Improvements in the Construction of the Oranks and Crank Shafts of Cycles and other Machines, and the Bearings therefor.
Year: 1889

page_text: Date of Application, 14th June, 1889
Complete Specification Left, 14th Mar., 1890-Accepted, 26th Apr., 1890
Improvements in the Construction of the Oranks and Crank Shafts
of Cycles and other Machines, and the Bearings therefor.
I, WILLIAM BLAKELY, of "Vernon," Princess Road, Bournemouth West,
Engineer, do hereby declare the nature of this invention to be as follows:-
My Invention relates to improvements in the construction of the cranks and crank-
shafts of cycles and other machines, and to the bearings therefor.
According to my invention, I build up the crank of stamped plates of sheet steel
upon a core of tough wood, whereby I am enabled to combine lightness with strength.
The metal plates are of channelled section or flanged so as to embrace and enclose the
wood core more or less on opposite sides, and are fine or coarse ribbed in the length-
wise part to add stiffness against the push of the treadle; the whole being securely
united by through bolts or screws. In addition to the metal side plates, one or two
angle strips of metal may also be used between the longitudinally divided wooden
core. The eyes of these metal plates are stamped with notched edges which enter
corresponding flukes formed in the shaft so as to dispense with the use of the loose
keys. When these notched eyes are driven on to the crank shaft they are, so to speak,
keyed thereto by the numerous intervals around the circumference, a set screw being
also provided, if necessary, to prevent it shaking loose. With this construction I am
enabled to provide a means of varying the radius of the crank pin or treadle, said
means consisting of a spring locking bolt contained in a channel formed in the wood
core and projecting therefrom at a suitable point for the purpose of being readily
operated. The crank pin or treadle is fitted to slide radially upon the crank arm or
arms, so that when the above-mentioned spring bolt is unlocked it may be moved by
gravity or by pressure upon it to a position nearer to, or farther from, the shaft. By
this means, the radius of the crank pin may be altered at the will of the rider for hill-
climbing or for running on level roads. The shaft is slotted throughout its length in
its curvilinear section, these slots extending all through the axle of the shaft for the
purpose of holding a lubricant. In addition to the flutes, the journals may be cut
with a coarse square-edged screw-thread, the threads of opposite journals being
reverse-handed so as to avoid end thrust and consequent wearing of the faces of the
bearings. The journals of the shaft may also have wearing surfaces of agate, or other
hard material, let into them or the journals of the shaft may have collars in undereut
slots at their ends which peripheries, when alone, constitute the wearing surfaces of
the journal. The main axle shaft may also be built up with two or more thin sheet
twisted steel or other metal tubes made like gun barrels so as to fit into each other
like telescope tubes. One of these tubes is heated so as to be shrunk on the other
outside axle. I also propose to build them up with a core of hollow metal of
triangular form, also placing three edgewise small keys all through the axle between
the two tubes if so wished, these plans will make both a light and very stiff shaft or
axle not likely to spring or bend with a heavy rider. This axle may have a 'core of
very hard stiff wood, such as lancewood, iron wood, or hickory, box, etc., dried sharply
then placed in by hydraulic pressure.
Dated this 13th day of June 1889.

page_text: part of this specification, wherein
Figure 1 represents a longitudinal section.
Figure 2 a face view, and
Figure 3 a cross-section (on line 3-3 figure 1) of a bicycle crank arm.
Figures 4 and 5 shew longitudinal and cross-sectional views of modified con-
structions of crank axle.
Similar letters of reference indicate like parts in all the figures.
According to my invention, I build up the crank of an external shell composed of
two stamped sheet steel plates a a¹ upon a core of tough wood b, whereby I am enabled
to combine lightness with strength. The plates aa' are both stamped up of channelled
section, as shewn in cross-section in figure 3, so that their flanges butt joint along the
edges of the crank arm, as at cc, and they are corrugated longitudinally to give
increased stiffness. They embrace the wood core, as shewn, the whole being firmly
united by rivets d. The crank arm is slotted at at which point the wood core is
replaced or strengthened by metal linings k to take the' wear.
The ends of the crank axle e are longitudinally fluted, as shewn in figure 1, and
the parts of plates at a' which form the eyes f of the crank arms are stamped with
notched edges corresponding to the flutes of the axle so as when driven on to the ends
of the axle they will be securely keyed thereon by the interlocking flutes without the
use of any loose keys. The flutes may continue throughout the length of the axle e
the flutes at the parts which form the journals being either filled up with agate or
other hard material to form a cylindrical journal, as at g, or being left wholly or
partially fluted for the purpose of holding lubricant. The flutes at the other parts of
the axle or shaft serve to receive the keys of the other parts of the driving gear (if
any) to be keyed thereon.
I further provide means of varying the radius of the crank pin or pedal, at the will
of the rider, for hill climbing or running on level roads. For this purpose the pin h,
on which the pedal is mounted, is fitted to slide in the longitudinal slot i in the crank
arm, the edges of said slot being lined with metal k, as above mentioned. The pin h
is carried by a bar / fitted to slide telescopically within the crank arm the wood core
of which is made hollow to receive it. This bar is of oblong cross-section so as to
have the necessary transverse strength and it is surrounded by a spiral spring m of
oval form in section which is confined between a cross pin at the inner end and a
shoulder b¹ on the core of the crank arm so as to tend to draw the crank pin inwards
to its shortest radius. It is shewn in its mid-position in figure 1 and is locked in
either of these positions by a spring-locking bolt n sliding through a transverse slot
in the crank arm and adapted to engage with either of three notches o¹ 02 03 in the
edge of the arm l. The locking bolt n is drawn into engagement with one of said
notches by a spring p and the head of the locking bolt projects from the face of the
crank arm in such position that it may be conveniently pressed inwards to disengage
the bolt from the notch in the arm by a side motion of the riders' foot at the same
time that by pressure of the same foot on the pedal the crank pin may be moved along
the crank arin to a greater radius; or, by relaxing the pressure of the foot, the
spring m is permitted to act so as to draw the crank pin inwards to a lesser radius, as
the case may be, the bolt in either case relocking the sliding bar automatically, Thus,

page_text: the radius of the cranks or pedals may be altered by the rider without dismounting
and whilst the vehicle is running.
•
Figure 4 shews a mode of constructing an axle or shaft of two or more thin steel
or other metal tubes r s shrunk the one on the other and upon a core t formed of a
metal rod of triangular (or it may be cruciform) cross-section. Figure 5 shews a
similar tubular construction, the outer tube being shrunk on the inner one which is
filled by a core u of hard tough wood, such as lancewood iron wood or hickory, dried
and forced tightly into the inner tube. By these constructions a light and very stiff
shaft or axle is produced which is not likely to spring or bend under the weight of a
heavy rider.
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. The herein described construction of crank arms of a shell formed of stamped
steel plates clamped upon a wood core, as specified.
2. The combination of fluted axle ends with notched eyes of the crank arms
whereby the latter are securely fixed to the former without loose keys.
3. Fluting the axle journals and filling the flutes with agate or other hard material,
as specified.
4. The herein described construction of radially-adjustable crank or pedal in
combination with a spring and locking bolt, substantially as specified.
5. The herein described construction of shaft or axle formed of two or more con-
centric tubes shrunk one on the other and upon a core composed of a metal rod of
triangular or cruciform section, as described.
6. The herein described construction of shaft or axle formed of two or more con-
centric tubes shrunk one on the other in combination with a filling or core of wood,
as described.
Bated thin 14th day of M 1000
Dated thin 14th
Mach 1900
WM. BLAKELY.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.