A shifting sleeve support of a synchronisation device includes an outer toothing for meshing with a shifting sleeve and a groove, which interrupts the outer toothing. The groove has groove walls with an asymmetrical cross-section, and a groove bottom. The groove may form a pressure piece receptacle, a stop for the shifting sleeve, or a stop for a synchroniser ring, for example.

A synchronizer for mechanical transmissions having a phasing system configured so as to include a plurality of first cavities on an internal cylindrical surface of a rim of a hub, the hub torsionally connected with a transmission shaft, forming the external teeth of the hub and, for each of the first cavities, either a tooth which radially protrudes from an external cylindrical surface of a synchronizing ring of the synchronizer and is arranged to engage in the first cavity, or a connecting pin arranged to engage on one side the first cavity and on the other a respective second cavity on the external cylindrical surface, wherein the first cavities have an arc- or round-shaped cross-section.

A synchronizer apparatus for a transmission includes first and second shifting gears rotatable on output shaft, a hub spline-coupled with output shaft and having a slope portion having slanted surfaces, a sleeve spline-coupled with hub, a key coupled with the slope portion, first and second clutch gears disposed between hub and shifting gears, first and second outer rings and first and second inner rings disposed between hub and clutch gears, first and second synchronizer cones disposed between first inner and outer rings and second inner and outer rings and engaged with clutch gears, a poppet ball unit disposed at sleeve and contacting key through a poppet ball, first and second push blocks disposed at slanted surfaces, and first and second push springs inserted in spring holes formed at push blocks. In addition, the push springs is abutted by key such to force push blocks to tightly contact slanted surfaces.

The synchronizer may have a hub provided with external teeth. An actuating sleeve may be provided with internal teeth meshing with the external teeth of the hub. At least one synchronizing ring may be provided with external teeth arranged to mesh with the internal teeth of the actuating sleeve and has, on its radially internal side, a friction surface arranged to cooperate with a friction surface associated to a respective gear wheel to allow generation of a friction torque between the synchronizing ring and the associated gear wheel. A pre-synchronization system may have more than two blocking elements operatively placed between the hub and the actuating sleeve. A phasing system may be provided to ensure a given angular positioning of the synchronizing ring with respect to the hub about the longitudinal axis. The phasing system may have a plurality of first cavities provided on an internal cylindrical surface of a ring gear of the hub forming the external teeth of the hub, each of the first cavities having an arc- or round-shaped cross-section, in particular a semi-circular cross-section.

A synchronizer apparatus for a transmission includes: first and second shifting gears rotatable on an output shaft; a hub spline-coupled with the output shaft and having a slope portion having slanted surfaces; a sleeve spline-coupled with the hub; a key coupled with a recess of a slope portion; first and second clutch gears disposed between the hub and shifting gears; first and second outer rings and first and second inner rings disposed between the hub and clutch gears; first and second synchronizer cones disposed between the first inner and outer rings and the second inner and outer rings; a poppet ball unit disposed at the sleeve and contacting the key through a poppet ball; first and second push blocks disposed at the slanted surfaces; and first and second push springs inserted in spring holes formed at the push blocks to force push blocks to the slanted surfaces.

A synchronizer unit for a manual transmission, in particular of a motor vehicle, has a hub which is adapted to be connected to a gear shaft for joint rotation therewith and includes a circumferentially continuous external toothing, a sliding sleeve which is received on the external toothing of the hub for displacement in the axial direction, but so as to be coupled in the circumferential direction to prevent relative rotation, at least one synchronizer ring which includes a preferably cone-shaped friction surface for friction coupling of the synchronizer ring to a speed change gear of the manual transmission and is adapted to be actuated by the sliding sleeve, and a spring ring which is arranged at an axial side of the external toothing of the hub and is configured to lock the sliding sleeve in a neutral position. The spring ring rests against a face side of the sliding sleeve and being operatively arranged between the sliding sleeve and the synchronizer ring.

A synchronizer apparatus for a transmission includes first and second shifting gears rotatable on output shaft, a hub spline-coupled with output shaft and having a slope portion having slanted surfaces, a sleeve spline-coupled with hub, a key coupled with the slope portion, first and second clutch gears disposed between hub and shifting gears, first and second outer rings and first and second inner rings disposed between hub and clutch gears, first and second synchronizer cones disposed between first inner and outer rings and second inner and outer rings and engaged with clutch gears, a poppet ball unit disposed at sleeve and contacting key through a poppet ball, first and second push blocks disposed at slanted surfaces, and first and second push springs inserted in spring holes formed at push blocks. In addition, the push springs is abutted by key such to force push blocks to tightly contact slanted surfaces.

A synchronizer apparatus for a transmission includes: first and second shifting gears rotatable on an output shaft; a hub spline-coupled with the output shaft and having a slope portion having slanted surfaces; a sleeve spline-coupled with the hub; a key coupled with a recess of a slope portion; first and second clutch gears disposed between the hub and shifting gears; first and second outer rings and first and second inner rings disposed between the hub and clutch gears; first and second synchronizer cones disposed between the first inner and outer rings and the second inner and outer rings; a poppet ball unit disposed at the sleeve and contacting the key through a poppet ball; first and second push blocks disposed at the slanted surfaces; and first and second push springs inserted in spring holes formed at the push blocks to force push blocks to the slanted surfaces.

A transmission synchronizer apparatus may include a sleeve coupled to an external peripheral surface of a hub gear while moving axially, and clutch gears disposed at both sides of the hub gear, each selectively synchronizing and engaging with the sleeve according to the axial movement of the sleeve, wherein the transmission synchronizer includes a plurality of main sleeve teeth protruding radially from an internal peripheral surface of the sleeve while being distanced from one another, and an auxiliary sleeve tooth protruding radially from the internal peripheral surface of the sleeve while protruding from one side of each of the main sleeve teeth to have a height lower than the main sleeve tooth.

A synchronizer of a transmission may include a lower key disposed slidable in a radial direction of a hub; an upper key disposed at an external side of the lower key in the radial direction to be slidable in an axial direction of the hub; a sleeve disposed at an external side of the hub to slide the upper key in the axial direction while being slid in the axial direction thereof, pressing the upper key toward a synchronizer ring; a key spring disposed between the lower key and the hub to press the lower key and the upper key toward an internal surface of the sleeve; and a displacement converting device converting relative displacement generated in a circumferential direction of the hub between the upper key and the lower key into relative displacement of the upper key in axial direction toward the synchronizer ring with respect to the lower key.