by Hole in the Cart: Controlling Rust

The hardest thing you may ever have to do is release your brakes when you so desperately need to stop. Sometimes that’s the only way to avoid doing a whole lot more damage. On slippery roads, locking up any or all of your wheels can cause a loss of traction that often results in a skid. This could lead to a jackknife or a trailer skid.

Either way, until you get the wheels rolling again, you’re at the mercy of the laws of physics: you will continue in your present direction until you encounter some form of resistance, like the vehicle you were trying to avoid hitting in the first place.

On slippery roads, it’s possible for the steering axle, the drive axle, or the trailer axle to skid. You can have any combination of the three, or all three happening together. Each type of skid is handled differently, but each relies on the same principle: getting the skidding wheels turning again in order to regain rolling traction.

Drive-axle lock-up is the most common skid that results in a jackknife. It’s usually caused by over-braking, but can be caused by over-acceleration as well, such as when powering through a turn or using cruise-control on slippery roads. Time is a major factor in correcting a drive-axle skid because a jackknife can develop in about 1.5 seconds. You want the wheels to regain rolling traction as quickly as possible. The best way to do this: push in the clutch and release the brakes (allowing the wheels to roll freely) while trying to steer the tractor out of the skid.

A trailer skid usually develops more slowly (allowing a better opportunity for recovery, and is caused by locking the trailer wheels. To correct this skid, you must get the wheels rolling freely again by releasing the brakes. If room permits, accelerate gently until the trailer is again following straight behind the tractor.

Trailer skids often happen on city streets during the winter. The trailer wheels lock, then begin sliding down the crown of the road towards the parked cars on the right. If the driver releases the brakes there is the possibility of running into a vehicle stopped in front, but continued braking will result in the trailer sliding into the parked vehicles. This is especially true in the LTL world where partial loads mean the drive axles may run heavier than the trailer axles.

The best way to counteract this type of skid is to use moderately heavy braking to make use of the traction the drive wheels have, but to release the brakes as soon as the trailer starts to slide off track. Reapply the brakes as soon as the trailer has straightened out. This of course demands that you watch the front of the vehicle to maintain adequate stopping distance, and watch the mirrors as well to observe the action of the trailer.

A steer-axle skid will result in the loss of steering control over the vehicle, causing it to travel in a straight line. To correct a steer-axle skid caused by over-braking, the driver must get the wheels pointed straight ahead again and release the brakes. In a skid resulting from loss of traction during a steering manoeuvre (too sharp a cut for road conditions), speed must be reduced to allow the steer tires to regain traction.

Once the wheels have regained rolling traction, the turn can be attempted again. But as often happens, the front end could again start to slide. This demands a series of short, sharp back-and-forth motions of the steering wheel — pulling in the direction of the turn, then back to centre. Each turn of the steering wheel generates a slight change in direction before traction is lost. Straightening the wheel re-establishes traction, then it’s turned sharply again, generating a slight change in direction, etc.

Even armed with this knowledge, don’t ever forget that the best way to control a skid is to avoid getting into the situation that caused the skid in the first place. Allow sufficient following distance, look far ahead, and plan your moves well in advance. If you’re forced to take evasive action, steering is often safer than braking. A driver should be constantly looking for a way out, just in case something happens up ahead.

Remember, drive for where you’re going, not for where you are.

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