Manual transmission#Synchromesh
Synchronizer rings are a part of modern synchromesh. They bring by friction gear shift sleeve and the selected gear to the same speed, so that it can be inserted without any intermediate gas.
Operation
A gearbox has three different rotational speeds.
During a switching operation, first the rotational speed of the shift sleeve and the gear of the corresponding passage to be adjusted. This is done by pressing on the intermediate synchronizing ring. The more energetic the pressing lever, the more friction will be generated and the faster the speeds of rotation are aligned. Once both rotate synchronously, you can slide the shift collar virtually powerless over the ring gear and the gear is engaged.
Subsequently, the engine speed must be adjusted. By releasing the clutch pedal friction is generated in the separation clutch between the engine and transmission, even to transmission input shaft and crankshaft are synchronized to a continuous traction is achieved.
History
In 1928, Cadillac introduced a the synchromesh. Nevertheless, it took decades for all cars, the gear " fully synchronized", ie all courses were provided with synchro rings. The VW Beetle had the standard version from November 1964 ( VW 1200 A, "savings beetle" ) a fully synchromesh transmission, ie while driving could also be switched back to first gear without any intermediate gas. Previously, only the second to fourth gear was synchronized. Also, especially for truck gearbox were synchronized relatively late. Nowadays it is often omitted in automated truck transmissions on the synchronization and the synchronization instead produced by intervening in the engine management and when upshifting where appropriate, through a multi-disc brake in the gearbox.
Until the use of synchronizer rings you had to apply to a higher gear so-called intermediate gas when shifting to a lower gear and double clutching.
Between gas means to change gear that you ...
When the shift lever is in neutral position and the clutch is closed, a part of the transmission is coupled to the engine speed, while the portion is coupled via the differential to the speed of the wheels. By blipping the speed of the motor-side transmission branch is increased and at a same speed as possible ( synchronous speed ) taken as the wheel-side transmission branch, so that may also be connected without synchronizing rings or with faulty synchronization.
The object of the Doppelkuppelns it is, however, only to give the driver a measure of time, so that the engine speed drops sufficiently, until the synchronous rotational speed is reached at the higher gear.
Principle can be combined with intermediate gas and double clutching a gear ( and synchronous transmission ) without depressing the clutch pedal switch, if the speeds are matched closely enough by intermediate gas / double domes. Synchronization of the higher gears with electronically controlled transmissions is not absolutely required, which is favored by the usual progressive gear stepping (smaller in engine speed in higher gears ).
Production
Synchronizing rings are made from metal and can be provided with friction linings. Common metals for the synchronizer rings are brass and steel. The friction linings may be made of molybdenum, iron, bronze, or carbon ( " carbon" ) are made.
The synchronizer rings are forged from starting material in the form of semi-finished or alternatively produced by sheet metal forming. In sheet metal forming is understood to be the punching of the blank of sheet metal strips with subsequent processing in the progressive or transfer tool.
The friction linings are used as wear protection layer, and typically consist of thermally splashed molybdenum, alternatively effective and efficient iron or bronze Sinterreibschichten Sinterreibschichten can be used. Carbon-coated synchronizer rings are particularly wear resistant and provide excellent friction characteristics, but are used because of their higher price, especially in high performance gears.