An Improved Self-sustaining Gear for Hoisting, Lifting, or Winding Machinery.
Year: 1899

page_text: Date of Application, 18th Nov., 1899-Accepted, 23rd Dec., 1899
COMPLETE SPECIFICATION.
An Improved Self-sustaining Gear for Hoisting, Lifting, or Winding
Machinery.
I, FREDRIC EASTMEAD, of 39, Victoria Street, Westminster, S.W., 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:-
In order
At
This invention consists in improvements in that class of self-sustaining gears
or automatic brakes for hoisting apparatus in which the load is sustained by
friction between moving surfaces attached indirectly or directly to the load and
fixed surfaces, and in which the pressure between the frictional surfaces necessary
to give the required holding power is obtained by the obliquity relative to the
plane of revolution of links connecting two of the moving surfaces.
that my invention may be more readily understood I have caused two sheets of
drawings to be made in which Fig. 1 Sheet 1 is a sectional elevation and Fig. 2
Sheet is another sectional elevation through Fig. 1 Sheet 1 at A B, and Fig. 3
and 4 Sheet 2 are respectively an end elevation and a section on A, B, looking
from H towards H showing the relative position of the feathers and flanges
when sustaining the load. The arrows in the figures shew the direction the shaft
must be rotated to lift the load. Fig. 1 Sheet 1 is a sectional elevation through
a cylindrical box E having flanges or frictional surfaces F F at each end, this
box is held by means of stays fixed to the arms G and G¹ the said stays being
fixed to the standards or other immovable parts of the hoisting apparatus.
each end of the box E I place two other flanges or covers having in their central
portions feather ways or slots D and 1 as shewn in Fig. 1 and 2 Sheet 1 a pinion
or the like is placed on the front cover or flange H and when it is required to
raise the load the shaft J is caused to rotate in the required direction until the
feather comes into contact with the end of the slot D and the feather C¹ comes
into contact with the end of the slot D', thus causing the links K and K'
to become parallel to the axis of the shaft and thereby permitting the
Hanges H and H¹ to revolve freely clear of the box E. When it is desired to
stop the ascent of the load the rotation of the shaft J is discontinued and as the
load is connected to the front flange H by means of the pinion or its equivalent
herein before mentioned it will in attempting to run down rotate the flange H
and shaft J in a contrary direction to that in which they were moving. The
flange H will however not rotate as the feather C will retreat from contact with
the end of the slot D. This action will cause the links K and K to lie in an
oblique position (i.e., not parallel to the axis of the shaft J) and the two flanges H
and H will thereby be drawn against the flanges F and F with a pressure pro-
portionate to the load which is being sustained. The length of the slot Dis
so arranged that when the gear comes to rest with the load sustained, the
feather is almost in contact with the end of the slot I¹ opposite to the end
with which it was in contact when raising the load, this being necessary to prevent
the jerk which would take place if the feather had any "play or lost motion to
take up before making contact. The position of the flange, H and feather C
"

page_text: when sustaining the load is shewn on Fig. 3 Sheet 2 and the position of the
flange Hand feather when sustaining the load is shown on Fig. 4 Sheet 2.
If now it is decided to lower the load the shaft J is rotated in the necessary
direction and the feather C¹ will come into contact with the end of the slot 11
and will push the flange H' round so as to lessen the obliquity of the. links K
and and so by freeing the pressure between the flanges Hand H and the flanges F
and Fallow the load to descend the speed of descent being regulated by the speed at
which the shaft J is rotated. If the load is very heavy the frictional faces of the two
flanges Hand F and F and H₁ may be grooved to give more surface. One of
the improvements in this sustaining gear consists in manufacturing each of the
links which connect the two moving Hanges H and H in the form of a double
eye piece that is to say a link furnished with an eye at each end through which
the staples or eyebolts L and L' attaching the links to the moving flanges pass,
but preferably the links K and K may be made in the form of a single long
link of chain. This improvement prevents the objection which has occurred to
the use of flexible links each composed of several links of chain by preventing
only four surfaces to wear in each link instead of more than double that number
where chain is used.
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. The use in selfsustaining gears or automatic brakes of long links or eye-
bolts for the reason above described.
2. The use in selfsustaining peas or automatic brakes of slots or featherways
of just sufficient length to preven jerking as and for the purpose herein described.
3. In self sustaining gears or automatic brakes the combination of Claims 1;^2,
as and for the purpose here in described.
Dated this 18th day of November 1899.