Abstract: A changing table has a changing surface on which an individual can lie to be changed or washed. The changing surface is formed from a sheet of semi-rigid material having a longitudinal center axis and having also, parallel to the center axis, first and second edges occupying nominal rest positions with respect to each other when there is no load on the surface, the said edges being fixed to first and second longitudinal members, the sheet and longitudinal members forming together a support system having for the first 10 mm of extension between the said center line and the said nominal rest position of the said first edge and between the said center line and the said nominal rest position of the said second edge an average spring rate in extension of more than 300 N/mm and the said semi-rigid sheet having a torsion coefficient of more than 10 Nm/radian.

Abstract: A changing table has a changing surface on which an individual can lie to be changed or washed. The changing surface is formed from a sheet of semi-rigid material having a longitudinal center axis and having also, parallel to the center axis, first and second edges occupying nominal rest positions with respect to each other when there is no load on the surface, the said edges being fixed to first and second longitudinal members, the sheet and longitudinal members forming together a support system having for the first 10 mm of extension between the said center line and the said nominal rest position of the said first edge and between the said center line and the said nominal rest position of the said second edge an average spring rate in extension of more than 300 N/mm and the said semi-rigid sheet having a torsion coefficient of more than 10 Nm/radian.

Abstract: A downhole unit for use in subsurface boreholes, for example a bias unit for imparting a lateral bias to the drill bit to control the direction of drilling, includes a main body and a number of pads pivotally mounted on the main body for engagement with the walls of the borehole. A thrust member is disposed inwardly of each pivotal pad and is movable along a guide passage in the main body to transmit movement to the pad. Each thrust member is movable by hydraulic pressure and a fluid-tight sliding seal is provided between the thrust member and its guide passage. The outer surface of each thrust member or the inner surface of the guide passage, or both, is in the form of a portion of a toroid centred on the pivot axis of the respective pad so as to minimise lateral movement of the seal as the thrust member moves along the passage. This also allows relative displacement between the thrust member and pad to be avoided, so that the thrust member can be integral with the pad or rigidly connected to it.