http://www6.atpages.jp/~raycy/Y/Trunnion-CollideArms.htm
→
http://www.google.com/patents?q=brass+OR+ring+sholes&scoring=2
type-arm
→
http://www.google.com/patents?q=brass+OR+ring+sholes&scoring=2
type-arm
A http://www.google.com/patents?id=kqpUAAAAEBAJ&q=type+arm#search
Patent number: 216232
Filing date: Feb 11, 1879
Issue date: Jun 3, 1879