Abstract: A hinge has two leaves (11?), (13?) connected by a hinge pin (42?) retained in alternate sleeves (17?), (19?) on the facing edges of the two leaves, with limited axial movement of the hinge leaves relative to one another along the pin. A spring (46?) biases the leaves towards one end of this movement, where sleeves (19?) on one leaf (13?) have slots (74, 84) at one axial end and sleeves (17?) are axially preceded by flanges (76) which, according to the angular opening of the hinge, either abut the ends of the respective sleeves (19?) or enter one or other of the slots (74, 84). When the flange (76) abuts the sleeve end, the hinge is free to rotate, but when the hinge reaches an opening angle at which spring pressure causes the flange (76) to enter one or other of the slots, the hinge is locked. It can be released by manually sliding the locked sleeves (17?), (19?) apart against the spring pressure.

Abstract: A hinge has two leaves (11?), (13?) connected by a hinge pin (42?) retained in alternate sleeves (17?), (19?) on the facing edges of the two leaves, with limited axial movement of the hinge leaves relative to one another along the pin. A spring (46?) biases the leaves towards one end of this movement, where sleeves (19?) on one leaf (13?) have slots (74, 84) at one axial end and sleeves (17?) are axially preceded by flanges (76) which, according to the angular opening of the hinge, either abut the ends of the respective sleeves (19?) or enter one or other of the slots (74, 84). When the flange (76) abuts the sleeve end, the hinge is free to rotate, but when the hinge reaches an opening angle at which spring pressure causes the flange (76) to enter one or other of the slots, the hinge is locked.