Machine element or mechanism – Control lever and linkage systems – Hand operated
Patent
1991-04-19
1992-03-24
Diehl, Dwight
Machine element or mechanism
Control lever and linkage systems
Hand operated
192 64, B62M 2504, B62K 2306
Patent
active
050977199
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a device for bicycles, which comprises a drive transmission which is coupled to the drive wheel of the bicycle and includes a gear change mechanism with a number of different size chain sprockets, a shifting means coupled to the gear change mechanism, and a free wheel coupling arranged between the drive wheel and the chain sprockets.
Previous chain gear change mechanisms at bicycles of the above type are disadvantageous in that the drive wheel and the chain sprockets have the same rotation speed at propulsion of the bicycle, which means that when changing from one chain sprocket to another, the drive wheel has to rotate basically a full revolution before the new gear is able to transfer a drive load for propulsion of the bicycle without unnecessary wear of the chain and the chain sprocket. At worst, the chain may jump off the actual chain sprocket. This is evident to everyone who has tried to change gear when going uphill or when the bicycle is stopped at a traffic light with a high gear engaged. Since it takes a lot of effort to get started on a high gear, it is desirable to shift down to a lower gear before starting.
This and other drawbacks are avoided by the invention in that a device according to the invention enables disangagement of the freewheel coupling of the drive wheel at gear changing, which makes it possible to shift gear with the bicycle at standstill and in uphill going or if you just want to change gear rapidly.
When changing gear in a common way, using the lever at the bicycle handle bar, the invention makes it possible to accomplish a disengagement of the freewheel coupling in the drive wheel, which means that the chain transmission may be rotated in spite of the drive wheel being at standstill. The disengagement takes place simultaneously with or just before the gear changing. When going uphill, rapid downshifting of the gears has to be performed to keep up the speed of the bicycle. This is made easy by the device according to the invention.
ON THE DRAWINGS
FIG. 1 shows a gear shifting device according to the invention
FIG. 2 shows a sideview of the device in FIG. 1
FIG. 3 shows an alternative gear shifting device according to the invention
FIG. 4 shows a sideview of the device in FIG. 3
FIG. 5 shows a disengage mechanism in the drive wheel hub
FIG. 6 shows the device in FIGS. 3 and 4 in engaged position
FIG. 7 shows an alternative location of the gear shift levers and shifting means
FIG. 8 shows an alternative arrangement of the wires for the device in FIG. 7.
The device shown in FIGS. 1 and 2 comprises a housing 2 attached to a frame tube 1 by means of a screw or welding joint. An axle 9 is supported in the housing 2 and carries two gear shift levers 3 and 13. The lever 3 is coupled to a cable 4 for controlling the chain gear shift mechanism in the rear wheel. Between the housing 2 and the lever 3, there is provided a disengage means 5, which comprises a lever 12 and is connected to the freewheel coupling in the rear wheel by a cable 11. The lever 13 is in a common way connected by means of a cable to the chain gear change mechanism for altering the chain engagement between two or more chain sprockets on the pedal crank assembly of the bicycle. The ring 14 with the lever 15 are pivotally mounted on the axle 9 in a similar way as the disengage means 5 on the opposite side. A connection piece 16 is attached to and intercouples the levers 15 and 12. The connection piece limits the movement of the levers 15 and 12 by abutting against the frame tube 1. A pretensioned spring 7 is connected between the ends of the cable 11 and the device for disengagament of the freewheel coupling so as to limit the load on the freewheel catches, in particular if gear changing is to be performed when the bicycle is at rest.
Limitation of the disengage means 5 and 14 as regards movement in the opposite direction takes place by contact between the screw axle 17 and the frame tube. Openings 18 in the disengage means 5 and 14 for receiving the screw axle 17 inables adjustment of the
REFERENCES:
patent: 4102215 (1978-07-01), Nagano et al.
patent: 4532825 (1985-08-01), Nagano
patent: 4674617 (1987-06-01), Nagano
patent: 4913500 (1990-04-01), Wauke et al.
patent: 4995280 (1991-02-01), Tagawa
patent: 5012692 (1991-05-01), Nagano
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