sentences:  When they stopped producing these, they used Blackburne engines of 532 cc and 896 cc with Roc patent gear hubs.When the company fired the founders in 1911, George Hemingway had in house engines made again, but models with other engines were still built.Rex made their first telescopic forks in 1906, used rotary-valve engines, and in 1908 were the first to put a downward angle on the top tube, lowering the riding position.