Improvements in End Thrust Roller and Ball Bearings.
Year: 1893

page_text: Date of Application, 15th Feb., 1893-Accepted, 15th Apr., 1893
COMPLETE SPECIFICATION.
Improvements in End Thrust Roller and Ball Bearings.
We, FREDERICK PURDON and HARRY ERNEST WALTERS, Civil Engineers,
both of No. 2 Great George Street, Westminster in the County of Middlesex,
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 object
has been to diminish friction between thrust collars and thrust blocks, and between
foot steps and their supports.
Our invention relates to improvements in ball and roller bearings.
Hitherto the ordinary method of supporting and of producing thrust collars and
bearings for shafts, has been to provide a surface of some suitable metals or alloy
such as gun metal, white metal, etc., which was held stationary, and the pressure put
upon the rotating shaft was carried by this stationary bearing. The surface of the
moving shaft therefore had a sliding movement over the whole or part of the said
bearing and the heating which would in the usual course be produced by the friction
caused by such sliding motion was and is diminished in a greater or less degree by
the application of lubricants such as oil or grease. The point aimed at in all
lubrication is to create a film of lubricant between the surface of the shaft and
the surface of the bearing and to so proportion the load to the dimensions of the
bearing that the load shall not cause the lubricant to be squeezed out but that the
load shall be carried upon a film of lubricant between the surface of the shaft
and its bearing. Very low co-efficients of friction have been obtained but always
at a cost of a large expenditure of lubricant and of special attention to the
preparation and material of the bearing.
Our object in this invention is to do away with the friction caused by two
surfaces sliding upon one another and to substitute for the sliding surfaces devices
in which rolling friction alone exists.
For this purpose we place between the shaft and the bearing a series of rollers
and balls. We are of course aware that balls have been largely used in bearings
and that rollers have been largely used also for the same purpose, but in the
majority of these cases the balls and rollers have been free to move in such a
manner that the adjacent surfaces of two neighbouring balls or rollers, as the case
may be, caused sliding friction between themselves.
It is obvious that if balls or rollers are rolling over any given surface the
adjacent surfaces of two neighbouring balls or rollers must be travelling in
opposite directions. Our object has been therefore to prevent such adjacent
moving surfaces from touching each other.
We attain these objects by the mechanism illustrated in the accompanying
drawings, in which
Figures 1 and 2 represent the arrangement we use for a footstep bearing, Figure 1
being an elevation the left half being in section, and Figure 2 a plan, the right
lower quadrant showing the cover and shaft in position, the right upper quadrant
the cover removed, the left upper quadrant the cover and shaft both removed, and
the left lower quadrant the cover, shaft, rollers and balls all removed.
Figures 3, 4 and 5 represent the arrangement we use for a thrust bearing, such
as is required for a propeller shaft.
Figure 3 shows a side elevation, the left half being in section.
Figure 4 is a plan, the left half in section.
Figure 5 is an end elevation, the left half in section, and Figure 6 is a detail
view of one of the rollers.
thuonghout the several views.

page_text: The vertical shaft a, Figures 1 and 2, is provided at its lower end with an
enlargement turned so that it forms the frustrum of a cone, the case c is bored
out with a surface.d, and the rollers e are so made as to roll between the surfaces b
and d. The single and essential requirement for correct working so that only
rolling motion is obtained, is that the rollers e and the surfaces d and b shall all form
parts of cones whose apices meet in the common point f. The next point
.requiring attention is to prevent the said rollers from touching each other; this
is effected by the interposition of a ball g between the upper ends of each adjoining
pair of rollers and of a ball between the lower ends of each adjoining pair of
rollers.
The spacing balls and h not only effect the purpose of keeping the rollers
from touching each other but they also run truly upon the stationary path provided,
as shown upon the adjustable portions of the cases, where the shaft is rotated and
in this manner sliding friction of the balls as well as of the rollers is entirely
avoided. In order to attain these objects the relative sizes of the balls g and h,
the diameter of the neck of the cones upon which the balls roll, and the diameter of
the stationary path upon which the balls roll must be so arranged that the said
balls g and shall in their circular motion round the axis of the shaft have the
same surface velocity imparted to them by their motion over their respective
paths as is imparted to them by their respective ends of the said rollers, and the
motion must be imparted to the balls in the same sense of rotation.
The upper end of each roller is hollowed out at i, and the lower end at j, to
form a suitable surface for the balls to work upon. As the proportion of the
downward pressure of the shaft upon each roller may be resolved into two com-
ponents, one of which is at right angles to the axis of the roller and the other
along that axis, it is obvious that the component at right angles to the axis has
no tendency to cause the roller to move in the direction of its own axis and away
from the apex f. The other and very much smaller component acting along the
axis would tend to cause a movement of the roller in the direction of its own axis
and in the sense away from the apex f, this motion is prevented by the path k turned
upon the inside of the case c, this path and the top of the roller are so formed that
if the roller were to touch the path kit would do so at a point lying upon the
surface of a cone with apex at fand so cause no sliding motion whatever.
The balls gare held in position by the cover which is formed to receive them
and to provide an internal path upon which they can roll. Similarly the balls are
held in position by the part m which has an internal path cut upon itself. In
Figures 1 and 2 we have shown the axis of each roller inclined to the vertical at
an angle of 45°, but there is no reason why this particular angle should be retained,
and it is obvious that the principle would remain the same were the axes inclined
at a different angle to the vertical.
The number and size of balls and rollers also depends upon the size of the
vertical shaft a and the load which is to be carried.
The cover may be secured to the case c in any suitable manner, and it is so
arranged in the case depicted that the cover can be let down slightly to take up.
wear of the balls g; the adjustment of the part m by the screw is obvious.
In Figures 3, 4 and 5 the essential features are similar to those in Figures 1
and 2. The shaft a is here horizontal and is provided with a collar a¹ with two
rolling faces b. The rollers are similar to those described heretofore, the essential
point in this design being that the conical surfaces and the rollers e should have a
common apex in f. The casings c are made in two halves, that is to
say,
the left hand
case is intended to take a pressure towards the left, and is made in two halves to allow
of erection; the right hand case is made also in two halves for a similar purpose.
A space n is left between the two cases in order to allow of adjustment in case of
wear of the two faces of the collar a'. Small projections k are made upon the
inside of the cases in order to prevent motion of the rollers in the direction of their
own axes and in a sense away from the apex f. In Figure 5 the outer ends p of the
rollers are described with a radius which must be less than the radius of the

page_text: chamber in which the rollers are placed in order that the ends may not cause a
sliding motion to be produced. In Figure 6 the point 9 which is designed to
bear upon the projection k inside the case must be upon a line which is a con-
tinuation of a line formed upon the surface of the roller by a plane passing through
the axis.
As we have heretofore mentioned we are aware that balls alone, rollers alone,
and combinations of balls and rollers, have been used for the purpose of diminishing
the friction in bearings. We do not therefore claim such a combination of rollers
and balls broadly, but what we do claim is :-
1. The combination in an end thrust bearing, of a system of rollers upon which
the load is taken, and of a system of balls by which the rollers are kept apart,
each roller having the form of a frustrum of a cone and all the rollers being
similar to one another, all substantially as set forth.
2. The combination in an end thrust bearing of a system of rollers upon which
the load is taken and of a system of balls by which the rollers are kept apart,
each roller having the form of a frustrum of a cone and all the rollers being
similar to one another, the part of the shaft which bears upon the said rollers being
formed as the frustrum of a cone, all substantially as described.
3. The combination in an end thrust bearing, of a system of rollers and balls,
each roller having the form of a frustrum of a cone and the part of the shaft
bearing upon the said rollers being formed as the frustrum of a cone, the cones of
which the rollers and part of the shaft are frustra having a common apex lying in
the axis of the said shaft, all substantially as described.
4. The combination in an end thrust bearing of a system of rollers and balls each
roller being the frustrum of a cone and the part of the shaft bearing upon the said
rollers being also the frustrum of a cone each roller being so formed that a series of
points forming a circle upon its head lie upon the surface of the cone of which it is a
frustrum and may bear upon a suitable path produced upon the stationary case, all
substantially as described.
5. The combination in an end thrust bearing of a system of rollers and balls
each roller being the frustrum of a cone and the part of the shaft bearing upon
the said rollers being also the frustrum of a cone with a suitable case or support
having a surface so formed that the rollers may roll freely upon it and provided
with a method of adjusting the relative position of the balls and rollers, all
substantially as described.
Dated thin 15th day of t 1002
JOHN P. O'DONNELL,
70 & 71, Palace Chambers, Bridge Street, Westminster, S. W.,
Agent for the said Applicants.