IMPROVED ACTIVATION DEVICE
A device for activating a downhole tool is described. The device comprises a first elongate member defining a toothed surface portion, a second elongate member defining a toothed surface portion and at least one pinion arrangement The/each pinion arrangement engages the toothed surface portions of the first and second members such that movement of one member in a first direction results in movement of the other member in a second direction, opposite the first direction.