Land vehicles – Wheeled – Occupant propelled type
Reexamination Certificate
2000-01-14
2001-09-04
Johnson, Brian L. (Department: 3618)
Land vehicles
Wheeled
Occupant propelled type
C280S261000, C192S217200, C192S01700D, C192S019000
Reexamination Certificate
active
06283486
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an improved bicycle pedal crank axle, and more particularly to a bicycle pedal crank axle including an engaging and disengaging gear that enables the axle and pedals connected thereto to keep unmoved while a chain wheel of the bicycle is caused to rotate reversely.
FIG. 1
schematically shows a bicycle and transmission gearing thereof. Typically, the transmission gearing of a bicycle include a pedal crank axle
11
pivotally connected to a five-way tube
1
on a frame of the bicycle, a large chain wheel
12
fixedly connected to the crank axle
11
, two pedals
13
connected to free ends of two cranks extended from two ends of the crank axle
11
, a small chain wheel
16
provided on a hub of a rear wheel
15
of the bicycle, and a chain
14
wound around the large and the small chain wheels
12
,
16
. When the two pedals
13
are alternately stepped, the crank axle
11
and the large chain wheel
12
fixed thereto are caused to rotate at the same time. The rotating large chain wheel
12
and the chain
14
together bring the small chain wheel
16
to rotate and thereby causes the rear wheel
15
to rotate forward. There are means provided between the small chain wheel
16
and the hub of the rear wheel
15
for the rear wheel
15
to keep rotating forward and the small chain wheel
16
to temporarily disengage from the rear wheel hub when the bicycle moves forward with the pedals
13
in a static state. However, when the bicycle is moved backward, the rear wheel
15
brings the small chain wheel
16
to reverse and the reversing small chain wheel
16
together with the chain
14
bring the large chain wheel
12
and accordingly the crank axle
11
to reverse at the same time. At this point, the pedals
13
are also moved reversely.
Reversing pedals
13
of a backward moved bicycle might cause little or even no trouble to general bicyclists, but they do bring considerable inconvenience to performers who play cycle tricks. The reversing pedals
13
tend to strike against or even dangerously stumble the cycle trick performers.
It is therefore tried by the inventor to develop an improved bicycle pedal crank axle to eliminate drawbacks existing in the conventional bicycle pedal crank axles.
SUMMARY OF THE INVENTION
A primary object of the present invention is to provide an engaging and disengaging gear for a pedal crank axle of a bicycle, so that when the pedal crank axle of the bicycle is caused to turn forward, it rotates a chain wheel of the bicycle, and when the pedal crank axle or the chain wheel is caused to rotate reversely, the axle disengages from the chain wheel and would not keep turning reversely along with the reversing chain wheel to possibly endanger a bicyclist walking the bicycle backward or hinder a cycle trick performer.
To achieve the above and other objects, the engaging and disengaging gear for a bicycle pedal crank axle mainly includes an axle rotatably mounted in a five-way tube on the bicycle to connect to two pedal cranks, a thimble fixedly connected to one end of the five-way tube, an internally threaded transmission bevel gear received in the thimble, a chain wheel mounted on the axle between the thimble and a collar of the axle, and a ring spring fixed to outer surface of the transmission gear. The axle has an externally threaded section between the thimble and the chain wheel for extending through and engaging with the internally threaded transmission gear. An outer periphery of the ring spring slightly contacts with inner wall of the thimble to provide a resistance to a maximum static friction force between the transmission gear and the axle that are screwed together. When the axle is caused to turn forward, the transmission gear moves along the axle toward the chain wheel and engages with the latter, causing the chain wheel to rotate forward, too. When the axle or the chain wheel is caused to rotate reversely, the transmission gear moves along the axle toward the five-way tube and disengages from the chain wheel, so that the axle and accordingly the pedal cranks connected thereto do not keep turning reversely along with the reversing chain wheel.
REFERENCES:
patent: 4108459 (1978-08-01), Alvigini
patent: 4644828 (1987-02-01), Kozakae
patent: 5027930 (1991-07-01), Reed
patent: 5904362 (1999-05-01), Yoo
patent: 5961424 (1999-10-01), Warner et al.
Bednarek Michael D.
Johnson Brian L.
Shaw Pittman LLP
Yeagley Daniel
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