Automatic transmissions create power flows through a combination of planetary gears and what other devices?

Automatic transmissions create power flows through a combination of planetary gears and what other devices?

• A. Powertrain control devices
• B. Hydraulic pumps
• C. Friction plates
• D. Clutches only

Answer: (A)

Automatic transmissions transfer power through planetary gear sets and the hydraulic control system that governs those gears. The planetary gear sets provide the different gear ratios, but the actual transmission of torque and the timing of gear changes depend on hydraulic pressure directed to clutch packs and bands. This pressure is generated by a hydraulic pump and routed through a valve body, then applied by actuators under the control of powertrain control devices. These control devices (the PCM and related actuators) decide when pressure is sent to which clutch or band, coordinating gear shifts. So the power flow in an automatic is the combination of planetary gears and the hydraulic control system managed by powertrain control devices.

Automatic transmissions transfer power through planetary gear sets and the hydraulic control system that governs those gears. The planetary gear sets provide the different gear ratios, but the actual transmission of torque and the timing of gear changes depend on hydraulic pressure directed to clutch packs and bands. This pressure is generated by a hydraulic pump and routed through a valve body, then applied by actuators under the control of powertrain control devices. These control devices (the PCM and related actuators) decide when pressure is sent to which clutch or band, coordinating gear shifts. So the power flow in an automatic is the combination of planetary gears and the hydraulic control system managed by powertrain control devices.