Measuring and testing – Specimen stress or strain – or testing by stress or strain... – By loading of specimen
Reexamination Certificate
1998-10-14
2001-01-30
Noori, Max (Department: 2855)
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
By loading of specimen
Reexamination Certificate
active
06178824
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to determining the amount of wear in a roller chain. More specifically, the present invention relates to chain wear indicator, which is used to determine when it is time to replace the chain.
2. Background Information
Roller chains are commonly used for transmitting rotational torque from one rotating chain gear or sprocket to a second rotating chain gear or sprocket. When a chain begins to wear, the overall length of the chain becomes longer. This elongation of the chain often results in the chain skipping or popping off the chain sprockets or gears. This results in stoppage of the apparatus or machine utilizing the chain. Moreover, this skipping or popping off of the chain can damage other components of the apparatus.
The most common and easiest way of testing a chain for wear, i.e., elongation, is done by lifting the chain up when it is on the sprocket or gear. If one of the teeth of the sprocket or gear is fully exposed beneath the chain, then the chain is worn out. Of course, this method is very inaccurate. Therefore, various types of devices have been developed to determine the amount of wear that has occurred in the chain. One example is disclosed in German Utility Patent No. 90-16 000. This device is relatively complicated in that it consists of numerous parts. Moreover, this device is relatively expensive to manufacture.
Another device for determining wear in a roller chain is disclosed in German Utility Model No. 91 10 896. This device is very easy to use and relatively inexpensive to manufacture. However, this device not only measures the wear between the link bushings and connecting pins which causes the chain to increase in length, but it also measures the amount of wear that occurs in the rollers. The frictional wear in the rollers of the chain does not result in elongation of the chain and does not significantly affect the performance of the chain. Rather, the elongation of the chain primarily affects the performance of the chain. Accordingly, using this prior art device may result in chains being discarded before the end of their useful life.
Bicycles primarily utilize roller chains for transmitting torque from the rider's pedaling action to the rear wheel via a pair of sprocket assemblies and a roller chain.
In the bicycle racing industry, it is very important to know if a chain needs to be replaced. If the chain is worn out, i.e., elongated, the chain may skip or pop off of the bicycle sprocket or gears and cause the bicycle racer to loose the race. Therefore, bicycle racers need to know precisely when a chain must be replaced.
In view of the above, there exists a need for a chain wear indicator which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a chain wear indicator that accurately determines whether a chain is worn out and/or detective.
Another object of the present invention is to provide a chain wear indicator that compensates for the wear in the rollers of the chain.
Another object of the present invention is to provide a chain wear indicator that is relatively inexpensive to manufacture while still capable of accurately measuring wear in a chain.
Another object of the present invention is to provide a chain wear indicator that is relatively easy to used.
In accordance with one aspect of the present invention, a chain wear indicator is provided for determining the wear of a roller chain. The chain wear indicator basically includes a chain wear indicator for determining wear of a roller chain having a plurality of pivotally coupled chain links, the chain wear indicator comprising a body portion; a first protrusion extending from the body portion and having a first roller engaging surface adapted to engage a portion of a first roller of one of the chain links; and a second protrusion extending from the body portion and having a second roller engaging surface adapted to engage a portion of a second roller of one of the chain links which corresponds to the portion of the first roller, the second roller engaging surface being configured and spaced apart from the first roller engaging surface by a distance corresponding to a predetermined number of the chain links plus a first pre-selected amount of wear per link to indicate unacceptability of the roller chain when the roller chain is placed under tension with the first roller contacting the first roller engaging surface and the second roller contacting the second roller engaging surface.
The foregoing objects can also basically be attained by providing a chain wear indicator that includes a body portion with a first end, a second end and first and second sides extending between the first and second ends. The first side of the body portion measures a first predetermined amount of wear in the chain, while the second side of the body portion determines if a new chain is defective. Alternatively, the second side of the body portion measures a second predetermined amount of wear in the chain. Each side of the body portion has three protrusions. The first protrusion extends from the first end of the body portion and has a first roller engaging surface facing in a first direction. The second protrusion extends from the middle of the body portion and has a second roller engaging surface facing in a second direction which is substantially opposite the first direction. The first and second roller engaging surfaces are configured and spaced apart from each other by a distance corresponding a predetermined number of the chain links to place the chain under tension therebetween. The third protrusion extends from the second end of the body portion and has a third roller engaging surface facing in substantially the second direction. The third roller engaging surface is configured and spaced from the second roller engaging surface by a distance corresponding a predetermined number of the chain links plus a pre-selected amount of wear per link to determine wear of the chain.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.
REFERENCES:
patent: D. 243232 (1977-02-01), Kuenzig
patent: 4150488 (1979-04-01), Behnke
patent: 4151625 (1979-05-01), Stevanovich
patent: 4888876 (1989-12-01), Meredith et al.
patent: 5689067 (1997-11-01), Klein et al.
patent: 90160002 (1991-03-01), None
patent: 91108969 (1992-01-01), None
patent: 29508570 U (1995-10-01), None
Fujimoto Tadao
Hayakawa Shun
Noori Max
Shimano Inc.
Shinjyu Global IP Counselors, LLP
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