A Closer Look at the Components of an Automatic Transmission
: Discs coated with high-grip material that grab onto the steel plates when hydraulic pressure is applied. tranny pacs
: Smooth metal separator plates that sit between the friction discs. A Closer Look at the Components of an
In an automotive context, "tranny pacs" (more formally known as ) are the critical internal components of an automatic transmission responsible for shifting gears . These packs consist of a series of alternating friction and steel discs stacked within a drum. When the transmission’s "brain," or valve body, directs hydraulic fluid to a specific drum, a piston squeezes the pack together. This pressure locks the discs, engaging the corresponding planetary gear set to change the vehicle's speed or direction. These packs consist of a series of alternating
: Oil pressure from the transmission's pump is the force that physically "packs" these plates together to transfer power.