Improved Device for Locking the Sprocket Wheel of Cycles and similar Chain Driven Vehicles to Prevent Theft.
Year: 1898

page_text: Date of Application, 1st Dec., 1898-Accepted, 28th Jan.,
1899
COMIENIE DITUITUATION.
Improved Device for Locking the Sprocket Wheel of Cycles and
similar Chain Driven Vehicles to Prevent Theft.
I, FRIEDRICH MENNICH, of Karlsruhe, in the German Empire, Technician, 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 improved device forming the subject of the present invention has for its
purpose to prevent the unauthorized use of a bicycle or similar vehicle the pro-
pulsive power of which is transmitted to the driving wheel by means of an endless
chain and a sprocket wheel. It simultaneously affords an effective protection
against theft when the cycle is left unguarded. The device is preferably fixed to
the lower part of the bottom bracket and possesses a pin in its exterior that can be
caused to project from the casing of the device so that it engages and locks the
sprocket wheel in its respective position. The said pin is actuated by means of a
suitable key. It is consequently impossible to use the cycle without disengaging
the pin from the sprocket wheel, as the locked condition of the latter will prevent
the movement of the driving wheel of the cycle. The hidden position of the device
will make it difficult for unauthorized persons to find out the mechanism of the
same and thus will render theft of a cycle provided with and locked by means of the
device forming the subject of the present invention a very difficult task.
By way of an example one mode of carrying out the invention has been illustrated
in the accompanying drawings, in which,
Figure 1, shews a longitudinal section through the device, when the operative
pin is in locking position, the device being secured to the lower side of the bottom
bracket,
Figure 2, is a side elevation of the device seen from the left hand side of
Figure 1,
Figure 3, is a section on line - of Figure 1, and
Figure 4, illustrates the key necessary for unlocking the pin of the device as
illustrated.
The device consists of a casing (a) with lateral projections (a¹) serving for
securing the device to the lower part of the bottom bracket by means of screws (b)
which penetrate the projections through previously provided suitable holes and
enter the body of the said bracket. In the side of the casing near to the sprocket wheel
is a hole for the passage of the locking pin (c). This locking pin, when fully
rojecting from the casing (a), engages one of the spaces between the spokes of
the sprocket wheel (d) or one of the apertures, should the sprocket wheel not be
provided with spokes. The rear end of the locking pin (c) is in connection with a
second pin (e) which is guided in a suitable bore in a partition wall (f) of the

page_text: casing (a). This second pin (e) is provided with one or more projecting studs (g, g)
which either form one piece with the pin (e) or are inserted into the latter.
The partition wall (f) in addition to the bore is provided with a groove (h) opening
towards the bore. This groove (h) serves for permitting the passage of the stud (g)
and consequently that of the pin (e), when the stud (g) appears opposite the
mouth of the groove (h). A key (i) the hollow of which corresponds to the reduced
end of the pin (e), and which key is further provided with a projection (1) in
accordance with a hole (m) in the end face of the pin (e) serves for turning the
pin (e). A suitable key hole (o) is formed in the casing (a) for the reception of
the key (i). A spiral spring (p) bearing at one end against the casing (a) and
at the other end against the end of a socket formed on the pin (e) and surround-
ing the inner end of the pin (c), tends to return the locking pin (c) to its
position of rest in the casing (a).
The operation of the device is as follows:-When in normal position, that is to
say, the position of rest, the pin (e) is situated in such a manner that the stud (g)
fits into the groove (h) and the locking pin (c) is retained in the casing (a) by
the action of the spring (p). To lock the sprocket wheel (d), the pin (e) is
pressed inward by means of the key (i) until the stud (g) leaves the groove (h).
To indicate this point the stud (g¹) may suitably serve, this stud also prevents the
further inward movement of the pin (e) by coming into contact with the partition
wall around the bore. By turning the key (i) and with it the pin (e) a little,
the stud (g) will be brought in front of the partition wall (f), which will obstruct
the action of the spiral spring (7) to return the pin (e). The locking pin (c)
being in connection with the pin (e) it is simultaneously moved forward and its
front end caused to engage and lock the sprocket wheel (d). From the above
description of the device it is obvious that the locking pin (c) cannot be forced back
and out of engagement with the sprocket wheel by ordinary means or without a
duplicate of the proper key. Turning the pin (e) by means of the key (i) until
the stud (g) is opposite the groove (h) will cause the release of the locking pin (c)
and its return to its position of rest by the expansion of the spring (2).
To prevent the locking pin (c) being disengaged from the sprocket wheel by
turning the pin (e), the connection between the pins (e) and (c) is formed in
such a manner that the rotary movement of the one does not affect the other. This
may be effected by providing a circular groove near the inner end of the pin (c).
The socket formed at the end of the pin (e) for the reception of the inner end of
the locking pin (c) is penetrated by a screw (9) which engages the said groove.
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:
Firstly. A device for locking the sprocket wheel of cycles and similar chain
driven vehicles comprising a casing (a) secured to the bottom bracket of the
vehicle, a locking pin (c) adapted to project from the casing so as to engage and
lock the sprocket wheel (d), a second pin (e) inside the casing connected with the
locking pin (c) in such a manner that they are independent of each other as regards
rotary movement, and a spiral spring (p) for the return of the locking pin (c) into
its normal position all constructed and operated substantially as set forth.
Secondly. In a device for locking the sprocket wheel of cycles of the class
described, the arrangement of a partition wall inside the casing (a) having a bore
and a groove for the passage of the pin (e) and its stud (g) respectively, substantially
as set forth.
Thirdly. In a device for locking the sprocket wheel of cycles of the class.
described, the arrangement of a second stud on the pin (e) transposed to the other
for the purpose of indicating the exit of the first stud from its groove by bearing
against the partition wall substantially as set forth.
Fourthly. In a device for locking the sprocket wheel of cycles of the class described,
the combination of a circular groove near the inner extremity of the locking pin (c)

page_text: and a screw or pin penetrating the socket enclosing said inner extremity and
entering the said groove for the purpose of causing the locking pin (c) to be
independent of the second pin (e) as regards rotary movement, substantially as
herein set forth.
Dated the 1st day of .......
1000
W. D. ROWLINGSON,
7, Quality Court, Chancery Lane, London, W.C.,
Agent for the Applicant.