Land Rover Discovery: Automatic Transmission Transaxle / Description and operation
COMPONENT LOCATION
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- Paddle switches - upshift / downshift
- Transmission Control Switch (TCS)
- Transmission Control Module (TCM)
- ZF 9HP48 Automatic transmission
- Automatic Transmission Fluid (ATF) cooler with integrated thermostat
OVERVIEW
The ZF 9HP48 automatic transmission is a 9 speed, electronically controlled unit manufactured by ZF. The transmission represents the latest in automatic transmission technology for a transverse, AWD (all-wheel drive) unit. The transmission features lock-up slip control, 'CommandShift' functions and automatic and driver selectable modes to give the optimum on and off road performance.
The automatic transmission is controlled by a TCM (transmission control module) which contains software to provide operation as a semi-automatic 'CommandShift' transmission. Driver selections for P, R, N, D and S on the rotary TCS (transmission control switch) are received by the TCM. The TCM operates solenoid valves and clutches to control transmission gear shifts, allowing the system to operate as a 'shift by wire' system, with no mechanical link to the transmission for drive selections.
The TCM allows the transmission to be operated as a conventional automatic unit by selecting P, R, N, D, S on the TCS. Rotation of the TCS to the 'S' position puts the transmission into electronic 'Sport' mode.
Operation of the steering wheel mounted + or - paddle switches puts the transmission into electronic manual 'CommandShift' mode.
For additional information, refer to: External Controls (307-05 Automatic Transmission/Transaxle External Controls, Description and Operation).
The ZF 9HP48 transmission has the following features:
- Designed to be maintenance free
- Transmission fluid is fill for life
- The torque converter features a controlled slip feature with electronically regulated lock-up control on gears 1 to 9
- Planetary gearset with 9 speeds, 4 planetary geartrains, and 6 shift elements
- Wide transmission ratio spread with small ratio steps
- The first-ever use of interlocking dog clutches in a passenger car automatic transmission
- Shift programs controlled by the TCM
- TCM has an adaptive capability to ensure efficient gear shift quality throughout the service life of the transmission
- Diagnostics available from the TCM via the high speed CAN (controller area network) Powertrain systems bus.
- Automatic Transmission Transaxle / Component Description
- Valve Block
- Drive Clutches
- Planetary Gear Trains
- Park Lock
- Instrument Cluster
- Transmission Fault Status
- Engine Speed and Torque Monitoring
READ NEXT:
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-Awa
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
SEE MORE:
Manual Transmission Transaxle
Transmission Fluid
Level Check (G2162887)
/ General Procedures
CHECK
WARNING:
Observe due care when draining, as the fluid can be very hot.
All vehicles
WARNING:
Make sure to support the vehicle with axle stands.
NOTE:
Make sure that the vehicle is standing on a level surface.
Raise and support the vehicle.
Refer to: Engine Undershield (501-02 Front End Body Pa
Four-wheel Drive Systems - Vehicles With- Active Driveline - Operation
OPERATION
POWER TRANSFER UNIT (PTU)
The Active Driveline Power Transfer Unit (PTU) input shaft is driven directly
from the transmission differential. When the hydraulically operated triple
cone synchroniser is in the disengaged position (B in the following
illustration), the crown wheel shaft and th
