Improvements in Parallel Screw Vices.
Year: 1899

page_text: Improvements in Parallel Screw Vices.
I, JOSEPHI BARROW, of the Firm of T. Shanks and Company, of the Union Iron
Works, Johnstone, in the County of Renfrew, North Britain, Engineer, do
hereby declare the nature of this invention to be as follows, that is to say:-
-
My said invention has for its object to improve the construction of parallel
vices so as to render them more satisfactory in use and so that a greater holding
power may be obtained, when desired, than is possible with such vices as
hitherto constructed.
In carrying out my invention one of the jaws is as usual made so as to be
capable of being bolted to a bench or table. The lower part of this jaw is,
according to my invention, made with an opening through it in which a
correspondingly shaped projection formed on the other movable jaw of the vice
can slide. The ordinary screwed spindle which actuates the movable jaw is
made with a collar which turns in a recess made for it in the movable jaw, the
end of the spindle projecting sufficiently past the collar and being made with a
squared head to permit of the application of a suitably shaped lever by which
the spindle can be turned to open or close the jaws. The lever can be removed
out of the way when desired and suspended underneath the vice. The screwed
spindle passes through a nut internally screwed to the same pitch as the spindle,
but having an external screw of a finer pitch engaging in a correspondingly
internally screwed projection by preference on the fixed jaw. This nut is made
with a handle and when the movable jaw has been screwed up by the ordinary
screw as hereinbefore described so as to hold the work as tightly as ordinarily
possible if additional holding power is still required this can be obtained by
giving a slight turn to the screwed nut the differential action between the two
screws bringing the jaws still closer together with great force.
Improvements in Parallel Screw
I, JOSEPI BARROW, of the Firm of T. Shanks and Company, of the Union Iron
Works, Johnstone, in the County of Renfrew, North Britain, Engineer, do
hereby declare the nature of this invention and in what manner the same is
DS17

page_text: to be performed, to be particularly described and ascertained in and by the
following statement, that is to say:-
My said invention has for its object to improve the construction of parallel
screw vices so as to render them more satisfactory in use and so that a greater
holding power may be obtained when desired than is possible with such vices as
hitherto constructed.
In carrying out my invention the fixed jaw of the vice is bolted to a bench or
table and is formed with guides in which a movable jaw is fitted to slide. The
spindle by means of which the movable jaw is actuated, is screwed to engage in
a differential nut or sleeve which is screwed into the fixed jaw, or it might be a
separate fixed part, the pitch of the external screw of the nut being slightly
different from that of the internal screw. The arrangement is such that when
the movable jaw has been screwed up to the work with ordinary grip by turning
the spindle in the usual way, an additional holding power can be obtained by
turning the screwed nut, to a small extent the differential action thus produced
causing the jaws to be brought still closer together with great force and thereby
largely increasing their holding power.
And in order that my said invention and the manner of performing the same
may be properly understood I hereunto append a sheet of explanatory drawings
to be hereinafter referred to in describing my improvements.
Figure, 1, of the drawings is a longitudinal section, Figure, 2, an end elevation,
and Figure, 3, a transverse section of the improvements. In these drawings the
same reference letters and numerals are used to mark the same or like parts
wherever they are repeated.
In carrying out my invention the vice is arranged as usual with a fixed jaw,
A, and a movable jaw, B, the jaw, A, being made with flanged parts, A1,
through which it is fixed to a bench or table, 12, by bolts, A 3. The lower part,
B1, of the movable jaw is formed to slide in upper, lower, and side guides,
A4, A5, A6, formed in the frame, A7, forming part of the fixed jaw. The
spindle, C, which actuates the movable jaw, B, is fitted to work freely through
that part of the lower part, 131, which projects down through the guide opening,
A8, in the frame A7, and it is formed with a collar, C1, on its outer end, the
inner side of which acts against the movable jaw when it is being moved towards
the fixed jaw, A, the outer side of the collar acting against a detachable stop, B2,
when the jaw is being moved away from the fixed jaw. The spindle, , is
turned by a box key handle, D, which fits on the squared head, C2, of the
spindle. The handle, D, can be detached from the spindle, B, and hooks, E,
fixed to the guide frame, A7, are provided on which the handle can be placed
so as to be out of the way when not in use. The screwed portion of the spindle,
C, works in a differential nut or sleeve, G, the nut being externally screwed to
work by preference in a boss, A9, formed on the fixed jaw part of the vice, the
pitch of the external screw being made slightly different from that of the
internal screw in which the spindle works, but having its threads running in the
same direction as the internal screw threads. The nut, G, is worked preferably
by a handle, G1, which is detachably fitted to engage in holes, G2, formed in a
ring or boss, G3, formed on the nut. A tube or casing, H, is provided for
protecting the spindle, C, one end of the tube fitting loosely in the boss, G3,
and the other end being fixed by a piu, H 1, to a bracket, H2, fixed to the bench,
A2. Then the movable jaw, B, has been screwed up as tightly as possible
against the work placed in the vice, by turning the spindle, C', in the nut, G,
and if additional holding power is still required it can be simply and con-
veniently obtained by turning the nut, G, to a slight extent, the differential
action thus produced causing the jaws to be brought still closer together with
great force and thereby largely increasing their holding power. The direction
in which the nut is to be turned to effect this object depends on whether the

page_text: pitch of the external screw is smaller or greater than that of the internal screw,
that is to say, the nut, G, is to be screwed inwards if its external screw is of the
smaller pitch and vice versa.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is:-
Improvements in parallel screw vices, consisting of a differential nut or sleeve,
screwed internally and externally, the pitches of the two screws being different,
the external screw working in a correspondingly internally screwed part of the
fixed jaw of the vice, the internal screw engaging in a correspondingly screwed
part of the vice spindle actuating the movable jaw of the vice, substantially as
and for the purposes herein before described with reference to the accompanying
drawings.
Dated this Eighteenth day of December 1800
EDMUND HUNT,
Applicant's Agent.