alfa-romeo (English, Русский)

Central epicyclic unit with Ferguson viscous coupling, Torsen rear differential Source

Figure: Alfa-Romeo 155 Q4

Figure: Alfa-Romeo 155 Q4 front differential with epicyclic torque distributor and Ferguson VC

Figure: Alfa-Romeo 155 Q4 rear differential

Figure: alfa romeo 155

Also see Lancia Dedra/Fiat Tempra.

1993 version:

• Front and rear: ZF plate-type limited slip differential
• Center: epicyclic unit with Ferguson viscous coupling (distribution F/R 33/67)

Figure: 155 V6 TI 1993

1995 version:

Figure: 155 V6 TI 1995

Figure: 155 V6 TI 1995

Full-time all wheel drive system with centre Torsen C (T3) differential.

Source (Italian)

Torsen? Source

AWD system available only with the 1.9 diesel engine JTDm 16v (110kW).

"About The ‘Alfa Q4’ system for this generation" :

The Alfa 159 / Brera adopts an evolved version of the permanent 4x4 system with three differentials (with a Torsen C self-locking unit at the centre). The heart of this design is the ‘Alfa Romeo Q4 four-wheel drive’ system, which splits torque constantly and dynamically between the four wheels, reaching the highest levels of active safety and sportiness. The Torsen C self-locking differential sends drive torque 57% to the rear wheels and 43% to the front. The system also guarantees excellent traction in all grip conditions by automatically checking any slipping.

The torque split between the front and rear axles is modulated constantly by the Torsen C central differential on the basis of grip.

This feature harnesses sportiness to enhance active safety. Modulation is mechanical, continuous and gradual, to enhance the perception of optimal, enjoyable, easy driving. There are no gaps in the torque delivery. Where grip is concerned, the behaviour adapts gradually and smoothly to changing road conditions. This ‘mechanical’ control is backed up by electronic stability control, which boosts performance and safety margins, in line with the Alfa Romeo philosophy.

The car is the state of the art in technical terms and offers important advantages:

• Q4 permanent four-wheel drive with a Torsen C self-locking differential makes for better roadholding, entertaining driving and smooth responses. Other technological archetypes with electronically controlled joints do not achieve the optimal balance between understeer and oversteer or the smoothness that are innate in the Alfa 159, and translate into superb active safety.

• The torque split in favour of the rear axle makes driving even more entertaining, because the car is even easier to handle, without detracting in any way from stability during sudden lane changes on the motorway, or other emergency manoeuvres.

• The possibility of travelling safely when grip is poor without having to use electronics to split torque, enhancing the enjoyment of driving.

NOTE: Depending on conditions Active power split can be as much as (72/28) and (22/78) front/rear.

AWD system: "Q4"

Full-time all wheel drive system with centre Torsen C differential ("Torsen T3 Twin diff").

Source

Distribution: 57% rear, 43% front.

Integrated with ASR and VDC (ESP by Alfa Romeo).

Source

Probably the same Q4 version of Alfa Romeo 156 Crosswagon.

AWD system available only with these "Q4" models:

3.2 petrol engine JTS V6 24v 191kW years 2005->2009 Automatic / Manual Transmission

2.4 diesel engine JTDm 20v 154kW years 2007->2009 Automatic / Manual Transmission

?Torsen Source?

ALFA-ROMEO Q4 system

-used on 159, Brera, Crosswagon

-transversely mounted engine

-Torsen C (twin diff?) center diff

-torque front/rear axle: 43/57%

Figure: alfa romeo 159 q4 crosswagon cutaway

Figure: alfa romeo 159 q4 schematic

BLUE - engine input

RED - front axle diff output

YELLOW - rear axle output

BLACK - front axle diff with drive shafts

Figure: alfa romeo 159 q4 scheme

Figure: alfa romeo 159 q4 torsen cutaway

Figure: alfa romeo 159 q4 torsen

Asymmetric full-time all wheel drive with electronically-controlled center differential lock.

The "Viscomatic" unit - central viscous coupling locking epicyclic unit located near the rear axle and Torsen rear differential.

The Viscomatic was developed by Alfa-Romeo in collaboration with Steyr-Puch. This is a further evolution of the device that was previously used on the Proteo.^[1]

Source

Figure: alfa romeo 164 q4 transmission

Figure: Alfa-Romeo 164 q4 rear differential housing with Viscomatic central differential unit.

Figure: alfa 164 q4 viscomatic

Figure: Gearbox with power takeoff to the rear wheels

Figure: All wheel drive control diagram

AWD system available only with the 3.0 V6 gasoline engine.

Part-time all wheel drive.

The 33 4x4 made its debut in 1983. The layout adopted for this compact saloon meant that the rear wheel drive had to be engaged by means of a lever in the passenger compartment. It also offered higher ground clearance than front wheel drive cars.

In 1990 the 33 4x4 was fitted with an electromagnetic coupling who disengaged the rear axle during safety braking to avoid interferences with the ABS system. The lever was replaced by an electric switch.

Figure: Alfa Romeo 33 4x4

Full-time all wheel drive.

In 1991, the Alfa 33 was fitted with a sportier interpretation of the four wheel drive concept. The transmission layout of the new Permanent 4 (this was the name of the version) was more complex than its predecessor: drive is transmitted to the viscous coupling from an electromagnetic coupling normally engaged and controlled by an electronic control unit which automatically disengages during high decelerations (safety braking).

In 1994 the car was renamed 33 Q4.

Figure: Alfa Romeo 33 Permanent 4

Figure: Alfa Romeo 33 Permanent 4

Figure: Alfa Romeo 33 Permanent 4 viscous coupling

Figure: Alfa Romeo 33 Permanent 4

Figure: Alfa Romeo 33 Permanent 4 transmission

Figure: Alfa Romeo 33 Permanent 4 - Safety braking system

Source

First Alfa Romeo to feature 4WD.

Figure: alfa romeo matta ar51

https://www.alfaromeopress.com/press/detail/6796