Example for searching for a impeller for a centrifugal pump, using any of the Primary Search Tools:
If you don't like your results, try using a USPTO Classification Code to look up the exact controlled search term. For example if you are working with a washing machine, you may need to try "agitator" instead of "impeller".
Be EXTREMELY skeptical. Patent researchers know that every innovation comes from “prior art.”
Use Classes arranged in Alphabetical Order (or similar term in other country's patent site) to find the best category for your idea. Patent classification schedules are very detailed.
On the Patent Office home page, type the category number in the A1 Enter a US Patent Classification field (or similar field in other country's patent site, using that country's class arrangement). The U.S. class field is at the top left of the site.
Click “submit” and then look through that list to determine where your idea fits.
Be sure to go all the way down the list to the "Cross Reference Art Collections" (or similar term in other country's patent site) to check for other categories.
