Planetary Train

Fig 1: Identifying Planetary Train

Courtesy of VOLVO CARS CORPORATION

X  = locked

Unique to the TF-80SC is a Ravigneaux planetary gear connected in series to a conventional planetary gear. The conventional planetary gear creates a reduction in RPM in the Ravigneaux planetary gear for 1st gear up to 5th gear and reverse.

The planetary gear's ratios are controlled by 3 clutches (C1, C2, C3) and 2 brakes (B1, B2).

The number of planetary gears depends on the engines cylinder displacement and can therefore differ from what is shown here.

Planetary train, Ravigneaux 

Fig 2: Identifying Ravigneaux Planetary Train

Courtesy of VOLVO CARS CORPORATION

The characteristic of a Ravigneaux planetary train is that several gears can be used in comparison to a conventional planetary train. It is compact (takes up little room) in relation to the number of possible ratios. The Ravigneaux planetary train has two sun gears of different diameters and sets of two planetary gears, an inner and outer set. The inner planetary gears are constantly connected to the outer planetary gears and the small sun gear. The outer planetary gears are constantly connected to the ring gear and large sun gear.

The planetary train has a common planetary gear carrier for both sets of planetary gears.

Principles of function 

Fig 3: Identifying Cross-Section Of Ravigneaux Planetary Train

Courtesy of VOLVO CARS CORPORATION

The ratios are obtained through different combinations of locked and/or connected components. The table displays the principle for how the ratios are obtained from large ratio, 1, to small ratio, 6, and counter rotation (i. e. reverse with large ratio).