provements in Brakes for Lifts.
Year: 1891

page_text: COMIDELE DI DUITIATION
Improvements in Brakes for Lifts.
JOHN SANDERS STEVENS and CHARLES GEORGE MAJOR, Engineers,
"Janus" Works. Queen's Road, Battersea, in the County of Surrey 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:—
Our invention is applicable to that class of lifts and hoists which are worked from
various levels by means of a hand rope running the full height of the machine, and
has for its object the attainment by more simple means of the advantages afforded
by the ordinary screw brake, viz. very great power of holding or stopping, com-
bined with facilities for putting on the brake at any level, so that it may remain
locked till intentionally released, and yet that the release may be effected at any
other level, thereby avoiding a journey to the floor where the brake had been
applied. And farther we place the brake ropes in a more convenient position than
is the case with a screw brake.
In carrying out our invention we employ on any shaft of the machine an ordinary
brake wheel A, embraced by a flexible band B, tightened and slackened by a lever C
in the ordinary well known manner. But at the end of the lever we provide a pin or
snug D which engages with a helical or other suitably formed cam E mounted on a
fixed pin H and free to revolve. Secured to the back of the cam E, or formed in
one piece with it, is a small snug, or pitched wheel, I, suitable to engage with, and
receive motion from, a chain J. A short piece of chain J is hung over this wheel
with one end depending from either side, and to these ends are secured two hand
lines K K passing down to the lowest level where they may be required.
Instead of the pitch chain wheel I, we sometimes use a plain drum L, Fig. 5, and
secure two hand chains, or lines to it, to give motion in opposite directions; but
the former is the neater arrangement.
If now the brake line on one side of the wheel I be pulled, the cam E is caused
to revolve, and the helix acting on the end of the lever C tightens the brake band B,
and if the incline or pitch of the helix be suitably designed, the lever will have no
power of driving the helix backward, and therefore the machine will be securely
and permanently held fast. To release the brake, the opposite brake line K is
pulled, and as both lines pass through all floors, both operations can be performed
at every level. The gripping power obtained is very much greater than with the
screw brake, and as the chain wheel I lies parallel with the face of the travelling
cage, both ropes may be brought down in the usual narrow space provided between
the face of the moving cage and the fixed enclosure, an advantage not attainable
with any simple arrangement of screw brake.
An obvious modification would consist in dispensing with the brake band B, and
replacing it by a friction or rubbing block M, Fig. 6, secured to the lever C, but we
Dreier the Danu arrangement.
Dreier the Danu arrangement.
DESCRIPTION OF DRAWINGS.
Fig. 1 is a general arrangement of the brake.
Fig. 2 is a face view of the cam E, shewing the helical groove.
Fig. 3 is a section of cam E, and attached chain wheel I, shewing end of lever
engaged with helix.
Fig. 4 is an edge view of lever C, shewing pin D.
Fig. 5 shews alternative drum arrangement instead of chain wheel.
Fig. 6 shews alternative block arrangement instead of brake band.

page_text: Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:
In lifts and hoists with an ordinary lever brake, the addition of a cam and chain
wheel or drum with two hand lines, as and for the purposes described.
Dated this 16th day of June 1891.
JOHN SANDERS STEVENS.
CHARLES GEORGE MAJOR.