2.19 Skid Control and Recovery

A skid happens whenever the tires lose their grip on the road. This is caused in one of four ways:

Over-braking. Braking too hard and locking up the wheels. Skids also can occur when using the speed retarder when the road is slip­pery.

  • Over-steering. Turning the wheels more sharply than the vehicle can turn.
  • Over-acceleration. Supplying too much pow­er to the drive wheels, causing them to spin.
  • Driving Too Fast. Most serious skids re­sult from driving too fast for road conditions. Drivers who adjust their driving to conditions don't over-accelerate and don't have to over­brake or over-steer from too much speed.

 2.19.1 Drive-wheel Skids

By far the most common skid is one in which the rear wheels lose traction through excessive braking or acceleration. Skids caused by accel­eration usually happen on ice or snow. Tak­ing your foot off the accelerator can easily stop them. (If it is very slippery, push the clutch in. Otherwise, the engine can keep the wheels from rolling freely and regaining traction.)

Rear wheel braking skids occur when the rear drive wheels lock. Because locked wheels have less traction than rolling wheels, the rear wheels usually slide sideways in an attempt to "catch up" with the front wheels. In a bus or straight truck, the vehicle will slide sideways in a "spin out." With vehicles towing trailers, a drive-wheel skid can let the trailer push the towing vehicle sideways, causing a sudden jackknife. See Figure 2.19.

2.19.2 Correcting a Drive­-wheel Braking Skid

Do the following to correct a drive-wheel braking skid.

  • Stop Braking. This will let the rearwheels roll again, and keep the rear wheels from sliding.
  • Countersteer. As a vehicle turns back on course, it has a tendency to keep on turning. Unless you turn the steering wheel quickly the other way, you may find yourself skid­ding in the opposite direction.

Learning to stay off the brake, turn the steer­ing wheel quickly, push in the clutch, and countersteer in a skid takes a lot of practice. The best place to get this practice is on a large driving range or "skid pad."

2.19.3 Front-wheel Skids

Driving too fast for conditions causes most front-wheel skids. Other causes include lack of tread on the front tires and cargo loaded so not enough weight is on the front axle. In a front­-wheelskid, the front end tends to go in a straight line regardless of how much you tum the steering wheel. On a very slippery surface, you may not be able to steer around a curve or turn.

When a front-wheel skid occurs, the only way to stop the skid is to let the vehicle slow down. Stop turning and / or braking so hard. Slow down as quickly as possible without skidding.

Test Your Knowledge - Subsections 2.17, 2.18 and 2.19

  • Stopping is not always the safest thing to do in an emergency. True or False?
  • What are some advantages of going right instead of left around an obstacle?
  • What is an "escape ramp?" 
  • If a tire blows out, you should put the brakes on hard to stop quickly. True or False?
  • How do you know if your vehicle has antilock brakes?
  • What is the proper braking technique when driving a vehicle with antilock brakes?
  • How do antilock brakes help you?

These questions may be on the test. If you can't answer them all, re-read subsections 2.17, 2.18, and 2.19.

2.20 Accident Procedures

When you're in an accident and not seriously hurt, you need to act to prevent further damage or injury. The basic steps to be taken at any accident are to:

  • Protect the area.
  • Notify authorities.
  • Care for the injured.

2.20.1 Protect the Area

The first thing to do at an accident scene is to keep another accident from happening in the same spot. To protect the accident area:

  • If your vehicle is involved in the accident, try to get it to the side of the road. This will help prevent another accident and allow traffic to move.
  • If you're stopping to help, park away from the accident. The area immediately around the accident will be needed for emergency vehicles.
  • Put on your flashers.
  • Set out reflective triangles to warn other traffic. Make sure other drivers can see them in time to avoid the accident.

2.20.2 Notify Authorities

 If you have a cell phone or CB, call for as­sistance before you get out of your vehicle. If not, wait until after the accident scene has been properly protected, then phone or send someone to phone the police. Try to determine where you are so you can give the exact location.

2.20.3 Care for the Injured

If a qualified person is at the accident and helping the injured, stay out of the way unless asked to assist. Otherwise, do the best you can to help any injured parties. Here are some simple steps to follow in giving assistance:

  • Don't move a severely injured person unless the danger of fire or passing traffic makes it necessary.
  • Stop heavy bleeding by applying direct pres­sure to the wound.
  • Keep the injured person warm.