IMPROVEMENTS IN PULLEY BLOCKS, PARTS OF WHICH. IMPROVEMENTS ARE ALSO APPLICABLE TO CRANES, OVERHEAD TRAVELLERS
Year: 1881

page_text: LETTERS PATENT to Thomas Henry Ward and Edmund Howl, of the Firm
of Howl, Ward, and Howl, of Tipton, in the County of Stafford, Engineers,
for an Invention of IMPROVEMENTS IN PULLEY BLOCKS, PARTS OF WHICH.
IMPROVEMENTS ARE ALSO APPLICABLE TO CRANES, OVERHEAD TRAVELLERS,
"
PROVISIONAL SPECIFICATION left by the said Thomas Henry Ward and
Edmund Howl at the Office of the Commissioners of Patents on the
17th September 1881.
IN
THOMAS HENRY WARD. and EDMUND HOWL, of the Firm of Howl, Ward, and
Howl, of Tipton, in the County of Stafford, Engineers. "IMPROVEMENTS
PULLEY BLOCKS, PARTS OF WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO
CRANES, OVERHEAD TRAVELLERS, HOISTS, AND OTHER LIKE APPARATUS."
Our Invention relates to imprevements in pulley blocks, parts of which are also
applicable to cranes, overhead travellers, hoists, and other like apparatus, and it
has reference more particularly to improvements in differential pulley-blocks of
the description known as Weston's.
The object of our Invention is to produce a pulley block which shall have the
advantages of a Weston combined with a more efficient lowering gear, whereby we
obtain a Weston's differential block, self sustained only when required, which shall
be capable of being lowered not by the effort of gravity direct which is relying on
a powerful break gear to arrest the descent of the load, but by the differential
effort only, and consequently having a speed much slower and much safer due to
that differential or retarded gravity.
In order to accomplish the object before mentioned we employ a Weston's block
complete, with chain and top and bottom sheaves, but these top sheaves have their
relative diameters proportioned so that the mechanical efficiency is slightly greater
than the friction, thus constituting a block which is non-self sustained, say, for
example, the ratio of diameters is as six is to five.

page_text: The shaft or axle supporting the top sheaves has a collar at one end and is
screwed at the other with a quick thread, hereinafter more particularly referred to,
and these top sheaves are cast together and serve as a nut which is screwed on to
the shaft at the other end.
Between these sheaves and the collar a ratchet wheel is threaded on to this shaft
having a detent fixed to some convenient part of the frame and facing in such a
direction that although the ratchet wheel is free to rotate in the direction
equivalent to raising the load as a Weston's, yet it is prevented from rotating in the
opposite direction.
The above mentioned thread of the screw should be as quick as possible, so
long as it is sufficient to pick up the load, otherwise if it is too slow it will be
difficult to release it in lowering the same. A spocket wheel is keyed to the
shaft.
Now the shaft represents a screwed bolt, the collar its head, the turn sheaves its
nut, and the spocket wheel a lever. If the bolt is rotated by its lever in the
direction of raising as a Weston it will be nothing more nor less than rotating a
screwed bolt inside its own nut, consequently this nut will grip the ratchet wheel
tightly between it and its head, and all four, videlicet, lever, bolt, ratchet wheel,
and nut will rotate together in raising the load, and since the detent prevents the
ratchet wheel from running back again, then until the bolt has been unscrewed.
again it remains suspended as a self sustained block. Now by rotating the lever in
the opposite direction, that is, unscrewing the bolt out of its nut, the ratchet wheel
is released, and since the nut which was previously prevented from turning by the
friction of this ratchet gripping it is once more free to rotate, it will grip the ratchet
again unless the bolt is being at the same time and at the saine speed rotated in
the direction of unscrewing; therefore in order to lower a load it requires attention
but not labour."
According to another modification of the said Invention we utilize the spocket
wheel instead of the sheaves as a nut, thereby gripping both the ratchet wheel and
the sheaves between head and nut. In this case, however, it will be seen that after
releasing by the nut (which is also a lever) the load will continue to descend until
this out is screwed up again.
Another modification of the same Invention is similar in action to the last, that
is, the spocket wheel forms the nut and lever at the same time, but this nut only
grips the ratchet wheel between it and its head, the twin sheaves being keyed
on the shaft on one side only, which shaft is arrested by the ratchet wheel.
According to another modification of the last we cast the sheaves separate, and
one at each end of the bolt with the spocket, nut, ratchet, and head between, and
for further convenience these sheaves may be outside the frame.
Modifications of the above may be made for heavier loads by adding another
shaft, which is rotated and drives by gear the main shaft, in which case either the
sheaves or the pinion can be gripped by the ratchet, as most suitable.
According to another modification of the last, which is adapted for very heavy
loads, a worm wheel actuated by a worm is driven by one or more spockets and is
in contact with the ratchet wheel on either one shaft or other.
In the three modifications last herein before described the power is applied
centrally, so that the block is perfectly balanced.
Like applications of this arresting gear where suitable may be made in the
bottom sheave instead of the top sheaves.
Other suitable break-gears may also be employed, such, for example, as the
brake-strap, arresting the differential effort of gravity and not the direct effort
itself, whether applied either to the top or bottom sheaves.
Referring to the explanation of this friction gear it has been herein before stated
that the two top sheaves were proportioned as non self sustained and that they
were cast together, and as such served as a nut to its corresponding screwed bolt.
Now according to another modification of this Invention the diameters of these

page_text: top sheaves are proportioned as a self sustained block; for example, having the
ratio of diameters proportioned, as eleven is to twelve, and these two sheaves are
cast separate and one only is used as a screwed nut, the other being gripped
between the head and the nut instead of the ratchet wheel in raising as before, but
in lowering by means of the spocket wheel or lever the one sheave will be released
so that these two sheaves (that is, the one loose sheave and the nut) will run in
opposite directions by the effort of gravity direct in place of the differential effort
of gravity, as before mentioned. This nut will grip the sheave again unless the
bolt is continually being rotated out of its nut and so constitute a self sustained
differential block again. It will be observed that the ratchet and the detent will
be dispensed with, since when gripped together these sheaves constitute a self
Bustained differential block. It will also be observed that in this case it requires
attention though not labor to lower a load.
As a modification of this arrangement the power may be applied centrally by
arranging the spocket wheel in the centre and keeping the sheaves to opposite ends
of a hollow shaft having an internal shaft with friction discs fixed at each end of
the same.
The Invention may be otherwise modified in its details without departing from
the principles herein before enunciated.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Henry Ward and Edmund Howl in the Great Seal Patent
Office on the 17th March 1882.
"
THOMAS HENRY WARD and EDMUND HOWL, of the Firm of Howl, Ward, and
Howl, of Tipton, in the County of Stafford, Engineers. IMPROVEMENTS IN
PULLEY BLOCKS, PARTS OF WHICH IMPROVEMENTS ARE ALSO APPLICABLE TO
CRANES, OVERHEAD TRAVELLERS, HOISTS, AND OTHER LIKE APPARATUS."
Our Invention relates to improvements in pulley blocks, parts of which are also
applicable to cranes, overhead travellers, hoists, and other like apparatus, and it has
reference more particularly to differential pulley blocks constructed somewhat after
the manner of those known as "Weston's" pulley blocks, but the object of our
Invention is to produce a pulley block which shall have the advantages of a
"Weston pulley block" combined with a more efficient lowering gear whereby we
obtain a Weston's differential block, self sustained only when required, which shall
be capable of being lowered not by the effort of gravity direct (which necessitates
reliance upon a powerful brake gear to arrest the descent of the load) but by the
differential effort only and consequently having a speed much slower and much
safer, due to that differential or retarded gravity.
In order to accomplish the object before mentioned, we employ a block complete
with chain and top and bottom sheaves after the manner of a Weston pulley, but
the said top sheaves have their relative diameters proportioned so that the
mechanical efficiency is slightly greater than the friction, say, for example, the ratio
of the diameters of the sheaves is as six is to five, thus constituting a block which
is not self-sustained.
And in order that our said Invention may be fully understood, we shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several Figures on the annexed sheet of Drawings, the same letters of reference
indicating corresponding parts in all the Figures.
Figure 1 represents in side elevation and transverse vertical section the top
sheaves-of-a-pulley-block-constructed-according-to-our-Invention.-The-two-
sheaves a and b are cast or formed in one or are rigidly connected together, after
the manner of the sheaves of a "Weston pulley block," but the sheave b is of such
diameter relatively with the diameter of the sheave a, that instead of the load
being self sustaining it is only partly so; or, in other words, the mechanical efficiency
or the action of the force of gravity is slightly greater than the friction. The shaft
or axle c of the sheaves is carried in bearings in the frame d which carries the hook
or shackle e.
The axle c has a collar f thereon, and is screwed at c² with a quick thread taking
into a female screw in the sheaves, which thus serve as a nut, which is screwed on
to the shaft from the end opposite the collar f. Between the sheave a and the
collar fa ratchet wheel g is threaded on to the shaft c, the said ratchet wheel being
provided with a detent à mounted upon a pin 2, carried by the frame d, the teeth
of the said ratchet wheel facing in such a direction that although the said wheel is
free to rotate in the direction for raising the load, as in a Weston pulley block, yet
it is prevented by the detent / from rotating in the opposite direction. The thread
of the screw c² should be as quick as possible, so long as it is sufficient to pick up
the load, otherwise if it is too slow it will be difficult to release it in lowering the
load. The nut c³ prevents the longitudinal movement of the shaft c. A sprocket
wheel is keyed to the shaft c, over which sprocket wheel the operating chain is
passed. It will be seen that the shaft c represents a screwed bolt, the collar f
constituting its head, the sheaves a and b its nut, and the sprocket wheel i a lever,

page_text: and if the bolt is rotated by this sprocket wheel in the direction of raising, as in a
Weston pulley block, it will be equivalent to rotating a screw bolt inside its nut.
Consequently this nut (the said sheaves a and b) will grip the ratchet wheel g
tightly between itself and the bolt head (the collar f) and all four, videlicit :-The
lever or sprocket wheel i, the bolt or axle c, the ratchet wheel g, and the nut or
sheaves a, b, will by their frictional bearing rotate together in raising the load, and
since the detent / prevents the ratchet wheel g from running back again, then
until the bolt or axle c has been unscrewed again it remains suspended as a
self sustained block. When the lever or sprocket wheel i is rotated in the opposite
direction, that is in the direction necessary for unscrewing the bolt or axle c out of
its nut (the sheaves a, b,) the ratchet wheel g is released from its frictional bearing
against the said sheaves, and since the said sheaves which were previously prevented
from trurning by the friction of this ratchet wheel gripping it are once more free to
rotate they will again run forward upon the screw to grip or pinch against the
ratchet wheel again unless the bolt or axle c is being at the same time and at the
same speed rotated in the direction of unscrewing which will be done by the person
lowering the load at such a rate as to compensate for this tendency of the sheaves
to grip or pinch against the said ratchet wheel g; therefore in order to lower a load
it requires attention but not labour.
According to another modification of the said Invention, we utilize the sprocket
wheel instead of the sheaves as a nut, thereby gripping both the ratchet wheel and
the sheaves between head and nut. In this case however, it will be seen, that after
releasing by the nut (which is also a lever) the load will continue to descend until
this nut is screwed up again.
Figure 2 represents in side elevation and transverse vertical section this
modification. The parts which correspond to the like parts in Figure 1 are
marked with the same letters of reference. The sprocket wheel is upon the
shaft c, and the screw c² engages in a female screw in the boss of the said sprocket
wheel, which boss has also a frictional bearing upon or in the boss of the sheaves.
The action, it will readily be seen, is analogous to that described with regard to
Figure 1, the rotation of the sprocket wheel in one direction causing it to run upon
the screw c², grip the sheaves a, b, and ratchet wheel g between itself and the
collar and the reverse rotation releasing this grip for lowering the load.
Figure 3 represents in side elevation and transverse vertical section a modifi-
cation of the arrangement shewn in Figure 2, the sprocket wheel i, as in that
arrangement, forming both the nut and the lever at the same time, but the said
nut only grips the ratchet wheel g between itself and the collar f, the twin'
sheaves a, b, being keyed on the shaft c, which shaft is arrested when the wheel i
is turned in the direction for raising a load by the frictional bearing of the ratchet
wheel upon the collar f. The parts are marked with the same letters which are
used to denote the like parts in the preceding Figures.
According to another modification of the last described arrangements, we cast
the sheaves a, b, separate, and keyed one at each end of the axle c with the
sprocket wheel i, ratchet wheel g, and its bearing surface between, this arrange-
ment of the sheaves being outside the frame, and the sprocket wheel between, in
vertical line with the load, to give the advantage of a central pull of the actuating
chain.
Figure 4 shews this last named modification in side elevation and transverse
vertical section, wherein the parts are marked with the same letters as are used
to denote like parts in the other Figures. The sheaves a, b, are keyed to the ends
of the axle c, which project beyond the frame d. The sprocket wheel i, as in the
arrangements, Figures 2 and 3, forms the nut for pinching, or tightening, and
releasing the sprocket wheel. The action of the parts is essentially similar to the
action explained with regard to the preceding arrangements, and will be readily
understood without further description.
Modifications of the above may be made for heavier loads by adding another

page_text: shaft, which is rotated, and drives by gear the main shaft or axle c, in which case
either the sheaves or the pinion can be gripped by the ratchet, as most suitable.
Figure 5 represents in side elevation and transverse vertical section an arrange-
ment according to this last mentioned modification, wherein parts which are like
those in the preceding Figures are marked with the same letters of reference.
This modification, Figure 5, is similar in general arrangement to that shewn in
Figure 4, but in place of the nut which runs upon the screw c² being in the boss
of the sprocket wheel, it is in the toothed wheel l, which takes the place of the
said sprocket wheel, which is keyed to a shaft j turning in bearings in extensions
of the framing d; the said shaft carries a pinion k revolving therewith. It will
readily be seen that this arrangement only differs in its general arrangement and
action from those before described in the matter of gain of power at the expense
of speed.
Figure 6 represents similar views of an arrangement according to this last
modification, wherein the supplementary shaft j carries the screw ², the equivalent
of c, the pinion & constituting the nut for running in one or other direction on
the said screw for gripping the ratchet wheel g by frictional contact therewith. In
this arrangement, Figure 6, the sheaves a and b are shewn as being cast in one with
the toothed wheel l. It will be readily understood that the principle of action is
the same as in the preceding arrangements, and we have marked in this Figure the
parts which correspond to those in the other Figures, with like letters of reference.
According to another modification of the last which is adapted for very heavy
loads, a worm wheel actuated by a worm is driven by one or more sprockets and
is in contact with the ratchet wheel on either one shaft or other.
Figure 7. is a diagram illustrating this arrangement. The sheaves are shewn
at a, b, and keyed to the shaft c is the worm wheel m, with which gears the
-worm n, which is the equivalent of the pinion in the arrangements shown in
Figure 6, and is on a shaft j carrying the ratchet wheel g, as in the said Figure 6.
In the four modifications last hereinbefore described, the power is applied or
conveyed to the axle c centrally so that the block is perfectly balanced.
Although we have described our Invention as applied to the top sheaves of
pulleys, yet it will be readily understood that like applications of our arresting
gear may be made where suitable or desirable to the bottom sheaves instead of to
the top sheaves, provided that the top or differential sheaves are proportioned as
before described, so that the whole of the load is not self sustained.`
_Other-suitable-break-gears-may-also-be-employed,such-for-example-as-a-brake-
strap for arresting the differential effort of gravity and not the direct effort itself,
whether applied either to the top or bottom sheaves. In this case the top sheaves
are proportioned, as hereinbefore described, with regard to the twin sheaves a, b,
that is to say-The one sheave is not so near the diameter of the other as to
render the pulley block self sustaining, but is so proportioned that the gravitation
of the load is to some extent in excess of the power of retention exerted by the
friction. In place of the screw c² and the ratchet wheel 9 a break is employed,
which may be either a brake strap or a brake lever, to be brought to bear upon a
friction pulley or the like upon the shaft c, to which the twin sheaves are keyed,
or upon the axis of the lower sheave, in order to restrain or prevent the descent of
the load. This is very readily effected by these means, owing to the fact that only
a small portion of the load to the extent to which the mechanical equivalent or
gravitation of the load exceeds the friction has to be arrested by the said brake.
It will be readily understood that some of the arrangements hereinbefore
described can be with advantage applied to cranes, and to or as overhead travellers
or hoists, and the like. For example, the arrangement, Figure 4, is well adapted
for a crane, and the arrangement, Figure 3, can be readily adapted as or to a hoist
by arranging the bearings of the shaft c in convenient standards or brackets.
Having now described and particularly ascertained the nature of our said
Invention, and the manner in which the same is or may be used or carried into

page_text: effect, we would observe in conclusion that we do not limit ourselves to the precise
details herein described, as the same may be varied without departing from the
nature of our Invention, but what we consider as novel and original, and therefore
claim as the Invention secured to us by the hereinbefore in part recited Letters
Patent is,-
1st. In the upper or the lower sheaves of chain pulley blocks and in analogous
apparatus, the employment in combination with differential sheaves so proportioned
as that the energy of gravitation of the load is in excess of the retarding force due
to the friction of the apparatus, of means for preventing the descent of the load
on releasing the hauling chain, and for allowing of the lifting and lowering of the
load, as desired, substantially as hereinbefore described with reference to the
accompanying Drawings.
20d. The hauling apparatus constructed or arranged substantially as hereinbefore
described and illustrated in Figure 1 of the accompanying Drawings.
3rd. The hauling apparatus, constructed or arranged substantially as herein before
described, under various modifications with reference to Figures 2, 3, and 4 of the
accompanying Drawings.
4th. The hauling apparatus, constructed or arranged substantially as herein before
described, under various modifications with reference to Figures 5, 6, and 7 of the
accompanying Drawings.
5th. In differential chain pulley blocks and like apparatus having sheaves which
are not proportioned to sustain the whole of the load, but which are so proportioned
as that the energy of gravitation of the load is in excess of the retarding force due
to the friction of the apparatus, the combination of a brake applied either to the
top or bottom sheaves, so that the said brake is employed to counteract or arrest
the gravitation in the load due only to the difference between the mechanical
efficiency and the friction, substantially as hereinbefore described.
In witness whereof, we, the said Thomas Henry Ward and Edmund Howl,
have to this our Specification set our hands and seals, the Sixteenth day
of March, One thousand eight hundred and eighty two.