IMPROVEMENTS IN DIFFERENTIAL PULLEY BLOCKS OR HOISTING GEAR
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I, THOMAS HENRY WARD, of the firm of Lee Howl Ward and Howl of Tipton
in the County of Stafford, Engineers, do hereby declare the nature of said invention
for "IMPROVEMENTS IN DIFFERENTIAL PULLEY BLOCKS OR HOISTING GEAR" to be
as follows:-
My Invention has reference to differential pulley blocks or hoisting apparatus and
has for its principal object to provide an efficient and cheap arrangement upon the
principle described in the Specification of my Patent No 4012 dated the
17th September 1881. According to my present Invention I provide a framing
preferably cast in one piece and carrying the hook or shackle or other means by
which the block is suspended or attached to the place where it is to be used. The
said frame also carries an axis or shaft upon which are carried a sprocket or hand
wheel and the differential sheaves of the pulley block which are preferably
proportioned so as to be non self-sustained-The sprocket or hand wheel has
formed upon its boss or otherwise fixed to it a pinion with which is geared a wheel
fast upon a short shaft mounted in and passing through the differential sheaves at
a distance from the main shaft upon which the said sheaves turn a sleeve piece or
bush intervening between the shaft and the hole in the said differential sheaves in
which it is mounted. The said shaft at the end opposite to that on which the
before named wheel is fixed is screwed and upon this screw is mounted a pinion
which gears with an internally toothed ring or circular rack fixed to the main
shaft or the framing or otherwise so that the said toothed ring or rack is not
capable of rotating. In the sides of the hole which contains the sleeve or bush
aforesaid is or are a wedge-shaped recess or recesses gradually deepening in the
direction of movement of the short shaft in winding up a load and containing a
roller which when the sleeve or bush turns in the direction of winding up a load is
by the movement of the bush moved towards the deep end of the recess and leaves
the bush free but which when the bush is moved in the reverse direction is moved.
towards the shallow end of the recess and binds the bush to the differential
sheaves. The pinion upon the screwed end of the short shaft when the said shaft
is rotated in the direction of winding up a load is caused by the said screw to press
upon the end of the sleeve or bush which in its turn is pressed upon the wheel at
the other end or a collar or projection on the shaft and the pinion shaft and bush
are all bound so as to move as one. The bush during this movement is free to

page_text: turn in its bearing in the differential sheaves and therefore the pinion is revolved
round the stationary internally toothed ring or circular rack and the differential
sheaves are rotated around the main shaft. Whenever the hauling is discontinued
the load is sustained as hereinafter described-When the reverse or lowering
movement is given in lowering the load the short shaft is screwed out of the
pinion carried by the said screw, the bush being held firmly by the aforesaid
gripping arrangement between itself and the differential sheaves.-The said pinion
is thereby loosened from its grip on the end of the bush whereby the differential
sheaves are allowed to turn under the weight of the load. Whenever the raising or
lowering is discontinued the load will remain suspended as the pinion will run on
the screw so as to grip the bush and the said bush will turn partially until the
rollers aforesaid wedge themselves between the bush and the recesses in the
differential sheaves and so the short shaft cannot revolve and the load is held
-suspended. Although I have described the recesses and rollers as the means for
giving adhesion in one direction it will be evident-that-a-pawl and ratchet or
equivalent arrangement may be used and although I have described the differential
sheaves as being proportioned so as to be non self-sustained yet they may be
proportioned so as to be self sustained in which case the sustaining parts viz:--tho
Caleeve.and frictional rollers and the screw on the short shaft will be unnecessary,
the-pinion-instead of being mounted on a screw-being-keyed_to_the_said_shaft.
In this case of course the lowering will be effected by the power-applied-in place of
by gravity.
My Invention may be applied to hoisting apparatus generally such for example
as to the hoisting gear of cranes The Invention has been described as applied to
the differential-sheaves but it will-be-evident that it can be applied if desired to
the snatch or single block in connection with the said sheaves if desired.

page_text: COMPLETE SPECIFICATION.
I THOMAS HENRY WARD of the firm of Lee, Howl, Ward and Howl of Tipton in
the County of Stafford Engineers do hereby declare the nature of said invention
for "IMPROVEMENTS IN DIFFERENTIAL PULLEY BLOCKS OR HOISTING GEAR" and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:—
My Invention has reference to differential pulley blocks (such as those known as
Weston's differential blocks) or liko hoisting apparatus, such for example as
differential hoisting gear for cranes, and has for one of its objects to provide an
efficient and cheap arrangement upon the principle of being non self sustained
described in the Specification of my Patent No 4012 dated the 17th September
1881. It is not confined however in its application to apparatus constructed upon
the principle of being non self sustained, but I will first describe it as so applied
and afterwards I will explain the modifications necessary to fit it for application to
apparatus not constructed upon this principle.
Figure 1 represents in vertical section an apparatus constructed according to my
present Invention and figure 2 is a section on the line 1-2 Figure 1-Figures 3
and 4 are external views of opposite sides-The framing A is preferably cast in
one piece and carries the hook or shackle B or other means by which the block is
suspended or attached to the place where it is to be used-The said frame also
carries a fixed axis or shaft a upon which are mounted to turn a sprocket or hand
wheel C and the differential sheaves D D¹ of the pulley block which are in this
case proportioned so as to be non-self sustained-The sprocket or hand wheel C has
formed upon its boss or otherwise fixed to it or in connection with it a pinion o
with which is geared a wheel ƒ fast upon a short shaft f' mounted in and passing
through the differential sheaves D D¹ at a distance from the main shaft a upon
which the said sheaves turn, a sleeve piece or bush f³ intervening between the
shaft f and the hole in the said differential sheaves in which it is mounted-The
said shaft f at the end opposite to that on which the wheelf is fixed is screwed
and upon this screw (f') is mounted a pinion g which gears with an internally
toothed ring or circular rack H fixed to the main shaft a or the framing or other-
wise so that the said toothed ring or rack H is not capable of rotating-As shown
in the drawing it is mounted on the shaft a but is held in position by the pro-
jections h which bear against the projections a² of the framing A as shewn in
figure 3 In the sides of the hole which contains the sleeve or bush ƒ³ is or are a
wedge shaped recess or recesses i (I have shewn two in the drawing sec figure 2)
gradually deepening in the direction of movement of the shaft f' in winding up a
load and containing a roller it which when the sleeve or bush f³ turns in the
direction of winding up a load, is by the movement of the bush moved towards the
deep end of the recess i and leaves the bush f³ free; but which when the bush is
moved in the reverse direction is moved towards the shallow end of the recess i,
and binds the bush f' to the differential sheaves D D¹. The pinion g upon the
screwed end of the shaft f", when the said shaft is rotated in the direction of

page_text: winding up a load, is caused by the screw ƒ¼ to press upon the end of the sleeve or
bush ƒ³, which in its turn is pressed upon the wheel fat the other end (or upon a
collar or projection on the shaft f²) and the pinions ƒ and g, shaft f, and bush ƒ³,
are all bound so as to move as one The bush ƒ during this movement, is free to
turn in its bearing in the differential sheaves, and therefore the pinion g is
revolved round the stationary internally toothed ring or circular rack H, and the
differential sheaves D D¹ are rotated around the main shaft a. Whenever the
hauling is discontinued the load is sustained as hereinafter described. When tho
reverse or lowering movement is given in lowering the load, the short shaft ƒª is
screwed out of the pinion g, the bush f³ being held firmly by the aforesaid
gripping arrangement between itself and the differential sheaves D D' (the
recesses i and rollers i³) The said pinion g is thereby loosened from its grip on
the end of the bush whereby the differential sheaves are allowed to turn under
tho weight of the load. Whenever the raising or lowering is discontinued the load
will remain suspended as the pinion g will run on the screw " so as to grip the
bushfs and the said bush will turn partially until the rollers wedge theniselves
between the said bush and the recesses i in the differential sheaves, and so the
short shaft f cannot revolve, and the load is held suspended-Although I have
described the recesses and rollers as the means for giving adhesion in one direction
it will be evident that a pawl detent or click and ratchet wheel or equivalent
arrangement may be used Figures 5 and 6 are sections corresponding to figures F
and 2 shewing a ratchet wheel j and detent or click & in place of the recesses and
rollers The other parts are marked with the same letters of reference as those
used to indicate the same parts in figures 1 and 2-The ratchet wheel is formed on
-the-bush and the detent or click-k-is situated in-a-recess-in-the-differential-
sheaves and is pressed outwards by a spring k By reference to Figure 6 it will
be clearly seen that the detent or click acts as a retaining device in substan-
tially the same way as do the rollers -The sheaves when proportioned as
a non-self-sustained pulley block should be of relative diameters as near a balance
as is consistent with the sheaves being non self sustained in order that the effort of
gravity tending to lower may be as slight as possible, thus avoiding excessive
strains on the lowering gear-Although I have described the differential sheaves as
being proportioned so as to be nonself sustained, yet they may be proportioned so
as to be self sustained in which case the sustaining parts namely the sleevo f³ and
frictional rollers or their equivalent and the screw on the short shaft are dis-
pensed with, the pinion g instead of being mounted on a screw being fixed or
keyed to or formed in one with the shaft ƒ³—In this case of course the lowering
will be effected by the power applied in place of by gravity. Figures 7 and 8
represent the mechanism as arranged to be self sustained, the views here shewn
being sections at right angles to each other, the section Figure 7 being taken on
the line 3 and 4 Figure 8 and the parts being marked with the same letters of
reference as those used to indicate the same parts in the other figures-In this case
it will be seen that the shaft f' has fixed to it both the wheels or pinions ƒ and g,
and passes through the hole or bearing in the differential sheaves without the
necessity for the intervention of a bush f³ This arrangement possessos (in common
with the preceding) the advantage of the parts being all compactly situated
within the framing, the diameter of sprocket wheel necessary for this arrangement
permitting of its placement within the framing which gives a more advantageous
pull upon the hauling chain, which pull in ordinary apparatus with large sprocket
wheels arranged outside the framing, tends to deflect the apparatus when in use.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declaro that what
I claim is
First In differential pulley blocks or differential hoisting gear the combination
with the differential sheaves of a wheel to which the hauling power is applied, and

page_text: a shaft passing through the sheaves and situated out of the centre upon which the
sheaves rotate, the said shaft being provided with gear engaging with a pinion on
or in connection with the hauling wheel, and with a stationary circular internally
toothed rack, substantially as herein before described.
Second The combination with the means claimed by the preceding claiming
clause of a sleeve or bush on the shaft therein named, and a screw upon which one
of the gear wheels carried by the said shaft can run, for bearing upon the sleeve or
bush, and a retaining device consisting of recesses and rollers or a ratchet wheel
and pawl detent or click or their equivalents substantially as and for the purpose
hereinbefore described.
Third The arrangements and combinations of parts constituting the soveral
constructions of apparatus hereinbefore described and illustrated in figures 1 to 4,
5 & 6, and 7 and 8, of the accompanying drawings.