Abstract: Apparatus for identifying the position of the movable portion of a fifth wheel which is useful on a multi-axle vehicle relative to the fixed rail portion (24) thereof. The apparatus includes sensing element (34) positioned on the movable fifth wheel portion for recognizing the successive, teeth-like elements (22) of the rail portion, and a signal processor (30) which is responsive to the sensing element (34) for determining the direction of movement of the fifth wheel and for counting the number of teeth (22) recognized by the sensing element (34).