What is the principle of operation of converters

What is an automatic converter and how does it work?

The so-called converter automatic istheclassic automatic. Here a fluid coupling - the torque converter - connects the engine with the gearbox consisting of planetary gear sets.

How the automatic converter works

When the accelerator pedal is not depressed (idling speed)

At idle speed, the converter acts like a separate clutch and transfers almost no torque (a bit, though, it is noticeable as the typical automatic creep).

When the accelerator pedal is depressed

However, if the driver steps on the accelerator, the engine initially rotates faster than the transmission and the converter works in this operating range as a type of continuously variable transmission.

Speed ​​difference between engine and gearbox

The greater the speed difference between engine and gearbox, the greater the associated and very welcome torque increase. At the end of the acceleration phase, the gearbox catches up with the engine, which also eliminates the differential speed and excessive torque. The converter now works like a normal, closed clutch. So a fine thing.

Car dictionary: The 4 types of automatic transmissions

Converter automatic, then and now

How the automatic converter works in older models

Planetary gear sets coupled to one another are located in the transmission itself. By cleverly connecting, separating or braking the rotating components, different gear ratios can be elicited from such a transmission. These clutches and brakes work hydraulically, the punctual activation used to be a complex, hydraulic control consisting of valves, ducts and centrifugal governors.

New (re) vehicles and hiking slip

Today electronic control units are entrusted with this. The generation of the oil pressure required for the control as well as the converter slip, which occurs predominantly in older devices, ensure a certain loss of efficiency relative to normal gearboxes.

Technical literature on the subject of vehicle transmissions


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