IMPROVEMENTS IN THE CONSTRUCTION OF SHEAVES FOR PULLEY BLOCKS
Year: 1883

page_text: LETTERS PATENT to William Alexander of Govan in the County of Lanark
North Britain, Block Maker for an Invention of "IMPROVEMENTS IN THE
CONSTRUCTION OF SHEAVES FOR PULLEY BLOCKS"
PROVISIONAL SPECIFICATION left by the said William Alexander at the
Office of the Commissioners of Patents on the 12th January 1883.
WILLIAM ALEXANDER, of Govan, in the county of Lanark, North Britain,
Block Maker, "IMPROVEMENTS IN THE CONSTRUCTION OF SHEAVES FOR PULLEY
BLOCKS,"
This Invention relates to improvements in the construction of sheaves for pulley
blocks.
As usually constructed such sheaves are formed from single blocks of lignum-
vitae which are turned down to the requisite shape. This material however is
becoming scarce and is deteriorating in quality. According to the present Invention
the sheaves are made partly of metal and partly of hard wood which is combined
in sections with the metal.
The improved composite sheaf is constructed with the central portion of metal
in the form of a wheel with a central eye or boss and rim or tyre connected to it
by arms or a disc. The grooved rim of the sheaf is made of elm, plane-tree, beech,
or other hard wood in the form of segments which are doweled or otherwise fitted
together round the rim or tyre of the central metal wheel part, which has a dove-
tailed or similar groove formed round it into which the wooden segments fit and are
firmly held. To permit of the insertion of the segments which are formed with
tongues to fit the dovetailed grooves, the central wheel part of the sheaf is split or
divided longitudinally; and after the segments are inserted, the two halves of the
wheel are bolted or rivetted together, through the tyre or rim, the bolts or rivets
being made to pass also through the tongues of the wooden segments forming the
grooved rim of the sheaf.
Instead of retaining the grooved rim of the sheaf by tongues fitting into grooves
of dovetail form, the grooves in the metal tyre or rim may be formed with outer
flanges fitting into annular grooves in the sides of the tongues, or the sides of the
groove in the metal tyre may be curved in section or otherwise formned to retain
the wooden segments of the sheaf.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Alexander in the Great Seal Patent Office on the 4th July
1883.
WILLIAM ALEXANDER, of Govan, in the County of Lanark, North-Britain,
Block Maker, "IMPROVEMENTS IN THE CONSTRUCTION OF SHEAVES FOR PULLEY
BLOCKS."
My said Invention relates to improvements in the construction of sheaves for
pulley blocks. As usually constructed, such sheaves are formed from single blocks
of lignum-vitæ, which are turned down to the requisite shape. This materinl
however is becoming scarce, and is deteriorating in quality. According to the
present Invention the sheaves are made partly of metal and partly of hard wood,
which is combined in sections with the inetal.
The Invention is illustrated by the accompanying Drawings, in which Figure 1
is a sectional elevation, and Figures 2, 3, and 4, are vertical sections showing
different modifications of my improved composite pulley block sheaves. T'he
improved composite sheaf is constructed with the central portion of metal in the
form of a wheel with a central eye or boss A and rim or tyre A' connected to it by
arms or a disc A². The grooved rin B of the sheaf is made of elm, plane tree,
beech, or other hard wood in the form of segments which are connected by dowel
pins b or otherwise fitted together round the rim or tyre A¹ of the central metal
wheel part, which has a dovetailed or similar groovo A³ formed round it into which
the wooden segments B fit and are firmly held, as indicated in figure 2. To permit
of the insertion of the segments which are formed with tongues B' to fit the dove-
tailed grooves, the central wheel part A of the sheaf is split or divided longitudinally;
and after the segments are inserted the two halves of the wheel are bolted or
rivetted together through the tyre or rim A', the bolts or rivets a being made to
pass also through the tongues B₁ of the wooden segments forming the grooved rim
B of tho sheaf.
Instead of retaining the grooved rim of the sheaf by tongues fitting into grooves
of dovetailed form, the grooves in the metal tyre or rim A' may be formed with
outer flanges a fitting into annular grooves b¹ in the sides of the tongues B' as
indicated in Figure 3, or the sides of the groove A³ in the metal tyre A' may be
curved in section as in figure 4, or they may be otherwise formed to retain the
wooden segments B of the sheaf.
Having now described the nature of my said Invention, and the manner in
which the same is to be performed, I declare that what I claim as my Invention
is,―
First. The construction of composite sheaves for pulley blocks substantially as
herein described and illustrated.
Second. A composite sheaf for pulley blocks consisting of a central metal eye or
hub and tyre and a grooved rim formed of segments of hard wood adapted and
secured thereto, substantially as herein described and illustrated.
In Witness Whereof, I the said William Alexander, have hereunto set any
hand and seal this Twenty-seventh day of June, in the year of our Lord, One
thousand eight hundred and eighty-three.
W ALEXANDER
Witness
WALLACE FAIRWEATHER C.E. Fel. Inst. P.A
Patent Agent
Glasgow.
W ALEXANDER
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