Abstract: A cutter head includes a first member, a cutting bit, and a second member. The first member includes a first end and a second end and includes a first mass. The cutting bit is coupled to the first member proximate the second end. The cutting bit includes a cutting edge rotatable about the axis. The second member is rotatable about the axis and includes a second mass eccentrically positioned with respect to the axis. Rotation of the second mass causes the first member and the cutting bit to oscillate.

Abstract: A rectangular frame set into the concrete surround at the head of a shaft supports one or more slab doors that are hinged to the frame. Adjacent each hinge line brackets fixed to the frame support a fixed spindle upon which a helical spring is secured. The spring has an extending limb at one end that bears against the under surface of the door. The other end of the spring is engaged with a winding bushing rotatable on the fixed spindle, and the bushing has a hollow hub for accepting a detachable winder so that the spring may be pretorqued to the proper loading to raise the door from its horizontal closed position to a substantially vertical attitude for access to the shaft or other opening.The frame defines a drip trough to collect moisture passing the door edges and when two doors are used a channel extending along the butt line of the doors collects water passing between the adjacent edges of the doors.

Abstract: A two part castable ceramic cement having low density, good thermal shock resistance, good temperature resistance and extended storage life. The first and second parts are mixed together prior to use. The first part is a slurry of solids in water. The solids comprise 0 to 10 weight percent organic fibers, about 35 to about 80 weight percent ceramic organic fibers, about 5 to about 15 weight percent colloidal silica and about 3 to about 10 weight percent organic adhesive. The second part is essentially dry and comprises from about 50 to about 100 weight percent calcium aluminate.The invention further includes a method for forming the cement by mixing the two parts and includes the cast cement resulting from casting and drying the mixed first and second parts.

Abstract: A method for uniformly coating ceramic fibers comprising from about 40 to 100 weight percent aluminum oxide with Cr.sub.2 O.sub.3. The method comprises precipitating Cr.sub.2 O.sub.3.xH.sub.2 O (chromium oxide hydrate) upon the fibers followed by converting the Cr.sub.2 O.sub.3.xH.sub.2 O to Cr.sub.2 O.sub.3. The resulting Cr.sub.2 O.sub.3 coated fibers have good shrinkage resistance, good temperature resistance and good flexibility in thick fiber articles.

Abstract: A ceramic fiber and a shrink resistant article manufactured therefrom. The fiber comprises at least 80 weight percent of a refractory compound selected from the group consisting of silica, alumina, aluminum silicate, titania, zirconia, zirconium silicate and mixtures thereof and which comprises less than 5 combined weight percent of alkali or alkaline metal oxide or alkali or alkaline metal silicate. The fiber is uniformly coated with from about 0.01 to about 5 weight percent of Cr.sub.2 O.sub.3.

Abstract: There is disclosed a fire-resistant seal for sealing around a member passing through a fire-resistant building divider. The seal is formed of an adhesive fire-resistant cement on at least one side generally in the plane of the divider surface, behind the adhesive cement is placed bulk ceramic fiber. The second surface of the seal may be covered with an adhesive cement.

Abstract: A ceramic fiber and a shrink resistant article manufactured therefrom. The fiber comprises at least 80 weight percent of a refractory compound selected from the group consisting of silica, alumina, aluminum silicate, titania, zirconia, zirconium silicate and mixtures thereof and which comprises less than 5 combined weight percent of alkali or alkaline metal oxide or alkali or alkaline metal silicate. The fiber is uniformly coated with from about 0.01 to about 5 weight percent of Cr.sub.2 O.sub.3.

Abstract: A refractory grain material consisting essentially of at least about 97 percent by weight MgO grains, from about 1 to about 3 percent by weight of a combination of CaO, SiO.sub.2, and Al.sub.2 O.sub.3, and up to about 1 percent by weight of at least one oxide selected from the group consisting of Fe.sub.2 O.sub.3 and B.sub.2 O.sub.3 wherein the relative amounts of CaO, SiO.sub.2 and Al.sub.2 O.sub.3 are controlled so that a solid ternary compound of CaO-SiO.sub.2 -Al.sub.2 O.sub.3 is present between the MgO grains.