Iм- PROVEMENTS IN AUTOMATIC FRICTION BRAKES FOR MACHINERY
Year: 1878

page_text: LETTERS PATENT to John Clayton Mewburn, of 169, Fleet Street, in the City
of London, Patent Agent and Consulting Engineer, for the Invention of "Iм-
PROVEMENTS IN AUTOMATIC FRICTION BRAKES FOR MACHINERY." A com-
munication from abroad by Thomas Aldridge Weston, of Stamford, Connecticut,
in the United States of America.
PROVISIONAL SPECIFICATION left by the said John Clayton Mewburn at
the Office of the Commissioners of Patents on the 9th July 1878.
JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of London, Patent
Agent and Consulting Engineer. "IMPROVEMENTS IN AUTOMATIC FRICTION BRAKES
FOR MACHINERY." [A communication from abroad by Thomas Aldridge Weston; of
Stamford, Connecticut, in the United States of America.]
This Invention relates to that class of speed regulators in which centrifugal force
and frictional resistance are the chief elements, as for example in the Invention of
James White, described and illustrated in his "Century of Invention," pages 364
and 365, and plate 46, Figure 2, published at Manchester, A.D. 1822.
The object of the present Invention is to provide a more efficient automatic speed
regulator, applicable equally to large as to small shafts, whether the said shafts be
horizontal, vertical, or inclined in position.
I will describe the said improvements as applied to a simple wheel and axle
hoist, but they are generally applicable to any other mechanism in which it is
desirable to limit automatically the velocity of the shafting.
Suitable framing or supports are employed to carry the main shaft of the hoist,.
and a winding drum keyed thereon, together with the regulator wheel which may
also serve as the driving wheel. Upon the inner side of the said regulator wheel,
adjacent to the winding drum, I pivot at points diametrically opposite two centri-
fugal weights or levers capable of outward motion under the impulse of centrifugal
force, whereby, through the intervention of the said levers, a frictional brake strap
Unies 1

page_text: carried by the regulator wheel is contracted around a stationary friction rim
attached to the hoist frame, thus controlling and regulating the rotatory motion of
the said regulator wheel and its attached shaft and drum. The said centrifugal levers
mutually balance each other in all positions by means of a linked connection uniting
them each with a vibratory centre piece or cross lever capable of turning freely on
the main shaft.
One of the said centrifugal levers is pivoted to a fixed stud in the regulator
wheel. The other centrifugal lever in corresponding position diametrically opposite
upon the same side of the regulator wheel is secured to and turns with a short shaft
passing through the said wheel, and at its other extremity this shaft carries a crank
disc, the stud or crank pin of which engages with the free end of a brake strap,
whose other or fixed end is secured to the regulator wheel by a screw bolt and nut
for adjusting the strap lengthwise to adapt it to frictional action upon the stationary
friction rim attached to the hoist frame. Besides the said stationary friction rim
carried by the hoist frame, and rotatory friction strap carried by the regulator
wheel and operated by centrifugal force, the regulator wheel is provided with a
friction rim, and an ordinary brake strap has its fixed end attached to the hoist
frame, and its free end to a hand lever pivoted to the said frame for the purpose of
controlling and arresting by hand the rotatory motion of the regulator wheel, shaft,
and winding drum.
The normal position of the rotatory friction strap and its connected system of
centrifugal levers, is that in which the strap is expanded and free of contact with
the stationary brake rim. The levers or centrifugal weights are then at the inner
end of their path of motion nearest to the shaft. This position is secured by the
natural elasticity of the rotatory strap in its tendency to uncoil; and further, by
supplementary springs of adjustable resistance, so that any speed of rotation
desirable can be attained before the centrifugal force thus evolved shall overcome
the said springs, and then by means of the rotatory friction strap, automatically
regulate and retard the said rotatory motion.
The aforesaid system of balanced centrifugal weights or levers and vibratory
centre piece is also readily applicable to friction surfaces of disc form, as shown in
the Specification and Drawings of Thomas Aldridge Weston's Letters Patent, dated
January 29, 1863, No. 263, by means of bell-crank levers pivoted on the body of
the regulator wheel, so that one arm of each bell-crank lever rests upon the edge or
arm of the aforesaid vibratory centre piece, and the other arın of the bell-crank
lever impinges upon the said discs. In like manner, and by the same parts and
mechanism, frictional cones of the well-known form could be employed to furnish
the required frictional resistance.
Although I have described the Invention as constructed to operate by means of
balanced centrifugal weights turning upon pivots carried by the regulator wheel, it
is obvious that a single weight or lever so arranged to be operated by centrifugal
force, would be capable, but with diminished efficiency, of exerting its force upon
the brake, and thus automatically regulating the speed of the said regulator wheel.
In lieu of pivoted centrifugal levers or weights and link connections, it is clearly
possible to employ upon the regulator. wheel, sliding weights, and flexible chain
connections, as shewn in the Specification, and Figures 20 to 24 of the Drawings of
Thomas Aldridge Weston's Letters Patent, dated December 2, 1865, No. 3093.
The number of centrifugal levers need not be limited to two, for any greater
number conveniently adapted to the size of the regulator wheel may be used if each
be provided with the same linked or other connection uniting it with the common
vibratory centre piece, by which the aggregate centrifugal force of all the weights
or levers is combined and applied to the friction brake.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said John Clayton Mewburn in the Great Seal Patent Office on the 9th
January 1879.
JOHN CLAYTON MEWBURN, of.169, Fleet Street, in the City of London, Patent
Agent and Consulting Engineer. "IMPROVEMENTS IN AUTOMATIC FRICTION BRAKES
FOR MACHINERY." (A communication from abroad by Thomas Aldridge Weston, of
Stamford, Connecticut, in the United States of America.)
This Invention relates to that class of speed regulators in which centrifugal forco
and frictional resistance are the chief elements, as for example, in the Invention of
James White, described and illustrated inh is "Century of Inventions," page 364 and.
365, and plate 46, Figure 2, published at Manchester, A.D. 1822.
The object of the present Invention is to provide a more efficient automatic spoed
regulator applicable equally to large as to small shafts, whether the said shafts be
horizontal, vertical, or inclined in position.
I will describe the said improvements as applied to a simple wheel and axle hoist,
but they are generally applicable to any other mechanism in which it is desirable
to limit automatically the velocity of the shafting.
Suitable framing or supports are employed to carry the main shaft of the hoist,
and a winding drum keyed thereon, together with the regulator wheel which may
also serve as the driving wheel. Upon the inner side of the said regulator wheel
adjacent to the winding drum, I pivot at points diametrically opposite two centri-
fugal weights or levers capable of outward motion under the impulse of centrifugal.
force, whereby, through the intervention of the said levers, a frictional brake strap.
carried by the regulator wheel is contracted around a stationary friction rim
attached to the hoist frame, thus controlling and regulating the rotatory motion of
the said regulator wheel and its attached shaft and drum. The said centrifugal
levers mutually balance each other in all positions by means of a linked connection
uniting them each with a vibratory centre piece or cross lever capable of turning
freely on the main shaft.
One of the said centrifugal levers is pivoted to a fixed stud in the regulator.
wheel. The other centrifugal lever in corresponding position diametrically opposite,.
upon the same side of the regulator wheel, is secured to and turns with a short
shaft passing through the said wheel, and at its other extremity this shaft carries a
crank disc, the stud or crank pin of which engages with the free end of a brake.
strap, whose other or fixed end is secured to the regulator wheel by a screw bolt
and nut for adjusting the strap lengthwise, to adapt it to frictional action upon the
stationary friction rim attached to the hoist frame. Besides the said stationary
friction rim carried by the hoist frame, and rotatory friction strap carried by the
regulator wheel, and operated by centrifugal force, the regulator wheel is provided
with a friction rim, and an ordinary brake strap has its fixed end attached to the
hoist frame, and its free end to a hand lever pivoted to the said frame, for the
purpose of controlling and arresting by hand the rotatory motion of the regulator.
wheel, shaft, and winding drum.
The normal position of the rotatory friction strap and its connected system of
centrifugal levers, is that in which the strap is expanded and free of contact with.
the stationary brake rim. The levers or centrifugal weights are then at the inner.
end of their path of motion nearest to the shaft. This position is secured by the
natural elasticity of the rotatory strap in its tendency to uncoil, and further by
supplementary springs of adjustable resistance, so that any speed of rotation
desirable can be attained before the centrifugal force thus evolved shall overcome
the said springs, and then by means of the rotatory friction strap, automatically
regulate and retard the said rotatory motion.
In lieu of pivoted centrifugal levers or weights and link connections, it is clearly
possible to employ upon the regulator wheel sliding weights and flexible chain:

page_text: Thomas Aldridge Weston's Letters Patent, dated December 2 186 5, No. 3093.
Having explained the nature of the Invention, I will proceed more particularly
to describe with reference to the accompanying Drawings the manner in which the
same is to be performed.
In the Drawings,―
Figure 1 is an elevation of the regulator wheel, showing its outer face and the
stationary brake strap and lever.
•
Figure 2 is an elevation of the inner face of the regulator wheel.
Figure 3 is a longitudinal sectional view of the complete hoist.
Figure 4 represents the lever G detached.
Figure 5 the links for g detached.
Figure 6 the lever X detached.
Figure 7 the shaft g¹ detached.
And, Figure 8 represents the shaft l'. detached.
A and B represent supports or side frames carrying the shaft C and drum D
keyed thereon. E represents the regulator wheel, and it may also serve as a driving
wheel for the shaft C to which it is keyed. F and G represent centrifugal or
weighted levers placed in equilibrium with each other by the link connection
formed of the pivoted connecting rods f, g, and intermediate lever X which turns
freely upon the shaft C. Pins or pivots connect or joint the ends of the rods fand
g respectively to the levers F, G, and X.
The lever F is pivoted to the wheel E by a fixed stud f'. The lever G is secured
to and turns with a short shaft g¹ passing through the wheel E, and at its other
extremity the shaft g¹ carries a crank disc g³, the stud or crank pin g³.of which
engages with the free end of the brake strap H. The strap H is secured at its
fixed end to the wheel E by a screw bolt and nut h for adjusting the length of the
strap to the fixed brake pulley I. e represents a rim or flange formed upon the
wheel E to receive the strap H when released, and compel it then to take a circular
form equidistant and free from the friction surface of the pulley I. e¹ represents a
circular flange cast upon the wheel E to form a brake pulley or friction rim for the
brake strap K, one end of which, k, is secured to the frame or support B. The free
end of the brake strap K embraces the crank pin 13 of the crank disc 2 and shaft l'
attached thereto. L represents a lever fixed to the shaft to operate it, and
thereby apply the strap K to the brake rim e¹ or withdraw it.
The operation of the Invention may be thus explained:-The normal position of
the strap H, in which it is free of contact with the fixed pulley I, and the cor-
responding position of the weighted levers F, G, as shewn in Figure 2, is secured by
the uncoiling tendency in the strap to straighten itself or unbend from the pulley.
This tendency may be further aided or secured where necessary by means of spiral
or other springs O, Figure 2, of adjustable tension, to pull back the levers F and G
to the position wherein the outer or weighted ends are as near as possible to the
shaft, as shewn in Figure 2. The shaft, the regulator wheel, and all the attached
parts are then free to rotate in either direction, at any velocity less than is sufficient
by centrifugal force to swing out the levers F and G into the position of the dotted
lines in Figures 1 and 2. In the latter position the strap H is drawn into contact
with the pulley I, and with a degree of force increasing with any increase of power
and velocity in the wheel E. Thus, between the strap H and pulley I, there is
obtained an amount of frictional resistance or brake action always proportionate
with and determined by the rotatory force or velocity of the wheel E, which in this
manner is self-regulated or automatically limited in its rotatory speed. In order to
reduce the speed of the wheel E due to any applied driving force to a still lower
rate than is effected automatically, the strap K may be applied as needed to the
pulling rim e by depressing the lever L, and by so applying sufficient force the
wheel E may be stopped and held at rest.
In the Drawings the wheel E is represented as being driven by the backward or
lowering motion of a winding drum, the speed of.. which is thereby automatically.

page_text: regulated in the manner described, and a self checked lowering action applicable to
hoisting machines generally is thus obtained. It is obvious that any shaft, wheel,
pulley, or machine, however driven, may by like means be made self-regulated in its
rotatory speed.
Although I have described the Invention as constructed to operate by means of
balanced centrifugal weights turning upon pivots carried by the regulator wheel, it
is obvious that a single weight or lever would be capable, but with diminished
efficiency of exerting its force, and acting upon the brake strap in like manner.
For like reasons, the number of centrifugal weights or levers need not be limited to
two, for any greater number may be employed which can be conveniently located
upon the regulator wheel, if each be provided with the same linked connection
uniting it with the common vibrating centre or intermediate lever X. The said
common connection of the two or more weights or levers with the lever X serves to
unite them in one system, so that their aggregate centrifugal force is united and
applied to the brake strap at its junction with the system.
And having now described the nature of the said Invention, and in what manner
the same is to be performed, I declare that I claim, the automatic friction brake for
machinery constructed and operating, substantially as herein-before described, and
represented in the accompanying Drawings.
In witness whereof, I, the said John Clayton Mewburn, have hereunto set
my hand and seal, this Ninth day of January, One thousand eight hundred
and seventy-nine.
J. C. MEWBURN. (L.S.)