A magnetic tape apparatus comprises a head-­mounting plate (6) which is movable towards two winding spindles (2, 3), which are arranged in line with each other, from a retracted position to a first position defined by a stationary stop. The winding spindles (2, 3) each carry coaxial winding idlers (4, 5) at their lower end portions, between which winding idlers (4, 5) a pivotable idler wheel (27) is arranged, which pivotable idler wheel can be driven in two opposite directions and is carried by a pivotal arm (25). After the pivotal movement the pivotable idler wheel (25) is engageable with the respective winding idler (4, 5). The pivotal arm (25) carries a sliding element (25a) on which a stop projection (25b) is arranged, which sliding element (25a) is guided on the pivotal arm for radial movement relative to the pivotal axis (17c) of the pivotal arm (25). The stop projection (25b) extends into a pivoting space which is bounded on two opposite sides by raised edges of the head-mounting plate (6). In each of these edges at least one recess (30a, 30b) is formed. By moving the head-­mounting plate (6) towards the winding spindles (2, 3) the stop projection (25b) is engageable with the recess (30b) after a pivotal movement towards the pivotal axis (17c) against the force of a spring (25b) from a non-­shifted first position to a second position in which it is shifted relative to the pivotal arm (25), in which last-mentioned position the stop projection (25b) occu­pies a stop position for positioning the head-mounting plate (6) in a second position situated between the retracted position and the first position.