Drive Clutches

Multiplate Clutch or Brake - Typical

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

There are three drive clutches and two brakes used in the transmission. Each clutch comprises a number of friction plates dependent on the output controlled. A typical clutch consists of a number of alternating steel plates and plates with friction material bonded to each face.

The clutch plates are held apart mechanically by a diaphragm spring and hydraulically by dynamic pressure. The pressure is derived from a lubrication channel which supplies fluid to the bearings and clutch cooling. The fluid is passed via a drilling in the input shaft into the chamber between the baffle plate and the piston. To prevent inadvertent clutch application due to pressure build up produced by centrifugal force, the fluid in the dynamic pressure equalization chamber overcomes any centrifugal pressure in the piston chamber and holds the piston off the clutch plate assembly.

When clutch application is required, main pressure from the Automatic Transmission Fluid (ATF) pump is applied to the piston chamber from the supply port. This main pressure overcomes the low pressure fluid present in the dynamic pressure equalization chamber. The piston moves, against the pressure applied by the diaphragm spring, and compresses the clutch plate assembly. When the main pressure falls, the diaphragm spring pushes the piston away from the clutch plate assembly, disengaging the clutch.

Planetary Gear Trains 

The eight forward gears and the reverse gear are produced by a combination of four simple planetary gear sets, three clutches and two brakes. The front two gear sets share a common sun gear. Power is output always through the planetary carrier of the fourth gearset.

Five shift elements comprising three clutches and two brakes, are responsible for all eight forward and reverse gears. High efficiency is achieved by the use of only two shift elements disengaged in each gear which reduces drag and so increases the efficiency.

Planetary Gear Set 1 

The planetary gear sets 1 comprises:

• Sunwheel
• Four planetary gears
• Planetary gear carrier (spider)
• Ring gear.

Planetary Gear Sets 2 and 3 

The planetary gear sets 2 and 3 comprise:

• Sunwheel - shared by both gear sets
• Three planetary gears per gear set
• Planetary gear carrier (spider) per gear set
• Ring gear per gear set.

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

Planetary Gear Set 4 

The planetary gear set 4 comprises:

• Sunwheel
• Four planetary gears
• Planetary gear carrier (spider) - output shaft
• Ring gear.

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC