Synchromesh Mechanism 2of 2


3. Triple-/Double-cone type synchromesh mechanism

To increase the synchromesh capacity, recent models have adopted a triple- cone or double-cone

synchromesh mechanism particularly for the 2nd and 3rd gears.

(1) Triple-cone type synchromesh mechanism The triple-cone synchromesh mechanism divides the synchronizer ring into an outer ring, middle ring, and inner ring. When the shifting key pushes the outer ring, the outer ring and the middle ring form a single cone, then the middle ring and the inner ring become a single cone. Furthermore, the inner ring and the gear piece become a single cone portion, so friction is generated by all three cone portions. Therefore, the capacity to absorb rotational speed differences between gears is large and the synchronizing process is completed smoothly.

(2) Double-cone type synchromesh mechanism The double-cone type synchromesh mechanism is basically the same as the triple-cone type synchromesh mechanism, except that it does not provide synchronizing between the inner ring and the gear piece.

4. Keyless type synchromesh

A keyless synchromesh mechanism has the key spring serving the role of the shifting key and is used for the transaxle 5th gear in some models.

a. Hub sleeve

There are three grooved protrusions inside the hub sleeve to push the key spring during synchronization.

b.Clutch hub

Three notches are located around the clutch hub to secure the synchronizer ring and key spring.

c. Key spring

The key spring has four claws. One claw is to secure the key spring itself, while the other three claws hold the shifting keys.

d. Synchronizer ring

There are grooves in which the key spring claws enter at three points along the circumference of the ring. The groove is chamfered partially.

5. Reverse synchromesh mechanism

The synchronizer ring for the gears for forward reduces the input shaft rotation speed before the reverse gear is shifted. In this way, the reverse idler gear and the input shaft reverse gear are connected smoothly. In recent models, the use of synchromesh mechanisms for reverse gear is becoming more common.

6. Reverse pre-balk mechanism

While the gears are being shifted to the reverse gear, the shift inner lever No. 3 makes contact with the pin of shift fork shaft No. 1 and moves shift fork shaft No. 1 the distance A in the direction of the “2nd gear”. This causes the 2nd gear synchronizer ring to operate in order to decrease the rotational speed of the input shaft. When shift inner lever No. 3 separates from the pin of shift fork shaft No. 1, the reverse gear shifting ends.

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