An automatic transmission piston set is a collection of pistons used within an automatic transmission system. These pistons play a critical role in engaging and disengaging the various clutches and bands that control the transmission's gear shifts. The pistons are typically actuated hydraulically by the transmission fluid under pressure.

Components of a Piston Set:

1. Pistons: Made of metal or composite materials, they move within cylinders to apply pressure to clutches or bands.
2. Seals and O-rings: Ensure a tight fit and prevent hydraulic fluid leaks.
3. Return Springs: Help return the piston to its original position after actuation.
4. Retaining Rings or Clips: Secure the pistons in place.

Common Applications:

• Gear Shifting: Transmit hydraulic force to the clutch packs, enabling smooth gear changes.
• Torque Converter Control: In some systems, they assist with controlling the torque converter lockup.
• Band Application: Apply pressure to bands that hold certain components of the transmission in place.

Replacement and Maintenance:

• Piston sets may need replacement due to wear, damage, or fluid leaks.
• Signs of failing pistons include delayed shifting, slipping gears, or erratic transmission behavior.
• Replacement typically requires disassembling the transmission, so it's recommended to have a professional mechanic perform the job unless you're experienced with transmission work.

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