Put simply, a skidding vehicle is out of control, and when you are operating a Class 8 heavy-duty commercial tractor with a trailer or two behind you, a skid could be deadly.
It is much easier to prevent a skid than to correct one. Once you are already skidding, the danger to you and those around you increases exponentially. Let’s take a deeper look at what causes a vehicle to skid, the types of vehicle skids, and what you should do if you find yourself in a skid.
The Dynamics of a Skid
The fact is, a skid happens when a vehicle’s tires lose their grip on the road. This could mean two or more tires entering a hydroplaning situation.
There are a number of factors that contribute to wheel skid. They include traction, wheel load, and the force of the vehicle’s motion. If any of these forces are imbalanced, a skid may occur.
Let’s take a look at each one individually:
- Traction: Traction is represented by the grip your tires have on the road. Of course, traction is one of the most important aspects of how much control your vehicle has over the road. If your traction is poor, your vehicle control will be poor, you may find yourself in a skid.
- Wheel load: Wheel load represents the downward force put on the wheel. The weight of the vehicle and the distribution of the load determine your final wheel load number. Although wheel load can increase downward force, this may not always improve traction.
- Force of motion: Force of motion is determined solely by the weight and speed of the vehicle. When the vehicle and its cargo are heavier, their proper motion is faster. Speeding up, braking suddenly or quickly changing direction can impact the vehicle’s force of motion.
What Causes a Skid?
There are a few major causes of a skid, outside of inclement weather – though even in inclement weather a capable, professional truck driver should be able to keep themselves from entering into a skid.
- Overbraking: If you brake too hard, your wheels will lock up.
- Oversteering: If you turn your wheels more sharply than the vehicle can actually make the turn, you may lose traction.
- Overacceleration: When you are applying too much power to the drive wheels, you could cause them to loose traction.
Above all, never drive too fast for the conditions. If you are on a wet or snowy road, you must always exercise extra caution to avoid loosing control of the vehicle.
If you overbrake or oversteer you can cause your trailer to jackknife. When this happens, the trailer tires lock, causing it to enter into a skid.
When you overbrake, you cause the trailer to move forward at a higher speed than the tractor. When you take a curve too fast, the rear of the trailer may continue on in the same direction as it was originally heading, even as the tractor in front enters into a turn.
To prevent this:
- Make sure your air system and brakes are in top working order
- Adjust your speed to suit the driving conditions
- Make sure you are reading the road ahead
- Try not to brake in curves
- Avoid hard braking
If your tractor is jackknifing, caused when the drive wheels loose traction, the drive wheels will attempt to overtake the steer wheels, while the trailer follows a path of least resistance. As the trailer pivots, the rear of the tractor is pushed outward.
To prevent a tractor jackknife, you must:
- Not overbrake, overaccelerate or downshift in a sudden manner
- Make sure your cargo is properly loaded and secured
- When conducting your pre-trip inspection, carefully examine your brake system and tire treads.
Skid control and recovery is not an easy task to perform. Learning to follow skid recovery steps takes a lot of practice. In the end, the best way to recover from a skid is to ensure you never enter into one in the first place.