This device comprises a motor (1), the output shaft (2) of which carries two coaxial worms (5, 6), offset axially and with opposite pitches, two pairs of wheels, (7, 9, 8, 11) meshing with the worms, mutually in pairs, at the rate of two wheels (7, 8; 9, 11) per worm, which wheels are arranged on either side of the worms, an output shaft (12, 13, 14, 15) traversing each wheel (7, 8; 9, 11) freely and intended to control an associated element at one or other of its opposite ends, and on each shaft (12 . . . 15) and facing each wheel (7 . . . 11), a clutch (E1, E2, E3, E4) independent of the other clutches and adapted in order to be able to link the selected shaft in rotation to the corresponding wheel. This arrangement makes it possible to produce a compact control assembly distributing, from a single location, multiple functions from a lightweight divider box ensuring the switching of the functions, with a reduced overall size and a simplified single connection.

The engagement between the first and second members is accomplished by the wedging of roller members so that the first and second members can be held rotationally fast to each other in a continuous manner or at any desired angular position. A pair of roller members are received in a chamber defined between the first and second members, and are normally urged into wedging engagement in the circumferential ends of the chamber under the spring force of a spring member, but may be disengaged so as to allow free relative rotation between the first and second members by displacing the roller members toward each other against the spring force of the spring member by using actuation members. Thus, the relative rotation in either direction can be prevented, and the releasing of the first and second members can be accomplished simply by slightly moving the roller members.

An arm connectible to a seat back and having teeth formed at one end is pivotally mounted to a seat bottom frame formed of first and second spaced, fixedly connected plates. A toothed drive gear mounted between the first and second plates and rotated by a drive unit meshingly engages the teeth on the arm to rotate the arm between infinitely adjustable positions. Aligned slots are formed in the first and second plates and receive opposed tenons of a rivet having the arm rotatably mounted about a central body portion. The tenons are angularly staked to the first and second plates such that one edge of each tenon farthest from the teeth on the arm is disposed in registry with the associated plate adjacent one edge of the slot and the diametrically opposed edge of each tenon is spaced above the opposite end of the slot in each plate to dispose the exterior end surface of each tenon at an acute angle with respect to the associated plate to urge the rivet and the arm in a direction toward the drive member to interlock the teeth on the arm with the teeth on the drive member.

An electrical actuator for a seat with an inclinable back in which irreversibility (or blocking of the mechanism) and efficiency are independent of each other, efficiency being obtained by the use of a reduction gear with straight gear wheels (8), and irreversibility being obtained by a current release blocking device (7) mounted in parallel on an electric motor (5) and energized by the same control device (9) as the motor.

A seat includes a first seat piece (10) and a further seat piece (12), which may be adjusted for inclination by a controllable operating device (14). The operating device (14) engages the further seat piece (12) by at least two adjusters (30), which are moved by a common drive mechanism (34) with a mechanical coupling (36) between the adjusters (30), for an effectively uniform motion. A uniform inclination adjustment of the further seat piece, such as backrest and/or leg rest is achieved. The drive includes an actuator device with a longitudinally displaceable operating piece (40), engaged with a rocker (44), connected to an adjuster piece (30) and operating the mechanical coupling (36), with a further rocker (46), for the other adjuster (30).