Who are you guys?

All mode 4x4 system nissan qashqai

In 2WD mode, the clutch is unlocked permanently. However, even when in 2WD mode, rear wheels can sometimes be engaged by electronic control unit, for example under heavy acceleration.

Figure: Nissan X-Trail All Mode 4wd system description

Why is it important to know how your all wheel drive works? First, it may appear that your all wheel drive system is not meant to be used on-road. For example, part-time all wheel drive cannot be used in non-slippery conditions - you'll have to drive this car in rear-wheel drive mode, even when it is raining or snowing - in the weather conditions where all wheel drive might be needed. Second, depending on the type of all wheel drive, your car behaves differently when driving and cornering in slippery conditions. You might want to know what to expect.

Don't get confused by the abbreviations the manufacturers use: "AWD" is not necessary a full-time all wheel drive, "4WD" is not just for off-road vehicles. There is a dozen of brands the car manufacturers are using to distinguish their four-wheel drive vehicles - "quattro", "4motion", and so on. None of these actually represent the type of all wheel drive system used on the particular vehicle.

In fact, just four types of all wheel drive systems exist:

Note: On this web site, when we describe details of the all wheel drive system used on a particular vehicle, we use the definitions that are listed here.

This is a "temporary" all wheel drive system. In normal driving conditions, just one axle (the rear axle normally) is driven. In slippery conditions, another axle is engaged by the driver, whether by a lever or a button. This type of all wheel drive does not have a centerdifferential - when all wheel drive is engaged, the front and rear driveshafts are mechanically connected and rotate at the same speed.

When a vehicle is turning, the front wheels travel greater distance than the rear wheels.

Figure: Wheels rotate with different speeds and travel different distances when vehicle is turning

Because the part-time all wheel drive system does not have a center differential. the front wheels cannot go faster than the rear wheels. This type of all wheel drive cannot be used on pavement. Turning on pavement (even on a wet pavement) with all wheel drive engaged causes transmission windup and increases the chances of the transmission breakdown. When all wheel drive is engaged, the vehicle heavily understeers and this can lead to an accident.

The all wheel drive mode should only be used on surfaces with low traction (mud, snow, ice, sand), for short periods, and at low speeds. In these conditions the transmission windup is eliminated by slipping of the wheels.

Note: "Part-time 4wd" mode of the Jeep Cherokee's SelecTrac transmission means "locking of center differential ". Jeep's SelecTrac is a selectable all wheel drive system.

This is a permanent all wheel drive or permanently engaged all wheel drive system. All wheels are powered at all times. The vehicles with full-time all wheel drive are equipped with a center differential that lets all wheels travel different distances while turning. This type of all wheel drive can be used both on and off road. In slippery conditions, the center differential can be locked, whether manually or automatically, depending on the vehicle.

When a manual center differential lock (available on off-road vehicles and some SUVs) is engaged, the transmission's behavior is similar to part-time all wheel drive. i.e. the front and rear driveshafts rotate at the same speed. The use of full-time all wheel drive with locked center differential is limited to surfaces with low traction.

In case of an automatic lock, a Torsen differential. viscous coupling. multi-plate hydraulic clutch, or similar traction device is used in conjunction with the center differential. When a wheel slip occurs (one driveshaft rotates faster than the other) the device locks the center differential and the torque is transferred from the axle that slips to the other axle that has traction. As soon as the wheel slip is eliminated, the device unlocks.

Some vehicles (Land Raver Discovery II, pre-xDrive BMW X5) do not have a locking center differential. but are equipped with an electronic traction control system (known as Electronic Differential Lock - EDL) on all four wheels. This electronic system detects slipping wheels by reading ABS sensors, then it applies brakes to the slipping wheels and the torque gets transferred to the wheels that have traction. While it performs well on slippery roads, the system cannot compete with a real mechanically locking differential when driving off-road.

This is an "on-demand" all wheel drive system. Under normal driving conditions, only one axle is powered. When wheel slipping occurs (the driving driveshaft rotates faster than the driven driveshaft), a multiplate hydraulic clutch, viscous coupling. or other similar traction device locks and engages another axle. The torque gets transferred to another axle. As soon as the difference in the front and rear axle speeds is eliminated, the device unlocks and the vehicle goes back to the two-wheel drive mode.

The difference between the traction devices that are used in full-time all wheel drive and automatic all wheel drive systems is that the device used in automatic all wheel drive system replaces the center differential .

Advanced electronically controlled all wheel drive systems can be proactive and lock the traction device even before wheels start to slip - the need of all wheel drive is determined in real-time, based on the information that is collected from different sensors (i.e. g-force sensor, accelerator pedal position, etc.).

Some vehicles let the driver to lock the multiplate hydraulic clutch manually when the driver feels that he needs all wheel drive engaged permanently and before wheels start to slip. For example, in Nissan X-Trail, this is accomplished by pressing a button on the dashboard console. In Subaru Legacy, the clutch is locked when the automatic transmission gear shift lever is at the position "1".

In this category fall Mitsubishi Pajero(Montero) with its Super Select transmission, Jeep Grand Cherokee with SelecTrac transmission, and a few other off-road vehicles. Mitsubishi, for example, has in fact a full-time all wheel drive transmission with two wheel drive possibility. In Mitsubishi, the driver can choose between the 2wd mode, 4wd mode with automatic distribution of torque via viscous coupling (acts like the full-time all wheel drive ), 4wd with locked differential (acts like the part-time all wheel drive) and 4wd with low gearing (low range part-time all wheel drive).

Well I would not use 4 wheel on pack ice. only to pull away. I would use it in heavy snow on normal roads you wont need it and you will save your tires So you will have to go to Cleethorpes and get on the beach and enjoy the 4 wheel drive feeling up and down the sand dunes here is a German 50000km test of the 4x4 Duster its pretty good http://translate.goo. 38.html&act=url

and also a little film But Hey dont go trying this stuff yet its also a lot to do with tires as well

I think a lot of people doubt the Duster's off-road credentials, but that vid should put that to rest once and for all! They just look so damned good in amongst the muddy stuff - like it's exactly where they belong. And all that for under £16k - it's almost enough to make me say 'hang the practicalities' and go for it.

u cant put the leaver in low gear on a LAND ROVER (for example)

The red lever can be moved during motion by doubleing the clutch. the Yellow lever can be pressed down to engage 4 wheel drive at any time. The Red lever is just to give a different gear ratio and actually when you have the Red Lever back you can drive in 3rd gear all the time and even pull away in it !and if you put the Red lever into the Middle postition you cannot drive at all because this is then the Power Take off. Thats another story. But HEY this is a Land Rover and not a Dacia

is for explaining to people that have 4wd dacia dusters how the system is working

and for understanding the difference between 4WD-4X4-AWD-QUATTRO and so on

the 4WD (not 4x4 not AWD) system comes from NISSAN X-TRAIL which is also on the NISSAN QASHQAI and on DACIA DUSTER

And I am sure they have 2 wheel drive, Auto ,and 4 wheel drive ,Auto would be the one for The snow season when snow is on the roads (good for in Supermaket carparks) while it would figure out if it needed to activate the 4 wheel drive or not. Using the 4 wheel drive all the time would bump up your fuel costs So only to be used on Cleethorpes Beach on the sand dunes and if there is no snow in site then its 2 wheel drive

Agree wholeheartedly with that - it's amazing the number of folk who think driving a 4x4 is a license to disregard things like black ice and snow, and plough on (no pun intended) regardless.

At the start of the bad winter of 2010/11, I found myself caught in the midst of a blizzard heading east on the M8. I was in the cleared left lane with no traffic ahead, at 40 - 50 when one of these big 4x4 pickup things went barging past in the (unploughed) outside lane at 70. I backed off and let him get ahead, and sure enough, up ahead, I saw his back end step out and the whole thing pirouetted through almost a full 360. He was very lucky there was nothing in the inside lane to hit, otherwise he was a gonner. As he was on his way (much more carefully!) I could practically smell the sh*t wafting through the air vents!

4x4, combined with appropriate tyres and good clearance will allow you to keep going (carefully) in thick snow where lesser cars would just get stuck and give up. It will NOT stop you sliding off the road and down an embankment or under the wheels of a truck if you don't adjust your speed and driving style to the conditions just as you would in any other car.

Please, please, all you Duster owners - especially those with no previous SUV experience - don't fall into the trap this winter. Enjoy your Dusters, but respect their limitations!

Please, please, all you Duster owners - especially those with no previous SUV experience - don't fall into the trap this winter. Enjoy your Dusters, but respect their limitations!

its always 50-50 with the driver knowledge to drive a 4wd, to know from experience how to drive and control the car (any car)

2WD”, “AUTO” or “4WD Lock” mode when the vehicle is being driven in a straight line.

I have Never had a accident in all my driving life and that a long time. I was taught on Landrovers in Wales in 68 and the best bit of info i had from my Army Instructor was Drive as if all the other drivers are idiots ! or in other words defensive driving (Typical Army ) He also said while doing country driving and I think this on every curve still and so does the wife. "Round every curve could be children walking home" Like Royale says Enjoy your car respect the weather and


Thats Stuarts Story hour finished for today I hope it has sunk in for a few

the best bit of info i had from my Army Instructor was Drive as if all the other drivers are idiots ! or in other words defensive driving (Typical Army )


Not just the army, Stuart - my PCV instructor gave exactly the same advice!