Section 2 – Driving Safely Page 2-34 Page 2-34  Section 2 – Driving Safely  2005 Model Commercial Driver’s License Manual • As you slow down, monitor your tractor and trailer  and back off the brakes (if it is safe to do so) to  stay in control.  • ABS won’t allow you to drive faster, follow more  closely, or drive less carefully.  • ABS won’t prevent power or turning skids–ABS  should prevent brake-induced skids or jackknifes,  but not those caused by spinning the drive  wheels or going too fast in a turn.  • ABS won’t necessarily shorten stopping distance.  ABS will help maintain vehicle control, but not  always shorten stopping distance.  • ABS won’t increase or decrease ultimate  stopping power–ABS is an “add-on” to your  normal brakes, not a replacement for them.  • ABS won’t change the way you normally brake.  Under normal brake conditions, your vehicle will  stop as it always stopped. ABS only comes into  play when a wheel would normally have locked  up because of over braking.  • ABS won’t compensate for bad brakes or poor  brake maintenance.  • Remember:  The best vehicle safety feature is  still a safe driver.  • Remember:  Drive so you never need to use  your ABS.  • Remember:  If you need it, ABS could help to  prevent a serious crash.  2.19 – Skid Control and Recovery  2.18.7 – Braking If ABS Is Not Working  2.19.1 – Drive-wheel Skids  2.18.8 – Safety Reminders  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 over-brake or over- steer from too much speed.  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.  As a system check on newer vehicles, the  malfunction lamp comes on at start-up for a bulb  check and then goes out quickly. On older systems,  the lamp could stay on until you are driving over  five mph.  If the lamp stays on after the bulb check, or goes  on once you are under way, you may have lost  ABS control on one or more wheels.  Remember, if your ABS malfunctions, you still have  regular brakes. Drive normally, but get the system  serviced soon.  Vehicles with ABS have yellow malfunction lamps  to tell you if something isn’t working. Without ABS you still have normal brake functions.  Drive and brake as you always have.  There is only one exception to this procedure. If  you drive a straight truck or combination with  working ABS on all axles, in an emergency stop,  you can fully apply the brakes. 