The device and technical description of the transfer case (Discovery 3)

Transfer case component locations

Item name	Spare part catalog number	Description
1	-	Instrument panel
2	-	Range selection switch
3	-	Transfer case
4	-	Central Junction Box (CJB)
5	-	Output shaft speed sensor for manual transmission
6	-	Gear position sensor (only for manual transmission)
7	-	Transfer Case Control Module

Transfer case disassembled

Item name	Spare part catalog number	Description
1	-	Synchronizing spring
2	-	Differential assembly
3	-	Bolt, 6 pcs.
4	-	Distance ring
5	-	Shift bushing
6	-	Bolt, 3 pcs.
7	-	Solenoid valve
8	-	Detail of the switching mechanism
9	-	Synchronizing spring
10	-	Retaining ring
11	-	Ball bearing
12	-	Rear housing
13	-	Retaining ring
14	-	Sealing ring
15	-	Needle roller bearing
16	-	Rear outlet flange
17	-	Needle roller bearing
18	-	Bolt, 2 pcs.
19	-	Selector Fork Position Sensor
20	-	Bearing
21	-	Retaining ring
22	-	Transfer case electric motor assembly
23	-	Bolt, 4 pcs.
24	-	Retaining ring
25	-	Shift fork
26	-	Fork axle
27	-	The crawler
28	-	Drive assembly
29	-	Filler plug
30	-	Sealing ring
31	-	Ball holder
32	-	Drain plug
33	-	Sealing ring
34	-	Magnet for collecting metal shavings
35	-	The crawler
36	-	Range shift fork
37	-	Sealing ring
38	-	Shift fork axle
39	-	Retaining ring
40	-	Retaining ring
41	-	Clutch hub
42	-	Clutch friction disc, 10 pcs.
43	-	Steel clutch disc, 10 pcs.
44	-	Disc spring, 6 pcs.
45	-	Clutch piston
46	-	Thrust needle roller bearing
47	-	Transfer case electric motor lever assembly
48	-	Balloon, 5 pcs.
49	-	Transfer case electric motor lever assembly
50	-	Thrust needle roller bearing
51	-	Needle roller bearing
52	-	Front output sprocket
53	-	Chain
54	-	Needle roller bearing
55	-	Star
56	-	Retaining ring
57	-	Thrust washer
58	-	Distance ring
59	-	Oil pump assembly
60	-	Needle roller bearing
61	-	Primary shaft
62	-	Sealing ring
63	-	Retaining ring
64	-	Disc spring, 2 pcs.
65	-	Bolt, 19 pcs.
66	-	Mounting pin (2 pcs.)
67	-	Front crankcase
68	-	Breather cartridge
69	-	Bearing
70	-	Retaining ring
71	-	Sealing ring
72	-	Front outlet flange
73	-	Sealing ring
74	-	Retaining ring
75	-	Bearing

General information

The DD295 transfer case is a permanent all-wheel drive unit with a 50/50 torque split between the front and rear propeller shafts. The transfer case is manufactured by Magna Steyr Powertrain. (graz, Austria) and has the following features:

• Permanent all-wheel drive with a bevel gear center differential that provides a 50:50 torque split.
• Possibility of range selection (high or low) to optimize vehicle performance for on- and off-road use
• A two-stage, fully synchronized on-the-go range-shifting system that allows the driver to change ranges without stopping the vehicle
• An electronically controlled multi-plate clutch that locks the center differential and changes the torque distribution, thereby improving the traction characteristics and dynamic stability of the vehicle.

The strategy by which the electronic control of the multi-plate clutch of the center differential assembly is carried out ensures the following:

• preload, increasing the locking moment with increasing drive torque;
• slip control, which increases the locking torque in off-road conditions and reduces it to achieve the best comfort, for example when parking.

Original version of the article on the website: LRMAN.ru
The transfer case is located under the car and mounted on a crossmember behind the gearbox. The same transfer case is used for all engine modifications.

The transfer case is acted upon by the primary torque of the gearbox output shaft, which is transmitted via the gearbox to the front and rear drive shafts.



The primary torque is distributed evenly by means of a bevel differential. For optimum torque distribution between the wheels under all road conditions, the transfer case is equipped with a device for locking and changing the torque distribution with electronic control. Based on signals received by the transfer case control module from various vehicle systems, this device determines the degree of wheel slippage and locks the differential accordingly. The locking torque is transmitted to the differential via a multi-plate clutch assembly.

The planetary gear set, located in the differential assembly, allows the driver to select high or low range while driving, known as "shift-on-the-fly." In low range, the planetary gear set provides a 2.93:1 gear ratio, allowing the vehicle to travel at very low speeds off-road and when towing. In high range, direct drive is provided from the transmission output shaft, providing a 1:1 gear ratio.

The torque-vectoring center differential lock and "shift-on-the-go" are provided by the transfer case DC motor, which is driven by the transfer case control module using pulse-width modulation (PWM) signals.