US Patent: 689,978
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Planimeter
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Patentee:
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Alpheus C. Lippincott (exact or similar names) - New York, NY |
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Patent Dates:
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Applied: |
Mar. 24, 1899 |
Granted: |
Dec. 31, 1901 |
Patent Pictures:
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Joel Havens Planimeter
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Description: |
William R. Baird - patent attorney
This invention has special reference to that type of planimeters in which the measuring wheel axis is substantially at right angles to the tracer-bar. In this type of planimeters the measuring-wheel has heretofore been mounted on a stationary shaft, so as to have rotative and longitudinal movement thereon. In order to secure the required free movement of the wheel on the shaft in said structures, a very loose fit of the wheel on the shaft is necessary, and said loose fit results in a degree of lost motion which, if not prevented, would render the action of the device wholly inaccurate; but it has been the practice to reduce said lost motion to a minimum by providing the wheel with a long bearing or hub, as shown in several of the figures of the accompanying drawings. The long bearing or hub necessitates the use of a shaft having compensating additional length and adds to the cost of the device. I have found that by mounting the shaft so that it will have longitudinal movement in its bearings or bearing and mounting the rotative measuring-wheel thereon, so that it will move longitudinally therewith all tendency to lost motion is eliminated and the device will act with the greatest accuracy, while its cost is reduced. This idea constitutes one of the main features of the invention. In the accompanying drawings it is shown as embodied only in a construction wherein the shaft is provided with teeth which mesh with a gear that is connected with the movable member of an indicating means of the plainmeter. While this specific construction is preferred and for this reason is made the subject-matter of specific claims, this part of the invention is not restricted to such embodiment.
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