Pintle exotic metal alloys. For World War II aircraft with sideways-retracting main gear units, carefully set-up "pintle angles" for such axes of rotation during retraction and extension allowed the maingear struts to be raked forward while fully extended for touchdown and better ground handling, while permitting retraction into rearwards-angled landing gear wells in their wings to usually clear the forward wing spar for stowing while in flight. Pintle A pintle is a pin or bolt, usually inserted into a gudgeon, which is used as part of a pivot or hinge. Other applications include pintle and lunette ring for towing, and pintle
Geared continuous hinge the door’s weight over the entire door length rather than concentrated on two or three spots as with butt or pivot hinges. The gears allowed fluid movement as the door opened and closed. Baer's patent expired in 1985. He sold his company to a national manufacturer in 1989. With the sale, and with other companies beginning to manufacture geared continuous hinges, the market soon went from regional to national. Later the hinges were tested to verify their endurance. In 2004, a geared continuous hinge earned 60 minute Ballistic Resistance and Forced Entry certification from the United States Department of State