Torque Converter Stall Test / Automatic Transmission Stall Test

What is the Stall Test?

Someone in the site had a question asking what the Stall Test is. The Stall Test is a special test used about Automatic Transmission Systems and Torque Converters. This is a brief description of it. Before we talk about the Stall Test, it’s important to have an idea about the Stall opportunity.

The Stall phase is one of the functional stages of a torque converter. This simply means that the turbine is still on while the impeller of the torque converter is rotating. Theoretically, the Torque converter turbine attached to the Transmission system has the maximum speed that the engine can rotate the impeller.

This particular speed is called Stall Speed ​​/ Stall RPM. Also called the Stall Phase. In this case, the slip in the Torque Converter is maximized.

About Stall Test Torque

Also, the maximum torque multiplication that can be provided by a torque converter is called stall torque. One of the many parameters to consider in the design of a torque converter is the stall speed. When designing a torque converter for a vehicle, the calculation is done to match the stall speed of the torque converter with the maximum torque/power and power band of the engine.

What is Engine Stall Speed?

Stall speeds of torque converters vary according to the needs of each vehicle. In practice, this stall in a Torque converter only exists for a short time. Put that D (or R) into gear and start accelerating. In practice, the torque converter’s engine impeller rotates at maximum speed, and the turbine attached to the gearbox stays quiet for only a short time.

Put that D (or R) into gear and start accelerating. In practice, the torque converter’s engine impeller rotates at maximum speed, and the turbine attached to the gearbox stays quiet for only a short time. After that, the turbine starts to spin. But torque converter stall speed directly affects vehicle performance, starting torque, and so on.

Now the problem is with the Stall test. As described earlier, the Stall test is used in the design of torque converters when performing performance testing and fixing on vehicles. This is done by practicing the aforementioned stall method and checking to see if the stall speed is set.

There are several ways that stall tests can be performed. Footbrake stall Flash stall Static stall. However, not all of these methods can be applied to every situation. Footbrake Stall All this is done is to start the vehicle, tighten the wheels, apply the brake fully (service brake + parking brake), put the gear into the D / R, and push the throttle under the accelerator pedal to record the maximum value of the engine RPM.

This value is called the stall speed/stall RPM (however, the stall speed value of this method can be slightly different than the actual value). Flash Stall, In this case, the stall speed is determined by considering the maximum engine RPM reached maximum initial acceleration of a loaded vehicle.

There are several things you can do with a stall test.

• Whether the Torque converter performs properly. Especially the stator’s overrunning / one-way clutch performance.
• Performance of holding devices inside the gearbox (eg, clutch packs, brake bands, one-way clutches)
• Transmission fluid pressure
• Proper operation and output of the engine When installing a stall test, the full-throttle acceleration should be done in a short amount of time to check the maximum engine RPM.

Usually, doing so for more than 5 seconds can cause severe damage to the system. Also, some vehicles can be severely damaged. Therefore, a stall test should always be followed by a manufacturer’s advice and only by someone with good knowledge and practice.