Automatic Transmission Components

Introduction:

Epicyclic gears are a special set of gears that are part of most automatic gearboxes. Most automatic gearboxes have two or more sets of planetary gears that are arranged in line.

Elements of Epicyclic gears:

In their basic form they consist of three main elements:

● a sun gear, located in the centre

● a carrier that holds two, three or four planet gears, which mesh with the sun gear and revolve around it

● an internal gear or annulus, which is a ring with internal teeth; it surrounds the planetary gears and meshes with them.

Any part of a set of planetary gears can be held stationary or locked to one of the others. This will produce different gear ratios. Most automatic gearboxes have two or more sets of planetary gears that are arranged in line. This provides the necessary number of gear ratios. As the gear selector is moved (automatically) into different positions, the power fl ow through the gearbox changes.

RAVIGNEAUX PLANETARY GEARSET:

This gearset has the following features:

● It offers the possibility of more gears than a conventional planetary gearset.

● It has a compact design (space-saving) in relation to the available transmission ratios.

● It has two sun gears with different diameters.

● It has two sets of planetary gears, inner and outer. The inner planetary gears are in constant mesh with the smaller, rear sun gear and with the outer planetary gears. The outer planetary gears are in constant mesh with the ring gear and the larger, front sun gear.

● The planetary gears are all fitted on a joint planetary gear holder.