Improvements in Differential Pulley Blocks.
Year: 1893

page_text: Date of Application, 18th Jan., 1893-Accepted, 18th Feb., 1893
COMPLETE SPECIFICATION.
Improvements in Differential Pulley Blocks.
A communication by EDWARD YOUNG MOORE, of Milwaukee City, in the
County of Milwaukee and State of Wisconsin, United States of America,
Manufacturer.
I, WILLIAM PHILLIPS THOMPSON F.C.S., M.I.M.E. of the Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool and 6 Bank Street.
Manchester, both in the County of Lancaster, and 323 High Holborn in the
County of Middlesex, Civil Engineer, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
The pulley-block (which is improved by this invention), is an apparatus for
raising and lowering great loads at a slow speed, by means of a comparatively
small amount of power, moving through a much greater space and at much greater
speed.
The chief object of the present invention is to provide means for locking the
active mechanism in the pulley-block against reversing its load-elevating move-
ments, or in other words, means for obviating its running down under the weight of
a load.
The invention consists in the mechanism hereinafter described and claimed, in
and by which said chief object is accomplished and other minor results are secured.
In the drawings:
Figure 1, is an elevation of the pulley-block partly in section, thus disclosing
features of the invention which are located interiorly about the axle ;
Figure 2, is a section of the device on line 2-2 of Figure 1 looking toward the
left;
Figure 3, is a top plan view of the pulley-block;
Figure 4, is an elevation of the chain wheel at the right of the line 2-2 in
Figure 1;
Figure 5, is an end view of the eccentric on the axle, which eccentric is partly
broken away showing a pawl pivoted therein, in connection with a fragment of the
encompassing ring and interposed rollers, thereby exhibiting the locking mechanisin
and illustrating its method of operation;
Figure 6, is a detail of the pawl;
Figures 7 and 8 show a modified form of the locking mechanism; and
Figures 9 and 10 show still another modified form of the locking mechanism.
A, is the frame of the pulley-block, which is of suitable size and form to carry
the operative mechanism mounted therein. The hook B is swivelled in the
op of the frame centrally, and is adapted for suspending the pulley-block. An
xle C journalled in the frame is provided with a fixed chain wheel D. An endless
chain (not shown in the drawings) runs on this wheel, and is adapted for rotating
he wheel by hand, to operate the mechanism. Two other chain wheels E and F,
of equal diameter, are mounted revolubly on the cylindrical studs or bosses G,
ntegral with the frame which are pierced centrally by the axle C. The wheels E
nd Fare concentric with the axle C. A chain H runs on the two wheels E
nd F, the chain being so arranged that it runs over one wheel, as E, from front to
ear or from rear to front, one line of the chain being carried diagonally
eneath the wheels and up over the other wheel F in the same direction
S over the wheel E, that is, from front to rear or from rear to front.
The load is supported on the free ends of the chain, conveniently by a
Price Rd1

page_text: roke (not shown in the drawings) to which the extremities of the cham
are attached. This yoke when carrying a load, rises and falls evenly with
the extremities of the chains pendent from the wheels an opposite sides of the
axle The chain Has described is "integral and is conveniently but not
necessarily so in practice as there may instead be two chains one running on each
wheel E and F, it being only necessary that the load is supported on two extremities
of the chains, one extremity of each chain, and that the two extremities depend on
opposite sides of the axle.
.
Interposed between and partially within the wheels E and F a cylindrical
Two spur wheels (or double
eccentric 11 is fixed on and rotates with the shaft C.
wheel) a greater wheel 12 and a less wheel 13 constructed integrally, and
arranged concentric with the ccentric 11, are carried thereby around the axle C
being mounted free on a ring 14 which is rotatable about and concentric with the
eccentric 11 on antifriction rollers 15 interposed between them. The chain wheel E
is provided with internal teeth or gear E' which meshes with the teeth of the
smaller wheel 13, the internal gear E' being considerably larger and containing
more teeth than the spur wheel 13 does which may differ in ratio but which in the
drawings are 31 in the gear E¹ and 25 in the wheel 13. The chain wheel F is
provided with an internal gear F which meshes with the spur wheel 12 but which is
larger and contains more teeth than the spur wheel 12 does. The difference in the
number of teeth in the gear F1 and the wheel 12 may vary as described but in the
drawings are shown as being 38 and 32 respectively, the difference (six, in
the device shown) in the number of the teeth on the wheels 12 and 13 being the
The teeth
same as the difference in the number of cogs on the wheels E and F.
on the wheels E and 13 and the teeth on the wheels F and 12 that respectively
mesh with each other, are constructed with the same pitch and are so proportioned
as not to wedge upon, strain or unduly grind each other. These several wheels and
their supporting devices are so constructed and arranged that the wheels 12 and 13
as they roll around the axle C with the eccentric 11, are constantly in mesh with
the wheels E and F on that side of the axle at which the eccentric has the greatest
radius, and are otherwise out of gear therewith.
The double wheel 12, 13, is fitted rotatably on the ring 14 so that ordinarily and
especially when the tackle block is supporting a load the ring held to the wheel
hy friction rotates therewith. The bearing surface of the periphery of this ring is
of such extent and contacts with the double wheel 12, 13 with so much resistance,
as to obviate the reversing of the motion of the wheel 12 and 13 on the ring 14
under the strain on the wheels of the weight of the load, even when the load is not
counterbalanced by force applied through the chain on the wheel D and axle C.
It only remains therefore to lock the ring 14 against reversing its motion on the
eccentric to perfectly lock the operative mechanism against running down, when
supporting a weight not counterbalanced by force applied through the hand chain
ruuning on wheel D. For this purpose a pawl 16 pivoted in a recess therefor in
the periphery of the eccentric 11, is arranged to engage the rollers 15 in one
direction, and force the roller engaged against the inner wall of the ring 14, and
directly and indirectly against the rollers following in the line of motion, thereby
preventing rotation of the ring 14 about the eccentric against the resistance of the
pawl. A spring 17 bearing against the pawl holds it up to its work yieldingly
permitting the rollers to pass the pawl in one direction, and to be engaged by it in
the other direction. This construction effectually prevents the running down o
the load when unbalanced otherwise than by the friction and differentiated or cros
strain of the mechanism.
In the modified form of device shown in Figures 7 and 8, the ring 18, corre
sponding generally with the ring 14 in the first form of device, is provided midway
between its ends with an annular inwardly projecting flange 19 having teeth on it
inner edge adapted to be engaged directly by the pawl 20, pivoted in the periphera
recess in the eccentric 11. This construction directly and positively locks th
ring 18 to the eccentric 11 against rotation thereon in a direction opposite to th

page_text: resistance of the pawl. In this form of device there are two sets of rollers, 21, 21,
oue set on each side of the flange 19, interposed between the eccentric 11 and
the ring 18 to receive the bearing of these parts respectively.
In the modified form shown in Figures 9 and 10, a loose cylindrical block 22
located in a recess therefor in the periphery of the eccentric 11 is made to serve
as a pawl engaging the rollers 15 in one direction, thereby locking the ring to the
eccentric against rotation thereon in one direction. The cylindrical block 22 is
advisably of substantially the same size as one of the rollers 15, and is located in
a recess in the periphery of the eccentric 11 being arranged longitudinally parallel
with the rollers 15. The recess in the eccentric 11 is elongated peripherally,
being of sufficient depth radially at one end to receive the block 22 so entirely
therein as to permit the rollers 15 to pass the block freely when in that location.
The rear wall 23 of the recess is, however, arranged obliquely to a radius of the
eccentric narrowing the depth of the recess toward its other extremity so that
the block being forced away from this widened part toward the other end of the
recess, is wedged between the rear wall of the recess and a roller 15, thereby
forcing the rollers 15 against the ring 14 and preventing its rotation about the
eccentric in opposition to the resistance of the block. The block is held yieldingly
up to its work by a spring 24, secured to the eccentric and bearing against the
block.
In use, the double wheel 12, 13, in raising a load engages the ring 14 by friction
sufficiently that the ring rotates with the wheel travelling on the rollers 15, and
the load is automatically sustained by the locking of the eccentric to the ring and
the friction of the double wheel on the ring, but when the load has been removed
or is to be run down, the movement of the elevating chain H is reversed or run
down, by reversing the motion of the wheel D, the double wheel 12, 13, during
such reversed motion or running down, rotating on the ring 14.
It will be understood concerning this device for locking the ring to the eccentric
against rotation thereon in one direction, that a pawl located in the ring and
adapted to engage the interposed rollers or rack teeth on the eccentric, would be
merely reversing the position of the pawl and would be an equivalent for the special
forms shown in the drawings.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
1. In a differential pulley-block, the combination with an axle, of an encircling
loose pulley provided with gear, a toothed wheel mounted on the axle meshing
with the pulley-gear for transmitting motion to and from the pulley, an interposed
free friction bearing ring and means for locking the ring against independent
rotation in one direction, substantially as described.
2. In a differential pulley-block, the combination with an axle, an eccentric rigid
on the axle and a double gear wheel mounted and revoluble thereon adapted for
transmitting motion to a loose pulley, of a free friction bearing ring within the
double wheel, and rollers interposed between the ring and eccentric, as set forth.
3. In a differential pulley-block, the combination with an axle, an eccentric rigid
on the axle, and a double gear wheel mounted and revoluble thereon, of a free
bearing ring within the double wheel, rollers interposed between the ring and
eccentric, and means for locking the ring to the eccentric against rotation thereon
in one direction.
4. In a differential pulley-block, the combination with an axle, an eccentric
rigid on the axle and a double gear wheel mounted and revoluble thereon, of a free
bearing ring within the double wheel, rollers interposed between the ring and
eccentric, and a pawl provided with a spring arranged to engage a roller, and block
the rotation in one direction of the ring on the eccentric.
5. In a differential pulley-block, the combination with an axle, of an encircling

page_text: loose pulley, a gear wheel for transmitting motion between the axle and the pulley,
a free friction bearing ring interposed between the gear wheel and the axle,
rollers on which the ring revolves about the axle, and means for locking the ring
to the axle against rotation thereon in one direction, as described.
Dated this 17th day of January 1893.
WM. P. THOMPSON & Co.,
Agents for the Applicant.