Patent drawing - Balance board rope-brake by Frederic G Ludwig.Fig 1 w heading Public domain image

The drawing is from the 1958 U.S. patent for a rocker-roller balance board designed by Frederic George Ludwig of Woodbridge, Connecticut.

In the online database of the U.S. Patent and Trademark Office, the version of the patent that includes the application for it that was filed on November 7, 1955 contains more drawings than the June 8, 1955 version does. There are also more descriptions in the November version than in the June version.

The November version's descriptions of the rope are of one that is elastic.

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