Abstract: A gearbox (BV) comprises a secondary shaft (AS) provided with a synchromesh (SB) comprising a flange (FL) comprising a sub-hub (SM) fixedly secured to the secondary shaft (AS) and provided with external splines (CE3), a hub (MO) comprising internal splines (CI1) collaborating with the external splines (CE3) of the sub-hub (SM) to allow translational movement with respect to the latter (SM), and a sleeve (MA) that can undergo a translational movement with respect to the hub (MO) so that the internal splines (CI2) thereof are closely coupled to dogs (CR) of an idling pinion (PF1). This translational movement of the hub (MO) with respect to the sub-hub (SM) guarantees close coupling of the internal splines (CI2) of the sleeve (MA) with the dogs (CR) with a minimal margin for translation, irrespective of dimensional variations in the manufacture of the sleeve (MA) and idling pinion (PF1).

Abstract: A gearbox (BV) comprises a secondary shaft (AS) provided with a synchromesh (SB) comprising a flange (FL) comprising a sub-hub (SM) fixedly secured to the secondary shaft (AS) and provided with external splines (CE3), a hub (MO) comprising internal splines (CI1) collaborating with the external splines (CE3) of the sub-hub (SM) to allow translational movement with respect to the latter (SM), and a sleeve (MA) that can undergo a translational movement with respect to the hub (MO) so that the internal splines (CI2) thereof are closely coupled to dogs (CR) of an idling pinion (PF1). This translational movement of the hub (MO) with respect to the sub-hub (SM) guarantees close coupling of the internal splines (CI2) of the sleeve (MA) with the dogs (CR) with a minimal margin for translation, irrespective of dimensional variations in the manufacture of the sleeve (MA) and idling pinion (PF1).

Abstract: The invention relates to a device which comprises a gear change fork (1), a hydraulic cylinder including a stationary cylindrical spindle (2) with a stationary transverse wall (3) projecting from said spindle (2) and a piston that is translatably movable by sliding over said transverse stationary wall (3). The piston consists of a piston body (4) closed by a radial closing part referred to as a “plug” (5) so as to define two inner chambers (6, 7) of the cylinder, which are situated on either side of said stationary transverse wall (3), respectively. Means for pressurizing both of the two cylinder chambers (6, 7) are provided for moving the movable piston (4, 5) in one direction or another. In the device according to the invention, the piston body (4) is directly built into the gear shift fork (1) whereby, as a result of the pressure in a cylinder chamber (6, 7), it is the fork (1) that moves translatably.

Abstract: The invention relates to a device which comprises a gear change fork (1), a hydraulic cylinder including a stationary cylindrical spindle (2) with a stationary transverse wall (3) projecting from said spindle (2) and a piston that is translatably movable by sliding over said transverse stationary wall (3). The piston consists of a piston body (4) closed by a radial closing part referred to as a “plug” (5) so as to define two inner chambers (6, 7) of the cylinder, which are situated on either side of said stationary transverse wall (3), respectively. Means for pressurizing both of the two cylinder chambers (6, 7) are provided for moving the movable piston (4, 5) in one direction or another. In the device according to the invention, the piston body (4) is directly built into the gear shift fork (1) whereby, as a result of the pressure in a cylinder chamber (6, 7), it is the fork (1) that moves translatably.

Abstract: The invention relates to a coupling device between a shaft (14) and a pulley (11) as well as to an engine block suitable for being installed in a motor vehicle. The shaft (14) and a pulley (11) can rotate relative to one another about an axis (15). According to the invention, the device includes a separate declutchable means (36, 37, 40, 42, 45, 50) for driving the shaft (14) by the pulley (11) only allowing the shaft (14) to be driven by the pulley (11) when the latter is rotating at a rotation speed that is higher than a predetermined rotation speed. The engine block includes a heat engine, a reversible alternator for starting the heat engine and generating electric power, an accessory, the heat engine and the reversible alternator being suitable for rotating the accessory by means of a belt. The engine block includes a coupling device according to the invention between an output shaft (14) of the heat engine and a pulley (11) driven by the belt (10).