Surface Currents Near the Greater and Lesser Antilles

Friction welding apparatus includes a support, which, in use, carries a workpiece and a carrier member arranged to receive a component to be friction welded to the workpiece. In use, the component and the workpiece can be pressed against one another and the component can be moved with the carrier member relative to the support to allow the component to be friction welded to the workpiece. A drive member is provided for moving the carrier member relative to the support, the drive member also being capable of rotational movement relative to the carrier member about an axis of the drive member. A first cylindrical shaft is secured to the drive member so that the axis of the shaft is parallel with, but spaced from, the axis of rotation of the drive member. A second cylindrical shaft is mounted around the first shaft so that the axis of the first shaft is parallel with the axis of the second shaft, but is spaced from the axis of the second shaft by a distance equal to the space in between the axes of the first shaft and the drive member respectively. Drive can be supplied to the second shaft to rotate the second shaft and the first shaft is movable angularly relative to the second shaft between an inoperative position and a welding postion. In the welding position, the axis of the drive member is spaced from the axis of the second shaft so that rotational movement of the second shaft causes the drive member to move the carrier member relative to the support along a circular path centered on the axis of the second shaft. In the inoperative position, the axis of the second shaft and the axis of the drive member are co-extensive so that rotational movement of the second shaft rotates the drive member relative to the carrier member so that the carrier member is not moved relative to the support.