Partition systems

1. A panel structure for a demountable partition system, usable for dividing a room or for forming rooms or corridors or other structures,

the panel structure having two opposite major faces and, in use, being positioned in a generally upright orientation, in which there are provided one or more rolling elements movable using a gearbox mechanism between an extended, ground-contacting position, and a retracted position within the panel structure, wherein

the panel structure comprises a base portion and a panel portion carried on the base portion, and said one or more rolling elements and said gearbox mechanism are self-contained within the base portion,

whereby the one or more rolling elements and the gearbox mechanism do not intrude into the panel portion to thereby maintain the integrity of the panel portion, in which

there is provided a reinforced substantially bullet-proof layer between the said two opposite major faces of the panel structure,

the said reinforced substantially bullet-proof layer lies in a plane inclined to the family of planes defined by the said two opposite major faces of the panel structure,

the panel structure being defined along at least two opposite sides by edges having half lap tongues which overlap one another when two like panel structures are placed in juxtaposition with respect to one another,

the said half-lap tongues on opposite edges of the panel structure are aligned with respective opposite major faces of the panel structure, and

the said bullet-proof layer extends into each said half-lap tongue, whereby the bullet-proof layers of adjacent like panel structures of the demountable partition system overlap one another.

2. The panel structure as claimed in claim 1 , in which the said one or more rolling elements comprise a plurality of wheels mounted in two or more groups with each group on a common support.

3. The panel structure as claimed in claim 2 , in which each group comprises two or four wheels.

4. The panel structure as claimed in claim 1 , wherein an operating characteristic of the panel structure is one of: bullet proofing, bullet proofing and acoustic proofing.

5. The panel structure as claimed in claim 1 , wherein maintaining the integrity of the panel portion includes maintaining the integrity of the said two opposite major faces.

6. The panel structure as claimed in claim 1 , in which the said one or more rolling elements comprise a plurality of wheels mounted in two or more groups with each group on a common support, in which the two or more groups of rolling elements are linked together for displacement of the rolling elements between the said extended and retracted positions in unison upon operation of a control member, and in which the gearbox mechanism for effecting displacement of the one or more rolling elements between the said extended and the said retracted positions comprises or includes a lead screw which causes or allows the wheels one or more rolling elements to move between the said extended and the said retracted positions when turned about its longitudinal axis.

7. The panel structure as claimed in claim 2 , in which the two or more groups of rolling elements are linked together for displacement of the rolling elements between the said extended and the said retracted positions in unison upon operation of a control member.

8. The panel structure as claimed in claim 7 , in which operation of said control member is effected by a lever or crank handle.

9. The panel structure as claimed in claim 2 , in which a plurality of said common supports are linked together by a gear train which causes or allows the rolling elements to move together between the said retracted and the said extended positions.

10. The panel structure as claimed in claim 2 , in which the said wheels are castor wheels.

11. The panel structure as claimed in claim 6 , in which there is provided between the control member and the lead screw one of: a bevel gear, a helical gear, or a worm gear.

12. The panel structure as claimed in claim 1 , in which at least part of the space between the said two opposite major faces of the panel structure contains a particulate material.

13. The panel structure as claimed in claim 12 , in which the said particulate material comprises a hard stone aggregate, ceramic or metal balls or other particles, or sand.

14. A demountable partition system incorporating one or more panel structures as claimed in claim 1 .