An Improved Brake for Rotary Shafts Subject to Endways or Axial Pressure.
Year: 1891

page_text: Date of Application, 7th Oct., 1891-Accepted, 14th Nov., 1891
COMPLETE SPECIFICATION.
An Improved Brake for Rotary Shafts Subject to Endways or Axial
Pressure.
A communication from Messrs. A. CRUZ & Ca, of 147, Rua do Almada, Porto,
Portugal.
I, FREDERICK JOHN BROUGHAM, of 110 St. Paul's Road, Camden Town, in
the County of London, Managing Clerk, 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 has reference to the use in conjunction with a rotary shaft subject
to endways or axial pressure, of an improved construction of brake that will permit
of the shaft being freely rotated in one direction, but will be automatically brought
into action to arrest or retard the rotation of the shaft in the opposite direction as
1 will now proceed to explain by aid of the accompanying drawings in which
Figs. 1 and 2 are sectional elevations at right angles to each other of a shaft or
spindle with a brake according to this invention.
Fig. 3 is a similar view to Fig. 2 but without the bearing, illustrating a modified
construction.
Referring to Figs. 1 and 2, 1 is a rotary shaft the rotation of which in one
direction is to be arrested or retarded, and which when in use is constantly subjected to
endways pressure acting in the direction of the arrow a. 3 is a collar formed upon
or fixed to the shaft so as to rotate with it. 4 is a sleeve mounted upon the shaft
so as to turn therewith in one direction but so that the shaft can turn within it when
necessary. This sleeve is provided with a collar 5 between which and the collar 3
may be placed as shown a ring 6 of suitable material such as leather, to prevent
abrasion of the adjacent surfaces of the collars and to increase the friction at this
part. The sleeve, which is carried by the bearing 2, is closed at its outer end, and
bears against a pivot 7 carried by the bearing 2. The periphery of the collar 5 is
formed with a number of recesses 8 of gradually decreasing depth in each of which
is placed a ball, or preferably as in the example shewn, a roller 9, the arrangement
forming in conjunction with the tubular extension 2 of the bearing 2 within which
the collar 5 works, a practically silently acting clutch that will permit the sleeve to
freely rotate with the shaft in the direction indicated by the arrow b, the rollers
then occupying the deepest part of the recesses 8, but will prevent rotation of the
sleeve in the opposite direction except to a very limited extent, by reason of the
rollers being caused by friction to roll along the inclined bottoms of the recesses
and become wedged between the same and the inner surface of the tubular
extension 2. With the arrangement described it will be readily understood that
when the shaft is in use, the collar 3 will be forced by the endways pressure on the
shaft, against the leather ring 6, or against the collar 5 if the ring 6 be dispensed
with, and the sleeve 4 will be pressed against the pivot 7. When the shaft is
rotated in the direction of the arrow b, the sleeve and rollers 9 will rotate with it,
but when the force acting to turn the shaft in the direction mentioned ceases and
the shaft commences to turn in the opposite direction, the backward rotation of the
sleeve will be prevented by the rollers 9 in the manner hereinbefore stated and the
brake will thus be automatically brought into action. The friction between
the collars 3 and 5 or between these collars and the ring 6 will then act to prevent
rotation of the shaft by the action thereon of a suspended load only whilst it will
act to retard the backward rotation of the shaft caused by a greater turning force
applied directly to the shaft by suitable means such as a wheel.
In the arrangement shewn in Fig. 3 the sleeve 5 is by means of a feather 10
arranged to always turn with the shaft but so as to be capable of longitudinal

page_text: movement thereon; and instead of forming the recesses 8 for the rollers 9 in the
collar 5, they are formed in a separate ring 11 which is arranged between the
collars 3 and 5: By this arrangement, the operation of which is similar to that
described with reference. to Figs. 1 and 2 except that the ring 11 will be held
_stationary instead of the sleeve 4, a large frictional surface between the collars 3
and 5 and ring 11 can be conveniently obtained to arrest or retard the rotation of
the shaft in the opposite direction to the arrow b. A ring 6 of material such as
leather may be interposed between the ring 11 and either or both of the collars 3
and 5 to increase the friction. In some cases the ring or rings 6 may be dispensed
with.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
.claim is :-
•
1. The improved brake for rotary shafts subject to end ways pressure, wherein a
sleeve 4 with collar 5 having recesses with inclined bottoms and balls or rollers 9 is
so arranged in conjunction with a collar 3 on the shaft and a fixed tubular part 2*
surrounding the collar 5, that when the shaft is rotated in one direction, the sleeve
with collar and balls or rollers will rotate with it, and when the shaft rotates or:
tends to rotate in the opposite direction the sleeve will be automatically held by
the balls or rollers, and the friction between the collars or between the collars and
an interposed ring of material such as leather will arrest or retard the rotation of
the shaft substantially as herein described and shewn in Figs. 1 and 2 of the
drawings annexed.
2. The modification illustrated in Fig. 3 wherein the sleeve 5 is arranged to
rotate with the shaft by a feather but so as to be movable endway's thereon, and
the recesses 8 for the clutch balls or rollers. 9 are formed in a separate ring 11
arranged between 'the collar 5 on the sleeve and the collar 3 on the shaft
substantially as described, and whether or not a ring of material such as leather be
interposed between the ring 11 and either or both of the said collars.
Dated this 7th day of October 1891
F. J. BROUGHAM.