Torque Converter Parts: The Components That Enable Smooth Automatic Shifts

The main parts of a torque converter are the impeller (pump), turbine, stator (reactor) with a one-way clutch, the lock-up clutch, and the sealed cover/housing, all working with automatic transmission fluid (ATF). Together, these elements transmit and multiply engine torque to the transmission input shaft, enabling smooth launches, efficient cruising, and reduced slip in modern automatic vehicles.

The Essential Components at the Core

At the heart of every torque converter are a few key hydraulic and mechanical elements that create, direct, and transmit fluid energy. These parts are common across most modern automatic transmissions, regardless of brand or vehicle class.

• Impeller (pump): The engine-driven half that throws ATF outward to create fluid flow.
• Turbine: The transmission-driven half that receives fluid momentum and turns the input shaft.
• Stator (reactor) with one-way clutch (sprag/roller clutch): Redirects returning fluid to multiply torque at low speed.
• Lock-up clutch (torque converter clutch, TCC): Mechanically links the engine to the transmission to eliminate slip at cruise.
• Sealed cover/housing (front cover and shells): The welded shell that encloses the fluid and anchors the impeller; bolts to the flexplate.
• Automatic transmission fluid (ATF): The working medium that transfers energy and cools the converter.

Together, these components enable both torque multiplication during launch and efficient, near-direct drive during steady cruising when the lock-up clutch engages.

Support and Structural Parts You’ll Also Find

Beyond the core elements, torque converters include a range of structural, sealing, and damping parts that ensure durability, smoothness, and pump drive—all critical for longevity and refinement.

• Clutch piston and friction lining: The internal plate and friction surface that form the lock-up interface.
• Damper springs (torsional damper): Reduce vibrations when the lock-up clutch is applied.
• Impeller hub and pump drive lugs: Connect to the transmission’s front pump to circulate ATF.
• Turbine hub: Splines to the transmission input shaft to deliver torque.
• Stator support (reaction shaft): Mounts the stator and houses the one-way clutch.
• Bearings and thrust washers: Control axial and radial loads between impeller, turbine, and stator.
• Seals and O-rings: Maintain internal pressure and prevent ATF leaks.
• Vanes/blades (within impeller, turbine, stator): Shaped surfaces that control fluid direction and speed.
• Balance weights and welds: Ensure rotational balance and structural integrity of the shell.

While not always listed in basic diagrams, these supporting components are essential for quiet operation, pump function, leak-free service, and reliable torque transfer.

How These Parts Work Together

The interaction of the impeller, turbine, stator, and lock-up clutch changes with driving conditions. Understanding the modes below explains why each component matters.

• Stall: With the vehicle stationary and engine revving, the impeller spins but the turbine is nearly still; the stator’s one-way clutch locks, boosting torque.
• Acceleration (torque multiplication): As the vehicle starts moving, redirected fluid from the stator increases turbine torque beyond engine torque.
• Coupling: At higher speeds, impeller and turbine speeds converge; the stator freewheels, and torque multiplication fades.
• Lock-up: The TCC engages to eliminate slip, improving efficiency, lowering heat, and giving a direct mechanical link.

This progression delivers strong launch performance without a manual clutch and efficient highway cruising comparable to a direct drive.

Common Issues Tied to Specific Parts

Knowing how parts fail helps diagnose drivability problems and prioritize repairs or rebuilds. Technicians often trace symptoms back to the elements below.

• Worn lock-up friction or damper springs: Shudder, vibration, or cycling lock-up at cruise.
• Failed stator one-way clutch (sprag): Sluggish launch, overheating, poor torque multiplication.
• Bearing or thrust washer wear: Whine, metal debris in ATF, accelerated internal wear.
• Cracked turbine or impeller hub: Loss of drive, erratic engagement, metal contamination.
• Leaking seals or ballooned cover: ATF loss, overheating, reduced performance.
• Blade/fin damage: Reduced efficiency, increased heat, and noise under load.

Timely fluid service, correct ATF type, and addressing cooling issues help prevent many of these failures, extending converter and transmission life.

What’s New and What to Know

Modern automatics nearly all use a lock-up clutch, often applying in multiple gears and at lower speeds for better fuel economy. Some designs modulate lock-up slip for refinement, while heavy-duty and performance converters may feature upgraded sprags, multi-disk lock-up clutches, and stronger hubs. Note that dual-clutch and many hybrid transmissions may not use a traditional torque converter, or they use specialized variants.

Summary

A torque converter’s key parts are the impeller (pump), turbine, stator with a one-way clutch, a lock-up clutch, and a sealed housing, all operating with ATF. Supporting elements—hubs, bearings, seals, damper springs, and friction materials—ensure durability and smoothness. Together, these components provide torque multiplication for takeoff and efficient, low-slip cruising when the lock-up clutch engages.

What does a torque converter consist of?

And send a higher torque to the transmission. The main components of a torque converter are the impeller turbine stator and output shaft.

What are the 5 components of a torque converter?

In an automatic transmission car, the torque converter connects the power source to the load. Torque converters are comprised of five main components: the impeller, the turbine, the stator, a clutch, and the fluid.

How many parts are in a torque converter?

Inside a Torque Converter. Three parts of a torque converter are (left to right): the turbine, stator and impeller (pump). There are four components inside the very strong housing of the torque converter: impeller.

What are the components of a converter?

The basic components of the converters are diodes, transistors and thyristors. – Cyclo-converter – A cyclo-converter is a single-stage (AC-AC) converter and converts AC with a constant frequency directly to an AC with a varying frequency, as required for the desired motor speed.