A robotic catheter device cartridge comprising: a first element (412, 414, 416, 418) of the cartridge (402, 404) configured to be operatively engageable with a second element (316, 318, 320, 322) of a manipulation base (308, 310), at least one of the first and second elements (412, 414, 416, 418; 316, 318, 320, 322) slidably engageable with at least one of the cartridge and the manipulation base, the manipulation base for releasable connection to the cartridge, at least one of the first and second elements (412, 414, 416, 418; 316, 318, 320, 322) being linearly driveable in a predetermined direction for operating the cartridge, further comprising at least one recess in one of the manipulation base (308, 310) and the cartridge (402, 404) for engagement with at least one complementary locator detent on the other one of the manipulation base (308, 310) and the cartridge (402, 404) for alignment of the cartridge (402, 404) relative to the manipulation base (308, 310), wherein the second element is a finger (516, 518, 520, 522; 716, 718, 720, 722) and the first element is a slider block (612, 614, 616, 618; 812, 814, 816, 818), characterized in that the finger and slider block are non-rigidly engageable such that one of the finger (516, 518, 520, 522; 716, 718, 720, 722) or the slider block (612, 614, 616, 618; 812, 814, 816, 818) is configured to push the other of the finger or slider block and to tension a steering wire coupled to the other of the finger (516, 518, 520, 522; 716, 718, 720, 722) or the slider block (612, 614, 616, 618; 812, 814, 816, 818) when linearly driven in the predetermined direction and unable to pull the other of the finger or slider block and unable to tension the steering wire coupled to the other of the finger (516, 518, 520, 522; 716, 718, 720, 722 or the slider block (612, 614, 616, 618; 812, 814, 816, 818) when linearly driven in an opposite direction. a first element (412, 414, 416, 418) of the cartridge (402, 404) configured to be operatively engageable with a second element (316, 318, 320, 322) of a manipulation base (308, 310), at least one of the first and second elements (412, 414, 416, 418; 316, 318, 320, 322) slidably engageable with at least one of the cartridge and the manipulation base, the manipulation base for releasable connection to the cartridge, at least one of the first and second elements (412, 414, 416, 418; 316, 318, 320, 322) being linearly driveable in a predetermined direction for operating the cartridge, further comprising at least one recess in one of the manipulation base (308, 310) and the cartridge (402, 404) for engagement with at least one complementary locator detent on the other one of the manipulation base (308, 310) and the cartridge (402, 404) for alignment of the cartridge (402, 404) relative to the manipulation base (308, 310), wherein the second element is a finger (516, 518, 520, 522; 716, 718, 720, 722) and the first element is a slider block (612, 614, 616, 618; 812, 814, 816, 818), characterized in that the finger and slider block are non-rigidly engageable such that one of the finger (516, 518, 520, 522; 716, 718, 720, 722) or the slider block (612, 614, 616, 618; 812, 814, 816, 818) is configured to push the other of the finger or slider block and to tension a steering wire coupled to the other of the finger (516, 518, 520, 522; 716, 718, 720, 722) or the slider block (612, 614, 616, 618; 812, 814, 816, 818) when linearly driven in the predetermined direction and unable to pull the other of the finger or slider block and unable to tension the steering wire coupled to the other of the finger (516, 518, 520, 522; 716, 718, 720, 722 or the slider block (612, 614, 616, 618; 812, 814, 816, 818) when linearly driven in an opposite direction.