IMPROVEMENTS IN DIFFERENTIAL PULLEY BLOCKS AND OTHER APPARATUS FOR MOVING HEAVY BODIES
Year: 1870

page_text: LETTERS PATENT to Peter Murray, Engineer, of Quebec, Canada, but
at present residing in Glasgow, in the County of Lanark, North
Britain, for the Invention of "IMPROVEMENTS IN DIFFERENTIAL PULLEY
BLOCKS AND OTHER APPARATUS FOR MOVING HEAVY BODIES."
PROVISIONAL SPECIFICATION left by the said Peter Murray at the
Office of the Commissioners of Patents, with his Petition, on the
16th September 1870.
I, PETER MURRAY, Engineer, of Quebec, Canada, but at present
residing in Glasgow, in the County of Lanark, North Britain, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN DIFFERENTIAL
PULLEY BLOCKS AND OTHER APPARATUS FOR MOVING HEAVY BODIES," to be as
follows:-
This Invention has principally for its object to secure increased
efficiency, durability, and reduced cost in differential pulley blocks, and

page_text: comprises a combination of parts which is also advantageously applicable
to winches, capstans, screw jacks, and other apparatus for moving heavy
bodies. The improved pulley block is made with the usual two pulleys,
one of which, herein-after termed the load pulley, has applied to and
gearing with it the chain to which the body to be moved or lifted is
attached, whilst the other, herein-after termed the power pulley, has
applied to and gearing with it an endless chain by which the actuating
force is communicated. The parts are carried by two frame pieces con-
nected by cross bolts, and furnished with a hook or ring at the top to
suspend the block by, and in some cases with a hook or ring at the
bottom to connect the end of the lifting chain or common pulley blocks
to when used in combination with one or more of the latter. The load
pulley runs loose on a centre spindle fixed across the frame pieces, and
has formed in the same piece with it an internally toothed wheel or rim
which gears with an externally toothed intermediate wheel loose on an
eccentric part of a tubular boss, on which the power pulley is fixed and
which runs loose on the centre spindle. The externally toothed inter-
mediate wheel has formed in one piece with it an internally toothed
wheel or rim, and this rim gears wth an externally toothed rim which is
stationary, being formed or fixed on one of the frame pieces. With this
arrangement every revolution of the power pulley will cause the load
pulley to turn to an extent equal to the number of teeth it has more
than the intermediate wheel, plus the extent corresponding to the number
of teeth the intermediate wheel has more than the fixed wheel, and there
will be the corresponding inverse leverage between the power applied
and the load.
In applying the arrangement to winches and other apparatus the
winch barrel, or a bevil, or spur wheel for transmitting the force takes
the place of what is herein-before termed the load pulley. In applying
the arrangement to capstans the head takes the place of the power
pulley, and the barrel that of the load pulley, and a clutch or bolt may
be provided for disconnecting the head from the eccentric and fixing
it to the barrel when speed is wanted without great power.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent;
filed by the said Peter Murray in the Great Seal Patent Office on
the 15th March 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PETER
MURRAY, Engineer, of Quebec, Canada, but at present residing in
Glasgow, in the County of Lanark, North Britain, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Sixteenth day of September, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-fourth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Peter Murray, Her special licence that I,
the said Peter Murray, my executors; administrators, and assigns, or
such others as I, the said Peter Murray, my executors, ádministrators,
and assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed,
should and lawfully might make, use, exercise, and vend, within the
United Kingdom of Great Britain and Ireland, the Channel Islands,
and Isle of Man, an Invention for "IMPROVEMENTS IN DIFFERENTIAL PULLEY
BLOCKS AND OTHER APPARATUS FOR MOVING HEAVY BODIES," upon the condition
(amongst others) that I, the said Peter Murray, my executors or adminis-
trators, by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature of
the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Peter Murray, do hereby declare
the nature of my said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and
by the following statement in writing, reference being had to the accom-.
panying Drawings, that is to say:-
'
My said Invention has principally for its object to secure increased
efficiency, durability, and reduced cost in differential pulley blocks, and
comprises a combination of parts which is also advantageously applicable
to winches, capstans, screw jacks, and other apparatus for moving heavy
bodies.

page_text: And in order that my said Invention and the manner of performing
the same may be properly understood, I hereunto append a Sheet of
explanatory Drawings, to be herein-after referred to, and representing
differential pulley blocks as made with my improvements. The same
reference numerals are used in these Drawings to mark the same or like
parts wherever they are repeated.
Figures 1 and 2, are vertical sections at right angles to each other of
one modification of my improved differential pulley block, and Figure 3
represents the frame as viewed from the under side and partly in hori-
zontal section. The block is made with the usual two pulleys, one of
which 1, herein-after termed the load pulley, is shaped in the well known
way for having applied to and gearing with it the chain (not shown) to
which the body to be moved or lifted is attached, whilst the other, 2,
herein-after termed the power pulley is similarly shaped for having
applied to and gearing with it an endless chain (not shown) by means of
which the actuating force is communicated. The parts are carried by
two frame pieces 3, 4, connected by cross bolts 5, 6, 7, and furnished
with a hook 8 (or it might be a ring) at the top to suspend the block
by; and in some cases with a hook or ring at the bottom to connect the
end of the lifting chain or common pulley blocks to, when used in com-
bination with one or more of the latter. The load pulley 1 runs loose
on a centre spindle 9 fixed across the frame pieces 3, 4, and has formed
in the same piece with it (being by preference malleable cast iron) an
internally toothed wheel or rim 10 which gears with an externally toothed
intermediate wheel 11 loose on an eccentric part 12 of a tubular boss 13,
on which the power pulley 2 is keyed or fixed, and which runs loose on
the centre spindle 9. The externally toothed intermediate wheel 11 has
formed in one piece with it an internally toothed rim 14, and this rim 14
gears with an externally toothed ring 15 which is stationary, being formed
or fixed on one of the frame pieces 4. With this arrangement every
revolution of the power pulley 2 will cause the load pulley 1 to turn to
an extent equal to the number of teeth, its rim 10 has more than the
external teeth of the intermediate wheel 11, plus the extent corresponding
to the number of teeth, the rim 14 of the intermediate wheel has more
than the fixed wheel or ring 15, and there will be the corresponding
inverse leverage between the power applied and the load. The drawing
represents the full size of a practically successful block suitable for lifting
a load of five hundredweight. The action between the load pulley 1

page_text: -
and the intermediate wheel 11, with the arrangements herein-before
described is such that the former turns faster than the latter, and it is
obvious that if both were to turn at the same speed a greater load could
be lifted by the application of a given power, but of course at a propor-
tionately diminished speed. The intermediate wheel 11 has an eccentric
motion due to the rotation of the boss 12, 13, but notwithstanding that
I make it communicate a uniform rotation to the power pulley 1 of a
rate equal to its own by interposing a cross 16 as shown in edge and face
view in Figures 4 and 5, and by forming snugs 17, 18, for the cross to
work between on the power pulley 1 and intermediate wheel 11 re-
spectively, two diametrically opposite pairs of the snugs 17 being on the
one and on the other, two other diametrically opposite pairs 18 at right
angles to the former. I however prefer the mode of obtaining the same
result shown in Figures 6 and 7; Figure 6 being an inside face view of
the power pulley 1 as modified; and Figure 7 a vertical section of the
combined parts. In this modification round pins 19 are formed on the
intermediate wheel 11, and gear into circular sockets 20 formed on the
power pulley, such sockets being as much larger than the pins 19 as to
allow for the eccentric motion of the intermediate wheel 11.
In applying my improved arrangement to winches and other apparatus
the winch barrel or a bevil or spur wheel for transmitting the force takes
the place of what is herein-before termed the load pulley 1, and the
actuating force is applied to the eccentric boss 12, 13, by means of a
wheel (2) or a handle fixed thereon, or on the spindle 9, the eccentric 12
being in the last case formed or fixed on such spindle.
In applying the arrangement to capstans the head takes the place of the
power pulley 2, and the barrel that of the load pulley 1, and a clutch or
bolt may be provided for disconnecting the head (2) from the eccentric 12,
and fixing it to the barrel (1) when speed is wanted without great
power.
Having thus particularly described my said Invention, and the manner
in which the same is to be performed, I have to state that I do not
restrict myself to the precise details herein delineated or described; but
that what I believe to be novel and original, and claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,
the improved modes herein-before described of combining parts to form
differential pulley blocks or other apparatus for moving heavy bodies; or
more particularly the interposing of a toothed wheel loose on an eccentric

page_text: between a stationary or fixed toothed wheel and the load pulley or its
equivalent, whereby the rotation of the eccentric produces a slower but
much more powerful rotation of the interposed wheel and of the load
pulley.
In witness whereof I, the said Peter Murray, have hereunto set
my hand and seal, this Fourteenth day of March, in the year of
our Lord One thousand eight hundred and seventy-one.
Witness,
EDMUND HUnt,
Patent Agent,
Glasgow.
PETER MURRAY. (L.S.)