Haldex (English, Polski, Русский)

Haldex all wheel drive(Edit)

Haldex-based all wheel drive systems are automatic all wheel drive systems. Haldex clutch is installed in the rear axle's differential housing and powers rear wheels.

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haldex generation I, 1998-(Edit)

Figure: haldex generation 1

The design of the Haldex LSC gen. I, II, and III is based on a Swedish patent acquired by the Haldex Group.

The unique design of the Haldex LSC comprises three functional parts

• The hydraulic pump driven by the slip between the axles/wheels.
• The wet multi-plate clutch
• The controllable throttle valve with its electronics.

The unit can be viewed as a hydraulic pump in which the housing and an annular piston are connected to one shaft and a piston actuator is connected to the other.

The two shafts are connected via the wet multi-plate clutch pack, normally unloaded and thus transferring no torque between the shafts.

When both shafts are rotating at the same speed, there is no pumping action. When a speed difference occurs, the pumping starts immediately to generate oil flow. It is a piston pump, so there is a virtually instant reaction with no low-speed pumping loss.

The oil flows to a clutch piston, compressing the clutch pack and braking the speed difference between the axles. The oil returns to the reservoir via a controllable valve, which adjusts the oil pressure and the force on the clutch package.

In traction/high slip conditions, a high pressure is delivered: in tight curves (i.e. parking), or at high speeds - a much lower pressure is provided.

Haldex Generation I and II based all wheel drive system is reactive. The coupling activates after a wheelspin is detected. However, the reaction is very quick and just 1/4 of a wheel turn is needed to engage all wheel drive. Electronics is capable of lowering the oil pressure only (when parking, ABS working, the handbrake is pulled, etc.), but cannot pre-tension the clutch.

Under normal driving conditions (driving at the constant speed, no silppage), the torque distribution is 90/10 front to rear. When the clutch is locked, torque is evently distributed between the axles (50/50).

Figure: haldex clutch

Figure: haldex clutch

Figure: haldex coupling generation 1 multi plate clutch

Figure: haldex generation 1

Figure: haldex generation 1

Figure: haldex generation 1

Figure: haldex generation 1

Figure: haldex generation 1

Figure: haldex generation 1

Figure: haldex generation 1 diagram of the oil pressure system

Figure: haldex generation 1 ecu mastervalve

Figure: haldex generation 1 skoda octavia

More info: http://audittrs.wordpress.com/2010/12/07/haldex-service-training-self-study-program/

Have you seen a better description of Haldex Generation I, 1998- on the web? Please send us the link to or post it in a comment below!

haldex generation II, 2002-(Edit)

This second generation of Haldex LSC is still using the mechanical hydraulic pump, but the linear throttle valve has been exchanged for a solenoid controlled proportional throttle valve.

Haldex Generation I and II based all wheel drive system is reactive. The coupling activates after a wheelspin is detected. However, the reaction is very quick and just 1/4 of a wheel turn is needed to engage all wheel drive. Electronics is capable of lowering the oil pressure only (when parking, ABS working, the handbrake is pulled, etc.), but cannot pre-tension the clutch.

Figure: haldex generation 2

Figure: haldex generation 2

Figure: haldex generation 2

Figure: haldex generation 2

Figure: Cut-away view of a rear differential with Haldex generation 2(?)

Figure: Borg-Warner's Haldex generation 2

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haldex generation III, 2004-(Edit)

A coupling with pre-tensioning capability of the hydraulic clutch by the means of existing feeder pump (PreX™ solution).

Haldex Generation III, IV, and V based all wheel drive systems are proactive. The electronics can pre-tension the clutch and activate all wheel drive before a wheel slip occurs.

Figure: haldex generation 3

Figure: Haldex generation 3 (left) and 4 on Ford Kuga

Figure: Borg-Warner's Haldex generation 3

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haldex generation IV, 2008-(Edit)

The fourth generation does not have the mechanical pump any more. The clutch is activated using the feeder pump.

Haldex Generation III, IV, and V based all wheel drive systems are proactive. The electronics can pre-tension the clutch and activate all wheel drive before a wheel slip occurs.

Figure: haldex generation 4

Figure: haldex generation 4

Figure: haldex generation 4

Figure: Rear differential and Haldex 4 on Audi TT quattro

Figure: Haldex generation 4 on Volkswagen Transporter

Figure: Borg-Warner's Haldex generation 4

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haldex generation V, 2012-(Edit)

Figure: haldex generation 5

Figure: haldex generation 5

Figure: haldex generation 5

http://www.borgwarner.com/en/Haldex-AWD/products/Pages/Haldex-Gen5.aspx

Haldex Generation III, IV, and V based all wheel drive systems are proactive. The electronics can pre-tension the clutch and activate all wheel drive before a wheel slip occurs.

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haldex XWD (cross wheel drive), 2007-(Edit)

A combination of two Haldex Couplings, one for the front/rear torque distribution, another for the torque distribution between the rear wheels. First introduced on Saab 9-3 in 2007 with earlier generation Haldex unit then replaced with Generation IV unit in 2008.

Figure: haldex generation 4 xwd

Figure: haldex generation 4 xwd

Figure: haldex generation 4 xwd

Figure: haldex generation 4 xwd

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More information(Edit)

For further information, see the Haldex Web site.

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