General 4×4 Terminology

By 11th Dec 2017 Sep 21st, 2018 4x4 Knowledge
General 4x4 Terminology

General 4×4 Terminology

 

The 4×4 lifestyle has its own set of terminology that can be quite daunting for beginners. Let’s unpack some of the general 4×4 terminology.

 

Traction control

The Differential Lock, is more commonly known to off-roaders as a ‘locker’ the differential lock or diff-lock is fitted to a standard open differential.

A vehicle axle has two drive shafts joined to the differential that are driven by the differentials gears. This allows wheels to rotate at different speeds when turning around corners. The gearing allows a different rotational speed. In a left hand turn, the differential will slow down the left hand rear wheel, allowing the right hand outside wheel (which has less traction) to cover the greater radius/distance. This also prevents tyre scrubbing or scuffing.

This is a drawback off-road. When the loss of traction to a wheel is sensed by the differential, more rotational speed is directed to that wheel causing it to spin – at this point you are generally stuck.

That’s when the diff-lock is useful – it locks both wheels, making them turn together regardless of the traction. This allows the wheel that has traction to drive through the obstacle.

A diff-lock may be engaged electronically, pneumatically or hydraulically. Engage the diff-lock before entering the obstacle.

The same principle applies to diff-locks fitted to front and rear axles as well as the centre diff-lock s fitted to full-time 4WD vehicles.

Open centre differentials prevent ‘wind up’ between the front and rear axles and should be engaged when the vehicle goes off-road.

Diff-locks are generally fitted as original equipment (OE) by most 4×4 vehicle manufacturers. They are engaged by a switch fitted to the dash or centre console. The benefits of this system are better drivability, with the on-demand locking capability.

Remember that the drive train components and tyres are under tremendous strain if you leave a diff-lock on while driving on a hard surface.

 

A diff-lock is very useful in vehicles fitted with independent suspension where axle articulation is limited.

Limited Slip Differentials These are a compromise, they operate automatically with a smooth action directing additional torque to the wheel with traction. They are more capable than open diffs, but are not as capable as the full lock-up of a diff-lock (50/50 power split). They are a safety feature as they will operate when slip is sensed e.g. If you skid in wet conditions!

Traction control systems use wheel-sensors coupled to a central processing unit (CPU) to monitor wheel speeds, if wheel-slip is sensed, the traction control system momentarily applies brakes to the slipping wheel, transferring power to the wheel that has traction. Many of these systems use the ABS system (anti-lock braking) to perform this function.

We hope that you find these tips useful and welcome your comments and personal input as well.

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