Shift device with synchronizer

A shift device with a synchronizer comprising:

• a shaft;
• a hub having a boss portion fixed to the shaft, a flange portion extending from the boss portion outwardly in a radial direction, and an annular portion formed with outer splines on an outer side, the annular portion and the flange portion being formed at the both sided thereof in an axial direction with a plurality of cut-off portions and a plurality of recessed portions, the cut-off portions being provided on the both sides thereof in a rotational direction with a first guide surface, and the recessed portions being provided on the both inner sides thereof in the radial direction with a second guide surface parallel to the first guide surface;
• a shift sleeve that is formed on a circumferential surface thereof with inner splines having slanted surfaces, the inner splines being engaged with the outer splines of the hub in such a way that the shift sleeve is movable in the axial direction;
• a pair of speed gears that are arranged at the both sides in the axial direction of the hub to be rotatably supported on the shaft, the speed gears being provided at each hub side thereof with a cone surface and splines engageable with the splines of the shift sleeve;
• a pair of synchronizer rings that are respectively arranged between the hub and the speed gears, the synchronizer rings being provided with a friction surface capable of being pressed selectively by one of the cone surfaces of the speed gears, and the synchronizer rings being provided at the hub sides with a plurality of projections projecting in the axial direction and a plurality of pressure receiving surfaces;
• and
• a plurality of lever members that are arranged at the both sides of the hub among the shift sleeve, the hub and the synchronizer rings, the lever members having a top portion and arm portions provided at the both sides in the rotational direction of the top portion, the top portion being provided on the both sides in the rotational direction thereof with a first slide surface contactable with the first guide surface of the hub and a press surface at a hub side thereof, the arm portion being provided on an end thereof in the rotational direction with a second slide surface contactable with the second guide surface of the hub, the top portion being engaged with the corresponding cut-off portion of the hub and contactable with the corresponding slanted surface of the shift sleeve to function as a point of effort of leverage, contact portions between radially inner sides of the arm portions and the hub functioning as a fulcrum of the leverage, contact portions between the pressure receiving surface of the synchronizer rings and the press surfaces of the top portions functioning as appoint of load of the leverage, and the lever members amplifying pressing force from the shift sleeve due to a leverage operation to transmit amplified force to the synchronizer rings, wherein
• the lever members are further provided with a torque receiving surface capable of receiving friction torque from the projections of the synchronizer rings on an intermediate portion of each arm portion between the top portion and the second slide surface.