Torque Converters - How they work.

The converter consists of 5 primary components.

Cover – The cover connects the torque converter to the engine and is welded to the impeller (pump) of the torque converter. This part is not participating with the performance characteristics of the converter with the exception of its ability to resist ballooning under high load capacity. Many times a cover is billet and with a lock up converter this will allow the use of an over sized clutch.

Turbine – The turbine is what connects to the input shaft of the transmission via a splined turbine hub. Once the turbine starts to move then the vehicle will move.

Impeller – The impeller is the outside half of the converter that is welded to the cover on the transmission side. The impeller is turned by the engines flexplate and fluid flow is started by centrifugally generating fluid flow inside the converter.

Stator – The stator resides between the impeller and turbine. The stators job is to redirect the fluid back into the impeller after leaving the turbine. The stator houses a mechanical one way clutch commonly called a Sprague. This allow the stator to stay stationary while multiplying torque and will free spin once turbine speed reaches roughly 40% of impeller speed.

Lock-Up Clutch – While not all converters have lock up clutch, those that do the job of the clutch is to eliminate all converter slippage, thus making the unit one to one and no longer a fluid coupling.

Overview – when the fluid enters the converter it is sent to the outside of the impeller centrifugally. Once the fluid leaves the impeller it feeds the outside fins of the turbine. This makes the input shaft move and therefore the car will drive. When the fluid leaves the turbine it is redirected back to the impeller via the stator. This is when torque multiplication occurs hence the name torque converter. Impeller blade angle and stator blade angle and blade count all denote how much torque will be multiplied in the converter.