Synchronizer - a connection between a claw and friction clutch.
A synchronizer is the connection of a dog clutch with a conical friction clutch. It consists of an inner sleeve, mounted on the splines of the main shaft of the gearbox, between the wheels of two adjacent gears. The sleeve has the same external toothing as the toothed rims of the coupled wheels and conical recesses on both sides.. A sliding sleeve with an internal toothing is slid over the inner sleeve. Both bushings are engaged with each other by means of ball latches. On the circumference of the sliding sleeve there is a recess for the sliding forks of the sliders. The gears have conical projections on the synchronizer side which correspond to the conical recesses of the inner sleeve. The synchronizer works as follows: Before switching on, the gear and synchronizer rotate at different speeds. When moving the synchronizer towards the coupled wheel, the conical surfaces on the gear wheel and in the recess of the internal sleeve of the synchronizer will contact and the synchronizer will start to rotate due to the friction between them.. Because it takes some time to press the oil out of the contacting tapered surfaces, the synchronizer will gradually turn faster and faster, until the moment, when its rotational speed is equal to that of the coupled gear. After equalizing the rotational speeds, due to further pressure of the slider's forks, the sliding sleeve will overcome the resistance of the ball latches and slide with its internal teeth onto the toothed rim of the coupled wheel.
Some cars often use gearboxes with all gears synchronized, e.g. in the Polish Fiat 125P, which has four fully synchronized forward gears and one reverse gear. The gear ratios of the individual gears on this car are as follows: 1 gear - 3,75;
2 gear - 2,30, 3 gear - 1,49 and 4 gear - 1,0; reverse gear - 3,87.