Improvements in or relating to Crank Bearings for Cycles.
Year: 1898

page_text: Date of Application, 23rd Sept., 1898-Accepted, 5th Nov., 1898
COMPLETE SPECIFICATION.
Improvements in or relating to Crank Bearings for Cycles.
I, GIUSEPPE EGGER, of 3, Piazza Caserma, Trieste, in the Empire of Austria,
Cycle Manufacturer, 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; --
The object of this invention is to reduce the friction in crank bearings for
cycles to a minimum and thus to attain easier pedalling.
The frictional resistance of a bearing depends, as is well known, on a normal
pressure acting on it, that is to say caeteris paribus, the friction is the smaller
the smaller the normal pressure. The normal pressure on a cycle bearing may
be lessened by diminishing the increase of the force exercised on the pedals
produced in the course of its transmission to the bearing. This increase is the
smaller the greater the distance between the planes E passing through the balls.
If for instance the distance between the planes E, in which the balls of the
bearings lie, be a quarter of the distance between the feet resting on the pedals,
or of their centre lines, then the normal pressure on the balls will be four times
as great as the pressure exercised by the feet on the pedals. If the distance
between the planes E were only a half of the distance between the pedals or
centre of feet, then the normal pressure on the bearing would be only half of the
pressure exercised on the pedals by the feet. As in the second case the normal
pressure is only half as great as in the first, the friction caused by it will also be
only half as great, and the bearing will be twice as easily moved.
As the construction according to this invention is such that the plane E passing
through the balls is nearly in the central plane K of the crank-arms and therefore
beyond the limit N of an ordinary boss (Fig. 4), and is brought as near as possible
the outer surface Z of the cranks, as clearly shown in the accompanying drawings,
the bearings are placed apart as far as possible. Their distance apart is maximum
for a given limited length of the whole crank bearing, or for a given tread,
consequently the normal pressure on them is minimum and the object aimed at,
the reduction of friction in cycle bearings to a minimum is attained.
This arrangement has another great advantage; the plane of the sprocket wheel
necessarily lies between the planes EE so that the normal pressure caused by the
tension of the chain is not increased in its transmission to the bearing. Besides
the surfaces of the races are better maintained. Said surfaces do not become so
easily depressed or corroded owing to the smaller normal pressure on the bearings.
The advantages of this invention become more particularly noticeable when a
great strain is put on the bearings such as in riding up-hill or against wind or
with high gear. It is also an advantage that there are no projecting parts to
interfere with the pedalling. The outward appearance of the new crank-bearing
is a very neat one, it is easily taken to pieces and cleaned, and easily put together
again, the parts for this purpose being few and easy to manufacture. A lubricated
felt or similar ring protects the bearings from dust.

page_text: In the accompanying drawings,
Figures and 2 show a longitudinal section and a front elevation of a crank
bearing constructed according to this invention, and
Figure 3 is a longitudinal section of an alternative form of the same. .
Referring to Figs. 1 and 2, in the bracket 1 a hollow spindle 2 is arranged with
ends, slightly tapering outwards, on which run the balls 3, the cups 4 and 5
are adjustably mounted in the bracket 1 by means of screw-threads in the usual
manner. The crank armis 8 and 9 terminate in peculiarly shaped bell-like bosses G
and 7, the outer projecting portion of which overlaps and covers the balls 3 and
cups and 5, the inner projecting portion 6 forming the boss proper.
This hollow boss, 6 is provided outside with a right hand screwthread for the
right hand crank, and with left hand thread for the left hand crank, by means of
which said bosses or hollow pins 6 are screwed into the hollow spindle 2.
Screws 10 and 11 with conical heads y serve to secure the parts against
unscrewing during back pedalling. If after the hollow-pin boss 6 has been
scrowed in place into the hollow spindle 2, these screws are tightened by means of
nuts 12 with loft hand and 13 with right hand threads, the conical head y presses
into the tapering hollow of the inner pin 6 which being correspondingly slotted
at is therefore springy, and thus is firmly wedged into the screw-thread and
locks the cranks against accidental unscrewing.
The driving chain wheel 15 is screwed on to the cup 7 of the right hand crank
boss by means of a screw thread and lock nut 14; said chain wheel may also be
secured by means of lugs and small screws.
To prevent dust from penetrating into the interior of the crank bearing, the
cups 4 and 5 are provided with circular grooves 17 and 18 filled with felt or
similar material impregnated with grease.
19 is a clamp screw usually arranged on the bracket 1 for preventing the cup
from becoming loose when the bearing is to be adjusted.
5
It is evident that the described construction and arrangement of crank bearings
can be applied to chainless cycles if, the chain wheel 15 be replaced by a suitable
toothed or bevel wheel.
The object of the crank bearing above described, viz. placing of the ball-bearings
as far apart as possible by the special shape of the bosses, could be attained by other
constructions. For instance, instead of being screwed into a hollow spindle, as
shown in Figure 1, the bosses may be secured to conical ends of a solid spindle 2,
as shown in Figure 3 by means of keys or the like and held by nuts 12 and 13
screwed on the threaded ends of said spindle. The ball races are then constituted
by sockets 7 slid on the bosses 6, instead of by the ends of the hollow spindle as
in Figure 1.
Several modifications may be made in the construction, but it will be extremely
difficult or even impossible to attain the desired end, viz.; the placing of the
crank bearings as far apart as possible, unless the shape of the boss substantially
as herein described be retained.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
1. In a cycle crank bearing placing each bearing surface so that a plane E
passing centrally through the same substantially corresponds with the central
plane K of the crank arm.
2. In a cycle crank bearing placing the bearing surfaces within the crank boss
for the purpose specified.
3. A cycle crank boss comprising an outer cup and a central hollow pin or boss,
forming with the cup an annular space, within which the ball bearing is contained
substantially as described.

page_text: •
4. In a cycle crank bearing forming the boss of each crank with an inner pin
or boss, 6, engaging with the hollow spindle, 2, by a right and left hand thread
respectively and provided with slots, a, said bosses being held in position by
screws, 10, 11; provided with conical ends, y, and screwed heads engaging
nuts, 12, 13, by left and right-hand threads respectively substantially as described.
5. In a cycle crank bearing forming the crank boss with an inner pin or boss, 6,
secured on the tapered end of a solid crank spindle, one bearing surface, 7, of the
ball race being fixed on the boss 6 substantially as described.
6. In a cycle crank. bearing such as described forming the ball race cups, 4, 5,
with circular grooves, 17, 18, filled with felt or similar material substantially
as and for the purpose described.
7. The cycle crank bearing substantially as described or illustrated in Figures 1
and 2 or in Figure 3 of the accompanying drawings.
Dated this 23rd day of September 1898.
• BOULT & WADE,
Agents for the Applicant.