Abstract: An aircraft seat has a chassis (21), fixed to a pallet which is fixed to the floor of the aircraft. The chassis has two load bearing sides (23) and opposite ends (24, 25). Fixed along the top edge of the sides (23) and facing outwards are pins (26) supporting bearing wheels (27). These on each side engage with a rectangular S form interconnection beam (28) having an inside groove (29) for receiving these wheels. On the outside, the beam has another groove (30) receiving similar wheels (31), on pins (32) fixed to the inside of side plates (41) of a sub-frame (42), these side plates being interconnected by front and rear beams (43, 44). Thus the sub-frame can move back and forth, with the wheels acting as rolling element bearings. The beams move half the distance of the sub-frame, in analogous manner to the bearing of filing cabinet drawers.