Synchronizer (car)

A typical mechanical gearbox contains a set of pairs of gears , some of which are located on the same intermediate shaft , and being in constant engagement with the gears paired with them, rigidly mounted on the input shaft, are able to rotate freely on needle bearings in their hubs .

Since the pairs of wheels have a different number of teeth and gear ratio , the operator can arbitrarily change the total gear ratio of the box, but this same factor leads to the fact that the driven gears rotate at different speeds.

For mechanical connection of the intermediate shaft of the box with one or another secondary gear wheel, clutches sliding on the splines on the intermediate shaft are used. But since the angular speed of the clutch and gear wheel is different at each specific moment of the transition from the neutral to the engaged state, the question arose of their preliminary equalization - either acceleration of the gear to the speed of rotation of the clutch, or its braking to it.

In modern mechanical gearboxes, as a rule, this problem is solved as follows. The end face of the gear gear has a conical surface, and an intermediate bronze ring of the synchronizer with a gear rim is placed between the clutch and this gear.

When the clutch moves to the gear, the clutch first captures the bronze ring of the synchronizer and presses it against the conical surface of the gear. Due to the frictional force arising in this place, the gear starts to slow down (or vice versa, accelerates if it rotates slower than the coupling), and in the end their angular velocities are equalized - now in the moving coordinate system the gear, synchronizer ring and coupling are a single whole, motionless relative to each other. The condition for shock-free coupling of the clutch and gear is satisfied, they rotate at the same speed. Further, the clutch has the ability to move forward, and already carries out a rigid force coupling with the gear with the help of gear rims - on it and on the wheel. Through this engagement, the transmission of power torque during the movement of the car is carried out (the bronze ring of the synchronizer does not take any part in the transmission of the working effort.)

The described scheme is used in most modern manual gearboxes; its weak point is a significant friction force on a relatively small area of ​​the conical surface of the bronze ring, which causes its wear. To increase the life of the rings, they are often made of two or three bronze cones.

The scheme described above is classical, but from the point of view of kinematics, it does not matter whether a synchronizer and a synchronized gear wheel are located on the drive shaft or on the intermediate shaft. Therefore, in modern gearboxes, synchronizers can be located on any of these shafts, as well as in pairs on both shafts, for example, the synchronizer of I and II gears on the input shaft, and the synchronizer III and IV - on the intermediate one.

In mass vehicle gearboxes, currently, as a rule, reverse gear does not have a synchronizer.

• Synchronization

• Popular science sync movie on YouTube