck is released
through the medium of the differential screw.
The whole mechanism may if desired be enclosed so as to run in an oil bath.
If preferred the screw-threaded sleeve may be operated by means of gearing
and clutches either from the countershaft of the lathe or from the back-gear
shaft of the lathe, or the sleeve may be controlled by means of a brake which
grips it and prevents it from rotating. In this case the fact of the lathe spindle
revolving wile the screwed sleeve is held stationary would operate the chuck
through the differential screw the release of the chuck being brought about by
reversing the rotation of the lathe spindle
It will be observed that this chuck has the following valuable feature, i.e, the
cap which forces back the collets or jaws into the chuck body does not revolve
in relation to the spindle, so that it has no tendency to twist the jaws, moreover
as the cap fits on a parallel portion of the chuck body it can be made quite true.
In chucks which have this cap screwed directly on the spindle there is first of all
the objection that the cap revolves and consequently tends to twist the jaws, and
secondly being on a screw thread it is impossible for well known mechanical
reasons to keep it quite true, thus one jaw is sometimes forced in further than
the others with the result that the work is not held so truly.
The details of construction may be varied without departing from the spirit of
the invention thus for example the guiding portion of the chuck body may be
modified where it is desirable to reduce the total length of the chuck.
Dated this 10th day of January 1899.
ALFRED HERBERT,.
OSCAR HARMER.
Boult & Wade,
Agents for the Applicants.

page_text: ирготещение шо голо
We, ALFRED HERBERT, of "Brantwood," Spencer Road, Coventry, County of
Warwick, Engineer, and OSCAR HARMER, of "Dalhousie," Spencer Park, Coventry,
in the County of Warwick, Engineer, do hereby declare the nature of this inven-
tion 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 lathe chucks and has for its object to provide a
chuck, which is not only capable of being opened and closed while the machine
is running but is also self adjusting to accommodate variations in the diameters of
the bars which it is intended to grip.
The chucks of this type which are at present in use have the disadvantage of
requiring the machine to be stopped to allow the adjustment to be made required
by variations in size of the bars. The improved chuck however will grip bars
varying by as much as 16th of an inch or even th of an inch from their normal
size without stopping the machine
A convenient construction of chuck according to this invention is shown in the
accompanying drawings of which
Figure 1 is a plan, part in section part in elevation of a chuck in operative
position on a lathe spindle.
Figure 2 is a vertical longitudinal section on the line 2-2 of Figure 1; and
Figure 3 is an end view partly in section.
Like letters indicate like parts in all figures.
The chuck comprises a cylindrical body A, jaws B a cap C and sleeve D.,
The body A is screwed on to the lathe spindle E. The body is bored. suffi-
ciently large. to freely admit bars of the maximum actual diameter which.,the
chuck is intended to. hold, the bore being formed conical at the outer or free, end
of the body for the reception of a correspondingly tapered collet B, divided
longitudinally into three or four pieces, which forms the jaws of the chuck, and
is bored parallel on its inside to suit the nominal size of bar to be, gripped. The
outer end or end, of largest diameter of this collet is provided with a groove B¹
which receives an internal flange C¹ of the cap C.
";
Externally the body A is provided with a screw thread throughout, the greater
portion of its length its back end is provided with a cog wheel A', and its front
end forms a plain cylindrical surface. The front end of the cap,C is formed to
slide freely on this surface, and is provided with a feather or pin C³ which engages
a longitudinal slot A in the body A, allowing the cap movement in a longitudinal
direction on the body but preventing any rotation of the cap thereon. The cap
is formed with an extension C3 of larger internal diameter, provided with, an
internal. screw thread of some convenient pitch, say for example seven threads
per inch leaving an annular space between the cap extension and the body for
the reception of a sleeve D. This sleeve is screw threaded internally to engage
with the thread on the chuck body already referred to and externally to engage
the corresponding thread on the cap extension C3 The two screw threads on the
sleeve D are of different pitch, say for example seven threads per inch for the
thread engaging the cap and eight threads per inch for that engaging the body.
The sleeve D is provided at the back end with a cog wheel D¹.
If now the sleeve I be rotated in one direction say that of the arrow in Figure 3
it will move. the cap C so that its flange presses upon the back edge of the
groove B of the jaws B and forces the latter into the coned end of the chuck
body thus closing the chuck and gripping the bar: if it be turned in the other
direction, or if it be retarded or held from rotating, whilst the chuck body is
a.

page_text: rotating in the direction of the arrow, the cap C will be moved so that its flange
presses the collets outwards opening the chuck It will be seen that with the above
described arrangement the screw; threads act differentially so that with threads
such as those mentioned above by way of example the cap is moved at the same
rate and with the same force as if it were actuated by a thread of 56 threads
per inch. By this means the necessary power is obtained and at the same time
threads may be employed of sufficiently coarse pitch to be durable and strong.
The mechanism for operating the screw threaded sleeve while the lathe 18 in
motion is as follows:--
A shaft F, capable of rotatory and also of slight longitudinal movement, is
mounted, parallel with the lathe spindle and chuck, in bearings in the lathe
head and chuck frame. A pinion G, running loose on the shaft F, gears with
the wheel A¹ before described, and carries a cone friction clutch G¹ Collars G³
are provided between the pinion and the frame to lessen friction.
Rigidly secured on the shaft F, so as to gear with the wheel D¹, is a pinion H,
and rigidly secured on a bearing block J of the shaft F is a coned friction
clutch K The bearing block J may be secured to the frame by a key J¹ or in
other convenient manner.
The pinion H is provided with conical recesses H¹ H³, one on either side,
corresponding in angle with the cones of the friction clutches G¹ K, and the pinion
is so positioned between these clutches that a slight longitudinal movement of
the shaft F causes the pinion to be engaged with one or other of them. A con-
venient device for giving this movement to the shaft is shown in Figure 3, a
vertical shaft L mounted in an upward extension of the chuck frame is provided
at its lower end with a cog wheel L' which gears with a flat rack F1 carried on a
loose sleeve F2 on the shaft F. The vertical shaft L may he operated by means
of a lever L³.
The operation is as follows:-
:-
If, whilst the lathe is running. by means of the lever L the shaft F be moved
endwise say to the left the clutch G₁ is brought into frictional contact with the
coned surface H¹ of the pinion H. The effect of this is to rotate the sleeve D) on
the chuck body faster than the rotation of the lathe spindle by an amount due
to the ratio of the gear wheels, the result of this action through the differential
screw causing the cap C to force the jaws B into the conical end of the chuck body
and so close the chuck. As soon as the bar is gripped sufficiently tightly the clutch
slips, the angle of the clutch cone being so arranged that it will slip when the
desired amount of pressure has been given to the bar
In order to release the chuck the lever is moved to the right, when the fixed
clutch cone K is brought into action, engaging the coned surface H of the
pinion H. By this means the sleeve D is retarded or prevented from rotating
with the result that as the lathe spindle revolves the cap C is moved outwardly
by means of the differential screw and the chuck is released.
The whole mechanism may if desired be enclosed so as to run in an oil bath. A
convenient form of cover and frame is shown in the figures comprising a body M,
which may be secured to the lathe head by bolts as at M, and a cover M³, secured
to the body M by set screws M³.
If preferred the sleeve D may be operated by means of gearing and clutches
either from the counter-shaft of the lathe or from the back gear shaft of the
lathe, or the sleeve may be controlled by means of a brake which grips it and
prevents it from rotating. In this case the fact of the lathe spindle revolving
while the screwed sleeve is held stationary would operate the chuck through the
differential screw the release of the chuck however would have to be brought
about by reversing the rotation of the lathe spindle.
It is evident that the details of construction may be varied without departing
from the spirit of the invention for example the guiding portion of the chuck
body may be modified where it is desirable to reduce the total length of the chuck:
the chuck body may form part of the lathe spindle instead of being attached

page_text: thereto. the cog wheel A¹ may be fixed on or form part of the lathe spindle
instead of the chuck body: the pinion G may run on a sleeve on the shaft F and
may be provided with a ball bearing between its side and the collar G2 to lessen
friction against the frame when engaged with the pinion H. the relative positions
of the male and female cones of the friction clutches moreover may be reversed.
It will be observed that this chuck has the following feature, i.e. the cap which
forces back the collet or jaws into the chuck body does not revolve in relation
to the spindle, so that it has no tendency to twist the jaws, moreover as the cap
fits on a parallel portion of the chuck body.it can be made quite true. In chucks
which have this cap screwed directly on the spindle there is first of all the
objection that the cap revolves and consequently tends to twist the jaws, and
secondly being on a screw thread it is impossible for well known mechanical
reasons to keep it quite true, thus one jaw is sometimes forced in further than the
others with the result that the work is not held so truly.
"
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 :-
1 A lathe chuck which can be adjusted while the machine is running to grip
work of different dimensions.
2. A lathe chuck which can be adjusted by the driving power of the lathe while
the latter is running to grip work of different dimensions.
3. The combination with a lathe chuck of mechanism for adjusting the chuck
while the machine is running.
4. A lathe chuck of which the jaws can be opened or closed by the diving
power of the lathe whilst the lathe is running, the jaws at the same time being
automatically adjusted to fit work varying in diameter.
5. In a lathe chuck opening closing and adjusting the chuck jaws whilst the
machine is running by means of a differential screw, the axis of which is
coincident with the axis of the lathe spindle.
6. In a lathe chuck the combination with a body for holding the jaws and a cap
for controlling the same of a rotatable sleeve having two screw threads of different
pitch engaging the body and the cap respectively for the purpose described.
7. In a lathe chuck the combination with a body to hold the jaws, and a cap
capable of rotation with and longitudinal reciprocation upon the body to actuate
the jaws, of a sleeve engaging the body of an internal screw thread of one pitch
and the cap by an external screw thread of a different pitch and mechanism by
means of which the sleeve whilst the machine is running will rotate at the same
speed as the chuck body or at the will of the operator may either be rotated at a
faster speed than the chuck body or be retarded so as to reciprocate the cap on the
chuck body and close or open the jaws respectively.
8. In a lathe chuck the combination with a body to hold the jaws, and a cap,
capable of rotation with and longitudinal reciprocation upon the body to actuate
the jaws, of a sleeve engaging the body by an internal screw thread of one pitch
and the cap by an external screw thread of a different pitch and mechanism by
means of which the sleeve whilst the machine is running may be retarded or
prevented from rotating at the will of the operator
9. In a lathe chuck the combination with a body to hold the jaws and a cap
to actuate the jaws of a sleeve such as 1) ]) a pinion such as H gearing with
the sleeve and mechanism controlled by the operator for either accelerating or
retarding the movement of the pinion, whilst the machine is running.
10 In mechanism actuated by the driving power of the lathe for adjusting
the jaws of a lathe chuck whilst the machine is running the employment to
operate the mechanism of clutches constructed to vield under a determined strain.
11. In a lathe chuck and in combination a body such as A A¹ jaws such as B a
cap such as C C a sleeve such as 1 D₁, mechanism for actuating the same com-
prising a shaft such as F capable of both rotatory and longitudinal movement, a

page_text: pinion such as H H H fixed on said shaft gearing with the sleeve D a loose
wheel such as G gearing with the chuck body A or with the lathe spindle, two
friction cones the one G on the loose wheel the other K on the chuck frame and
means such as lever L shaft and gearing L L' F' for engaging at the will of
the operator either of the friction cones with the pinion H substantially as
described.
12 The combination and arrangement of parts constituting the complete chuck
substantially as described or as illustrated in the accompanying drawings.
Doted this 25th day of September 1899
14
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