Foster very actively pursued patents related to his scooters. He apparently purchased a number of pre-existing patents that were scooter-related, and spent a good deal of money applying for and obtaining patents related to his scooter innovations. Foster never enforced his scooter related patents, however. Later in life, Foster indicated that he considered enforcing his patent rights against Cushman, but that enforcing the rights would have been prohibitively expensive, so he opted to ignore the possible use of his intellectual property by his competitors.

Importantly, Foster built a viable business around his variable drive technology after the scooter business died, so his investment in patents arguably paid off ultimately.

Foster's Sales Promotion Book for the post-war scooters listed the patents Foster controlled thru July 1945:

Foster's Motor Glide Related US Patents (click on the icon to pull up a pdf for each patent):