Synchronizer apparatus for transmission

A synchronizer apparatus for a transmission, comprising:

• first and second shifting gears rotatably disposed on an output shaft;
• a hub spline coupled with the output shaft, the hub having a plurality of slope portions having slanted surfaces at axially forward and rearward sides of the hub, the plurality of slope portions being symmetrically disposed along a circumferential direction of the hub;
• a sleeve spline coupled with an external circumference of the hub;
• a plurality of keys installed in key catching recesses that are formed radially outward respectively by the plurality of slope portions;
• first and second clutch gears disposed between the hub and the first and second shifting gears, respectively;
• first and second outer rings and first and second inner rings disposed between the hub and the first and second clutch gears, respectively;
• first and second synchronizer cones disposed between the first inner and outer rings and the second inner and outer rings and engaged with the first and second clutch gears, respectively;
• a plurality of poppet ball units disposed at an interior circumference of the sleeve at locations corresponding to the plurality of keys, the poppet ball units configured to contact an exterior surface of the plurality of keys through a poppet ball;
• a plurality of first and second push blocks disposed at both slanted surfaces of the plurality of slope portions, respectively;
• and
• a plurality of first and second push springs inserted in spring holes formed at outer surfaces of the plurality of first and second push blocks, respectively, the first and second push springs being abutted by interior surfaces of the plurality of keys such that cam surfaces of the push blocks tightly contact the slanted surfaces of the plurality of slope portions of the hub, respectively,
• wherein each of the plurality of keys comprises an insertion end integrally formed at a bottom center of the key such that the key is coupled with the hub by the insertion end as being inserted in the key catching recess.