Improvements in Brake Apparatus for Electrically Driven Cranes and the like.
Year: 1898

page_text: Date of Application, 12th Nov., 1898
Complete Specification Left, 11th Aug., 1899-Accepted, 14th Oct., 1899
PROVISIONAL SPECIFICATION.
Improvements in Brake Apparatus for Electrically Driven Cranes
and the like.
I, JAMES BOYD REID, of Cranstonhill Engine Works, Helen Street, Govan,
in the County of Lanark, North Britain, Civil Engineer, do hereby declare the
nature of this invention to be as follows, that is to say:
-
My invention relates to electrically driven cranes and the like which are
usually provided with brake apparatus for controlling and regulating the descent
of the load; and my object is to combine with what is known as Weston's brake
improved automatic mechanism to act whilst a load is being lowered and to pre-
vent acceleration or when the load is being raised backward movement in the
event of the raising power failing or ceasing to act from any cause.
In carrying out my invention I fix to or form in one piece with the pulley
of the Weston or similar brake, a brake pulley to which is applied a jointed brake
strap arranged as in what is known as the differential brake, its ends being
connected to the two arms of a lever, which arms are of different lengths. When
the shaft and brake pulley turn in the hoisting direction the brake strap frees
itself, but the opposite motion causes the brake strap to grip the pulley and
hold it.
Dated this Eleventh day of November 1898.
.
EDMUND HUNT,
Applicant's Agent.
COMPLETE SPECIFICATION.
Improvements in Brake Apparatus for Electrically Driven Oranės
and the like.
I, JAMES BOYD REID, of Cranstonhill Engine Works, Helen Street, Govan,
in the County of Lanark, North Britain, 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, that is
to say:
-
My said invention relates to electrically driven cranes and the like which are
usually provided with brake apparatus for controlling and regulating the descent
of the load and my object is to combine with what is known as Weston's brake
improved automatic mechanism to act whilst a load is being lowered and to
prevent acceleration or when the load is being raised backward movement in
the event of the raising power failing or ceasing to act from any cause.

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 hereinafter referred to in describing my improvements.
Figures, 1, and 2, of the drawings, are respectively a transverse, and a longi-
tudinal vertical section of my improvements in brake apparatus. In these
drawings the same reference letters and numerals are used to mark the same
or like parts wherever they are repeated.
In carrying out my invention, which is shown in the drawings as a combination
of the Weston brake with other parts I provide a brake pulley, A, which is fitted
to rotate freely on two disks, B, C, fixed respectively to the shaft, D, and to a
sleeve, E, screwed internally to work on a correspondingly screwed part, D1,
of the shaft, the shaft being turned by a pinion (not shown) fixed to it, and the
pinion being driven by a spur wheel (not shown) from the motor. A jointed
brake strap, A 1, is applied to the brake pulley, A, and is arranged as in what
is known as the differential brake, its ends, A2, A3, being connected by links,
A 4, A5, to the two arms, H1, H2, of a lever, H, fixed to a shaft, H3, mounted
in a bracket, H4, fixed to the framing. A lower brake shoe, H 5, is also fixed
to the shaft, H3, for acting on the brake pulley, A. The two arms, H1, H2,
are of different lengths, and to the longer arm, H 1, a weight, H 6, is attached
for imparting the requisite tension to the brake strap. Friction braking plates,
J, K, such as are usually employed in the Weston brake, are fitted loosely on
the screwed sleeve and within the pulley, A, between the disks, B, C, feathers
or keys, L, fixed to the sleeve and pulley being arranged to engage in slots, L1,
formed in the plates, so as to cause the plates to turn with the sleeve and pulley.
The hoisting drum (not shown) is driven by a pinion, G, fixed to the sleeve, E,
and gearing with a spur wheel on the drum shaft. When it is desired to turn
the hoisting drum (the plates, J, K, being assumed to be released) so as to raise
the load, the shaft, D, is turned by the motor in a direction, as shown by the
arrow in Figure, 1, so that the screwed sleeve, E, and the disk, C, are moved
slightly along the shaft towards the disk, B, thereby causing the friction braking
plates, J, K, to act and impart rotative movement to the pinion, G, and the
hoisting drum. The brake pulley, A, also rotates as one piece with the disks,
B, C, as a turning movement of the pulley in the direction shown by the arrow
releases the differential brake. An opposite movement of the pulley, however,
puts the brake into action, and thereby prevents any backward movement when
the load is being raised. When it is desired to turn the hoisting drum so as to
lower the load, the shaft, D, is turned in a direction opposite to that shown by
the arrow, so as to give an opposite longitudinal movement to the sleeve, E,
and disk, C, whereby the friction plates and disk, C, are released and the hoisting
pinion, G, permitted to revolve, the brake pulley, A, with its plates, J, being
however held by the differential brake. The action of the load causes the
pinion, G, and sleeve, E, to rotate more quickly than the shaft, D, and this gain
in speed causes the sleeve to move back towards the disk, B, causing the friction
plates, J, K, again to act thereby braking or momentarily stopping the rotation
of the hoisting pinion, G. The continued rotation of the shaft, D, however
again releases the plates, J, K, and disk, C, and the hoisting pinion, G, is again
free to turn. These automatic momentary braking and releasing actions continue
during the lowering of the load and combine to give an easy and safe descent
to the load and prevent any acceleration of speed. And should the raising
power fail or cease to act from any cause, the shaft, D, and the hoisting pinion, G,
are immediately braked and stopped from rotating, by the combined action of
the differential brake and the friction plates, J, K. A stop, M, fixed to the end
of the shaft, D, and engaging in a groove M 1, in the sleeve, E, is provided for
the purpose of limiting the separate or independent circular movement of the
sleeve, E, and the shaft, D, so as thereby to limit the longitudinal movement
of the sleeve in either direction.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
In brake apparatus for electrically driven cranes and the like, improved auto-
matic braking mechanism, comprising a differential brake in combination with
a Weston or similar friction brake, the parts being combined arranged and
operating substantially as and for the purposes herein before described with
reference to the accompanying drawings.
Doted this Month of A.
1000
EDMUND HUNT,
Applicant's Agent.