AN IMPROVED ROPE GRIPPING DRIVING PULLEY
Year: 1879

page_text: LETTERS PATENT to Frederick Hurd, of Wakefield, in the County of York, and
of 109, Ferry Road, Edinburgh, Engineer, for the Invention of "AN IMPROVED
ROPE GRIPPING DRIVING PULLEY."
Sealed the 24th June 1879, and dated the 13th March 1879.
.
PROVISIONAL SPECIFICATION left by the said Frederick Hurd at the Office
of the Commissioners of Patents on the 13th March 1879.
FREDERICK HURD, of Wakefield, in the County of York, and of 109, Ferry Road,
Edinburgh, Engineer. "AN IMPROVED ROPE GRIPPING DRIVING PULLEY,"
My Invention consists in improvements on the Invention for which former
Letters Patent were granted to me, in conjunction with Samuel Firth, on the 26th
day of February 1870, No. 571.
My present Invention consists in making the rim of the pulley of a curved
U shape, the sides being connected by midfeathers at equal distances apart, which
midfeathers act as bearings for the gripping levers, and strengthen the sides. On
the sides of the rim are cast suugs or projections to receive the spokes or arms of
the pulley, which vary in number and strength according to the amount of power
to be transmitted.
In each division between the midfeathers are three or other convenient number
of gripping levers hinged to a forked bolt which passes through the bottom of the
rim, and is prevented from sliding out beyond the required distance by a cottar,
split pin, or other equivalent. These levers are hinged in such a manner that the
rope is held close to the fulcrum, and they are formed or recessed so as to grip
about three fourths of the circumference of the rope. The outer ends of the levers
are so arranged that they close with the slightest pressure of the rope, and grip the
rope, in proportion to the power that is being transmitted, sufficiently tight to
prevent the possibility of slipping. The lower ends of the levers cross each other
and project beyond the fulcrum, and rest on a bearing plate or block resting on any
suitable elastic bearing, through which the bolt passes. These plates or blocks
slide freely on the bolts, and bear against the midfeathers, and take the driving
strain of the rope. This elastic bearing gives elasticity to the gripping action, thus
enabling the pulley to be run at a high speed without jar.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Frederick Hurd in the Great Seal Patent Office on the 12th
September 1879.
FREDERICK HURD, of Wakefield, in the County of York, and of 109, Ferry
Road, Edinburgh, Engineer. "AN IMPROVED ROPE GRIPPING DRIVING PULLEY."
My Invention consists in improvements on the Invention for which former
Letters Patent were granted to me in conjunction with Samuel Firth, on the 26th
day of February 1870, Number 571. My present Invention consists in making
the rim of the pulley of a curved U shape, the sides being connected by midfeathers
at equal distances apart, which midfeathers strengthen the sides and act as bearings
for the gripping levers. On the sides of the rim are cast snugs or projections to
receive the spokes or arms of the pulley, which vary in number and strength
according to the amount of power to be transmitted. In each division between the
midfeathers are three or other convenient number of gripping levers hinged to a
forked bolt, which passes through the bottom of the rim, and is prevented from
sliding out beyond the required distance by a cottar, split pin, or other equivalent.
These levers are hinged in such a manner that the rope is held close to the fulcrum,
and they are formed or recessed so as to grip about three fourths of the circum-
ference of the rope. The outer ends of the levers are so arranged that they close
with the slightest pressure of the rope, and grip the rope in proportion to the power
that is being transmitted sufficiently tight to prevent the possibility of slipping.
The lower ends of the levers cross each other and project beyond the fulcrum,
and rest on a bearing plate or block resting on any suitable elastic bearing, through
which the bolt passes. These plates or blocks slide freely on the bolts, and bear
against the midfeathers, and take the driving strain of the rope. This elastic
bearing gives elasticity to the gripping action, thus enabling the pulley to be run at
a high speed without jar.
And in order that my Invention may be fully understood and readily carried
into operation, I will proceed to describe the three accompanying Sheets of Drawings,
reference being had to the figures and letters marked thereon.
On Sheet 1, Fig. 1 is a transverse section, and Fig. 2 an elevation partly in
section of one of my improved rope gripping driving pulleys. The rim a is made
of a curved U shape, and the sides of the rim are connected at intervals by the
midfeathers b, which are placed at equal distances apart around the circumference
of the pulley; these midfeathers strengthen the sides of the rim. On the sides
of the rim a are cast snugs or projections c to receive the outer ends of the spokes
or arms d, the inner ends of which are cast in the nave of the pulley.
In each division or space between the midfeathers bare placed the three gripping
levers e, e, and f, which work freely on the stud g which passes through the forked
head of the bolt h. The bolts h pass also through the plates i, the blocks j, the
india rubber k, and then through the bottom of the rim a, and at the end of
each bolt is a cottar, split pin, or other equivalent, to prevent the bolts sliding out
too far.
The
The levers e and f are hinged in such a manner that the rope bears close to the
fulcrum stud g, and they are so shaped as to grip about three fourths of the circum-
ference of the rope.
As the pulley revolves the rope presses the levers into the rim,
and the outer ends of the levers acting on the insides of the rim close the levers on
to the rope, and grip it with a force proportionate to the power transmitted.
lower ends of the levers cross each other, and project beyond the fulcrum stud, the
ends resting on the plates i which fit between the midfeathers b. The tension on
the rope causes one edge of the plate i to bear against the midfeather, thereby
taking the driving strain of the rope off the gripping levers.
As soon as the rope is released from the gripping levers the bolts h are forced
partly out of the rim a by the action of the springs k, and they remain in that
position until they are again acted upon by the rope, as shewn in Fig. 2.

page_text: This improved gripping pulley may be keyed on the driving axle, or it may be
connected to it by the friction box, shewn in Fig. 1, or other equivalent for trans-
mitting the power.
On Sheet 2, Fig. 3 is a transverse section, and Fig. 4 an elevation of one of my
improved rope gripping driving pulleys, in which the gripping levers are held in a
bearing box actuated by a volute spring, which keeps the levers wide open ready
to receive the rope, and allows them to close when the strain of the rope comes on
to them. The lower ends of the levers rest in recesses formed in the bearing box,
and the bottom of the box is acted upon by the spring, which is retained in its
position on the bolt by a cotter. This spring has no bearing at the bottom of the
rim, and has its action between the cottar, which retains it in its position on the
bolt, and the stud on which the levers hinge. Thus the bearing box and the levers
are supported always on the outer extremities of the levers, and when the pressure
of the rope comes on the levers they slide downwards into the groove of the rim
as far as the diameter of the rope will admit, thus gripping the rope in proportion
to the power transmitted. The bearing box, which is marked i, above mentioned
is in lieu of the plate i shewn in Figs. 1 and 2. is the volute spring, and all the
other parts have letters of reference similar to the corresponding parts on Figs. 1
and 2, but the pulley shewn in Figs. 3 and 4 needs no elastic bearings, as the rope
and the extremities of the gripping levers form the bearings.
On Sheet 3, Fig. 5 is a transverse section, and Fig. 6 au elevation of one of my
improved rope gripping driving pulleys, almost exactly similar to that shewn in
Figs. 3 and 4, the difference being that the bolt h does not pass through the bottom
of the rim, but is kept from sliding out too far by the same cottar which secures the
volute spring in its position coming in contact with the top of slots formed in the
sides of the rim, which allows this principle to be applied to pulleys of very small
diameter, and to the periphery of internal toothed wheels, or cast with screw pro-
pellers or turbines, as shewn in Figs. 7 and 8.
Having thus stated the nature of my Invention, and described the manner of
performing the same, I declare that I claim,-
First. The improved construction of rim with the midfeathers, as shewn, and for
the purpose described.
Secondly. The india rubber or other elastic bearing k combined with the block i,
shewn in Figs. 1 and 2, to keep the levers wide open ready to receive the rope
freely when the pulley is in a horizontal or any other position.
Thirdly. The bolt h, substantially as shewn and described.
Fourthly. The gripping levers, as shewn and described.
Fifthly. The bearing box and volute spring, as shewn and described.
Sixthly. Forming slots or stops in the side of the rim for limiting the outward
movement of the gripping levers, as shewn in Figs. 5, 6, 7, and 8, and thus allowing
the gripping pulley to be cast with internal toothed wheels, turbines, centrifugal
pumps, or screw propellers.
In witness whereof, I, the said Frederick Hurd, have hereunto set my hand
and seal, this Tenth day of September, One thousand eight hundred and
FREDERICK HURD. (L.S.)