Improvements in and relating to the Crank Shafts of Velocipedes.
Year: 1896

page_text: Date of Application, 24th Oct., 1896
PROVISIONAL SPECIFICATION.
Improvements in and relating to the Crank Shafts of Velocipedes.
I, HIRAM STEVENS MAXIM, of 18 Queen's Gate Place, in the County of Middlesex,
Mechanical Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to the crank-shafts or axles of such vehicles as bicycles
and tricycles and consists in the novel construction and manner of uniting the
parts of the crank shaft.
According to my invention the crank shaft is formed of a tubular portion and of
separately formed crank-arms secured to the said tubular portion as hereinafter
described. The said tubular portion is formed exteriorly and adapted to work in a
ball bearing in the ordinary manner or in any convenient and suitable manner.
interior of the tubular portion is polygonal and preferably hexagonal, and I form
each crank on the end of a similarly polygonal bar or shank. These bars or
shanks are made to fit the hexagonal interior of the tube so that, when in place
therein, they will form a practically solid connection therewith but so that they
can be readily withdrawn and reinserted when necessary. The said shanks should
be of such a length that when both are in place in the tube a slight space exists
between their inner ends.
One of the said shanks is made hollow to admit a screw, which is inserted therein
and which extends through the said shank into a screw-threaded hole in the other
shank and by means of this screw the two shanks are securely held together within
the tube. The chain, or sprocket, wheel also has its boss or hub of a like polygonal
interior form and the shank of one of the cranks is passed through the same. In
this manner I am enabled to provide cycles with crank shafts in a very simple
convenient and durable manner.
Improvements in and relating to the Crank Shafts of Velocipedes.
I, HIRAM STEVENS MAXIM, of 18 Queen's Gate Place, in the County of Middlesex,
Mechanical Engineer, 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:-
My invention relates to the crank-shafts or axles of such vehicles as bicycles
and tricycles and consists in the novel construction of the parts thereof, and in
the manner of uniting them.
According to my invention the crank shaft is made tubular and its interior sur-

page_text: face as well as that of the boss of the chain wheel are polygonally formed for the
reception of similarly shaped bars or shanks carrying the cranks, the whole of
these parts being held together by means of a detachable or adjustable fastening
device such as a screw bolt.
In order that my said invention may be clearly understood and readily carried
into effect I will proceed to describe the same more fully with reference to the
accompanying drawings in which:-
Figure 1 is a longitudinal section; and Figure 2 is a transverse section on the
line 1, 1, of Figure 1 showing my improved crank shaft.
A is the tubular portion of the crank shaft. B B are the cranks and b 6' their
bars or shanks. C is the chain or sprocket wheel. D is the detachable fastening
device which in the example illustrated consists of a screw.
The said tubular portion A is mounted in the bracket A' within which it is
capable of revolving freely on ball bearings A2 A2 of ordinary construction. In
the example illustrated the interior surface of the tubular portion A is hexagonally
formed, as clearly shown in Figure 2, but the cross section thereof may be of any
other desired polygonal shape. The bars or shanks b b of the cranks are also of
hexagonal shape in cross section to enter and fit the said tubular portion A, and
when in place these shanks form a practically solid connection with the tubular
portion but are capable of being readily withdrawn longitudinally and reinserted
when necessary. The said shanks are of such length that when in place in the
tubular portion, a slight space a exists between their inner ends. The shank bis
made hollow and the shank 61 is formed with a screw threaded hole 6 so that the
screw D can be inserted through the hollow shank b and its threaded end can be
screwed into the hole 6 of the shank b whereby the two shanks will be forcibly
drawn together and rigidly held in place.
The shank b is made somewhat longer than the shank 6' in order that it may
receive the sprocket wheel C which is formed with a polygonally shaped boss c to
fit the said shank; when in place it occupies a position between the crank B and
the end of the bracket A¹ as shown in Figure 1.
It will be seen that by constructing the crank shaft in this manner the two crank
shanks, the sprocket wheel and the shaft are all firmly held together by a single
screw in a way that will permit of their being very readily disconnected when
desired by the removal of the said screw.
In some cases it may be found more advatageous to employ some other fasten-
ing device instead of the screw D for connecting the parts together.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
1. A velocipede crank-shaft consisting of a tubular portion having a polygonal
interior and of cranks provided with polygonal shanks to fit the said tubular por-
tion in which they are held by a detachable or adjustable fastening device for the
purpose specified.
2. A velocipede crank-shaft of which the cranks, the shaft and the chain wheel
are all separately constructed and connected and held together substantially as
described with reference to the accompanying drawing for the purpose specified.
Dated this 23rd day of July 1897
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.