Miscellaneous hardware (e.g. – bushing – carpet fastener – caster – Hinge – Including means to hold or retard hinged members against...
Patent
1989-03-06
1996-01-30
Larson, Lowell A.
Miscellaneous hardware (e.g., bushing, carpet fastener, caster,
Hinge
Including means to hold or retard hinged members against...
182152, E05D 1110
Patent
active
054872073
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a hinge element for a folding support provided with longitudinal uprights and cross pieces, particularly for scaffolding or a folding ladder, including two identical metallic shells each comprising a shaped tip, intended to be fixed at one end of an upright of the support, and a circular part made of dished metal plate provided with a bottom positioned transversely with respect to the hinge axis and a peripheral flange having mutual anchoring members with the other shell to make the two shells solidary in rotation around said axis, the element comprising in addition locking members arranged to press the two shells against one another axially so as to maintain in mutual engagement their anchoring members.
There is already known a hinge element of this type for a ladder by the document FR-A-2 534 307. In this known element, each of the shells comprises a peripheral flange which is positioned axially following a cylindrical shape. To be able to fasten on to the identical flange of the opposite shell, the flange comprises on its free edge a circular row of rectangular or trapezoidal teeth separated by hollows having the same profile as the teeth.
This type of shell has various disadvantages, particularly in shells made of dished metal plate, which obviously permits a much less expensive manufacture. As the teeth of the flange are cut in the edge of the metal plate, their support surfaces have a width equal to the thickness of the metal plate and are thus very small. Consequently, there are superficial pressures which can alter rather quickly the state of the metallic surfaces and particularly the protective coating which is generally provided. On the other hand, as said flange is interrupted in the area of the shaped tip, the meshing of the two flanges of the shells does not guarantee the reciprocal centering of the shells because the narrow teeth can easily disengage from one another by a small transverse displacement or a slight deformation. Finally, the rectangular or trapezoidal shape of the teeth is disadvantageous, because in usage the adjustment of the opening of the ladder and its locking into position require the user to insert the teeth of one of the hinge shells in the hollows of the other, which necessitates a certain amount of care given that the steadiness of the ladder depends on the precision of adjustment of the anchoring members of the two complementary elements. Furthermore, the repeated insertion of the edges of the teeth the hollows inevitably leads to wear and tear which the long run a looseness in the hinge.
The present invention proposes to overcome these different disadvantages by realizing a hinge composed of two identical shells made of dished metal plates which are designed to be adjusted into position with respect to one another and locked in the position selected without any difficulty. The anchoring members nest semi-automatically and there is no danger of looseness due to wear and tear following prolonged use of the hinge. In addition, the construction of this hinge element is very simple and its assembly is facilitated because of the fact that the two shells are identical.
These ends are attained by the hinge element according to the invention, characterized in that said flanges extend substantially radially with respect to the hinge axis, in that the metal plate of these flanges has a corrugated profile in the circumferential direction and in that this corrugated profile comprises rounded crests and rounded hollows, the crests having substantially the same profile as the hollows.
According to a preferred embodiment, each shell is constituted by a single piece of dished metal plate.
The corrugated profile of the flange is at least approximately sinusoidal.
According to a preferred embodiment, the circular part of each shell is concave on the side of the opposite shell and comprises a flat bottom, and the locking members comprise a bolt mounted axially through the two shells and a tightening nut, these members exerting an axial pressure on the bo
REFERENCES:
patent: 1328874 (1920-01-01), Henault
patent: 4363561 (1982-12-01), Hsieh
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