IMPROVE- MENTS IN PULLEYS, CAPSTANS, AND OTHER MACHINES FOR RAISING WEIGHTS, AND TRANSMITTING MOTIVE POWER
Year: 1863

page_text: PROVISIONAL SPECIFICATION left by Thomas Aldridge Weston and
Charles Vivian at the Office of the Commissioners of Patents, with their
Petition, on the 25th April 1868.
We, THOMAS ALDRIDGE WESTON, of Birmingham, in the County of Warwick,
Mechanical Engineer, and CHARLES VIVIAN, of Birmingham, aforesaid,
Machinist, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN PULLEYS, CAPSTANS, AND OTHER MACHINES FOR RAISING WEIGHTS, AND
TRANSMITTING MOTIVE POWER," to be as follows:-
Our Invention consists of the improvements in pulleys, capstans, and other
machines for raising weights and transmitting motive power, herein-after
described; the said improvements having for their object the holding of the
rope, chain, or band, firmly on the pulley, capstan, or other machine, during
the time the said rope, chain, or band is passing over the pulley or other
machine, and communicating motion thereto, or receiving motion therefrom.
For convenience of description, we will describe our Invention as applied to
an ordinary or single pulley. On the circumference of the said pulley, and
near one of the sides or flanges thereof, we fix a series of pins or axes, the
said pins or axes being in the positions of radii to the axis of the pulley, and
by preference at equal distances apart. On each of the said pins or axes, and

page_text: capable of turning upon it, is a small block of metal, the acting face of which
has a curvature excentric to the axis on which it turns.
We will call the said blocks of metal cams. The lower part of each of the
said cams carries a projecting piece or foot which rests upon the circumference
of the pulley. The said cams are capable of turning upon their axes through a
quadrant, that is, from the position in which the feet are parallel to the axis of
the pulley to a position in which the said feet are at right angles with the axis
of the pulley or parallel with the flanges of the pulley. The normal position of
the said cams is that in which their feet are parallel or nearly parallel to the
axis of the pulley, and to this position they are brought when free to move by
means of light springs. A rope passed over the pulley bears upon the feet of the
cams, and if the motion of the pulley is opposed, the rope may momentarily
carry forward the said feet without moving the pulley. But immediately the
said fect move, the excentric or acting faces of the cams press against the side
of the rope, and grip it or wedge it against the flange of the pulley. The rope
thus wedged between the cams and flange of the pulley can only continue its
motion by carrying round the pulley with it. As soon as any cam is brought
by the rotation of the pulley into such a position that the rope, chain, or band
no longer presses upon its foot the said cam ceases to wedge the rope, chain, or
band, and is brought by its spring into its normal position ready to act again
when by a semi-rotation of the pulley the cord, chain, or band, again acts
upon it. When the pulley is to be worked with a flat band, we prefer to make
an arm or projection on the top of each cam to prevent the band from rising
when it is wedged. The said arm is in a plane parallel to that in which the
foot is situated, but makes an angle with the font. By this arrangement the said
arm does not interfere with the passing of the band from off the pulley when
the said band ceases to press upon the foot. The cams may be made capable
of acting in one direction only, or in both directions, so as to grip or wedge
the cord or band only when it moves in one direction, or to grip or wedge it
when it moves in either direction. Pairs of cams may be employed instead of
single cams, so as to bind the rope, cord, or band, at each point between two
cams instead of between a cam and the flange of the pulley.
In making capstans and other machines for raising weights and transmitting
motive power, according to our Invention, we apply the cams described in a
way differing in no essential respect from the manner in which we apply them
to pulleys, as herein-before described.
In capstans made according to our Invention, a rope or cable may be
hauled in or payed out without surging or passing the rope or cable more thau
once round the barrel.

page_text: In cranes, crabs, and windlasses, made according to our Invention, a rope or
chain may be hauled in or let off by simply passing it once over or partly
round the barrel. Our Invention is applicable to all machines in which it is
required to effect the secure attachment of a rope or band to any rotating
wheel, barrel, or pulley.