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Torque Converter Operation Explained

Posted on November 21, 2019 by Trevor Schoborg

The torque converter is among the least understood components within an automatic transmission equipped vehicle. I'll try to explain what it can and how it can it.

The torque converter includes a few different functions.

  • We first have to understand that there is absolutely no direct link between your crankshaft and the transmission input shaft (except regarding a secure style converter, but we'll discuss that later). Which means that the initial function of the converter would be to connect the crankshaft and the input shaft therefore the engine can move the automobile; that is accomplished through the use of a fluidic coupling effect.
  • The torque converter also replaces the clutch that's needed is in a manual transmission; this is one way a computerized transmission vehicle will come to an end while still being in gear without stalling the engine.
  • The torque converter also acts as a torque multiplier, or extra gear ratio, to greatly help the car get going from the stop. In present day converters this theoretical ratio is ranging from 2:1 and 3:1.
  • Torque converters contain 4 major components that people have to concern ourselves with for the intended purpose of explanation.

  • The first component, that is the driving member, is named the impeller or "pump". It really is connected right to the within of the converter housing and as the converter is bolted to the flexplate, it really is turning anytime that the engine rotates.
  • The next component, that is the output or driven member, is named the turbine. The transmission's input shaft is splined to it. The turbine isn't physically linked to the to the converter housing and will rotate completely independently of it.
  • The third component may be the stator assembly; its function would be to redirect the flow of fluid between your impeller and the turbine, gives the torque multiplication effect from the standstill.
  • The final component may be the secure clutch. At highway speeds this clutch could be applied and can give a direct mechanical link between your crankshaft and input shaft, that will bring about 100% efficiency between your engine and transmission. The use of this clutch is normally controlled by the vehicle's computer activating a solenoid in the transmission.
  • Here's how everything works. With regard to simplicity, I am going to utilize the common analogy of two fans which represent the impeller and the turbine. Suppose that people have two fans facing one another and we turn only 1 of these on- another fan will soon commence to move.

  • The first fan, that is powered, could be regarded as the impeller that's linked to the converter housing. The next fan- the "driven" fan could be likened to the turbine, which includes the input shaft splined to it. In the event that you were to carry the non-powered fan (the turbine) the powered one (the impeller) would be in a position to move- this explains ways to pull to an end minus the engine stalling.
  • Now imagine a third component put into between your two, which may serve to improve the airflow and cause the powered fan in order to drive the non-powered fan with a reduced amount of speed- but additionally having an increase of force (torque). That is essentially what the stator does.
  • At a particular point (usually around 30-40 mph), exactly the same speed could be reached between impeller and the turbine (our two fans). The stator, that is mounted on a a proven way clutch, will now commence to submit conjunction with another two components and around 90% efficiency between your crank and the input shaft may be accomplished.

    The remaining 10% slippage between your engine and transmission could be eliminated by connecting the input shaft to the crankshaft through the use of the secure clutch that has been mentioned before. This can have a tendency to lug the engine, therefore the computer is only going to command this in higher gears and at highway speeds if you find hardly any engine load present. The primary function of the clutch would be to increase fuel efficiency and reduce the quantity of heat that's generated by the torque converter.

    Another term that could be unfamiliar is that of a "high stall" torque converter. A higher stall converter differs from the stock converter in the sense that the rpm is raised of which the inner converter components- the impeller, the stator and the turbine begin to turn together, and therefore, stop the torque multiplication phase and commence the coupling phase. The point where engine rpm will minimize climbing with the drive wheels held stationary and the throttle fully opened is known as "stall speed".

    The idea behind an increased stall torque converter would be to permit the engine to rev more freely until where in fact the powerband begins, and for that reason, enable the automobile to accelerate from the stop under more power.

    This becomes increasingly important when an engine is modified. Engine modifications such as for example ported heads, bigger cams, bigger turbos (in some instances), bigger intakes, etc. have a tendency to improve the point where in fact the powerband begins. For best performance, the stall speed must be raised accordingly to work optimally with the given vehicle alterations.

    In simple terms, for best performance, the stall speed ought to be raised at the very least to the stage where in fact the torque curve is heading towards its peak. Generally of thumb, the stall speed ought to be set to complement the rpm of which the engine is making at the very least 80% of its peak torque for a street driven vehicle.

    As imaginable, a vehicle that may accelerate from the stop with 80% of its peak torque will easily outperform an otherwise identical vehicle that may only launch at 50% of its available torque.

    For a performance or "high stall" torque converter to create maximum gains, it requires to be configured to the precise vehicle where it'll be installed.

    Factors such as for example engine torque and the rpm of which it really is greatest, differential gear ratio, vehicle weight, camshaft design, compression ratio, kind of induction- forced or naturally aspirated, and a bunch of other variables all have to be taken into account. Remember that the "off the shelf" type performance torque converters sold by some manufacturers have become unlikely to be optimized for several vehicles and their particular requirements.