Machine element or mechanism – Control lever and linkage systems – Elements
Reexamination Certificate
1997-09-30
2001-02-06
Bonck, Rodney H. (Department: 3681)
Machine element or mechanism
Control lever and linkage systems
Elements
C074S551400
Reexamination Certificate
active
06182528
ABSTRACT:
A. TECHNICAL FIELD
This invention concerns an improved construction of handlebar for a bicycle, motorcycle or other two wheeled power vehicle or all terrain vehicle (including watercraft and snowmobiles).
B. DESCRIPTION OF RELATED ART
Hitherto handlebars of motorcycles and cycles have comprised a single length of tube appropriately bent to provide a central region and respective handgrip regions, the former being clamped at one or two positions to form a connection to the main cycle frame via an intermediate top yoke or stem. For added strength it has been conventional to provide a brace (sometimes called a crossbrace) spanning the central region of the tube. An alternative to this has been the provision of a tubular handlebar having a greater external diameter in its central region, said diameter reducing to the handgrip portions of the tubing.
U.S. Pat. No. 5,257,552 discloses an integrally formed unitary hollow tubular handlebar of the latter type wherein the wall thickness is greatest and constant in the central region, least and constant in the handgrip portions, and gradually tapering from the greatest to least thickness in respective bent portions which extend between and connect the central region and the respective handgrip portions.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved construction of handlebar which would have greater resistance to impact damage or fatigue failure than any known style of motorcycle or cycle handlebar, and which would not necessarily need a brace or crossbrace, although the latter could be provided for even greater strength.
The present invention proposes a unitary handlebar comprising an inner tubular member of constant diameter and constant wall thickness and an outer tubular sleeve surrounding the inner tubular member, both the inner tubular member and the outer tubular sleeve, having a central region, bends at each end of the central region leading to symmetrical oblique regions, and further bends at the distal ends of the oblique regions leading to respective handgrip regions, in which respect the respective handgrip regions of said inner tubular member extend beyond the handgrip regions of said outer tubular sleeve.
The use of two or more layers of material to provide the tubular body of the handlebar has numerous advantages.
Firstly, it limits crack propagation upon severe impact, since a crack in one of the layers will not spread into the other layer or layers. This is important in preventing complete failure of the handlebar in the event of a crash—crashes being frequent in the sport of motocross and other activities involving off-road motorcycles and other all terrain powered vehicles. The use of two or more layers of material also helps to stop cracks propagating because of metal fatigue through long term use.
Secondly, it allows use of two or more different materials so that, for example, a stronger, but more notch sensitive material can be used for the inner member or members, and a more ductile but less notch sensitive and less brittle material with better fatigue resistant properties can be used for the outer sleeve or sleeves. This should be particularly useful in minimizing stress and impact damage at the locations where the handlebar is clamped to the top yoke or stem connected to the main cycle frame. Perhaps it may be suitable, in this respect, to use two or more different grades of aluminium, but numerous other combinations of metals or other materials would be possible. The materials of both the inner member and the outer sleeve or sleeves would, of course, have to be substantially rigid.
REFERENCES:
patent: 332092 (1885-12-01), Latta
patent: 4707389 (1987-11-01), Ward
patent: 4939950 (1990-07-01), Girvin
patent: 5117708 (1992-06-01), Boyer
patent: 5119690 (1992-06-01), Shu
patent: 5199322 (1993-04-01), Wu
patent: 5832785 (1998-11-01), Costahaude et al.
patent: 2915437 (1980-11-01), None
patent: 10282 (1894-10-01), None
patent: 22414 (1897-12-01), None
patent: 264754 (1927-01-01), None
patent: 402573 (1933-12-01), None
patent: 442238 (1936-02-01), None
Bonck Rodney H.
Ho Ha
Oliff & Berridg,e PLC
Renthal Limited
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