The present invention relates to a collapsible stairway having, in the position of use, vertical suspension ropes, lines or similar, and whereby the stairway in the position of use mainly having a vertical axis, and whereby the stairway forms a kind of winding stairway. Such stairways can be used when the use of firmly mounted stairways is not appropriate, for instance for offshore platforms or as rescue stairways for ships and buildings. In the stand-by or stored condition the stairways may be hoisted up, whereby they do not occupy space and are inconvenient.

Such a stairway is shown in NO 180032. The stairway comprises separate steps. When the stairway is hanging in the position of use, each step is hanging in the ropes, lines or similar, whereby the steps are situated along a helix. The known stairway may be somewhat unstable during use, in that the ropes, lines or similar may swing laterally or perform a twisting movement about a vertical axis. The stairway is surrounded by a net hose, which can be situated tightly against the external boundaries of the steps. The primary object of the hose is to prevent persons from falling out from the stairway, but it will also to some extent prevent or reduce swinging and twisting movements. Moreover, the print discloses the use of stabilizing lines or rails, which, however, make the stairway more complicated.

A rescue device for buildings is known from GB Patent 1430653, and consists of cable or chain suspended platforms having step units between adjacent platforms. Each step unit is at the top hinged to the superjacent platform, whereby each step unit can pivot to a horisontal position in that the lower end of each step unit slides along the underlying platform when the platforms are moved away from and towards each other. Each platform has an aperture giving access to the step unit which in the position of use extends sloping downwards from the platform. The platforms are large and cover the entire cross section of the device, because the platforms are adapted to form access platforms from the windows of the building. The known device is, in particular due to the weight of the platforms, not much appropriate for use in cases where there is no need for access to the device, except from at the top and bottom.

With the present invention a stairway has been provided which is characterized in comprising step units having bending stiffness, with a plurality of interconnected steps in each unit, and that plate shaped, mutually similar, horisontal stair heads to which the

ropes, lines or similar are fastened constitute connection between successive step units and are in hinge connection therewith, whereby the stair heads in the collapsed condition of the stairway will be lying mutually overlapping and approximately against each other in vertical stacks, while the step units will also be lying approximately horisontally.

Thus, the stairway constitutes a physically continuous assembly, in which the ropes, lines or similar mainly have the supporting function. The step units and the stair heads are physically interconnected as a hinged mechanism. The ropes, lines or similar are not fastened to the step units, but only to the stair heads. This is a simplification relatively to the known stairway disclosed in NO 182032, in which all the steps are supported by and have to be fastened to the ropes, lines or similar. The same ability of collapsing as for the known stairway is achieved. The extent of the stairway according to the invention increases somewhat (horisontal dimension) when it is collapsed, because the position of the step units is changed from sloping to horisontal.

By hinge connection is not necessarily meant that actual hinges are present between the step units and the stair heads. The hinge connection may consist of the suspension ropes, lines or similar being, which are bent at or near the fastening regions for the stair heads when the stairway is collapsing.

The invention will in the following be explained more detailed, with reference to the accompanying drawings.

Figs. 1-3 show, seen laterally and from above, three different embodiments of a stairway according to the invention, in the condition of use.

Fig. 4 shows an embodiment of a stairway according to the invention, seen laterally and from above, in a collapsed state.

Fig. 5 shows a stair head included in the stairway, seen laterally and from above.

Fig. 6 shows an embodiment of a stairway according to the invention, having an external net hose and internal railing rods or tubes.

Fig. 7 shows a cut-out portion in the region of fastening of a rope or a line to a stair head.

Fig. 8 shows, in another embodiment relatively to Fig. 7, a cut-out portion in the region of fastening of a rope or a line to a stair head.

In the following description the designation rope is used for the suspension members,

even when these may be for instance lines, wires, chains or similar.

Figs. 1-3 show step units 1, being in hinge connection with stair heads 2 hanging in ropes 3. The step units 1 may comprise a suitable number of steps relatively to the stairway dimensions, whereby the step units 1 make the stairway suitably sloping. Each step unit is a unit having bending stiffness and sufficient strength for withstanding the bending moment when persons are walking in the stairway. Fig. 1 shows stair heads 2 having a triangular shape, while Fig. 2 shows stair heads 2 having a rectangular shape, whereby the longest sides are hinged to the step units 1. The stairway shown in Fig. 1 is externally an octagon, having four sets of stair heads 2. By set is meant stair heads being mutually lined up vertically. The stairway shown in Fig. 2 is pentagonal, because the external edges of the stair heads 2 are in line with the external sides of the step units 1. Inwardly of the stair heads 2 and the step units 1 is defined a vertical aperture or chute 15. This may be used for lowering of goods or persons not able to walk in the stairway.

Fig. 3 shows rectangular stair heads 2, and the shape of the stairway seen vertically is also rectangular. The step units 2 are adjacent to each other, whereby no aperture or chute is present in the middle of the stairway.

Fig. 4 shows, seen laterally and from above, a stairway having a rectangular cross section. The side view shows the stairway in a collapsed state, with the stair heads 2 lying in two vertical stacks. Similarly the step units 1 are lying in two vertical stacks between the stacks of stair heads 2. The stairway shown in Fig. 4 is adapted for use above water. At the bottom of the stairway are mounted a lower plate 6, floats 8, a weight 7 and a transition float 9. The transition float 9 is stationary and is used by persons coming down the stairway, for entering the floats 8, which are transportation floats. For use on land the float arrangement is of course omitted.

The figure shows how the external dimensions of the stairway increase in the horisontal direction when the stairway is collapsing, because the step units 1 assume horisontal positions.

Fig. 5 shows a triangular stair head 2, having hinge ears 4 for being coupled to step units and a sleeve 5 at each corner for threading through and fastening of ropes.

Fig. 6 shows the lower end of a hanging stairway according to the invention. The stairway contains railings 10, in the form of rods or tubes fastened to some of the ropes 3. Correspondingly as the stairway shown in Fig. 4 the stairway has a lower plate 6 and a float arrangement having a weight 7, floats 8 and a transition float 9. The stairway is surrounded by a net hose 16 which prevents that persons can fall out of the stairway, and which may have apertures for entry and exit at requisite levels, for instance at floors in buildings. When the stairway is collapsing the net hose 16 is widened in the horisontal direction and gives room for the increasing horisontal dimensions due to the step units taking up horisontal positions.

Fig. 7 shows details of a possible solution with respect to fastening of ropes 3 to a stair head 2. Two sleeves 17 and 18 are clamped around the rope 3 with such a spacing that sleeves 19 and 20 on the stair head 2 and the step unit 1 can be moved along the rope 3, whereby the rope can be bent and acts as a hinge when the stairway is collapsing.

Fig. 8 shows details of another possible solution with respect to fastening of ropes 3 to a stair head 2. A sleeve device 5 comprises a sleeve 11 fastened to the stair head 2, a clamp nut 12 that can be screwed onto the sleeve 11, an inner slide sleeve 13 in the sleeve 11 and a compressible material that is pressed against the rope 3 when the nut 12 has been tightened.

The stair heads and the step units are shown made of plate, for instance metal plate. It will be appreciated that the stair heads and the step units can be made from any other suitable materials, such as reinforced plastics, composite material, expanded metal, and that the stair heads and the step units can be reinforced in any suitable manner.