US Patent 7451523 Hinge

A hinge has a stationary bracket having multiple limiting slots, two resilient spacers, a pintle having a bar and an enlarged head, a stop element mounted in the pintle between the enlarged head and the resilient spacers and having multiple limiting tabs corresponding to and mounted in the limiting slots in the stationary bracket to make the limiting tab and the pintle to seal the opening and a keyhole provided the pintle to mount in and having an inner diameter being not bigger than an outer diameter of the bar to provide a tightness between the keyhole and the pintle. So the pintle is sturdy in the sleeve and the oil would not leak out of the sleeve.