US Patent: 3,738,152
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| Pointers, Dials, and Methods of Calibrating Dials for Measuring Instruments
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Patentee:
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| Talmage O. Green (exact or similar names) - Schaumburg, IL |
| Manufacturer: |
| Not known to have been produced |
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Patent Dates:
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| Applied: |
Sep. 08, 1969 |
| Granted: |
Jun. 12, 1973 |
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Stan Schulz
Snap-On Tools Company History
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Description: |
| Harry C. Alberts - patent attorney
Abstract
Improved mechanical dial pointers and methods of calibrating dials for precise measuring instrumentalities wherein the mechanical pointer operating linkage moving in a non-linear path, is compensated to reflect the action of their equivalent movements in a linear direction, and take into account the yield in the load applying member. The effective non-linearity of the mechanical linkage between the applied turning load in fastening or loosening fasteners and the meter operating linkage, however small, is caused by an ever increasing linkage angle of movement as such approaches the extremes of displacement around a meter dial. The compensations for the non-linear movement of the linkage are arrived at trigonometrically by resort to the mechanical secant which has a direct relationship with the equivalent arc of movement of any given angle of mechanical linkage movement from zero to their extreme angle of displacement to rotate a calibrated dial pointer within its range for any calibrated dial measuring capacity. The standard method of calibrating measuring meter dials involve uniform graduations of the entire 360.degree. range of a complete circle, but this method is not sufficiently accurate for the state reasons. By utilizing the trigonometric functions of secants, the dial graduations will be farther apart at the full extreme dial scale than at the lower or near zero range of mechanical linkage movements with proportional secant variations between these extremes which also take into account yield in the load applying member. This more closely matches the actual values applied by trigonometrically using the mathematical secant for greater accuracy in graduating the markings around a calibrated dial to more closely interpret the linear displacement in terms of the equivalent non-linear movements of the mechanical linkage, and by measuring the angularity of the mechanical linkage at the maximum rated capacity of the measuring instrument, this reflects the yield in the load applying member.
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