The present invention relates an elevating apparatus based on a hetero-oriented non-isometric, dual-spiral drive structure, comprising a first carrier and a second carrier, further comprising a first support and a second support that are telescoped together in a manner that they can rotate with respect to each other, the first support is provided with a first recessed portion and a first raised portion that shares the same spiral direction and spiral pitch, the second support is provided with a homo-oriented, isometric, dual-spiral second recessed portion that has a spiral direction different from that of the first recessed portion. The carrier of the present invention is provided in a simply-supported-beam, and the carrier force can be achieved without additional weight, and the operation is stable and reliable.

The present invention relates an elevating apparatus based on a hetero-oriented non-isometric, dual-spiral drive structure, comprising a first carrier and a second carrier, further comprising a first support and a second support that are telescoped together in a manner that they can rotate with respect to each other, the first support is provided with a first recessed portion and a first raised portion that shares the same spiral direction and spiral pitch, the second support is provided with a homo-oriented, isometric, dual-spiral second recessed portion that has a spiral direction different from that of the first recessed portion. The carrier of the present invention is provided in a simply-supported-beam, and the carrier force can be achieved without additional weight, and the operation is stable and reliable.

A method is disclosed of attaching a tread assembly of a spiral staircase to a vertical support column. One step of the method involves providing a tread assembly having a tread portion attached to an arcuate mounting plate defining at least one hole through which extends a fastener defining external threads, the mounting plate having a first face defining a first radius of curvature. Another step involves providing a support column extending along an axis, the support column having a plurality of axially and angularly spaced apart tread attachment locations, each of the tread attachment locations having an arcuate outer surface defining a corresponding aperture for receipt of the fastener, the arcuate outer surface defining a second radius of curvature that is greater than the first radius of curvature. According to another step of the method, the tread assembly is loosely connected to one of the tread attachment locations of the support column. According to another step, the fastener is tightened such that the arcuate mounting plate of the tread assembly is elastically deformed to be in substantial engagement with the tread attachment location and applies tension to the elongate fastener to inhibit loosening thereof.

A method is disclosed of attaching a tread assembly of a spiral staircase to a vertical support column. One step of the method involves providing a tread assembly having a tread portion attached to an arcuate mounting plate defining at least one hole through which extends a fastener defining external threads, the mounting plate having a first face defining a first radius of curvature. Another step involves providing a support column extending along an axis, the support column having a plurality of axially and angularly spaced apart tread attachment locations, each of the tread attachment locations having an arcuate outer surface defining a corresponding aperture for receipt of the fastener, the arcuate outer surface defining a second radius of curvature that is greater than the first radius of curvature. According to another step of the method, the tread assembly is loosely connected to one of the tread attachment locations of the support column. According to another step, the fastener is tightened such that the arcuate mounting plate of the tread assembly is elastically deformed to be in substantial engagement with the tread attachment location and applies tension to the elongate fastener to inhibit loosening thereof.

A method is disclosed of attaching a tread assembly of a spiral staircase to a vertical support column. One step of the method involves providing a tread assembly having a tread portion attached to an arcuate mounting plate defining at least one hole through which extends a fastener defining external threads, the mounting plate having a first face defining a first radius of curvature. Another step involves providing a support column extending along an axis, the support column having a plurality of axially and angularly spaced apart tread attachment locations, each of the tread attachment locations having an arcuate outer surface defining a corresponding aperture for receipt of the fastener, the arcuate outer surface defining a second radius of curvature that is greater than the first radius of curvature. According to another step of the method, the tread assembly is loosely connected to one of the tread attachment locations of the support column. According to another step, the fastener is tightened such that the arcuate mounting plate of the tread assembly is elastically deformed to be in substantial engagement with the tread attachment location and applies tension to the elongate fastener to inhibit loosening thereof.

A method is disclosed of attaching a tread assembly of a spiral staircase to a vertical support column. One step of the method involves providing a tread assembly having a tread portion attached to an arcuate mounting plate defining at least one hole through which extends a fastener defining external threads, the mounting plate having a first face defining a first radius of curvature. Another step involves providing a support column extending along an axis, the support column having a plurality of axially and angularly spaced apart tread attachment locations, each of the tread attachment locations having an arcuate outer surface defining a corresponding aperture for receipt of the fastener, the arcuate outer surface defining a second radius of curvature that is greater than the first radius of curvature. According to another step of the method, the tread assembly is loosely connected to one of the tread attachment locations of the support column. According to another step, the fastener is tightened such that the arcuate mounting plate of the tread assembly is elastically deformed to be in substantial engagement with the tread attachment location and applies tension to the elongate fastener to inhibit loosening thereof.

The present invention relates to a spacer for a prefabricated spiral staircase, which allows adjustment of a height of a gap between footboards for a prefabricated spiral staircase in multiple steps by using minimal disks, and a prefabricated spiral staircase using the same. The spacer for a prefabricated spiral staircase comprises a cylindrical pipe, a lower cap or upper cap, a disk, a height adjustment member, and a location determining member, wherein the height of the spacer is adjusted in multiple stages according to relative rotation between the upper cap and the disk or between the lower cap and the disk.

The present invention relates to a spacer for a prefabricated spiral staircase, which allows adjustment of a height of a gap between footboards for a prefabricated spiral staircase in multiple steps by using minimal disks, and a prefabricated spiral staircase using the same. The spacer for a prefabricated spiral staircase comprises a cylindrical pipe, a lower cap or upper cap, a disk, a height adjustment member, and a location determining member, wherein the height of the spacer is adjusted in multiple stages according to relative rotation between the upper cap and the disk or between the lower cap and the disk.

A spiral staircase comprises a mounting column extending along a longitudinal axis. A plurality of tread assemblies each having a tread portion attached to a mounting plate is also provided. The tread assemblies are axially and angularly offset from an adjacent tread assemblies along the mounting column. In this aspect, each mounting plate has a first face that engages a corresponding portion of an outer surface of the mounting column and a second face from which the tread portion extends. Each of the tread assemblies further have attachment hardware that secures the mounting plate to the mounting column. Prior to attachment to the mounting column and in an unstressed state, the mounting plate has a first radius of curvature and the corresponding portion of the outer surface of the mounting column has a second radius of curvature. The first radius of curvature is less than the second radius of curvature so that when the mounting plate is secured to the column with the attachment hardware and the second face of the mounting plate substantially engages the mounting column, the mounting plate is in an elastically deformed state applying tension to the attachment hardware to inhibit loosening thereof.

A spiral staircase comprises a mounting column extending along a longitudinal axis. A plurality of tread assemblies each having a tread portion attached to a mounting plate is also provided. The tread assemblies are axially and angularly offset from an adjacent tread assemblies along the mounting column. In this aspect, each mounting plate has a first face that engages a corresponding portion of an outer surface of the mounting column and a second face from which the tread portion extends. Each of the tread assemblies further have attachment hardware that secures the mounting plate to the mounting column. Prior to attachment to the mounting column and in an unstressed state, the mounting plate has a first radius of curvature and the corresponding portion of the outer surface of the mounting column has a second radius of curvature. The first radius of curvature is less than the second radius of curvature so that when the mounting plate is secured to the column with the attachment hardware and the second face of the mounting plate substantially engages the mounting column, the mounting plate is in an elastically deformed state applying tension to the attachment hardware to inhibit loosening thereof.