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

Location of transfer box components

Item name	Spare part number	Description
1	-	Dashboard
2	-	Range select switch
3	-	Transfer case
4	-	Central distribution block (CJB)
5	-	Manual Transmission Output Shaft Speed Sensor
6	-	Gear position sensor (only for manual transmission)
7	-	Transfer case control module

Disassembled distribution box

Item name	Spare part number	Description
1	-	Timing 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	-	Timing spring
10	-	Retaining ring
11	-	ball bearing
12	-	Rear case
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 motor assembly
23	-	Bolt, 4 pcs.
24	-	Retaining ring
25	-	shift fork
26	-	fork axle
27	-	crawler
28	-	Drive assembly
29	-	Filler plug
30	-	Sealing ring
31	-	ball holder
32	-	drain plug
33	-	Sealing ring
34	-	Magnet for collecting metal chips
35	-	crawler
36	-	range fork
37	-	Sealing ring
38	-	range 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	-	The lever of the electric motor of a distributing box assy
48	-	Ball, 5 pcs.
49	-	The lever of the electric motor of a distributing box assy
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	-	input shaft
62	-	Sealing ring
63	-	Retaining ring
64	-	Disc spring, 2 pcs.
65	-	Bolt, 19 pcs.
66	-	locating 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 50/50 front and rear driveshaft with permanent all-wheel drive. Transfer case manufactured by Magna Steyr Powertrain (Graz, Austria) and has the following features:

• Permanent all-wheel drive with a bevel center differential providing a 50:50 torque split.
• Range selection option (high or low) for optimizing vehicle performance on and off the road
• Two-stage, fully synchronized on-the-go range shifting system that gives the driver the ability to change ranges without stopping the vehicle
• An electronically controlled multi-plate clutch that locks the center differential and changes torque distribution to improve traction and vehicle stability.

A strategy that electronically controls the multi-plate center differential clutch assembly provides the following:

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

The transfer case is located under the vehicle and is mounted on the cross member at the rear of the gearbox. For all engine modifications, the same transfer case is used.

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

Primary torque is evenly distributed by means of a bevel differential. For optimal distribution of torque between the wheels in all road conditions, the transfer case is equipped with an electronically controlled torque lock and change device. Based on the signals received by the transfer case control module from various vehicle systems, this device determines the degree of wheel slip and, in accordance with this, blocks the differential. The locking moment is transmitted to the differential through the multi-plate clutch assembly.

The planetary kit, located in the differential assembly, allows the driver to select high or low range while driving, which is called "switching on the go". In low range, the planetary kit delivers a 2.93:1 gear ratio that allows the vehicle to travel at very low speeds off-road and when towing. The high range is directly driven by the gearbox output shaft and provides a ratio of 1:1.

Locking center differential with torque redistribution and "switching on the go" are carried out by the transfer case DC motor, which is driven by the transfer case control module using pulse width modulation signals (PWM).