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Synchronizer lever synchronizer About Synchronizer
Lever synchronizer
  Newly developed lever synchronizer Video References
Newly developed lever synchronizer
lever synchronizer Lever synchronizers can be classified into two types, “high-performance” type and “reverse” type. High-performance type takes advantage of the principle of leverage where sleeve pushes synchronizer ring with magnified force through a lever inside the synchronizer. The reverse type prevents gear noise when it is shifted into reverse, by lever’s reverse effect.
Viewed from the front, each lever is shaped like an arc with apex at its center, which is pushed by slanted surface formed inside the sleeve.
High-Performance Type
High-Performance TypeHigh-Performance Type
Using lever apex as a “point of force”, the slanted surface of the sleeve pushes the apex in the direction of the shaft. This causes the synchronizer ring to be pushed at “point of application” between apex and both ends of the lever, based on principle of leverage using both ends of the lever as “fulcrum”.
Unlike conventional Warner-type synchronizers, this allows the synchronizer ring to be pushed with a force greater than that applied by the sleeve, which enables enhanced frictional contact in synchronization, thus obtaining an increased frictional force. As a result, improved synchronization performance may be obtained, enabling quick synchronization with less operating force.
Synchronizers have another important function which is to balk the movement of a sleeve until synchronization is successfully completed.
Each synchronizer, thus, has two lugs in the direction of the shaft to push two levers outward by using the friction torque applied to the synchronizer ring.

As described above, since the sleeve pushes the apex of levers with its slanted surface, it cannot move unless the levers are pushed inward.
That is, the synchronizer is designed so that the movement of the sleeve is prevented (balked) until synchronization is successfully completed since the lugs of the synchronizer ring apply a large force to the levers to push them outwards by using a torque accompanying the synchronization.

When synchronization has been achieved, the sleeve would allow the levers to move inward and, at the same time, it moves forward while slightly turning its mating cone connected to the synchronizer ring. The speed can be changed only when the sleeve and its mating gear have reached the same rpm, and are smoothly engaged with each other. Maximum leverage available for pushing the synchronizer ring is 2.

Reverse Type
Reverse Type
When fifth gear and reverse gear are in-line on the shift pattern of a transmission, the lever synchronizer may be applied to the fifth gear to make use of the reverse effect.?
In this case, a groove is provided inside the sleeve and both sides of the groove have slanted surface. Since the lever top is fitted into this groove, it is pushed toward the shaft where the sleeve shifts either into the fifth gear or reverse.

When the lever is pushed toward the 5th gear, the lever synchronizer operates as the fifth gear synchronizer , just like in the high performance type.
The leverage in this case ranges approximately from 1.2 to 1.5. The characteristics of the reverse type can be shown when the sleeve is shifted not into the fifth but into reverse. That is, when the sleeve shifts into reverse while a vehicle is not moving, the slanted surface of the sleeve pushes the lever apex in the direction opposite to fifth. When the lever apex moves in the direction opposite to the fifth, both ends of the lever push the synchronizer ring against the fifth gear by using a fulcrum between the lever apex and its ends. This allows the clutch disc and the input shaft to stop spinning, synchronizing their speeds with the fifth gear that is stationary.

When the spinning of the input shaft has stopped, the sleeve becomes movable and allows the engagement of the reverse gear located in the another position.
Click here to view animations.
For detailed information click here to view references. 
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