Hinge joint assemblies

Claim 1

For use with a hinge joint between two structural members pivotally connected together about a pivot axis, an assembly comprising: a first lock member adapted to be fixed with respect to one of said structural members about said pivot axis, said firSt lock member including a plate having a central aperture and an integral axially extending peripheral flange integrally supporting a plurality of radially inwardly extending teeth spaced equidistantly from said pivot axis and defining substantially identical recesses opening inwardly and arranged as diametrically opposed pairs spaced around said peripheral flange, a second lock member adapted to be fixed with respect to the other of said structural members about said pivot axis, said second lock member including a plate having a central aperture, said last-mentioned plate supporting partition means defining tracks, two finger members adapted to reciprocate along said tracks in opposite directions radially of the pivot axis, each finger member including an outwardly projecting finger, each finger member being adapted to reciprocate along said tracks between a first position in which its respective finger lodges in any one of said recesses and a second position in which its respective finger is withdrawn from said recesses, the fingers being rounded and the recesses being substantially complementary to the fingers, the spring means urging the finger members apart toward said first position, said spring means being braced against each finger member to exert force on the other finger member such that the separative force on the finger members is substantially the same, whereby relative rotation of one lock member with respect to the other lock member with sufficient torque will urge the finger members radially inwardly against said biasing means to permit the lock members to move from a first relative orientation in which the fingers are lodged in one pair of diametrically opposed recesses to a second relative orientation in which the fingers are lodged in an adjacent pair of diametrically opposed recesses.