IMPROVEMENTS IN BREAKS AND APPARATUS FOR GIVING MOTION TO MACHINERY
Year: 1867

page_text: LETTERS PATENT to Robert David Napier, of 20, Church Row, Lime-
house, in the County of Middlesex, for the Invention of "IMPROVEMENTS
IN BREAKS AND APPARATUS FOR GIVING MOTION TO MACHINERY."
Sealed the 26th July 1867, and dated the 2nd February 1867...
PROVISIONAL SPECIFICATION left by the said Robert David Napier
at the Office, of the Commissioners of Patents, with his Petition, on the
2nd February 1867.
I, ROBERT DAVID NAPIER, of 20, Church Row, Limehouse, in the County
of Middlesex, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN BREAKS AND APPARATUS FOR GIVING MOTION TO MACHINERY,"
to be as follows:-
The first part of my Invention consists in improvements in differential
breaks. By a differential break I mean a contrivance by which a band is
made to press on a wheel in such a way that the friction between the two
which is caused by turning the wheel in one direction increases the pressure
of the band on the wheel, and likewise in such a way that the same action.
that moves the one end of the band round the wheel in one direction-moves.
the other end, or slacks or allows it to move in the same circular direction but:
at a different rate. Usually I prefer to effect this by means of connecting,
directly or otherwise, the ends of the band which I call the break band to a.
lever either straight or bent, which I call the differential lever,. and whose

page_text: fulcrum I call the differential fulcrum. By the break band I mean any
strap, rope, chain, ring, or segment or segments of a ring employed for the
purpose specified above, and the differential fulcrum may be either a joint or
any third position of the differential lever taking the place of a joint, of which
the other two positions are the places to which the break band is connected.
My first improvement in differential breaks consists in arrangements for
obtaining the differential and self-holding or partially self-holding action of
the break patented by J. D. Napier in 1861 (No. 3060), without the necessity
of having both of the band joints on the same side of the differential fulcrum.
For this object I place the joints to which the band is connected on opposite
sides, or in other convenient position with regard to the differential fulcrum
and at different distances from it, but always in such relative positions that
the strains on the joints tend to turn the lever in opposite directions. One
advantage of this arrangement is, that the differential lever may be at any
distance from the wheel which is often a great convenience, and another
advantage that when desired a very much smaller break wheel can be used
than is practicable in the other case if there is to be much strain on it. By
this arrangement also a small segment may be used, and the break be made
at the same time as self-holding, and as easily slacked as if a band nearly
surrounded the wheel which is of great use where it is inconvenient or
impossible to have a band encircling the wheel, as, for instance, in applying
breaks to carriage wheels.
Another part of my improvements in differential breaks consists in substi
tuting a pulley or other contrivance for the differential lever.
In the next part of my improvements in differential breaks, in place of the
differential fulcrum being in a permanently fixed position, it is so connected
to any mechanical appliance that it can be moved through an are of a circle,
whose centre would be that of the break wheel. In applying this arrange-
ment as a pall break, that is, a self-holding break which can be slacked when
desired, a stop is introduced in such a position as to limit in one direction
the movement of the fulcrum in the before-mentioned arc, and to make any
further movement in that direction release the pressure of the band on the
wheel; this arrangement does not require so much care in the making, and
is in many cases more suitable.
The next part of my Invention consists in arrangements by which a
differential break with a moveable fulcrum may be used for communicating
power and rotary motion to machinery. By one adaptation I obtain an
improved hoisting purchase applicable to windlasses and other hoisting
machines, and to other purposes such as screwing down screw piles and

page_text: turning drilling braces in place of the usual ratchet and pall, and by another
adaptation: I obtain an improved friction clutch specially suitable for rolling
mills or other heavy machinery which has to be suddenly thrown into gear.
For the hoisting purchase of a windlass I use a hoisting break consisting
of a differential break with a moveable fulcrum, and also a pall break or palls
or a second hoisting break. The movement of the differential fulcrum of
the hoisting break in one direction turns the wheel and raises the hoisted
weight some distance, when a reverse movement lets the other break or its
substitute take the strain and slacks the hoisting break, which is then pulled
backwards for a fresh grip when the hoisting is repeated. When there are
two hoisting breaks they are supposed to be generally used alternately to
obtain what I call a differential friction clutch; the pin of the differential
fulcrum is fixed on a crank or wheel which revolves round the same central
line as that of the break wheel, which may either be the driving or the driven
wheel, and various methods may be adopted for throwing the clutch into and
out of gear.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert David Napier in the Great Seal Patent Office on the
2nd August 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
DAVID NAPIER, of 20; Church Row, Limehouse, in the County of Middlesex,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Second day of February, in the year of our Lord One
thousand eight hundred and sixty-seven, in the thirtieth year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said Robert
David Napier, Her special licence that I, the said Robert David Napier, my.
executors, administrators, and assigns, or such others as I, the said Robert
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 BREAKS AND
APPARATUS FOR GIVING MOTION TO MACHINERY," upon the condition (amongst
others) that I, the said Robert David Napier, my executors or administrators,
by an instrument in writing under my, or their, or one of their hands and seals,

page_text: 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 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 Robert David Napier, do hereby
declare the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement thereof, that is to say:-
1.
My Invention has reference to differential brakes, and their application for
various purposes including the working of windlass barrels and giving motion
to other machinery.
In describing my Invention I shall use the terms "differential brake,"
"brake band," "differential lever," and "differential fulcrum " as explained
in my Provisional Specification, that is to say:-By a differential brake
I mean a contrivance by which a band is made to press on a wheel in such
a way that the friction between the two which is caused by turning the wheel
in one direction increases the pressure of the band on the wheel, and likewise
in such a way that the same action that moves the one end of the band
round the wheel in one direction moves the other end, or slacks or allows it
to move in the same circular direction but at a different rate. Usually I
prefer to effect this by means of connecting, directly or otherwise, the ends
of the band which I call the brake band to a lever either straight or bent,
which I call the differential lever, and whose fulcrum I call the differential
fulerum. By brake band I mean any strap, rope, chain, ring, or segment
or segments of a ring employed for the purpose specified above, and the
differential fulcrum may be either a joint, or any third position of the differential
lever taking the place of a joint, of which the other two positions are the places
to which the brake band is connected.
The first part of my Invention consists in arrangements for making friction
brakes self-holding or partially self-holding, without requiring to have both of
the joints by which the brake band is connected to the differential lever on the
same side of its fulcrum as is required in the brake patented by J. D. Napier
in 1861, (No. 3060). For the purpose stated I place the joints by which
the brake band is connected to the differential lever on different sides of its
fulcrum at different distances from it and in such relative positions that the
strains on the joints tend to turn the lever in opposite directions round its
fulcrum. One advantage of this arrangement is that the differential fulcrum
may be at any desired distance from the brake wheel; another advantage is
that a very much smaller brake wheel can be used than is otherwise practicable

page_text: when it has to carry much strain, for when the brake wheel is small and has to
bear much strain, the joints have to be so large that if they are on the same
side of the fulcrum they require to be closer together than it is practicable to
place them.
..:
This part of my Invention will be better understood by reference to the
Drawings hereunto annexed.
In Figures 1 and 2, weights W, W, are represented as held in suspension
by self-holding brakes arranged according to my improvements. In each of the
diagranis the movement of the handle H towards I will slack the brake and
allow the weight W to descend. I prefer that the differential lever A, F, B,
should be so shaped that the strains on A and B should act at nearly right
angles to the arms F, A, and F, B, of the lever.
The Figure 2 represents the arrangement which I in most cases prefer.
Another advantage obtainable from placing the joints on different sides of
the fulcrum is that the brake band may be a semicircular or smaller segment
placed between the brake wheel and the differential lever or bell crank. This
arrangement leaves one side of the brake wheel clear so that it can be applied
to the wheels of railway and other carriages. Figure 3 represents this arrange-
ment, a weight W is held suspended by a self-holding brake of this description
where the movement of the handle H towards I would allow the weight W to
descend as in Figures 1 and 2, but the strains on A and B are compressive
and not tensile..
A useful application of self-holding brakes constructed as above described
is to obtain what I call a self-acting revolving bit for riding aud veering out
by, intended mainly for the use of vessels provided with capstans. For the
object in view I employ a barrel similar to a windlass barrel arranged for
taking several turns, and curved so as to fleet the chain as the barrel revolves,
or otherwise a chain wheel for taking a portion of a turn of a chain, and
provided with stops to prevent the chain from passing over it without turning
the wheel. The barrel or wheel is actuated by a self-holding brake, such
for example as that shown at Figure 3, which allows it to revolve in one
direction but not the other till the brake is slacked: The barrel or wheel is
placed between the hawse pipe and the capstan; the chain is passed several
times round the barrel or partly round the wheel, as the case may be, and
one part or end being passed through the hawse pipe, the other for the
purpose of being hove in is 'taken to the capstan.. When heaving in the
barrel, or chain wheel turns round in the direction
should any accident happen to the capstan the
from running out by means of the barrel or chain
that frees the brake, and
chain' will be 'prevented
wheel being held in that

page_text: direction by the differential brake, and when it is desired to veer out the chain
is taken off the capstan and the brake is slacked as much as desired. By this
arrangement the capstan requires no pawls, and is therefore always free to work
in either direction, many accidents have occurred through the pawls of capstans
being left out of gear, these would be prevented by the use of the self-holding
revolving bit.
1
A very advantageous arrangement in many cases is that shown in Figure 4,
where a chock.c, c, is introduced to transmit the strain on the differential
fulcrum to the brake wheel, and a pair of links D, D, are jointed to the
chock c, c, and to a standard E. By this arrangement the strains on the
brake band and differential lever are much reduced, and the strength required
to mount the standard E is not nearly so much as what would be required to
hold the differential fulcrum in its position. In the preceding arrangements
the direction in which the brakes are self-holding is permanent, but it is
frequently desirable that the action should be capable of being reversed, as
for instance when applied to capstans intended for heaving both ways. For
this object I make a two-fold differential fulcrum in the manner shown in
Figure 5, where A, B, is the differential. lever, as in the previous cases.. If
the handle H, on which is a small weight w, is situated as in the Drawing,
then F is the differential fulcrum, and the brake is self-holding in the direction
to keep the hoisted weight W in suspension; but if the handle be moved over
to I, then becomes the differential fulcrum, and the self-gripping direction is
reversed, and if the handle be placed in an upright position the brake wheel
will be free to turn in any direction.
Another part of my Invention consists in connecting the differential fulcrum
of differential brakes to a lever or any other mechanical appliance in such a
way that it can be moved through an arc of a circle whose centre is that of
the brake wheel, and in placing a stop in such a position that the movement of
the fulcrum beyond a given distance in one direction will release the pressure
of the band on the wheel. One mode of effecting this is represented in
Figure 6, where the differential fulcrum F is held in its position by means of
the link G jointed to the handle H, which is fixed by a pin through the
standard I, when the brake wheel would be free to turn in the direction that
would raise the weight W, but would be prevented from turning in the
opposite way. If the pin be taken out of the standard I and the handle H
lowered till the lever F, A, touches the stop D, then any further lowering of
the handle will slack the brake band and allow the weight to descend. The
lever F, A, should be heavy enough, or should have sufficient weight added
to it, or should be so actuated by a spring as to ensure the action of the

page_text: brake when the handle H is raised high enough, and the stop D may be made
to act on a stud on any part of the brake band in place of on the lever F, A,
thus, as is shown in dotted lines, a stud L may be fixed on the brake band,
which when the pin I is removed comes against a fixed stop L'. One
advantage of this arrangement as compared with placing the fulcrum F in a
permanently fixed position, as in J. D. Napier's Patent already referred to is,
that while it is equally applicable as a substitute for pawls, it becomes for
lowering purposes according to the position of the stop as nearly equivalent in
action to a common brake as may be desired, and it is not therefore so liable
to be subjected to undue strain through being thrown too suddenly into gear
by a careless attendant. From the same cause also it arises that in as far as
lowering is concerned there is no objection to giving any amount of differential
action to the brake, whereas with the fixed fulcrum the effect of excessive
differential action is to make it difficult to lower steadily, so that with a
moveable fulcrum as described there is not so much care required in making
and adjusting as where the fulcrum is in a permanently fixed position.. The
arrangement for slacking a self-holding brake by the movement of the fulcrum
may also be applied to differential brakes with the band joints on different
sides of the fulcrum.
According to another part of my Invention I make use of differential
brakes for giving motion to the barrels of windlasses and other . hoisting
machines. When a differential brake is used for driving machinery I call it
a hoisting brake, and when used as a substitute for pawls I call it a pawl
brake.
In applying my improvements for working windlasses I use one or more
hoisting brakes and one pawl brake. The hoisting brakes may be arranged
in a similar manner to that shown in Figure 6, where, if the fulcrum Fis
moved upwards, it will turn the wheel and raise the weight W. Having
raised the weight a certain distance the fulcrum F. is then to be lowered;
which will allow the pawl brake to take the strain caused by the weight W
and slack the hoisting brake band, which will then be drawn round the brake
wheel by the weight of the lever F, A. By thus alternately raising and
lowering the fulcrum F the weight may be hoisted any distance. By lowering
the fulcrum till the stop comes in contact with the lever (or band) as explained
in describing the method of lowering by the movement of the fulcrum, the
hoisting brake will be slacked, and the barrel left entirely under the control
of the pawl brake. Other means may be adopted besides the weight of the
lever F, A, for causing the hoisting brake band to turn round the wheel when
the fulcrum F is being lowered, as for instance by placing a small chain

page_text: from m ton of sufficient length to allow the brake band to slack a little.
Usually I prefer that a windlass should be provided with two hoisting brakes
worked independently of each other, and one pawl brake, when the hoisting
brakes may be worked alternately, except on the occurrence of a temporary
extra strain, such, for instance, as when breaking an anchor out of the ground,
when all the men at the windlass can immediately place themselves and the
hoisting handles in the position in which they can use their strength to the
greatest advantage, and they can then all work together till the extra strain
is overcome, when they can immediately go on working alternately as before..
By using the arrangement described for slacking the hoisting brakes and
having them independent of one another, then when it is required to slack
back the windlass, all that has to be done is to leave off hoisting and slack
the pawl brake, for the hoisting brakes will free themselves sufficiently for
veering out whenever the differential lever or brake band touches the stop,
which will take place by the backward movement of the windlass barrel; by
this arrangement also the hoisting brakes may separately, or together, be
used as lowering brakes. Figure 7 is an end elevation, and Figure 8 is a
plan of a windlass thus arranged; Figure 9 is a section taken at the line A, B,
of Figure 8. a, a, are the standards, and 6 the windlass barrel carried thereby ;
c, c, are the hoisting brakes; they receive motion independently, the one of
the other by means of hand levers d and links e. The brake strap is - pre-
vented opening too wide at the return stroke by means of an adjustable screw
stop c¹ on the differential lever. a¹, a¹ are stops on the standards, against
which the differential levers rest when the hand levers are in their highest
positions, so as to slack the brake strap and allow the chain to be veered out;
fis the pawl brake, it is constructed in a manner similar to that represented
at Figure 4, and already described; it grips the windlass barrel when the
strain tends to turn it in a backward direction, but allows it to rotate freely
forward; g is a hand wheel and screw; when screwed down it acts as a stop
to the brake band and prevents it gripping, or regulates the amount of grip
that may be required; it is used when the windlass is required to turn back-
wards in veering out. I am aware that it has before been proposed to work
windlass barrels by means of the friction between a wheel and a band nearly
surrounding it, and jointed to a lever in a similar way to the brake band and
differential lever in Figure 6; but I claim as my Invention the arrangement for
throwing out of gear, by allowing the differential lever or brake band to press
on a stop placed in a position suitable for the purpose; and I also claim the
working of windlass and other barrels by means of hoisting brakes similar to
that described in conjunction with the substitution of a differential brake in

page_text: place of the ordinary pawls. The main advantage of working windlasses
by hoisting brakes, as compared with other plans in use, is the facility for
veering out, and if pawls are used this advantage is not gained, or only in a
comparatively slight degree.
An important application of differential breaks similar to that described,
and which forms another part of my Invention, is for screwing down screw
piles, such as are used for bridges and piers, for which purpose the brake
band is made to grip the outside of the pile, which is cylindrical and usually
of cast iron, but in this case it is advisable, as is represented at Figures 10;
to have attached to the brake band and nearly opposite to the differential
lever another lever, to the outer end of which, as well as to the extreme end
of the differential lever, ropes or chains are attached, by which to pull them
alternately one way, then the other. The two levers mentioned are allowed
to rest in the manner shown on guide rails on a framework erected round the
pile, and these guide rails are. slanted to suit the pitch of the screw of the
pile; then by pulling the levers in one direction the brake band grips the pile,
turns it round, and screws it down, and the.reverse movement slacks the band,
and by means of the slanted framework acting on the levers the brake band is
made to slide up the pile and into a position for a fresh grip, and in this way
by alternately pulling the in opposite directions piles of any length may
be screwed down, and great saving of time is thus effected as compared with
repeatedly keying on a capstan afresh, as is the usual practice.
Another part of my Invention consists in using a differential brake for the
purpose of obtaining what I call a differential friction clutch for communicating
power and rotary motion to machinery that requires to be occasionally started
and stopped, especially to machinery liable to violent shocks, such, for instance,
as rolling mills and dredging machines. In these arrangements a differential
lever is not pulled backwards and forwards, but is connected by its fulcrum to
a crank or wheel which revolves in a continuous direction round the same
central line as that of the brake wheel, so that the differential fulcrum
describes a circle concentric with but of larger diameter than the brake wheel.
A clutch of this description is shown partly in section at Figure 11. A is a
spur wheel running loose upon a shaft I driven continuously by a steam
engine, or otherwise; B is a wheel gearing with the wheel A, and forming
part of a machine which it is desired to throw into and out of action from
time to time without concussion; C is a disc forming part of the wheel A; it
together with some of the other parts is shown in end view at Figure 12; it
carries the fulcrum of the differential lever M, to the ends of which a brake
band is fixed; this band encircles a pulley D which is fast. upon the shaft I;

page_text: E is a boss which can both slide and turn upon the axis I; it has two arms K
and L upon it, the extremities of which pass through slotted plates F and G.
The plate F, which is shown separately in plan at Figure 13, is fixed on the
brake band; the other plate G is similar, but it is fixed upon the disc C; the
slots in the plates F and G are inclined, as is shown; thus it will be seen that
by moving the boss E along the shaft I by means of its lever handle H the
differential lever M can be caused to rock on its fulcrum, and the brake band
tightened or slackened; when it is slack the machine in connection with the
wheel B will be out of gear, and as the band is tightened by moving the
handle H the machine will be gradually put into motion. If it is desired that
the friction clutch should give way should an undue strain come on the
machine which is driven, an adjustable stop may be employed to limit the
motion of the differential lever M, or of the band lever H. By the use of a
differential friction clutch machinery may be thrown into or out of gear with
great ease and safety, and because the gripping power is self-acting, or as
nearly so as may be desired, very little force is required to keep the clutch
in gear, as compared with that required when driving machinery by common
frictional gearing. These clutches possess all the properties of a friction cone
for limiting the strain to be transmitted through them, and have much greater
certainty of action, ery time the clutch is thrown out of gear the friction
surfaces are changed, so that they never get any chance of setting fast, and
the amount of power that can be transmitted through them may be regulated
by the turning of a single bolt, either when the clutch is in or out of gear.
In witness whereof, I, the said Robert David Napier, have hereunto set
my hand and seal, this Second day of August, in the year of our Lord
One thousand eight hundred and sixty-seven.
ROB. D. NAPIER. (L.S.)