CHAPTER 18

SKID CONTROL & RECOVERY

 

Introduction

 

A sliding vehicle is an uncontrollable vehicle, to put it simply. A skid may be avoided far more easily than it can be stopped. This chapter of our online ELDT course will discuss what causes a vehicle to skid, several kinds of vehicle skids, and safe response strategies.

 

Skid Dynamics

 

Traction, wheel load, and force of motion are among the variables that influence vehicle control. A skid will happen if there is an imbalance between these vehicle control elements.

 

Traction — The grip your tires have on a road surface is referred to as traction. How much control you have over your car depends in part on traction. Your car will be difficult to manage if traction is inadequate, which might cause it to slide.

 

Wheel load — The downward force of the weight on a wheel is referred to as wheel load. Wheel load is determined by the vehicle's weight and load distribution. Keep in mind that while wheel load may increase the amount of tire tread on the ground and the downward force, this may not enhance traction.

 

Force of motion — Force of motion is determined by the weight and speed of the vehicle. The heavier the vehicle and its cargo, and the faster it travels, the greater the force. Speeding up, braking too quickly, or changing direction too quickly can affect the force of motion.

 

Causes of Skids

 

Skids are mostly brought on by excessive braking, turning, and acceleration.

 

Overbraking — Overbraking refers to abrupt, excessive braking that causes the wheels of the car to lock up.

 

Oversteering — Oversteering is turning the wheels more sharply than the vehicle can turn.

 

Overacceleration — When the drive wheels get too much power, they start to lose traction.

 

The most frequent skid occurs when the tractor's rear wheels lose traction as a result of severe braking or acceleration. Overacceleration-related skids most often happen in the rain, ice, or snow on slick terrain.

 

Tractor-Trailer Skids

 

Tractor-trailer skids are classified based on what occurs during the skid. There are four major kinds of skids: Trailer jackknife; Tractor jackknife; Front wheel skid; and All-wheel skid.

 

Trailer jackknife — A trailer jackknife may be caused by excessive braking or maneuvering. When a trailer jackknifes, the tires lock, forcing the trailer to slide.

 

The trailer will keep moving forward at a faster rate than the tractor while overbaking. It will slide about since it can't go ahead.

 

The rear of the trailer could keep moving in the same direction as the tractor and the front of the trailer turns when a bend is taken too quickly for the surface conditions.

 

To prevent a trailer jackknife:

  • Inspect your air system, and check brake adjustments;

  • Adjust your speed to suit conditions;

  • Read the road ahead;

  • Avoid braking in curves (brake before entering the curve); and

  • Avoid hard braking.

 

Tractor jackknife — The loss of traction on the driving wheels causes a tractor to jackknife. Wheel lock-up or excessive acceleration may be the cause of this. In this case, the driving wheels try to replace the front wheels, which causes the tractor's back to swing out. The trailer keeps moving in the direction it was headed while the tractor takes the route of least resistance. The tractor will then jackknife when the trailer pivots and pulls the back of the vehicle outward.

 

To prevent a tractor jackknife:

  • Prevent excessive braking, excessive acceleration, and abrupt downshifts;

  • Properly load your stuff, ensuring sure it's secure; and

  • When doing your pre-trip examination, give the braking system and tyre tread particular attention.

 

Front wheel skids — Front-wheel skids are mostly caused by decreased front-wheel traction. Decreased front wheel traction may be caused by a heavy load on the fifth wheel, worn-out front tires, hydroplaning, oversteering, and braking system problems, among other things.

 

A good inspection of the following vehicle components can aid in pre- venting front wheel skids:

 

  • Tires;

 

  • Front wheel alignment;

 

  • Suspension system; and

 

  • Fifth wheel lubrication.

 

On slick or wet roads, slowing down the speed of the car may also assist avoid skids.

 

All-wheel skids —In an all-wheel skid, all wheels are locked. The traction/friction changes from rolling to sliding when the wheels are not spinning. Normally, even when you try to turn, an all-wheel skid keeps your automobile rolling ahead. The most important contributing component is over braking in slippery situations. Avoiding excessive speed and braking is the greatest approach to avoiding an all-wheel skid, particularly on slick surfaces.

 

Skid Recovery

 

The following technique can be used to recover from the majority of tractor skids.

 

  • Stop braking or accelerating — Disengage the clutch and steer. If you have an automatic, shift it into neutral. This allows the drive wheels to roll again, keeping them from sliding any further.

  • Turn quickly — When your vehicle begins to slide sideways, quickly steer in the direction you want the vehicle to travel.

  • Countersteer — Your tractor can continue turning while it returns to its original path. Countersteering stops your car from swerving in the other direction.

 

Once your vehicle is again traveling in a correct path, you can use your brakes to stop. A light, steady application is the preferred technique.

 

Front wheel skids — wheel skids are the result of driving too fast for the road conditions. Other factors include the front tires' lack of wear and inappropriate cargo loading (not enough weight on the front axle).

 

In a front wheel skid, the front end tends to go in a straight line regardless of how much you turn the steering wheel. On a very slippery surface, you may not be able to steer around a curve or a turn.

 

The only method to halt a front-wheel skid is to allow the car to slam on the brakes. Do not turn when braking or hard-brake. As soon as it's secure to do so, slow down.

 

 

SUMMARY

 

You have learned about the causes of skids and skid prevention in this chapter. Additionally, you have learned about the typical methods for recovering from a skid