SYNCHROMESH GEARBOX

This type of gearbox is similar to the constant mesh type gearbox. Instead of using dog clutches here synchronizers are used. The modern cars use helical gears and synchromesh devices in gearboxes, that synchronize the rotation of gears that are about to be meshed.

SYNCHRONIZERS

This type of gearbox is similar to the constant mesh type in that all the gears on the main shaft are in constant mesh with the corresponding gears on the lay shaft. The gears on the lay shaft are fixed to it while those on the main shaft are free to rotate on the same. Its working is also similar to the constant mesh type, but in the former there is one definite improvement over the latter. This is the provision of synchromesh device which avoids the necessity of double-declutching. The parts that ultimately are to be engaged are first brought into frictional contact, which equalizes their speed, after which these may be engaged smoothly.

It is that gear box in which sliding synchronizing units are provided in place of sliding dog clutches as in case of constant gear box .with the help of synchronizing unit, the speed of both driving and driven shaft synchronized before they are clutched together through train of gears the arrangement of power flow for the various gears remains the same as in the constant mesh gearbox

Synchromesh gear devices work on the principle that two gears to be engaged are first brought into frictional which equalizes their speed after which they are engaged readily and smoothly. The following types of such devices are mostly used in vehicles:
i) Pin type
ii) Synchronizer ring type

Synchronizing system is used for smooth meshing. A synchromesh works like a friction clutch.









The above fig shows two conical surfaces cone1 is the part of the collar and cone-2 is part of the gear wheels cones1,2 are removing at the different speeds.



The above figure shows collar2 and gear wheel are separate and revolving at different speeds. The internal cone of the collar comes in contact with the outer cone of the gear wheel.



The above figure shows the collar And gear wheel rotate at the same speed.in the spring loaded outer ring of the collar is fused forward. The dogs slide smoothly into mesh without clashing. The collar and gear wheel lock and revolve at the same speed this is the principle of synchromesh