centre diff lock question

[albundy]

On behalf of one of the Consultants at my work.
He was travelling down an icy skifield road and the arse started to overtake the front. He was wondering if the centre diff lock engaged would have been helpful in preventing this I don't know much about centre diff lock but my thoughts would be that he should have had chains on . Any thoughts
Al

[mike]

On behalf of one of the Consultants at my work.
He was travelling down an icy skifield road and the arse started to overtake the front. He was wondering if the centre diff lock engaged would have been helpful in preventing this I don't know much about centre diff lock but my thoughts would be that he should have had chains on . Any thoughts
Al

I would say your totally correct and chains would be the only thing that would have made any difference. Traction is at the most when when the wheel speed of a vehicle matches the ground speed, any controlling force that is either trying to accelerate or decelerate the wheel is removing what limited traction there is between the tyre and ice/packed snow. The best device on your car in very very slippery conditions when you dont have chains is the clutch if your out of control, it gives you steering back and head towards the nearest snow bank or jump if there is an edge! How many people have gone over that bank at mount hutt? Brakes, you will speed up, engine breaking - same as breaks you will speed up (any form of breaking results in loss of grip), the only thing is that dreaded clutch, you prepare the vehicle for when the ice stops, like aqua plaining in a car, there is nothing you can do but clutch in and prepare the vehicle for landing

Thats how I see it, could be wrong but its always worked for me.

Mike

[Steve_t647]

Nice post Mike.

I agree with you both the centre diff lock would have done nothing unless it had grip at the front, and if that was the case the car/4wd would have pivoted around the front.

like mike states clutch and counter the slide as you would on a road and wait for the slide to stop extra grip is the only thing that would have prevented the slide.

Also the back of a vehicle usualy has less weight so is more likley to slide this is usualy why the back goes first on ice.

[TJ]

Limited slip diff (LSD) in the back would cause to fishtail as well in snow. Ask anybody with a tight LSD or full time locker.

If you have an auto, put it in NEUTRAL (park will destroy a few things). Don't touch the brakes. Control the slide with steering if you can or just sit and enjoy. I had to learn this when I used to live in North America with a lot of snow around for half the year.

[Mark]

On behalf of one of the Consultants at my work.
He was travelling down an icy skifield road and the arse started to overtake the front. He was wondering if the centre diff lock engaged would have been helpful in preventing this I don't know much about centre diff lock but my thoughts would be that he should have had chains on . Any thoughts
Al

The way I see it is that it is possible that using the centre diff lock would possibly help. Because the centre diff apportions power between the front and rear axles it is possible that because the rear wheels would have less weight on them from going downhill then the engine braking could have been apportioned more to the back than the front, meaning that the rear wheels could have started to slip as if he was applying the handbrake.

Kind of like one wheel loosing traction and spinning under power on a single diff, but in reverse.

Does that make sense? If all wheels are turning at the same time with same amount of power then you are less likely to start slipping.

[Steve_t647]

or become a 4 wheel drift and you have no control, on a skifield road like mount hut that may not be such a good look.

With a good driver well trained and who know's their 4x4 there are benefits to using the centre diff lock but not for anyone who doesn't drive these type of roads or offroad a lot, with the centre diff locked you have to be very carefull turning as you have power (locked 2wd) to the front and back wheel's with the least grip, this can cause the car to pivot around a wheel or slide sideways.

You or I may feel what is happening and be able to unlock the centre and regain control but asking someone new to 4wd to do that on ice is a pretty big ask.

Chains on the driving wheels or on the back of my 4wd is the best soloution (I did see once a front drive car attempt to go up the skifield with chains on the back), and I know the front helps cornering but you have to hang onto the steering wheel! after a day snowboarding in a leaf sprung hilux.

4wd will get you across a lot of rock mud rivers etc but Ice is a little more tricky, going slower (if possable) also makes the whole slide a lot slower too.

[albundy]

thanks for the info guys, I will feed it back to him. Might offer him a spot on the next training day . Asked him out on a tag along trip but after seeing the photos of some of opur trips he politely declined my offer, wonder why
Al

[Petemcc]

just like alot most driving situations most people dont know the dangers or exactly what they are doing. people go way to fast on the ski feilds in my opinion. take it slow and you will get down safe or in the worst case slide slowly into a bank etc. yes engine breaking will cause you to slide more if you are in a slide but use it instead of breaks to help prevent the slide. if you start sliding then do as mike said or accelerate and try to keep the wheels spinning at the same speed as the car to get max control.

4wd will help you on the way up but wont really do shit when you are going down, alot of people think they are bullet proof with 4wd and a just as many 4wds if not more than 2wd are in the accadents on ski fields.

Pete