Land Rover Lesson 2 Auto Trans Coolingine Rover Manual

							Transfer Box Component Location
Instrument cluster1
Range change selection switch2
Transfer box3
Central junction box (CJB)4
Manual transmission output shaft speed sensor5
Gear position sensor (Manual transmission only)6
Transfer box control module7
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							Transfer Box Exploded View
Synchronisation spring1
Differential assembly2
Bolt, 6 off3
Spacer ring4
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							Shifting sleeve5
Bolt, 3 off6
Solenoid7
Shifting element8
Synchronisation spring9
Circlip10
Ball bearing11
Rear housing12
Circlip13
Seal ring14
Needle roller bearing15
Rear output flange16
Needle roller bearing17
Bolt, 2 off18
Selector fork position sensor19
Bearing20
Circlip21
Transfer box motor assembly22
Bolt, 4 off23
Circlip24
Shifting fork25
Fork pin26
Sliding block27
Actuator assembly28
Fill plug29
Seal ring30
Ball retention31
Drain plug32
Seal ring33
Particle collector magnet34
Sliding block35
High/low shifting fork36
O-ring37
High/low fork pin38
Circlip39
Circlip40
Clutch hub41
Clutch friction plate, 10 off42
Clutch steel plate, 10 off43
Disc spring, 6 off44
Clutch piston45
Axial needle roller bearing46
Transfer box motor lever assembly47
Ball, 5 off48
Transfer box motor lever assembly49
Axial needle roller bearing50
Needle roller bearing51
Front output sprocket52
Chain53
Needle roller bearing54
Sprocket55
Circlip56
Thrust washer57
Spacer ring58
Oil pump assembly59
Needle roller bearing60
Input shaft61
O-ring62
Circlip63
Disc spring, 2 off64
Bolt, 19 off65
Dowel pin (2 off)66
Front housing67
Breather cartridge68
Bearing69
Circlip70
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							Seal ring71
Front output flange72
Seal ring73
Circlip74
Bearing75
GENERAL
The DD295 transfer box is full time, permanent
four-wheel-drive unit, with 50/50 torque distribution to
the front and rear driveshafts. The unit is manufactured
by Magna Steyr Powertrain in Graz, Austria and
supports the following features:
•Permanent four-wheel-drive with a bevel gear centre
differential, providing a 50:50 torque split
•Selectable high and low range for optimum on-road
and off-road performance
•Two-speed, fully synchronized shift-on-the-move
system allows the driver to change the range without
having to stop the vehicle
•Electronically controlled multi-plate clutch providing
a centre differential lock and torque biasing function
to give improved traction performance and vehicle
dynamic stability.
A strategy, to electronically control the centre
differential multi plate clutch assembly, has been
developed to provide:
•a pre-loading function, increasing locking torque
with increased driving torque
•a slip controller to increase locking torque under
off-road conditions and decrease locking torque for
optimum comfort, e.g. parking.
The unit is located under the vehicle and is mounted on
the cross-member, behind the transmission. The unit is
identical for all engine derivatives.
The transfer box receives a torque input from the
transmission output shaft, which is passed through the
unit to two outputs for the front and rear drive shafts.
The input torque is equally distributed via a bevel gear
type differential. In order to provide an optimal torque
distribution to each wheel in all driving conditions, the
unit is equipped with an electronically controlled locking
and torque-biasing device. This device detects wheel
slip via various vehicle system inputs to the transfer box
control module and locks the differential accordingly.
The locking torque is applied through a multi-plate
clutch assembly.
A planetary gear set, located in the differential assembly,
allows the driver to select high or low range whilst
driving, this is known as shift on the move. When in
low range, the planetary gear set provides a ratio of
2.93:1, which gives the vehicle an extremely low crawl
speed for off road driving and trailer towing. High range
is a direct drive from the transmission output shaft and
provides a 1:1 ratio.
Both the centre differential locking and biasing and the
shift on the move features are actuated via a DC transfer
box motor, which is controlled by the transfer box
control module, via a Pulse Width Modulation (PWM)
signal.
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							Transfer Box - Sectional View
Planetary gear set1
Rear output flange2
Centre differential assembly3
Multi-plate clutch4
Transfer box motor module5
Rear housing assembly6
Front output sprocket7
Chain drive8
Front output flange9
Transfer box motor levers10
Sprocket11
Oil pump assembly12
Input shaft13
Front housing assembly14
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							Transfer Box Power Flow
The input torque, from the transmission, is transferred
to the input shaft of the transfer box and then onto the
planetary sun gear and planetary pinion gears. The
planetary pinion gears are held in place by the planet
pinion shafts, which are connected to the differential
carrier, and drive the differential pinion gears. The
torque is then distributed to both the front and rear
carriers, which are connected to the outputs of the
transfer box. The rear carrier is connected directly to
the rear output flange; the front carrier is connected to
the sprocket and therefore to the chain drive, which
provides the front output flange rotation.
TRANSFER BOX CASINGS
The front and rear casing assemblies are manufactured
from cast aluminium.
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							Front Casing Assembly
The front casing assembly provides the location for the
input shaft bearing and the front output flange bearing.
It is also equipped with threaded holes to mount the
chassis mounting bush, two lifting eyes and a breather
cartridge for the transfer box breather pipe. The breather
pipe allows an equalisation between atmospheric and
internal transfer box pressure.
Rear Casing Assembly
The rear casing assembly provides the location for the
rear output flange bearing, the transfer box motor and
the oil fill and drain plug. Fins are cast into the rear
casing assembly to improve the heat dissipation. The
unit number is also stamped into the rear housing.
OIL PUMP
An oil pump assembly is located in the front casing to
provide lubrication for the bearings and rotary
components through cross-drillings in the input shaft.
A flat-sectioned coupling on the input shaft drives the
rotor of the pump; the stator is fixed to the front housing
assembly. A tube is attached to the pump, which leads
into a calm suction area at the bottom of the two casing
assemblies. The collector magnet in the suction area of
the pump collects any metallic debris.
CHAIN DRIVE
The chain-drive transfers drive from the centre
differential to the front output flange. A 3/8 pitch chain
connects the sprocket on the transfer box input shaft
with the sprocket on the front output flange. As both
sprockets have the same number of teeth, the rotational
speed of both sprockets is identical.
TRANSFER BOX MOTOR
One motor operates both the high/low range change and
the differential locking and torque-biasing device
(multi-plate clutch). The motor solenoid switches
between the two functions, while the motor provides
the rotational movement for both operations.
Transfer Box Motor Position For Clutch
Control Mode
Motor shaft1
Solenoid shift fork2
Solenoid3
Clutch control disc4
Shifting sleeve5
To actuate the multi-plate clutch, the transfer box control
module energizes the solenoid (3). The solenoid pin
pivots the solenoid shift fork (2), which engages the
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							shifting sleeve (5) into the dogteeth on the clutch control
disc (4). The rotational movement of the motor shaft
(1) is then linked to the clutch control disc via the
shifting sleeve.
This is the normal operating mode of the transfer box.
In this position, the range change function is disengaged
and mechanically locked.
Transfer Box Motor Position For High/Low
Range Mode
Motor shaft1
Solenoid shift fork2
Solenoid3
Shifting sleeve4
Actuation cam5
To actuate the high/low range change, the transfer box
control module de-energizes the solenoid (3). A spring
in the solenoid retracts the solenoid pin and rotates the
solenoid shift fork (2). This engages the shifting sleeve
(4) to the dogteeth on the high/low actuation cam (5).
The rotational movement of the motor shaft (1) is then
linked to the cam.
In this position, the multi-plate clutch is open, the
differential cannot be locked and torque cannot be
biased. Once the range change is complete the system
returns to clutch control mode. In the event of an
electrical failure, the motor will default to this position.
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							CENTRE DIFFERENTIAL ASSEMBLY
Synchronisation cup and spring1
Planetary ring gear2
Differential carrier3
Pinion gears4
Pinion gear shafts5
Planetary pinion gears6
Planetary pinion gear shafts7
Planetary sun gear8
Differential cover9
Differential side gears10
Multi-plate clutch basket11
Dogteeth12
The centre differential assembly is the primary feature
of the transfer box. Torque is transmitted through the
centre differential carrier and distributed to the
differential gears and the front and rear output flanges.
The planetary gear set, for the high/low range change
function, is also an integral part of the centre differential
assembly.
The assembly comprises 3 differential pinion gears (4)
and shafts (5), which are equally spaced within the
centre differential carrier (3). The differential shafts
have a rigid connection to the differential carrier.
Located between the pinion gears are 3 planetary pinion
gears (6) and shafts (7). The planetary sun gear (8) and
two differential side gears (10) are located in the centre
line of the carrier.
The planetary ring gear (2) is supported in both
directions by the differential casing and the differential
cover (9). The planetary ring gear is connected to a
shifting sleeve, which is engaged in either high or low
range.
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							The multi-plate clutch basket (11), which is welded to
the differential casing, supports the friction plates, the
dogteeth (12) for high range engagement and the
synchronisation cup and spring (1) for the
shift-on-the-move function.
High range positionA
Low range positionB
Dogteeth1
Planetary pinion gears2
Planetary ring gear3
Shifting sleeve4
Low range dogteeth5
Rear carrier assembly6
When high range is engaged, the shifting sleeve (4)
connects to the differential carrier via dogteeth (1). The
planetary ring gear (3), via the shifting sleeve, and the
planetary pinion gears (5), via the planetary shafts, are
also attached to the differential carrier. The planetary
gear set rotates as one unit and therefore turns the
differential side gear with a 1:1 ratio.
In low range the motor moves the shifting sleeve (4) in
the direction of the low range dogteeth (5). The low
range dogteeth, with the synchronisation cup and spring,
are fixed to the rear carrier assembly (6). When the
shifting sleeve is engaged with the low range dogteeth,
the planetary ring gear (3), via the shifting sleeve, is
stationary and the planetary pinion gears (2), via the
planetary bolts, turn the differential side gears with 2.93:
1 ratio.
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