Improvements in Artificial Hands.
Year: 1890

page_text: Complete Specification Left, 16th Oct., 1890-4ccepted, 17th Jan., 1891
COMPLETE SPECIFICATION.
Improvements in Artificial Hands.
I, SAMUEL LUCAS of Poquetanuck in the County of New London State of Connecticut
United States of America, Woollen Manufacturer 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:-
The object of this invention is to provide an artificial hand that may be used to
perform certain kinds of manual labour, which shall he strong and serviceable and
cheaply constructed.
To more clearly illustrate said invention, two sheets of drawings are annexed hereto,
in which
Figure 1 is a side view of a hand embodying said invention and
Figure 2 a view of the same from the back or top side.
Figure 3 is a sectional view on line z-z of Figure 2, and
Figure 4 a similar view of those portions adjacent to the hinge joint, but with
the spring pawl thrown out of engagement with the ratchet-teeth, as hereinafter
described.
Figure 5 is a sectional view on line x-x of Figure 1, and
Figure 6 is a perspective view of the thumb, detached from the hand and inverted
to expose the tenon or boss by means of which it is strongly connected with said
hand.
In Figure 7 is shown the index finger with a fork attached thereto and in
Figure 8 an end view of the claniping ferrule by means of which said fork, or
any similar tool, may be attached to said finger.
Referring to the drawings
The letter a denotes the body or main section of the hand, made of wood or other
light material. This section a is provided with a shank that is fitted to enter a
socket in a false wrist secured to the stump of the arm, in any of the ways common to
this class of devices. It has been a common practice in securing artificial hands to
the stump to provide a shank substantially like shank in outward appearance, but
fastened rigidly in the hand section. In the hand here shown, the said shank is
pivotally secured in a recess in said hand, by a screw or pin e, as shown in Figures 3
and 5, and is held normally in alignment with the hand by a bow spring d made of
flat metal, whose free ends support the shank on either side. This construction
relieves the rigidity which otherwise would result and prevents any sudden and painful
shock to the natural stump of the wearer. When lateral pressure is brought to bear
on the artificial hand, the spring d may yield as shown in dotted lines in Figure 5,
but said spring is of sufficient strength to return the hand to its normal position when
such pressure is removed.
Section a is slotted to receive a set of artificial fingers e that are hinged in place by
a rod or pintle f extending through the entire series, and each of said fingers is
formed at its inner or binge end with ratchet-teeth g that are preferably concentric
with the pintle f. A spring-pawl h is provided to operate with each finger, said pawl
being screwed to the back side of section a and preferably formed of a single piece of

page_text: slit sheet metal as shown. When one or all of the fingers are swung on their hinges,
as in the act of closing the fingers, the described spring-pawls drop in the rear of the
ratchet-teeth and hold said fingers firmly in the position to which they have been
adjusted until the pawls are raised, which is accomplished through, and by means of,
a flattened bar that lies in a channel in section a under the pawls hand near the fres
ends of said pawls. One end of this bar i is bent at a right angle to form an
operating handlek and thus rock the bar into the position shown in Figure 4
when the pawls are all raised and the fingers may be returned to their extended
position. A guard plate m may be provided to protect the operating handle k
and also to limit its downward movement, although such a plate is. not absolutely
necessary.
In connection with each finger a spring n is provided for automatically. returning
the fingers to their extended position when the pawls are raised. These springs as
here illustrated consist of rubber bands or strips having one end fastened by a screw o
to the back of the hand and the other end or loop attached to a wire eye q secured to
the finger.
When the pawls hare disengaged from the ratchet-teeth, these springs n
immediately contract and draw the fingers back to their extended position. Springs
of wire could be substituted for the described rubber bands if desired, but the
latter are found cheap and effective and easily replaced when worn out or
broken.
The thumb of this artificial hand is hinged to the side of section a by a
screws, and, while allowed to move freely on the pivot thus provided, is limited in
such movement by a projecting portions that may abut a corresponding projection t
on section a as best shown in Figure 1. To ensure great strength to the thumb r, a
boss or tenon is provided that is concentric with the pivot screws and enters a
corresponding mortise in section a.
The first and second joints of the several fingers of said artificial hand are
intentionally partially closed at all times and are so constructed for the following
reason:-
•
When said fingers are swung around toward the palm of the hand, they then
form a hook (see Figure 3) of great strength, by means of which various things
may be lifted, as, for example, the bail of a pail or of a coal-hod, whereas, if said first.
and second joints were in line with the ratchet joints, so perfect a book could not be
formed.
Various tools may be attached to the fingers, one of which, a fork, is illustrated in
Figure 7. Said fork is provided with two ferrules through which the finger passes,
one of which, v, is formed of two overlapping plates of spring metal (shown most
clearly in Figure 8) that clasp the finger firmly and prevent the accidental displace-
ment of the fork.
The artificial hand, as a whole, is strong and serviceable, is not expensive to
make and enables one crippled by loss of a hand to perform many duties otherwise
impossible.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In combination with a palm having hinged thereto a series of fingers with
ratchet-teeth, a corresponding series of spring-pawls, as set forth, and a corresponding
series of springs connecting the said palm and fingers, substantially as and for the
purpose specified.
2. In an artificial hand formed, essentially, of a series of hinged fingers with
ratchet-teeth and pawls, as set forth, and in combination therewith, a thumb pivotally
attached to said hand and formed with a strengthening boss that is seated in a mortise
in said hand, substantially as specified.
3. In an artificial hand, a series of hinged fingers with ratchet-teeth, a corre-
sponding series of pawls engaging said teeth, and means, as set forth, for raising said

page_text: pawls, the said fingers being rigid from the hinge joint outward and partly closed, as
and for the purpose specified.
4. In combination with an artificial hand, a shank pivoted therein and arranged to
yield laterally under pressure and a spring, substantially as described, for holding said
shank normally in alignment with the hand.
5. In an artificial hand, a series of hinged fingers with ratchet-teeth, a corre-
sponding series of pawls engaging said teeth, and a fork or similar tool clamped to
one of said fingers by a spring ferrule, as described.
Dated this 15th day of October 189n
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.