Year: 1897

page_text: Date of Application, 2nd Sept., 1897-Accepted, 23rd Oct., 1897
I, WILHELM VON PITTLER, of 144 High Holborn, in the County of London,
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:
-
This invention relates to improvements in lathe chucks and has reference more
particularly to an improved construction of what are known as self-centreing chucks,
that is to say chucks in which the jaws move simultaneously towards the object
to be held.
An important feature of the said invention consists in forming the jaws with
tapered or conical rear portions which fit into a conically recessed sliding piece or
tube adapted to be forced towards the jaws by means of a wedge working trans-
versely to the axis of the chuck. The construction may either be such that the
wedge can be operated by a handle while the chuck is revolving, or the wedge
may be adapted to be operated by a key.
In order that the invention may be clearly understood and readily carried into
effect I will proceed to describe the same by aid of the accompanying drawings in
which;
Figure 1 is a longitudinal section, and
Figure 2 is a transverse section on the line x x Figure 1, showing one construc-
tion of my improved chuck combined with the headstock of a lathe and provided
with means for operating the jaws whilst revolving.
Figure 2 shows the relative disposition of the jaws in end view.
Figures 3 and 4 are respectively a longitudinal section and a transverse section
of another construction of my improved chuck, the jaws of which are adapted to
be operated by a key.
Figure 5 is a horizontal section on the line y y Figure 4.
Referring more particularly to Figures 1 and 2, a is a hollow mandrel rigidly
connected with the speed pulleys. 6 is the wedge which is arranged to work trans-
versely of this mandrel. c is the sliding piece or tube having a conically recessed
end by which the jaws e are forced together, this tube c being moved endwise by
the wedge b. d is a screw ring or nut whereby the jaws e are kept in position.
The transverse movement of the wedge b is effected by a sleeve m having inclined
surfaces m against which the extremities of the wedge abut. This sleeve is pro-
vided with an annular groove into which a feather carried by a block f enters,
and longitudinal movement is imparted to the sleeve by a handle h mounted on a
spindle h¹ carrying a pinion 9 in gear with a rack which carries the aforesaid
block f.
It will be readily understood that when the sleeve m is moved to and fro, the
inclined surfaces m³ cause the wedge to move transversely to the axis of the tube c.
and that when the wedge is moved inwards, that is into the position shown in
Figure 1 the tube c will be moved to the right, and its conically recessed end will
press together the jaws e. The movement of the tube in the opposite direction to

page_text: release the jaws is effected, when the wedge is moved outwards, by a spring 1
which is compressed between a screw and a stop 7.
Referring now to the arrangement shown in Figures 3, 4 and 5, the wedge b
is operated by a screw n which is turned by a key in the manner usual in self-
centreing chucks. The screw is inserted between the wedge and the wall of the
recess in which the latter works and is prevented from moving endwise by a stop
or plug o secured in the body of the chuck by a set screw p. In this case the
spring is dispensed with and the tube c is provided with a reduced portion c¹
(Figure 5) which is adapted to fit into a recess in the wedge, and has a notch ca
to receive a corresponding projection on the wedge b thus forming a direct connec-
tion between the tube and the wedge and enabling the latter to move the tube
positively in both directions.
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. A self centreing chuck the jaws of which are operated by a sliding piece or
tube which is acted upon by a transversely moving wedge, substantially ab
described.
2. A self-centreing chuck constructed substantially as described with reference to
Figures 1, 2 and 24, or with reference to Figures 3, 4, and 5 of the accompanying
drawings.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.