Improvements in Weston Centrifugal Machines.
Year: 1899

page_text: Date of Application, 30th Aug., 1897
Complete Specification Left, 23rd Apr., 1900-Accepted, 26th May, 1900
PROVISIONAL SPECIFICATION.
Improvements in Weston Centrifugal Machines.
We, JOHN LAIDLAW, of the Firm of Watson, Laidlaw & Co., of 98, Dundas
Street, South, in the County of the City of Glasgow, North Britain, Engineers,
and JAMES WRIGHT MACFARLANE, Manager of said Firm, do hereby declare
the nature of this invention to be as follows:-
-
This invention is to improve the construction of the footstep Learing of the
spindle of the suspended Weston centrifugal.
The spindle consists of a main revolving spindle of sufficient diameter to
permit of it being bored for about half its length from the upper end, and a
spindle which is stationary is placed inside the main or revolving spindle. The
stationary spindle, which projects above the revolving spindle, is attached to
the frame work supporting the machine. There is a bush at the upper end
of the revolving spindle, and a bush near the lower end of the hole which has been
bored in it. These bushes form a bearing surface sideways for the stationary spindle.
The lower end of the stationary spindle after it passes the bottom bush is reduced
in diameter and screwed for a nut, and between the nut and the lower bush a
number of discs or washers of steel or other metal are introduced to form a footstep
or bearing to carry the weight of the revolving spindle and the basket or cage
of the centrifugal, which is fixed to its lower end. The lower bush in the revolv-
ing spindle is secured in its place by a pin passing through the spindle and partly
through the bush.
The steel or other metal discs or washers, which are placed between the lower
bush and the nut on the lower extremity of the internal or stationary spindle,
are sufficiently numerous to reduce the velocity of any two surfaces in contact to
prevent the abrasion which might take place if only two surfaces were exposed.
Hitherto
The upper washer is attached to the lower bush and therefore revolves with
it, the lower washer is attached likewise to the nut on the end of the stationary
spindle and therefore does not revolve. The intermediate washers are loose
and are therefore free to divide the revolutions of the revolving spindle between
them, and if the surfaces are uniform it may be assumed that there is a pro-
portionate decrease of motion from the upper washer to the lower washer, accor-
ding to the number of washers between the upper one and the lower one.
it has been the practise to make these washers all alike in respect of their outside
diameter and the size of the hole in the centre, they, therefore, when piled one
above the other, form a hollow cylinder with parallel sides. These washers must
have a working clearance both inside and outside, and if the clearance is greater
between them and the revolving spindle, than between them and the stationary
spindle the speed of the washers will cause them to assume an eccentric motion
equal to the amount of clearance between them and the stationary spindle, and
they will therefore bear upon the stationary spindle. It has been found in
practice that the washers which revolve fastest abrade the surfaces in contact
with the stationary spindle so that small particles of metal are detached, and these
getting between the horizontal surfaces of the washers cause heating and abrasion.

page_text: Figure 1 illustrates part of a Weston centrifugal machine.
Figure 2 is an enlarged section of the spindle showing the improved construc-
tion of the footstep bearing.
The spindle consists of a main revolving spindle A of sufficient diameter to
permit of it being bored for about half its length from the upper end, and a
spindle B, which is stationary is placed inside the main or revolving spindle
The stationary spindle B, which projects above the revolving spindle, is attached
to the frame-work supporting the machine. There is a bush at the upper end
of the revolving spindle, and a bush E near the lower end of the hole which has
been bored in it. These bushes form a bearing surface sideways for the stationary
spindle. The lower end of the stationary spindle after it passes the bottom bush
is reduced in diameter, as shown at B' and screwed for a nut F and between the
nut and the lower bush E a number of discs or washers C, C, etc., of steel or
other metal are introduced to form a footstep or bearing to carry the weight of
the revolving spindle and the basket or cage of the centrifugal, which is fixed
to its lower end. The lower bush in the revolving spindle is secured in its
place by a pin passing through the spindle and partly through the bush.
The steel or other metal discs or washers, which are placed between the lower
bush and the nut F on the lower extremity of the internal or stationary spindle,
are sufficiently numerous to reduce the velocity of any two surfaces in contact
to prevent the abrasion which might take place if only two surfaces were exposed.
The upper washer C' is attached to the lower bush and therefore revolves with it;
the lower washer C' is attached likewise to the nut on the end of the stationary
spindle and therefore does not revolve. The intermediate washers C³, C³, 0, 0, 0,
are loose and are therefore free to divide the revolutions of the revolving spindle
between them, and if the surfaces are uniform it may be assumed that there is a
proportionate decrease of motion from the upper washer to the lower washer,
according to the number of washers between the upper one and the lower one.
Hitherto it has been the practice to make these washers all alike in respect of
their outside diameter and the size of the hole in the centre; they, therefore,
when piled one above the other, form a hollow cylinder with parallel sides.
These washers must have a working clearance both inside and outside, and if the
clearance is greater between them and the revolving spindle than between them
and the stationary spindle, the speed of the washers will cause them to assume
an eccentric motion equal to the amount of clearance between them and the
stationary spindle, and they will therefore bear upon the stationary spindle.
It has been found in practice that the washers which revolve fastest abrade the
surfaces in contact with the stationary spindle so that small particles of metal
are detached and these getting between the horizontal surfaces of the washers
cause heating and abrasion.
In a similar manner when the clearance between the washers and the stationary
spindle is greater than between the washers and the revolving spindle the washers
will bear on the revolving spindle and those which are running slowest tend
to abrade in the same way and produce the same results. When the clearances
are equal, the washers with the highest velocity of rubbing contact will produce
abrasion, which may be with the inner edges of the upper washers or the outer
edges of the lower washers.
The object of this invention is to overcome the defect arising from having
the washers made uniform in diameter and in the size of the hole. It is intended
to increase the size of the holes in the faster running upper free washers C¹, C³, C³,
or increase their outside diameter, as the case may be, or partly both, as shown,
so that the washers will be in contact with the revolving spindle before they
can touch the stationary spindle. The lowest washer, namely C³, in the group
of the faster running washers will be the one where the velocity of rubbing con-
tact of the outer and inner edges are equal or nearly so. The washers below this
point would form a group C4, C5, C6, of slower running washers which would