IMPROVEMENTS IN BRAKES
Year: 1861

page_text: LETTERS PATENT to John David Napier, of Glasgow, in the County of
Lanark, North Britain, Engineer, for the Invention of "IMPROVEMENTS IN
BRAKES." A communication from abroad by Robert Napier, residing at
Newcastle, New South Wales.
ealed the 30th May 1862, and dated the 6th December 1861.
PROVISIONAL SPECIFICATION left by the said John David Napier at the
Office of the Commissioners of Patents, with his Petition, on the 6th
December 1861.
I, JOHN DAVID NAPIER, of Glasgow, in the County of Lanark,.North
Britain, Engineer, do hereby declare the nature of the said Invention of
"IMPROVEMENTS IN BRAKES," (communicated to me from abroad by Robert.
Napier, residing at.Newcastle, New South Wales,) to be as follows, that
is to say :-
This Invention relates to the class of brake in which a friction strap or its.
equivalent is applied to the periphery. of a wheel, pulley, or drum, the rotation
of which it is desired to control, and has for object. to increase the efficiency of
such appliances, and to render them self-acting or partially so..
In one modification of the improved brake apparatus both ends of the
friction strap are jointed to one lever; but both connections are to one side of
the fulcrum or fixed centre of the lever, and one of them at a greater distance
from the fulcrum than the other. From this arrangement there, arises a
differential action between the two ends of the strap, of such a nature. that the

page_text: rotation of the wheel in one direction tends to free or open the strap, whilst
rotation in the opposite direction tends to tighten or close the strap. In
applying the improved contrivance to apparatus for raising and lowering heavy
weights, for example, the parts are arranged so that the descent of the weight
calls the tightening action into play, and the friction strap of itself holds the
weight from descending. In order that the weight may descend, the lever
must be slightly moved to relieve the strap, and must be held as long as
required, as the weight would be stopped upon the lever being left to itself.
The force required to work the lever is very small compared with what is
necessary in ordinary arrangements. The arrangement may be beneficially
substituted for the ordinary ratchet and pall movement used to prevent the
backward motion of weights or machinery, and it may be modified in its
details to suit different circumstances and requirements.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John David Napier in the Great Seal Patent Office on the
6th June 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
DAVID NAPIER, of Glasgow, in the County of Lanark, North Britain,
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixth day of December, in the year of our Lord
One thousand eight hundred and sixty-one, in the twenty-fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John David Napier, Her special licence that I, the said John David
Napier, my executors, administrators, and assigns, or such others as I, the said
John David Napier, my executors, administrators, and assigns, should-at-any
_time_agree with,_and_no_others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands; and Isle of Man, an Invention for "IMPROVEMENTS IN
BRAKES," (a communication to me from abroad by Robert Napier, residing at
Newcastle, New South Wales,) upon the condition, amongst others, that I, the
said John David Napier, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great

page_text: Seal Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW'YE, that I, the said John David Napier, do hereby declaré
the nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement in writing, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon (that is to say) :-
3
The said Invention relates to the class of brake in which a friction strap
or its equivalent is applied to the periphery of a wheel, pulley, or drum, 'the
rotation of which it is desired to control, and has for object to increase. the
efficiency of such appliances and to render them self-acting, or partially so.":
And in order that the nature of the said Invention and the manner of per-
forming the same may be properly understood, there is hereunto appended an
explanatory Drawing, showing the application of the improvements to..the
friction brake of an ordinary winch...
In this Drawing, the friction strap A, B, is represented as applied to the
periphery of a wheel or pulley C, fast on the shaft D of the winding barrel,
and the lever E, to which. the strap A, B, is jointed, and by which it is con-
trolled, is centred on a stud pin F, fixed in a projecting. part of the, winch
frame, G. In this modification, both ends A, B, of the friction strap are
jointed to the one lever E, but. both connections are to the same side of the
fulcrum or fixed centre F, one of them, b, being at a greater distance from the
fulcrum than the other,.a. From this arrangement there arises a differential
action between the two ends of the strap, of such a nature that the rotation of
the wheel in one direction tends to free or open the strap, whilst rotation in
the opposite direction, that of the arrow in the Drawing, tends to tighten or
close the strap. This differential action consists in one joint a of the strap,
moving through a shorter space, in consequence of its being placed nearer the
centre of motion of the lever E than the other joint b, whilst the lever is
moved slightly in one direction or the other through the strap itself, in con-
sequence of the frictional adhesion thereof on the wheel rim. An adjustable
weight H is, by preference, applied to the lever E in such a way as to tend
slightly to tighten the strap and to insure there being always the slight adhe-
sion between the strap and wheel rim which is necessary for the wheel to act
on the strap.
In applying the improved contrivance to apparatus for raising and lowering
heavy weights, for example, the gearing and details are arranged so that the
descent of the weight (causing rotation-in-the-direction-of-the-arrow-in-the-
Drawing) calls the tightening-action into play, and the friction strap of itself

page_text: holds the weight from descending. In order, that the weight may descend, the
lever E must be slightly lifted or moved to relieve the strap A, B, and must be
held as long as required, as the descent of the weight would be stopped on the
lever being left to itself. The force required to work the lever is very small
compared with what is necessary in ordinary arrangements.
The arrangement may be beneficially substituted for the ordinary ratchet
and pawl movement used to prevent the backward motion of weights or
machinery, and it may be modified in its details to suit.different,circumstances
and requirements...
Having thus particularly described the said Invention and the manner in
which the same is or may be performed, I have to state that. I do not restrict
myself to the precise details herein described or delineated, but that what I
consider to be novel and original, and claim as the Invention secured to me
by the herein-before in part recited. Letters Patent is, the jointing of the ends
of a friction brake strap upon the actuating lever at different distances from
the centre of motion of the lever, and so that the turning of the lever causes
both ends of the strap to move in the same direction, or in an equivalent.
manner, and the using of such arrangement. as a self-acting appliance for pre-
venting backward motion, substantially as berein-before described..
In witness whereof; I, the said John David Napier, have hereunto set
my hand and seal, this Sixth day of June, One thousand eight hundred
and sixty-two.