A LEVER OPERATING UNIT FOR A MOTOR-VEHICLE GEARBOX

The operating unit (1) comprises a support housing (2) in which an operating lever (3) is mounted pivotably by means of a ball-and-socket joint (4-6). The joint (4-6) includes an at least partially spherical body (5) which is fixed firmly to the lever (3) and is movable relative to a seat (6) of at least partially complementary shape which is fixed firmly to the housing (2). The lever (3) is pivotable at least in a first plane and in a second plane which are inclined at an angle to one another, for the selection and for the engagement, respectively, of a gear ratio. A detector device (15) which is suitable for supplying electrical signals indicative of the position of the lever (3) includes a permanent magnet (16) mounted eccentrically on the body (5) and a monolithic Hall-effect magnetic field sensor (18) in the form of a single integrated chip suitable for supplying output signals indicative of the components of the magnetic flux which is applied thereto in operation. The sensor (18) is mounted on a plate or board (17) which is fixed to a stationary portion (2) of the operating unit (1) so as to be operatively exposed to the magnetic flux generated by the permanent magnet (16) in operation.