IMPROVEMENTS IN RATCHET-BRACES
Year: 1882

page_text: COMPLETE SPECIFICATION filed by Cemer Thomas Colebrook at the Office
of the Commissioners of Patents on the 13th January 1882.
CEMER THOMAS COLEBROOK, of Islington in the County of Middlesex, Engineer.
"IMPROVEMENTS IN RATCHET-BRACES."
This Invention, which relates to improvements in ratchet-braces, has reference
to that class of ratchet-braces which are known as automatic or self-feeding ratchet-
braces; and the objects of this Invention, are, to simplify the construction and to
avoid all complication in the arrangement of the parts of such ratchet-braces.
The principle of the present Invention consists in combining with a drilling or
ratchet-brace, and in using for the purpose of effecting the automatic feeding of the
drill up to its work, a differential arrangement of gearing,-so arranged and com-
bined with the ratchet which turns the drill, as that in the forward stroke of the
ratchet-lever or handle, the additional or feeding gearing shall have more or less of
a start of the ratchet which actuates the drill, and shall thus advance the usual
screw and feed the drill up to its work before the ratchet which actuates the drill,
is, in the further forward motion of the handle, turned to effect the required
drilling. This is a totally new principle as adapted to ratchet-braces, and great
practical advantages attend the application thereof thereto.
I would remark that the principle of my present Invention is susceptible of being
carried into practical effect in a variety of ways, and I therefore wish it to be
distinctly understood that I lay more particular claim to the mechanical application
of the said principle to the purpose of my present Invention than to any particular
means of so doing; I have however hereinafter described the most simple and yet
effective method and combination of parts of which I am aware of fully attaining
the objects of my present Invention.
This modification is illustrated on the accompanying Drawings in Figs 1 to 5,
which respectively represent an elevation, and a vertical section of the ratchet-brace,
and plan views of the gearing.
1, represents the body of the brace which has the usual socket for the drill at 2,
and is provided or made in one piece with the usual ratchet 3, for turning the drill.
4 is the usual screw, which, according to my Invention, works freely within the
body 1, (which is cylindrical internally) and is slotted, so as to be prevented from
CD

page_text: turning by a pin 5 inserted through the collar 6 of the body 1 and engaging in the
slot 7. 8 is the usual handle or lever for actuating the ratchet 3, the ratchet body 1,
and the drill it carries, and it fits freely round the collar 6.
The utility of my present Invention has reference to the application of the part
(or of its equivalent) next to be referred to,-and this consists of a single (or it may
be a double) differential ratchet or ratchet-nut 9, which is simply run down the
screw 4, and is concentrically recessed at 10, at one end if a single nut, or at each
end, if (as shown on the accompanying Drawings) a double nut, and which recess
fits around a washer 11, resting on the upper edge of the collar 6.
12, represents the pin for the usual pawl 13, which actuates the ratchet 3, and
turns the drill, and it is, according to my Invention, extended above the handle or
lever 8, and the extended part is fitted with a pawl 14, which similarly gears with
the ratchet nut 9, or the lower toothed rim of the double nut 9. The two rims of
the ratchet-nut form distinct ratchets, and have a different number of teeth in each,
but they are formed in one piece having an annular recess 15, between them, in
which a projection 16, of the pawl 14, enters, and keeps the ratchet-nut and screw
in place.
It will of course be understood that it is not necessary that the double ratchet-
nut should be used, it is illustrated on the annexed Drawings simply as a very
convenient means of getting a greater or lesser average amount of feed, the one
most suitable for the softer metals, and the other for the harder metals,-also for
different sized holes; and that a single feed ratchet-nut may be used, and would
answer exactly the same purpose, but would of course not have so extensive a
range of use.
I would also wish it to be understood that it is not absolutely necessary that the
periphery of the feed-nut or nuts should be formed as a ratchet or should be toothed
in any way, as it may be formed with a plain surface, or with a hollowed V-periphery,
and acted upon or turned by any device or contrivance equivalent to a pawl,
carried by the lever, and which will give a start in the turning to the feed-nut,
before the drill-turning ratchet is turned by its pawl.
The principle of the present Invention depends upon the feed and drill-turning
ratchets having different numbers of teeth (so far as this modification is concerned),
and it is preferable that they have such relative numbers of teeth as are not
divisible by a common divider other than unity. No particular numbers of teeth
in the different ratchets are essential, but some relative numbers are more advan-
tageous in use than others in the modification illustrated, the upper rim of the
feed-ratchet has 51 teeth, the lower rim thereof has 29 teeth, and the turning
I ratchet has 19 teeth.
The action of the improved automatic feeding device is as follows: Upon the
backward stroke of the lever or handle, the pawls 13, 14, are both carried back
equally; but in the forward stroke thereof owing to the difference in the number
of teeth in the geared rim of the feeding ratchet, and in the turning ratchet, there
is always, or nearly always, a slight turn of the feeding ratchet by its pawl, and a
consequent feed of the drill, before the turning ratchet is actuated by its pawl, and
this is at times more or less, but the average of consecutive movements is such as
to give the required average feed for the metal being drilled.
In using the double ratchets, this facility is very advantageous, as the screw
with its feed-nut can be at once withdrawn from the stock of the drill, and
inverted, and then a different average feed at once results upon actuating the
handle or lever in the usual way.
Having now described the nature and objects of my present Invention together
with the manner in which the same is to be or may be performed or carried
into practical effect I would remark in conclusion that what I consider to be novel
and original and as the improvements constituting the Invention secured to me by
the hereinbefore in part recited Letters Patent, is :-
The combination with a drilling or ratchet-brace, and the use therewith for the
purpose of effecting the automatic feeding of the drill up to its work, of a differential

page_text: arrangement of feeding and turning gearing, the gearing being so arranged and
combined as that in the forward stroke of the ratchet-lever or handle the feeding-
gearing receives more or less of a start of the drill-turning ratchet, and thus
advances the drill up to its work before the drill is turned,-substantially as and
for the purpose hereinbefore described, and as illustrated on the accompanying
Drawings.
In witness whereof I the said Cemer Thomas Colebrook have hereunto set
my hand and seal this Thirteenth day of January, in the year of our Lord,
One thousand eight hundred and eighty-two.
Witness.
CHARLES AUBREY DAY,
Patents, Trade Marks, & Designs Offices,
95, Navarino Road,
Dalston Rise.
C. T. COLEBROOK. (L.S.)