Improvements in or relating to Cranks and Axles for Cycles and the like.
Year: 1899

page_text: Date of Application, 15th Aug., 1899 -Accepted, 30th Sept., 1899
COMPLETE SPECIFICATION.
Improvements in or relating to Cranks and Axles for Cycles and
the like.
I, GIUSEPPE EGGER, 3, Trieste, in the of Piazza Caserina Empire of Austria,
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 produce a connection between the two cranks
of the crank supports of a cycle or the like, which is very readily made and dis-
connected, and at the same time is perfectly rigid and secure.
In the accompanying drawings:
Figure 1 represents a longitudinal section through the crank bearing of a
cycle;
Figure 2 is an elevation shewing the right hand side;
Figure 3 an end view shewing the left hand side ;
Figure 4 is a cross section on the line -y of Figure 1.
Figure 5 is a cross section on the line of Figure 1.
Figure 6 is an outer elevation of a crank shaft according to this invention,
and
Figure 7 is a developed crank shaft stump to illustrate the length of the slots.
The crank discs S S consist of broad and comparatively thin, flat dises or
plates provided on the one hand with cranks K K and on the other hand being
provided with cylindrical, hollow axle stumps or tubular projections A. A, so
that the outer edge or outer surface of the shaft or axle lies in one and the
same plane as the outer surface of the crank discs. Upon the cylindrical outer
surface of the axle stumps A A, twelve or other number of grooves are formed
in a longitudinal direction, whereby a corresponding number of longitudinal
ribs with parallel sides are formed. The cross sectional form of each groove
and rib is preferably trapezoidal as shown in Figure 4.
The hollow shaft or axle W forms the connecting link between the two crank
axle stumps A. A. The interior of the ends of the hollow shaft are likewise
provided with corresponding longitudinal grooves and ribs being in cross sectional
shape, similar to those on the axle stumps A A, so that the sides of the grooves
and ribs of the axle stumps A A on the one hand fit exactly the sides of the ribs
and grooves in the interior of the hollow shaft W, and, on the other hand, the
top surfaces of the ribs and grooves come into very accurate and intimate contact.
By these ribs and grooves respectively engaging with each other, first of all an
extremely rigid connection of the two crank axle stumps A A, with the shaft or
axle W as intermediate link, is effected, while at the same time the corresponding
position of the cranks at an angle of 180 degrees is also thereby secured.
The direction of the ribs and grooves may, however, be oblique relatively to
the axis of the axle, that is to say, the direction of the grooves in the interior
of the hollow axle W may be such as shewn by the corresponding ribs upon the
axle stumps A A, Figure 6, similar to the rifles in a rifled gun, and this in the
direction of a left hand screw thread for both cranks.

page_text: Thus tho pressure exerted by the cyclist when pedalling on both sides upon the
lever arm of the pedals becomes a to and fro action upon the axle stumps A A
inserted in the hollow axle W. The forces thus produced in a to and fro direction,
cause components of forces having a tendency to force the crank axle stumps A A
out of the ends of the hollow axle W. In order to prevent this pulling out
movement, the crank-axle stumps A, A are slotted at their ends so that by means
of the 12 slots the 12 ribs pass over into 12 strips or flanges L L as represented
in Figs. 1 and 5 and 6 and 7. Owing to the thickness of these flaps or flanges LL
which are made taper towards the end of the axle stumps A A by reason of the
hollow or bore of the stumps being turned conically, these strips or
flanges will be of a sufficient elasticity as soon as the said strips or
Hanges are forced apart by the inner conical heads P P of parts tt when the
nuts M M are tightened. In order to prevent the screw threaded pins t t from
turning during the operation of tightening the nuts M M each of the heads P P
is provided with a nose or projection adapted to fit into one of the slots or one
of the slits or openings between the parts L L.
.
By the pressing of each individual strip or flange L in an outward direction
owing to the tightening of the screw pins t t the parts L L are forced apart
at the ends of the axle stumps A A. and thereby the outer diameter is increased
and thus each axle stump A A is locked absolutely rigidly and is prevented from.
sliding or working out of the hollow shaft W so that consequently a rigid and
thorough connection is separately secured between each crank KK and the hollow
shaft W.
The operation of forcing the parts L L apart at the same time causes the
ribs to be forced like a wedge, into the grooves on the interior of the shaft W,
owing to the trapezoidal cross section of the ribs. By the frictional resistance
thus produced on the sides at the ends of the ribs, or on the axle stumps A A
respectively, another guarantee against any working out of the crank shaft from
the shaft W by friction is obtained. Moreover each crank is prevented from
being loosened under the action of the distorting forces during the crank action
and during the pedalling motion.
If, moreover, the ribs and grooves are arranged obliquely on the two crankc
axle stumps A A and in the interior of the hollow shaft W like a left handed
screw thread, the extent of the components of forces which have a tendency to
pull the stumps out, will not only become reduced according to the extent
of obliquity but will be completely suspended or over come so that the cranks
during pedalling are together with the axle the axle stumps A. A pressed inwards
towards the interior of the axle W. Thus a third guarantee for a reliable securing
of the two cranks K K or the axle stumps A A separately and jointly with the
intermediate link of the hollow axle W is obtained.
The amount of the force which has a tendency to draw one of the axle stumps A
out of the hollow axle W is on the one and dependent upon the amount of
pressure exerted by the pedalling action upon the pedal and upon the length
of the pedal as a lever arm and on the other hand upon the length and the
position of the axle stump A. Thus if under otherwise equal conditions the base
of one of the axle stumps A is placed as closely as possible to the outer edge or
surface of the crank shaft K or in other words the thinner the disc S is made
the less will be the tendency of the crank axle stumps A A to come out of the
interior of the hollow shaft W. For this reason the parts S S are constructed in
the form of thin discs or plates which in their middle diameter are made suffi-
ciently wide in order to thoroughly meet the bending strain resulting from the
action of the crank.
Apart from the advantages as regards the method of connecting the constituent
parts of the cranks K K with the axle Was the intermediate link individually
and relatively to each other, in view of obtaining a rigidity and guarantee against
any parts becoming loose of themselves by comparatively simple means this con-
necting device also presents the further advantage of being easily and rapidly

page_text: detachable and of permitting of each crank being removed individually. In
order that a portion of the interior of the interior of the bearing may be inspected
it is only necessary to slacken the nut M to the extent of from 2 to 3 turns in
order by making a light blow upon the nut M to drive the pin together with
the head P inwards whereupon the crank can be withdrawn by hand since the
strips or flanges L springing back into their normal position no longer offer a
resistance to the pulling out of the crank. These parts can also be equally easily
and rapidly replaced. Thus each crank is individually secured and individually
detachable.
The number of ribs as well as spring strips on each side of the crank the equal
or different length of the same the dimensions of these parts the obliquity of the
ribs and grooves may of course be varied according to the constructional require-
ments without the principle of this method of connection being materially
influenced.
The outer ends of the axle W are provided with flanges which form inward
conicities which can be used as ball races or passages or cups of the ball bearings.
The outer paths or passages are formed by bearing boxes or rings B B which are
screwed into the tubular parts T of the crank bearing. Between the tubular
axle W and the discs S S suitably shaped cases or covers of sheet metal are tightly
jammed thus being caused to rotate with the cranks and protecting the bearing
toward the outside against the entrance of dust etc. The disc S of the right hand
crank K is provided with arms o on which the chain wheel can be fixed in any
suitable manner. The construction of the devices described in this paragraph
by way of example only may be greatly varied.
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. Means for securing cycle cranks and the like comprising tubular axle
stumps such as A A fixed to or formed on flat thin and wide discs or crank
plates said axle stumps being provided with longitudinal or slightly oblique
ribs and grooves with parallel sides adapted to engage with corresponding grooves
and ribs in the interior of the hollow axle forming the connection between both
cranks the axle stumps being slotted at their inner ends the elastic strip thus
made being forced apart and locked to the tubular axle by concial pins in
order to prevent axial displacement substantially as described.
2. A crank plate provided with a tubular projection slotted at its end and
having exterior longitudinal or slightly oblique ribs adapted to engage corre-
sponding grooves in a tubular axle and a conical pin provided with a nut at its
outer end and adapted to press the slotted portion of the tubular projection of the
crank plate outwards and so lock it to the tubular axle substantially as described.
3. The complete crank construction for cycles substantially as described or
illustrated in the accompanying drawings.
Dated this 15th day of August 1899.
BOULT & WADE,
Agents for the Applicant.