IMPROVEMENTS IN OR RELATING TO DOWN HOLE SURVEYING

摘要

In one aspect, there is disclosed an apparatus for indexing a device about an indexing axis, the apparatus comprising an indexing drive mechanism comprising a drive portion configured in driving engagement with a driven member for indexing the device about the indexing axis. The driven member is arranged in operable association with an assembly comprising at least one resilient element arranged so as to be capable of transitioning to/from a state of bias such that exposure of the device to any undesirable physical forces is reduced to at least some extent.