Land Rover Lesson 2 Auto Trans Coolingine Rover Manual

							ZF 6HP26 Automatic Transmission Component Location
PRND LCD display1
M/S LCD display2
Selector lever assembly3
Instrument cluster4
Automatic transmission5
Transmission fluid cooler6
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							GENERAL
The ZF 6HP26 transmission is an electronically
controlled, six speed unit. The transmission is
manufactured by ZF Transmissions GmbH in
Saarbrücken, Germany. This transmission represents
the latest in automatic transmission technology and
incorporates new features to enhance the transmission
functionality:
•The hydraulic and electronic control elements of the
transmission are now incorporated in a single unit
located inside the transmission and is known as
Mechatronic
•Another new strategy is Adaptive Shift Strategy
(ASIS). ASIS represents the continuous adaptation
of shift changes to suit the driving style of the driver
which can vary from sporting to economical. Further
details of the ASIS function are contained in the
Driving Modes section.
The transmission is controlled by an Transmission
Control Module (TCM) which contains software to
provide operation as a semi-automatic
CommandShift™ transmission. The TCM allows the
transmission to be operated as a conventional automatic
unit by selecting P, R, N, D on the selector lever.
Movement of the selector lever across the gate to the
M/S position puts the transmission into electronic
Sport mode. Further movement of the lever in a lateral
direction to the + or – position puts the transmission
into electronic manual CommandShift™ mode.
The 6HP26 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 control of lock-up,
creating a smooth transition to the fully locked
condition
•Shift programs controlled by the TCM
•Connected to the ECM via the High Speed CAN for
communications
•Default mode if major faults occur
•Diagnostics available from the TCM via the CAN
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							ZF 6HP26 Automatic Transmission – Exploded View
NOTE: The transmission shown is exploded to the extent of the serviceable items
Breather tube1Plug2
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							Seal sleeves3
Seal - Selector shaft (2 off)4
Gasket5
Drain plug6
Fluid pan7
Torx screws8
Mechatronic valve block9
Element seal10
Electrical connector – guide sleeve11
O-ring12
O-ring13
Pump housing14
Input shaft seal15
Torque converter16
The gearbox comprises the main casing which houses
all of the transmission components. The main case also
incorporates an integral bell housing.
A fluid pan is bolted to the lower face of the main case
and is secured with bolts. The fluid pan is sealed to the
main case with a gasket. Removal of the fluid pan allows
access to the Mechatronic valve block. The fluid pan
has a magnet located around the drain plug which
collects any metallic particles present in the transmission
fluid.
A fluid filter is located inside the fluid pan. If the
transmission fluid becomes contaminated or after any
service work, the fluid pan with integral filter must be
replaced.
The integral bell housing provides protection for the
torque converter assembly and also provides the
attachment for the gearbox to the engine cylinder block.
The torque converter is a non-serviceable assembly
which also contains the lock-up clutch mechanism. The
torque converter drives a crescent type pump via drive
tangs. The fluid pump is located in the main case, behind
the torque converter.
The main case contains the following major
components:
•Input shaft
•Output shaft
•Mechatronic valve block which contains the
solenoids, speed sensors and the TCM
•Three rotating multiplate drive clutches
•Two fixed multiplate brake clutches
•A single planetary gear train and a double planetary
gear train.
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							ZF 6HP26 Automatic Transmission – Sectional View
Torque converter lock-up clutch1
Torque converter2
Fluid pump3
Single planetary gearset4
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							Clutch A5
Clutch B6
Clutch E7
Brake C8
Brake D9
Double planetary gearset10
Park lock gear11
Output shaft12
Park lock pawl13
Drain plug14
Magnet15
Pressure regulator16
Mechatronic valve block17
Fluid filter18
Fluid pan19
Input shaft20
Transmission casing21
TORQUE CONVERTER
Torque Converter Components - 4.0L V6 and 4.4L V8
Models
Impeller1
Turbine2
Stator3
Freewheel4
Torque converter hub5
Stator shaft6
Turbine shaft7
Drive plate8
Journal - Drive plate location9
Torque converter cover10
Lock-up clutch piston11
Lock-up clutch plate12
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							Torque Converter Components - TdV6 Models
Turbine1
Impeller2
Stator3
Freewheel4
Torque converter hub5
Stator shaft6
Turbine shaft7
Journal - Drive plate location8
Torque converter cover9
Lock-up clutch piston10
Drive plate11
Lock-up clutch plate12
Torsional vibration damper13
The torque converter is the coupling element between
the engine and the gearbox and is located in the
transmission 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 converter housing cover has threaded bosses which
provide for attachment of the engine drive plate which
is connected to the engine crankshaft. The threaded
bosses also provide for location of special tools which
are required to remove the torque converter from the
bell housing.
The torque converter used on TdV6 models is similar
in construction to the torque converter on petrol models
but contains a torsional vibration damper. The damper
smooths the output from the engine and prevents
unwanted vibration from being passed to the
transmission.
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							Impeller
Fluid Flow
NOTE: Typical torque converter shown
Turbine1
Stator2
Impeller3
When the engine is running the rotating impeller acts
as a centrifugal pump, picking up fluid at its centre and
discharging it at high velocity through the blades on its
outer rim. The design and shape of the blades and the
curve of the impeller body cause the fluid to rotate in a
clockwise direction as it leaves the impeller. This
rotation improves the efficiency of the fluid as it contacts
the outer row of blades on the turbine.
The centrifugal force of the fluid leaving the blades of
the impeller is passed to the curved inner surface of the
turbine via the tip of the blades. The velocity and
clockwise rotation of the fluid causes the turbine to
rotate.
Turbine
The turbine is similar in design to the impeller with a
continuous row of blades. Fluid from the impeller enters
the turbine through the tip of the blades and is directed
around the curved body of the turbine to the root of the
blades. The curved surface redirects the fluid back in
the opposite direction to which it entered the turbine,
effectively increasing the turning force applied to the
turbine from the impeller. This principle is known as
torque multiplication.
When engine speed increases, turbine speed also
increases. The fluid leaving the inner row of the turbine
blades is rotated in an anti-clockwise direction due to
the curve of the turbine and the shape of the blades. The
fluid is now flowing in the opposite direction to the
engine rotation and therefore the impeller. If the fluid
was allowed to hit the impeller in this condition, it
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							would have the effect of applying a brake to the
impeller, eliminating the torque multiplication effect.
To prevent this, the stator is located between the
impeller and the turbine.
Stator
The stator is located on the splined transmission input
shaft via a freewheel clutch. The stator comprises a
number of blades which are aligned in an opposite
direction to those of the impeller and turbine. The main
function of the stator is to redirect the returning fluid
from the turbine, changing its direction to that of the
impeller.
The redirected fluid from the stator is directed at the
inner row of blades of the impeller, assisting the engine
in turning the impeller. This sequence increases the
force of the fluid emitted from the impeller and thereby
increases the torque multiplication effect of the torque
converter.
Stator Functions
NOTE: Typical stator shown
Blades1
Stator held – fluid flow redirected2
Stator rotates freely3
Roller4
Converter at coupling speed5
Fluid flow from turbine6
Converter multiplying7
Fluid flow from impeller8
Drive from engine9
Impeller10
Stator11
Turbine12
Output to transmission13
Refer to the Stator Functions illustrationFluid emitted from the impeller acts on the turbine. If
the turbine is rotating at a slower speed than the fluid
from the impeller, the fluid will be deflected by the
turbine blades in the path A. The fluid is directed at
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							and deflected by the stator blades from path B to path
C. This ensures that the fluid is directed back to the
pump in the optimum direction. In this condition the
sprag clutch is engaged and the force of the fluid on the
stator blades assists the engine in rotating the impeller
As the rotational speed of the engine and therefore the
turbine increases, the direction of the fluid leaving the
turbine changes to path D. The fluid is now directed
from the turbine to the opposite side of the stator blades,
rotating the stator in the opposite direction. To prevent
the stator from resisting the smooth flow of the fluid
from the turbine, the sprag clutch releases, allowing the
stator to rotate freely on its shaft.
When the stator becomes inactive, the torque converter
no longer multiplies the engine torque. When the torque
converter reaches this operational condition it ceases to
multiply the engine torque and acts solely as a fluid
coupling, with the impeller and the turbine rotating at
approximately the same speed.
The stator uses a sprag type, one way, freewheel clutch.
When the stator is rotated in a clockwise direction the
sprags twist and are wedged between the inner and outer
races. In this condition the sprags transfer the rotation
of the outer race to the inner race which rotates at the
same speed.
One Way Free Wheel Clutch – Typical
Sprags1
Inner race2
Outer race3
Sprag and cage assembly4
Sprag outer race5
Sprag inner race6
Retaining ring7
The free wheel clutch can perform three functions; hold
the stator stationary, drive the stator and free wheel
allowing the stator to rotate without a drive output. The
free wheel clutch used in the 6HP26 transmission is of
the sprag type and comprises an inner and outer race
and a sprag and cage assembly. The inner and outer
races are pressed into their related components with
which they rotate. The sprag and cage assembly is
located between the inner and outer races.
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