Improvements in Safety Brakes for Cranes, Winches, and the like.
Year: 1898

page_text: Date of Application, 29th Oct., 1898-Accepted, 17th Dec.,
1898
COMPLETE SPECIFICATION.
Improvements in Safety Brakes for Cranes, Winches, and the like.
I, THOMAS SMART, of 3, Dorvil Street, Blaenau Festiniog, Wales, Inventor,
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:-
This invention relates to improvements in safety brakes for cranes, winches
and the like and my invention consists in the application of a brake drum having
normally applied thereto a band brake or equivalent, said drum being provided
with pawls or equivalents which, while allowing the spindle to revolve when a
load is being hoisted, will automatically engage with a ratchet wheel or equiva-
lent on the spindle so as to prevent said spindle turning in the opposite direction
the turning of the spindle in the opposite direction and consequent lowering
of the load being accomplished by slackening the band or other friction brake.
In order that my invention may be readily understood reference is made to
the accompanying drawing wherein like letters of reference indicate correspond-
ing parts throughout the several figures and in which:
Fig. shows one form of my invention in side elevation the front plate being
removed and―
Fig. 2 shows an alternative form of my invention and
Fig. 3 is a plan view partly in section of the clutch hereinafter referred to.
In carrying my invention into practice and referring firstly to Fig. 1-A is the
crane or winch spindle which may be rotated in any suitable manner and by
means of which a load may be hoisted in any usual way. Said spindle is
preferably formed with a square part on which is mounted a ratchet wheel B
but said ratchet wheel may be fixed on the spindle in any other suitable manner.
The brake drum consists of a more or less ring shaped casting or part C enclosing
or surrounding the ratchet wheel B and provided on, preferably each side, with
a plate D, which plates (the front one is not shown) are bolted to the part C
by bolts d and said plates are mounted on the round part of the spindle A and
therefore carry the part C. Said plates also carry pawls E which are held in
engagement with the ratchet teeth by springs e about as shown, and the outer
periphery of the brake drum is provided with a band brake F the ends of
which may be brought together so as to tighten the band on the drum, by means
of a crank handle & fitting on a screw H which passes through the lugs F so
that if the handle be turned in one direction the band will be tightened on the
drum and if turned in the reverse direction the band will be slackened.
In the alternative construction shown in Figs. 2 and 3 I dispense with the
ratchet wheel and pawls and employ a clutch of suitable construction which
grips only in one direction. For example the brake drum may be formed with
one part c¹ of the clutch and the other part 61 is mounted on the square portion
of the crane or winch spindle A on which square portion said part b' is capable
of sliding so as to be moved into or out of engagement with the part c¹. The
part 6 is normally held or pressed against the part c¹ by a spring d¹ and the

page_text: arrangement of the clutch is such that if the band brake F¹ be applied so as to
hold the brake drum then the spindle A can only turn in one direction to raise
the load the clutch preventing said spindle rotating in the opposite direction
while the brake is applied.
The band brake may be applied as shown in Fig. 1 and hereinbefore described
or I may pivotally attach the brake lever J to one end of said band F which
lever carries one or a pair of pivotally attached racked or toothed bars K to
which bars the opposite end of the band is pivotally connected at L. A pawl M
which is also carried by the lever J normally engages with the rack K the
arrangement being such that if the lever be pulled in a direction as indicated
by the arrow N the band will be tightened on the drum and the brake thus
applied the pawl serving to keep said brake applied.
In using my improved safety brake it is only necessary to first supply the
brake then the load may be hoisted in any usual manner and should there be
a sudden tendency either through the breaking of the gearing or other like
accident, of the weight to reverse the motion of the spindle said spindle will
be at once automatically locked either by the pawls engaging with the toothed
wheel or by the action of the clutch as described. For lowering the load the
band brake is released as required in the usual manner.
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:
1. An improved safety brake for cranes, winches and the like in which the
spindle is prevented from rotating in one direction while the brake is applied
all for the purposes and substantially as described and illustrated.
2. An improved safety brake for cranes, winches and the like consisting of a
brake drum containing or enclosing a ratchet wheel and pawls all for the pur-
poses and substantially as described and illustrated.
3. An improved safety brake for cranes, winches and the like having a safety.
clutch such as 61 for the purposes and substantially as described and illustrated
in Fig. 3.
4. In a safety brake for cranes, winches and the like a band Fi, a brake
lever J, toothed bar K, and pawl L all for the purposes and substantially illus-
trated.
5. The combination with the improved brake hereinbefore described, a brake
band F having lugs or equivalents F adapted to be drawn together by means
of a screw having a crank handle such as G for the purposes and substantially
as described and illustrated.
1
a
1
1
1000