Abstract: The invention describes a composite palatal arch for the correction of the position of teeth, which is built up from a plurality of wire sections (1, 2, 3, 4, 5) made from different materials. One of the materials is a shape-memory alloy that assumes a superelastic state at the temperatures prevailing in a human mouth. The palatal arch comprises two end sections (2, 3), which are intended to fix the palatal arch in a tooth lock (16, 17) and which are made from of a normal-elastic material. The superelastic section (4, 5) of the arch is softer than are the normal-elastic sections (1, 2, 3). The superelastic material is present only in two intermediate sections (4, 5) between the two end sections (2, 3) and a central section (1), the two intermediate sections (4, 5) are each arranged adjacent one of the end sections (2, 3), and the central section (1) of the palatal arch consists of a normal-elastic material.

Abstract: An orthodontic device includes an upper jaw thrust plate and a lower jaw thrust plate. These plates are connected to the teeth and are provided in the front teeth region with activating rods and slideways respectively, cooperating to effect a sagittal displacement of the jaws relative to each other. Two treatment stages are to be combined and an optimum result of the treatment within a reduced time is to be ensured. The upper or lower jaw thrust plate includes two sections, which are connected by a jackscrew mechanism, to which the activating rods are secured.

Abstract: A subsurface coal bunker operating to receive and discharge coal is structured with an assemblage of nested telescopic container members including one stationary member and a plurality of movable members, with the container members being formed in size in a graduated series with each container member being sized to fit into a next larger container member adjacent thereto. The movable members are telescopically extensible and contractible in order to vary the volume of the assemblage and the bunker assembly is provided with a first belt conveyor for feeding material into the assemblage and a second belt conveyor for transporting material therefrom. A reversible drive mechanism, consisting of hydraulic cylinder devices actuating a system of drive chains and pulleys, is mounted on a support frame of the bunker and operates to drive the movable members between the extended and contracted positions.