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Summary........................................................................................... 9 Related Problems Section 3 Transmission................................................................................ 11
Turbine The turbine is enclosed in the torque converter and is splined to the input shaft of the transmission. It is driven by fluid thrown from the impeller. Thus, the turbine transmits horsepower and torque from the engine and impeller to the transmission.
Stator The stator, which is mounted on a one-way sprag clutch, is also enclosed in the torque converter. The stator and sprag clutch are mounted on the stationary stator support shaft which is bolted to the transmission case. The sprag clutch contains tiny wedges which allow the stator to rotate only in the direction that the impeller rotates. When fluid hits the stator and tries to turn it in the opposite direction, the wedges lock the stator to the stator support shaft which prevents any reverse rotating. When the stator locks to the shaft, the converter begins to multiply torque.
Adaptor Turbine Clutch Shaft
Drive Housing
Plate
You can get a better understanding how the converter multiplies torque by tracing the flow of fluid from impeller to turbine, turbine to stator, and stator to impeller from the time the engine is started until the converter no longer multiplies torque. I.When the engine is started, the flywheel turns the impeller. When transmission fluid in the converter hits the impeller's cup blades, the fluid changes direction. The impeller's speed causes the transmission fluid to be hurled from its blades onto the turbine blades forcing them to turn. The fluid flows through the turbine and is thrown from it at high speeds.
2.The fluid then enters the stator and tries to turn it in a direction opposite of the impeller's. Since the sprag clutch locks and prohibits movement opposite impeller rotation, the fluid flows at high speed off the curved stator blades, changes direction, and races out of the stator in the same direction the impeller is turning. When this fluid hits the impeller, it creates torque. 3.The fluid, still travelling at high speed, reenters the impeller. The energy of the fast moving fluid is added to the energy of the tw·ning flywheel creating more force to drive the impeller blades. This increased energy represents increased torque. 4.The torque converter produces a maximum torque multiplication in most models ranging from 2 to 1 to more than 3 to 1. The stall point of the converter occurs when resistance is greater than the energy produced by the torque converter and engine. When the converter reaches its stall point, the impeller will be turning, but the turbine will not. Note The stall point is the fixed rpm that must be achieved so that the truck will be able to operate at maximum torque when pushing loads and climbing ramps.
When the stall point is reached, the truck will not be able to overcome resistance and will not move.
5. When enough torque is developed by the engine and converter, the turbine begins to rotate. This rotation tw·ns the turbine and the input shaft that drives the transmission components. 6.Torque multiplication gradually tapers off as turbine speed approaches impeller speed and becomes 1 to 1 when the tm·bine rotates at about 90% of the impeller's speed. At this point, the converter is no longer multiplying torque. 7.When the turbine rotates faster than 90% of the impeller's speed, the fluid leaving the turbine hits the back faces of the stator blades. The one-way clutch now permits the stator to freewheel (turn with the impeller and turbine). At this point, the converter is an efficient fluid coupling and remains one as long as turbine speed remains greater than 90% impeller speed. A fluid coupling occurs whenever the truck encounters no resistance. This can happen when the engine is idling in neutral or when it is cruising at high speeds. Once resistance is met (such as going into gear, accelerating rapidly, carrying a heavy load, or travelling up a grade), extra torque is needed. The resistance causes the turbine to drop below 90% of the impeller's speed and the converter begins to create more torque to overcome the resistance. The more resistance that is encountered, the more torque that is required for the truck to perform.
From the time the turbine is not rotating to the point where the converter becomes a fluid coupling (when the tm·bine rotates above 90% of the impeller's speed), the converter acts as an infinitely variable, fluid-operated transmission based on resistance. Whenever the truck encounters resistance, the converter will multiply the needed amount of torque to overcome this resistance as long as it falls within the 1 to 1 and 4 to 1 boundaries.
