IMPROVEMENTS IN DRILL BRACES
Year: 1884

page_text: I, GEORGE RICHARD POSTLETHWAITE of Park Road Aston Manor, Birmingham
in the County of Warwick, Mechanical Engineer-do hereby declare the nature of
said invention for "IMPROVEMENTS IN DRILL BRACES" and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement :-
My invention has reference to what are commonly know as drill braces for
boring and drilling metals and other substances; and my said invention consists in
constructing drilling or boring braces without ratchet teeth, pawls, catches or
springs which are commonly employed in braces known as ratchet braces; from
the fact that the moving of the spindle of the brace, is effected by a pawl or catch
engaging with ratchet like teeth for the rotation thereof. By using ratchet braces
as described, a great loss of time and labour occurs in their use, owing principally
to a considerable portion of energy expended by the operator, being lost, in what is
technically called back-lash, this back lash created in an ordinary ratchet brace
being very considerable, mounting in many instances to one half the available
stroke, therefore double time is required to be expended upon the work; and to
avoid such loss as far as possible, ratchet braces from time to time have been
constructed with double ratchet wheels pawls and the like which certainly reduces
some of the back lash which commonly occurs, but the entire loss cannot be
obviated so long as ratchets or toothed wheels are employed, although each
additional wheel may reduce the loss to some slight degree, yet it adds considerably
to the cost and bulkiness of the brace itself, and consequently liable to derange-
ment, by the duplication of parts described.
The whole cause of the above mentioned back-lash or loss of useful energy, is
well understood by the makers and users of these articles; and needs only to be
recapitulated to show the great difference between my improvements from those of
the so called ratchet braces, now in common use.
In the backward motion of the lever of an ordinary ratchet brace, the pawl has
to travel over the teeth and their spaces of the toothed annulas or wheel. This
backward motion or stroke may bring the pawl end just upon the summit of an
extreme tooth, but fails to exactly catch or engage on the back of it, then no effect
can be given to the forward stroke, until the pawl engages with the next forward
tooth; this may mean a traversing distance of about three eights of an inch for the
pawl, but amounts to many inches at the end of a lever handle measuring sixteen

page_text: inches long, and even shou'd the backward stroke of the lever handle end, in
passing over such extreme tooth as before mentioned, there is still a great loss of
useful effect in the forward stroke before the pawl is properly engaged rigidly
enough with the tooth to advance the working drill, owing to the necessary shape
and depth of such teeth, and other mechanical disadvantages. The object of my
said invention is to dispense with ratchet teeth, wheels, pawl and springs, and to
utilise the whole of the available stroke of the forward movement of the lever
handle, and thereby very materially economises time and labour, and moreover a
drill brace constructed according to my invention is not only more efficient in its
action and effective in its working, but is much simpler in its construction and
consequently less costly to manufacture.
Therefore my invention as described consists of an entirely novel mode of
working or actuating drill braces, or new action drill brace and consists of a lever
handle and body or spindle with the usual socket arrangements to receive the
different sizes of working drills but both lever handle and body or spindle are of a
modified form or shape to meet in some respects the novel mode of accomplishing
the forward motion of the working drill.
Upon the body or spindle of the brace, a plain wheel or disc is affixed rigidly
thereto, by means of a key or feather, in place of what is usually employed in the
form of a ratchet or toothed wheel; the said plain wheel or collar is perfectly
smooth on its outer edge or periphery. And above and below this plain wheel
or collar, aro coupling straps of hard metal, which aro made to work and rotate
freely upon the body of the spindle. These coupling straps are tapered outwardly
along their sides, but are parallel in regard to their thickness, and are made to
project outwards at one end, slightly beyond the plain wheel or collar; and at the
other or narrow end, holes are formed through which a pin or centre passes, in
the attachment of the coupling straps to the forward end of the lever handle as
herein-after described, and between the forks made by the said coupling plates, the
space of which is determined, by the thickness of the plain ring or collar, the lever
handle is attached to the coupling straps or plates by a joint pin which constitutes
the fulcrum upon which the lever turns; the lever handle has therefore no attach-
ment or connection to the body or spindle, other than by the two coupling plates
or links hereinbefore described, the coupling plates are therefore free to move
around the body or spindle, and in a forward direction upon the joint pin. By
arranging and connecting the lever handle, and coupling straps by a joint pin,
the fulcrum being the spindle body, the ratchet handle is converted into what is
known as a powerful compound lever, being about twelve to one more or less; the
mechanical power thus effects the forward movement of the working drill, by acting
upon the plain periphery of the wheel or collar situated between the coupling straps
which is effected in the following manner-
The inner end of the lever handle is widened out to somewhat the same width
as the diameter of the plain wheel or collar-The front of one half of this widened
part is curved, so as to embrace a portion of the plain wheel or collar, which I will
hereinafter call the back half-The front half is shaped to that of a tangent line to
the periphery of the plain wheel; or on a line at right angles to the axis of the
lever handle-If this last named front part of the shank of the lever was shaped
radially from the centre of the joint pin, which forms the centre of motion of the
lever handle, it would have no effect upon the plain wheel or collar in its forward
movement; so that the difference between such a radial line and the before
described tangent line, constitutes a wedge of the finest and most powerful
description; which on the slightest forward motion of the lever handle, effects such
a rigid grip or hold upon the periphery of the plain wheel or collar, as to compel its
rotation against any resistance the working drill may offer; the said grip being
just as safe and effectual as a pawl acting upon the tooth of a ratchet wheel; the
reverse movement of the lever handle instantly releases the grip, and allows the
lever and its coupling straps to rotate the necessary distance or stroke for the next
forward movement.

page_text: I will now describe with reference to the accompanying. Drawing the manner in
which my invention is to be performed.
Figure 1 is a sido elevation, and figure 2 a complete vertical section of a drill
brace constructed according to my invention; the lever handle is left in figure 2
partly in elevation. Figure 3 is a part vertical section of the said drill brace
figure 1, the view exhibits the coupling straps and handle partly in section.
Figure 4 is a plan of the brace, the dotted lines represent the position which tho
lever and coupling plates tako, when the spindle of the brace is in the act of being
rotated by the drawing forward of the lever or handle, when tho grip is upon the
wheel or collar. Figure 5 is a plan showing the centres upon which the combined
coupling plates and lever turn; this view also shows the grip, or shank end of
the lever forcibly holding or retaining the brace spindle on a forward movement
being imparted to the lever handle. Figure 6 is a plan on a larger scale of the
brace, with the top coupling plate removed. Figure 7 is one of the coupling plates
separately, and figure 8 is a section and elevation of the grip wheel or collar.
Figure 9 is a plan and elevation of the lever and its grip end.
The same letters of reference indicate the same parts in the several figures of the
Drawing.
a is the spindle or body of the brace consisting of three diameters, and is
provided at its top with a feed or pressure screw c which works within a screw
box a², formed in the axis of the said spindle, so as to give the requisite feed to the
drill on the rotation of its axis, by the lever g; but any other ordinary method of
feed, may be employed with like effect. The lower end of the spindle a is provided
with the usual socket 7, to receive different sized working drills. b is the wheel or
collar which is plain upon its periphery; this wheel or collar may be solid with the
spindle or it may be made separate, and rigidly affixed thereto, by a feather or
key as represented or by other suitable means. cc are the coupling plates
situated on the top and bottom sides of the wheel or collar b, the holes m of the
said coupling plates fit and turn upon the neck of the spindle a³. p is the centre
of the said coupling plates through which the pin or axis h passes in their connection
to the shank of the handle g. The under coupling plate c rests upon the shoulder
of the spindle beneath it, and is free to work and move freely around the neck-of
the said spindle; the wheel or collar being made separate from the spindle is forced
tightly upon the feather to fit close down upon the coupling plate; it must be
observed that the length of the feather must not exceed the depth of the wheel
or collar b, also that the length of the neck of the spindle is of the depth of the two
coupling plates and the thickness of the wheel or collar, so that the affixing ring d
when tightly fitted by a set screw or pin r, the said affixing ring takes its bearing
against the upper shoulder a' and also keeps the two coupling plates and grip wheel
or collar in position, allowing sufficient freedom for coupling plates to move around
the body or neck of the spindle. g is the lever handle, and f is its shank, and
when combined with the coupling plates cc constitute a powerful compound lever.
The shank part is of the same thickness as the plain wheel or collar b, and is
accurately fitted to occupy the space between the projecting ends of the two
coupling plates. It will be observed that the breadth of the shank is made broader
at the grip end, than at the other; that is, it is widened out so as to embrace at
its back part, the wheel or collar, and at the front part the grip, which is made at
right angles or there-abouts to the axis of the lever and coupling plates.
The fulcrum joint pin h answers the double purpose of sustaining the thrust of
the lever and connecting the coupling plates to the shank of the said lever, and
thereby converting the handle and coupling plates into a compound lever.
The shape, form and position of the shank part f of the lever handle, is most
important, for the proper and effectual grip of the shank f. With regard to position,
it is desirable that the axis o the lever handle should pass through the hole m.
The curvature of the back part v of the shank is shaped or curved to the periphery

page_text: of the wheel or collar; this curved extension is for the purpose of insuring
a better gliding backward motion of the lever handle, guided by the coupling
plates.
The front portion of the shank as before described marked w is shaped at right
angles or thereabouts to the axis of the lever handle, or forms a tangent line taken
from the circumference of the wheel or collar b; and to fully explain the value of
this shape or form of the part w, I show a dotted line t, struck from the fulcrum
pin p; from this it will be seen that if the shank part were given the shape indicated
by the dotted lines, see figure 6, it would have no gripping effect upon the plain
wheel or collar; but would simply roll thereon; but by giving it the shape w,
a wedge like action is produced, so that the slightest forward movement of the
handle, causes the front end w of the shank f to press forcibly upon the periphery
of the wheel or collar b, so as to compel the spindle and the whole part of the drill
brace to move together, on drawing forward the lever handle against any resistance
the working drill may offer; I wish it to be observed that the greater the power
applied in the forward movement of the lever handle, the firmer will be the grip w
of the shank fupon the wheel or collar b.
The wheel or collar marked b is of highly tempered steel; and the acting surface
of the shank of the handle is steel faced along its acting surface, and is also highly
tempered. The coupling plates and fulcrum pin is also of steel, and all other parts
of the drill brace which are necessary.
In using the drill brace hereinbefore described and represented, it is only
necessary to adjust the working drill by means of the pressure or feed screw c,
which takes into the spindle as best seen in figures 3 and 4, when by moving the
lever handle into the position represented in dotted lines figure 4, the face v, w of
the shank of the lever, glides over the plain periphery of the wheel or collar b, in
consequence of the back movement of the lever handle taking its radius from the
axis of the spindle; therefore the lever handle and its link which turns upon the
spindle moves back upon the said spindle as a centre, and without any effect. The
spindle and its drill at the same time remaining stationary. By now pulling
forward the lever handle (dotted lines) in the direction indicated by the arrow
figure 4, the front end w of the widened out part moves in a direction towards the
edge or periphery of the wheel or collar 6 by turning upon an independent pin or
axis p; the result is that the lever handle g becomes slightly inclined to the coupling
plates, and thereby compelling the part w to firmly grip and hold the brace spindle,
so that the brace spindle, drill, lever handle and coupling plates move forward
together, at the same time giving the necessary feed to the drill, by the pressure
screw e
Grease, dirt or other foreign matters getting upon the acting surfaces will not at
least interfere with the action of the drill; from the fact that the oiling of the
acting surfaces, is favourable to its working and durability.
Having now particularly described the nature of my said invention, and in
what manner the same is to be performed, I declare that what I claim is.
First. The improvements in ratchetless drill braces herein before described and
illustrated in the accompanying Drawing; that is to say, rotating a drill brace
spindle without teeth or sirrations by the friction or grip action of the end of
a jointed lever, which holds and compels the said spindle, and its drill, to move
forward with it, as if the lever handle and spindle were rigidly connected together,
the backward movement of the lever handle relaxes its hold upon the spindle,
leaving the spindle stationary, while the said handle and the parts connected with
it, move back without effect, the parts being arranged, combined and acting in the
way and for the purpose substantially as described and set forth.
Secondly-The use and substitution of a toothless or plain wheel or collar, by
which the spindle carrying the working drill of a drill brace is rotated; whether
the said plain wheel or collar be made separate from or in one piece with the spindle
for the purpose as described and represented.

page_text: Thirdly The lever handle g with its shank f, combined with the coupling
plates c. c. constituting a compound lever; for the purpose of effecting the necessary
grip or hold upon a plain wheel or spindle of a brace as described and illustrated.
Fourthly The grip and guide of the acting face v. w, which grips and holds the
spindle of a drill brace when the handle is moved in a forward direction, and
relaxes its hold when moved in the reverse direction as described and illustrated.
Fifthly Constructing, arranging and combining the parts of friction drill braces
substantially as described and illustrated.