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-   -   Do Diff locks compensate for lack of articulation? (https://www.team-bhp.com/forum/4x4-technical/77930-do-diff-locks-compensate-lack-articulation.html)

A question about articulation and diff locks.
In my opinion, if a vehicle has diff locks, then articulation stops being a bothersome point.
I mean what will articulation do? Ensure all 4 wheels are touching the ground even if all 4 are on different levels.
In a vehicle with poor articulation, one wheel will lift off, with only 3 wheels on ground. But if there are diff locks in the vehicle, it does not matter, right?
From what I read and know. the biggest problem in 4x4s is 2 wheels losing traction, 1 front and 1 rear. In a diff lock equipped vehicle, it won't be a problem at all, right?
Why is it then diff locks are considered "just another feature". In my opinion, a diff lock is the best thing a 4x4 can have! Isn't it so?

So if you have choice between articulation and Diff locks, which would you choose?

A very view. Yes Diff locks are a big plus! But it doesn't entirely is a compensation for lack of articulation. There are certain draw backs of diff locks and hence must be used only when required.

Diff locks slows down the vehicle considerably as there is more resistance, turning radius increases and puts severe stress on the aggregates.

In a situation like moving on uneven sandy terrain and negotiating shrubs and driving you cannot lock all your wheels always as you will have to stop too often to taken even a minor turn.

Yes, but in all OTRs I have been too, there are only few places and climbs where articulation plays a part. Here even the jeeps stop, to take a re-look at the trail. Engaging diff locks here will take only few seconds.
So only at the toughest sections where one wheel would lift, you would engage diff locks. Not everywhere.

As TSK already said that you need Diff locks only when one front and one rear wheel looses traction and vehicle is unable to move or if the vehicle is stuck. I haven't seen anyone doing offroading with diff locks on during the entire offroad event so why would anybody apply diff loacks unless he is stuck and put unnecessary strain on aggregates.

I think if jeeps have more articulation then gurkha, the only advantage that jeep would have is that it will require less need for diff locks but in india jeeps can just dream of diff locks.

That's the reason i said Diff locks are most definitely a big plus!! No taking credit away from it. Depends upon situation to situation! This is the precise reason why even some jeeps have diff locks!

The problem with Gurkha is when terrain becomes just about more than even it needs diff locks to move. This is more observed in sand and slush than on hard ground or hard rocky surfaces.

No, one feature can't compensate for the other completely.

1) Even if all 4 wheels are on the ground, if the one front and one rear wheel has no traction, the vehicle is stuck. Articulation has no advantage here. Only diff locks will help.

2) In an extremely uneven ground, your wheels may go up in air and you may be in a danger of tipping over. Having good articulation would reduce this danger to a good extent. While diff locks will help you retain torque when wheels are up in air, it won't stop you from tilting or tipping over.

Both have their advantages, but one cannot replace the need for the other.

But if you compare the two, which feature you think is more desirable in an OTR event?

Hi TSK,

Diff-Locks can compensate for lack of Articulation.

I think of articulation;

As the combined action of Chassis, Body, Suspension and Transmission (Wheels & Axles) setup in a vehicle, to allow the wheels to adhere to undulating terrain, or bear the weight of the vehicle down on uneven ground, to get more traction.

Also Articulation can be expressed as the ability of the vehicle’s chassis, body, suspension and Transmission (Wheels & Axles) to move over undulating terrain, with out causing a change in Centre of Gravity (Major Change or Rapid Change = Roll-Over), and facilitating vehicle movement.

Articulation is more desirable.

Regards,

Arka

Rightly said,agree:

Arka, whenever weight transfer takes place (lateral or longitudinal) CG gets affected, by flexing of transmission you mean only wheels and axles right?

Spike:D

Great question. Good you asked this and should make for some interesting discussion and view points.

The examples/scenarios you mentioned are spot on.

Also depends what kind of event/terrain it is -- but for me it is diff-lock any day.

You know what, here is a nice traction vs articulation article. Has all the details.

2007 Jeep Wrangler Rubicons - 4Wheel & Off-Road Magazine

Hi Spike,

Even the Gearbox and Divorced T-Case (where applicable) flexes, so do the cross-members.

Hope that clarifies:D

Regards,

Arka

Look at articulation not only as expansion but also contraction. As already pointed out articulation would reduce roll over chance and allow the control of steering/direction. Diff lock will be a plus in many situations. For really tough OTR's having both would be essential alongwith buckets of torque, short wheel base, over square chasis and ground clearance.

Good interesting topic and a great concise explanation.


Everything has a part to play, even LSD. A rough turning, LSD will come into play - diff locks may be not. LSD with controlled torque flow by accelerator can be effective too till some extent may be but not for too rough OTRs.

Articulation with short bursts of controlled torque - a 2wd can surprise oneself.

Got a query from that "never-ending" Thar thread - a rut with coil spring better or IFS for traction - diff lock will be needed more here with coil or leaf spring for traction? rather than for the IFS? Any explanation.

Hi ADC,

A Solid Axle will always offer better traction as the vehicle weight is distributed on the Axle, hence the wheels.

In IFS application of weight does not shift from one side to the other, as the Independent Suspension arms move up or down.

This makes for good rough road handling.

However if the COG changes, then the lower side independent arm takes up most of the weight.

Diff-Lock will be needed more with Leaf-Spring, as Solid Axle Coil Spring offers better articulation.

However the Solid Axle Coil Spring suffer from a slight axle wrap under acceleration, which does not happen in Solid Axle Leaf Spring.

Regards,

Arka

Hi ADC,

A Solid Axle will always offer better traction as the vehicle weight is distributed on the Axle, hence the wheels.

In IFS application of weight does not shift from one side to the other, as the Independent Suspension arms move up or down.

This makes for good rough road handling.

However if the COG changes, then the lower side independent arm takes up most of the weight.

Diff-Lock will be needed more with Leaf-Spring, as Solid Axle Coil Spring offers better articulation.

However the Solid Axle Coil Spring suffer from a slight axle wrap under acceleration, which does not happen in Solid Axle Leaf Spring.

Regards,

Arka