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Torque Converter


Throughout history majority of inventions have arisen out of a desire for convenience and efficiency. Internal combustion engines were not transferring the full amount of power being produced into used energy. In order to solve the problem, the torque converter came into existence. However with the invention of automatic transmission for cars and trucks is when the Torque Converter hit its stride. It was in the 1950’s the modern converter came into existence making way for advanced designs such as twin disc torque converter.

The automatic transmission torque converter is what provides the physical connection between the engine and transmission. This fluid coupler operates through the principles of hydraulic force provided by 3 internal components and the hydraulic oil. The torque converter takes the spinning motion of the crankshaft and applies that to the input shaft of the transmission. A clever and ingenious part of this is that the converter automatically engages and disengages power from the engine to the drive line in relation to engine speed. This low RPM area and when power begins to flow is known as stall speed. With the engine running at the correct idle speed there is not enough fluid flow for power to be transferred to the wheels. This allows the engine to run at idle speed with almost no load, like the neutral position, without moving the vehicle in forward or reverse with the brakes lightly applied. When the engine speed increases the increased fluid flow creates a sufficient amount of force to transmit the engine’s power and move the vehicle.


The Internal Converter Components

The front side of the hard shell physically bolts to the engines crankshaft. This is usually done by either a fly wheel or a flex plate that provides this physical connection to the crankshaft. The attaching bolts are usually coated with Loctite (very important) to prevent them from coming loose with vibration. The backside has a hole in it where the input shaft of the transmission slides in and seals. Inside the transmission torque converter is always filled with fluid and as mentioned above it is this fluid that connects the two halves together. The automatic transmission torque converter consists of three internal components to help control the fluid coupling between the engine and transmission.


Torque Converter

The three components are a pump assembly often called an impeller, a stator assembly and the turbine. Working from the flywheel side it is the impeller assembly or pump that is driven by the crankshaft. Moving towards the rear of the converter it is the stator assembly that is in the middle and provides a smooth fluid reaction and torque multiplication that is generated from the pump. The turbine side of the torque converter is what provides the movement to the input shaft of the transmission.


How the Torque Converter Works

It’s this hydraulic fluid that pulls all the components together. As the crankshaft rotates the pump impeller provides a centrifugal force that throws the transmission fluid outward and upward due to the curve shape of the impeller blades. The faster the impeller rotates the greater this centrifugal force becomes and more fluid is pushed outward with greater force. This fluid then strikes the curved blades of the turbine causing the turbine to rotate in the correct direction. Now a stator is a device that mounts between the impeller blades and the turbine blades. It basically provides an efficient fluid motion and smooth flow.

A turbine is connected to a hub that has splines inside. The input shaft of the transmission slides into the turbine hub. An interesting point to make here is a turbine and the impeller are running at close to the same speeds, but they’re not running at exactly the same speed, because of energy lost to the fluid. This creates slippage that can harm fuel economy. It is for this reason that manufacturers came up with a way to lock it all together to spin at a one-to-one ratio. They do this with a clutch that is operated by a solenoid that is computer controlled.

In the right conditions the torque converter clutch is applied and the crankshaft and transmission input shaft spins at the same speed. This clutch needs to be disengaged when the brakes are applied or the engine will stall.

Signs of Torque Converter Problems

Overheating –The most common sign of torque converter problems is overheating because a drop in fluid pressure. This could also be a sign of low fluid levels or a malfunctioning solenoid.

Transmission slipping – If too much fluid is passed to the transmission will cause gears to slip and there will be a loss of acceleration and because and this might also cause a sudden drop in your car’s fuel economy. Low or ineffective fluid can also be one of the reason for transmission slipping.

Shuddering – When driving about 30-45 Km if you start to feel shuddering this means there is problem in torque often feel like running over the rough road or bumps. Shuddering happens suddenly, so once you feel it, get your transmission checked.

Contaminants in fluid – if there are large amounts of black material in the fluid, it means that your transmission or torque converter clutches are damaged.

Strange sounds – Any foreign sounds such as clicking or a revving noise could indicate a bad torque converter.

The above article explains the torque converter in a nut shell . So that next time you come across the signs explained , you will know exactly what it is trying to tell you.

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