Land Rover Discovery Owners & Service Manuals

Land Rover Discovery: Automatic Transmission  Transaxle / Component Description

The transmission comprises the main casing which houses all of the transmission components. The torque converter is located in a separate converter housing, bolted to the main casing.

ZF 9HP48 Cut-Away View

ZF 9HP48 Cut-Away View

ZF 9HP48 Sectional View

ZF 9HP48 Sectional View

  1. Fluid pan
  2. Valve block
  3. Planetary gear set 4
  4. Planetary gear set 3
  5. Planetary gear set 2
  6. Planetary gear set 1
  7. Dog clutch A
  8. Spur pinion
  9. Park interlock gear
  10. Multiplate clutch 'B'
  11. Multiplate brake 'C'
  12. Multiplate brake 'D'
  13. Left splined output shaft (connection to halfshaft)
  14. Right splined output shaft (connection to Power Transfer Unit (PTU))
  15. Right splined output shaft (connection to halfshaft)
  16. Differential
  17. Automatic Transmission Fluid (ATF) pump
  18. Multiplate clutch 'E'
  19. Dog clutch 'F'
  20. Input shaft
  21. Torsional damper
  22. Torque converter stator
  23. Torque converter lock-up clutch
  24. Torque converter turbine
  25. Torque converter assembly
  26. Torque converter impeller

The main casing retains the ATF (automatic transmission fluid) at the bottom. A drain plug is located in the main casing. The oil level is checked by removal of a level plug, with the engine running and the transmission fluid at a temperature of between 37 to 45ºC (99 to 113ºF). The level is correct when the oil flow becomes a drip from the level plug hole.

The transmission has a fluid cooler which is located at the front of the transmission, adjacent to the fluid pan. The cooler is connected to the transmission casing by two sealed connections. The fluid cooler is connected into the engine cooling system and cools the transmission fluid by heat transfer through the cooler to the engine coolant.

For additional information, refer to: Transmission Cooling (307-02 Transmission/Transaxle Cooling, Description and Operation).



  1. Torque Converter fitted to GTDi 2.0L and TD4 2.2L Engines
  1. Turbine
  2. Impeller
  3. Stator
  4. Transmission connection
  5. One-way clutch
  6. Lock-up clutch
  7. Engine drive plate attachment studs
  8. Torsional damper
  9. Torque converter housing
  1. Torque Converter fitted to Ingenium I4 2.0L Diesel Engine
  1. Turbine
  2. Impeller
  3. Stator
  4. Transmission connection
  5. One-way clutch
  6. Lock-up clutch
  7. Engine drive plate attachment bolts
  8. Torsional damper - including pendulum masses

The torque converter is the coupling element between the engine and the transmission and is located in the torque converter housing, on the engine side of the transmission. The driven power from the engine crankshaft is transmitted hydraulically and mechanically through the torque converter to the transmission. The torque converter is connected to the engine by a drive plate.

The torque converter comprises an impeller, a stator and a turbine. The torque converter is a sealed unit with all components located between the converter housing cover and the impeller. The two components are welded together to form a sealed, fluid filled housing. With the impeller welded to the converter housing cover, the impeller is therefore driven at engine crankshaft speed.

The torque converter contains a hydraulically operated lock-up clutch which is controlled by the TCM via a solenoid in the valve block. The solenoid actuates spool valves to control the hydraulic pressure applied to the clutch.

This allows the TCM to provide 3 modes of converter operation; unlocked, partially locked and fully locked.


     Valve Block

    The valve block is located in a vertical position at the front of the transmission main casing, behind a sealed cover. The valve block contains a number of solenoids and spool valves to control the t

     Drive Clutches

    Multiplate Drive or Brake Clutch - Typical Cylinder Piston Disk spring Metal plates Friction plates Baffle plate Pressure equalization chamber Piston chamber There are two multiplate drive

     Planetary Gear Trains

    Gear set 1 Gearset 2 Gear set 3 Gear set 4 The planetary gear trains used on the 9HP48 transmission comprise four planetary gear sets; GS1, GS2, GS3 and GS4. Engine torque is transferred, via


     General Information / Diagnosis and Testing

    Inspection and verification CAUTION: Diagnosis by substitution from a donor vehicle is NOT acceptable. Substitution of control modules does not guarantee confirmation of a fault, and may also cause additional faults in the vehicle being tested and/or the donor vehicle. NOTES: If the control modul

     Engine - Ingenium i4 2.0l Diesel Intake Manifold (G1875868) / Removal and Installation

    PART(S) REMOVAL NOTE: Removal steps in this procedure may contain installation details. Refer to: Fuel System Pressure Release - GTDi 2.0L Petrol (310-00 Fuel System - General Information, General Procedures). Disconnect the battery ground cable. Refer to: Specifications (414-01 Battery, Mounting

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