Measuring and testing – Spring testing
Reexamination Certificate
1998-12-03
2001-03-13
Noori, Max (Department: 2855)
Measuring and testing
Spring testing
Reexamination Certificate
active
06199427
ABSTRACT:
37 C.F.R. §1.71(E) AUTHORIZATION
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO A MICROFICHE APPENDIX, IF ANY
Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, generally, to testing apparatus and methods. More particularly, the invention relates to electromechanical testing apparatus for measuring the spring rate of leaf springs used on automobiles.
2. Background Information
Balancing a car optimizes performance, particularly the cornering characteristics of a racing class automobile. The traction, adherence or grip between the tires and the track at each end of a car is proportional to the percentage of the weight at that end of the car. A car's grip is optimized when both the front tires and the rear tires begin to slide at the same time and at the same rate, resulting in the car having responsive, near-neutral handling characteristics. However, if the front tires slide first, the car tends to understeer and slide off of the track, and if the rear tires slide first, the car tends to oversteer and spin.
Numerous factors contribute to the near-neutral handling characteristics of a balanced car, including tires, wheel alignment, suspension, weight distribution, center of gravity and aerodynamics. A properly suspended car has more braking and acceleration control when the car is moving in a straight line and more steering control when the car is maneuvering around corners. A leaf spring suspension exerts resistance against up and down movement by the flexing action of leaf springs. One end of a leaf spring is rigidly mounted to the frame as both the axle end and the shackle location of the leaf spring freely move with the rising and falling of the wheel. The leaf spring flexes and absorbs shocks when the wheel rises.
Leaf springs have a spring rate that identifies the amount of resistance that it provides against up and down movement. This spring rate may change over time and may change because of use. It is therefore desirable to be able to accurately measure the spring rate of leaf springs in order to calculate the resistant force, balance the car, and ultimately improve the handling characteristics of the car.
Applicant's invention provides an apparatus and method for testing and measuring the spring rate of leaf springs which is believed to constitute an improvement over existing technology.
BRIEF SUMMARY OF THE INVENTION
The present invention provides an apparatus and method for testing leaf springs. The leaf spring test apparatus generally comprises a frame constructed and arranged to support both a first and second end of a leaf spring, a force applicator disposed on the frame for applying a force to a predetermined area of the leaf spring, a force measurement gauge for gauging the amount of force applied to the leaf spring by the force applicator, and a distance measurement gauge for gauging movement of the leaf spring upon the application of force by the force applicator.
The leaf spring test apparatus accurately rates leaf springs because it closely approximates the actual installed conditions of leaf springs on a car. The leaf spring is rigidly mounted to the car at the frame end and is free to move at the axle end and the shackle location. The leaf spring test apparatus accurately gauges the spring rate of all commonly used leaf springs using a load cell and an electronic digital indicator. It is anticipated that the leaf spring test apparatus can be modified within the teachings of the present invention to accurately gauge the applied force and movement to appropriately rate uncommon leaf springs that are currently manufactured or any leaf springs that may be developed.
The features, benefits and objects of this invention will become clear to those skilled in the art by reference to the following description, claims and drawings.
REFERENCES:
patent: 4215754 (1980-08-01), Hagedorn et al.
patent: 5161628 (1992-11-01), Wirth
patent: 5212657 (1993-05-01), Uchikawa et al.
Evenson Randie
Kroll William P.
Intercomp Company
Noori Max
Skinner and Associates
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