How to cross diverse terrain in a 4×4 vehicle

By 20th Jan 2019 Mar 18th, 2019 4x4 Knowledge, Terrain Crossing
crossing diverse terrain

How to cross diverse terrain in a 4×4 vehicle

The driver should always be comfortably seated. You should be in a position that ensures that you are not pulled away from the wheel when ascending a slope or pushed forward when descending a slope.

Keep your seatbelt on and your thumbs away from the steering wheel spokes. Your thumbs could get injured if the steering wheel ‘kicks back even with power steering. Your legs and arms should be bent when holding the steering wheel and using the foot pedals.

The vehicle dynamics of an off-road vehicle are different to a road car. An off-road vehicle has different handling due to it’s intended purpose, some of the differences you will notice are:

  • Off-road tyres are ‘noisier’ and your stopping distance is increased.
  • The centre of gravity has an influence on handling, a heavily weighted roof rack may cause weight transfer when cornering – lower speeds are necessary.
  • The heavier weight of the vehicle also influences your stopping distance.
  • Your driving speed must be adapted to road conditions especially if your vehicle is laden.

Hand Positions

A ten-to-two position was taught in the past. With the advent of air-bags, one should drive with your hands in a ‘quarter-to-three’ position. If the air-bag deploys your arms will be away from the force of the bag.

Keep the vehicle’s windows closed almost fully, as you do not want branches to swing into the vehicle and injure you or your passengers. This is also safe practice in the event of a roll-over, as all the occupants’ arms will be inside the vehicle.

seating positionsYour ‘Line’

A key off-road skill is the ability to select or ‘read’ a ‘line’. A good ‘line’ allows you to keep all four wheels in contact with the ground and maintain traction through an obstacle. Learning to ‘read’ a ‘line’, coupled to the knowledge of your vehicle, will enhance your off-road experience.

Look Before You Proceed

If conditions allow, get out of your vehicle and check the obstacle by walking through it to determine a safe entry and exit point. Use a passenger to guide you through difficult obstacles that may have hidden hazards. Take nothing for granted.

It may be necessary to fill ruts and axle twisters with rocks or sand to maintain your ‘line’. Rebuilding a section of the trail will ensure your safe passage and it also helps maintain the trail for other vehicles.

Wheel-spin is not advised as it results in a lack of traction and damages the trail. You should decelerate and re-evaluate your ‘line’.

Keep a safe distance between vehicles. Only enter an obstacle when you are sure the vehicle in front of you has cleared the obstacle and is a safe distance away.

You should avoid travelling after sunset. This is when most vehicle collisions occur between animals and other unlit vehicles.

  • Use the correct gear (high- or low-range).
  • Tyres should be at an appropriate pressure for the terrain.
  • Use the vehicle’s traction control systems. This may be a limited-slip differential, a differential lock or electronic traction control.
  • Where precise throttle control is required, force your foot against the side-wall next to the accelerator and ‘roll’ it onto the accelerator. If things get rough, you should be able to maintain smooth throttle control.

The Stall-Start

Learn the stall start and practice.

Manual Transmission

  • Once you have stalled, hold the vehicle on its foot-brake and handbrake.
  • Then engage the low-range reverse gear or 1st gear if stalled on a descent.
  • Remove your foot from the clutch.
  • Release the handbrake.
  • Remove your foot from the brake.
  • The vehicle will hold itself on the slope.
  • Turn the ignition key.
  • The vehicle will start and move back slowly or forward if on a descent.
  • Check and control your descent until you are in a position to stop and re-negotiate the obstacle.

Automatic Transmission

You are not going to stall with an automatic transmission, but may come to a halt caused by the terrain. You will need to establish why you stopped as you may have to move a rock or fill a small hole or rut.

  • Hold the vehicle with its foot-brake, engage handbrake.
  • Engage reverse-low range or 1st gear if stopped on a descent.
  • Release the handbrake.
  • Release the foot-brake slowly and reverse or descend.

If you have a vehicle that only starts with the clutch depressed

  • Engage the handbrake.
  • Depress the clutch and foot-brake.
  • Engage the appropriate gear.
  • Start the engine.
  • Release the handbrake, clutch and foot-brake simultaneously, then reverse or descend slowly.

In a ‘stall-start’, you may have to cadence brake while ascending or descending the slope until the engine braking takes place.

If you stalled on a descent, check the front of your vehicle. There may be an obstacle that has caused the stall.

On an ascent, one generally stalls because of insufficient momentum.

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