Braking Heavy Vehicles Flashcards
How long is the average driver’s reaction time?
3/4 of a second
What factors make up total stopping time?
- driver’s perception
- driver reaction
- brake lag
- brake time
How many seconds behind should larger trucks and buses be behind the car in front of them?
5
How much more stopping power is required if the speed is doubled?
4 times the power
How much more stopping power is needed if the weight is doubled?
2 times the power
How much more stopping power is required if both the speed and weight are doubled?
8 times the power
What is brake fade and how can it affect a vehicle?
Brake fade occurs when the brakes overheat from overuse. It can take longer to stop, especially if speed is not already controlled.
What are the main types of retarders?
-engine, exhaust, electric driveline, hydraulic driveline
When is an engine retarder more efficient?
At a higher RPM and lower speed.
How do you ensure a smooth controlled stop every time?
- ensure an adequate following distance
- travel at a speed that allows you to see a safe distance ahead
- use good braking skills
What factors, other than driver actions, will affect safe vehicle braking?
To stop safely, ensure that your brakes are correctly adjusted, your load is balanced and your tires are in good condition. Also, be certain that your tires
are properly inflated
What braking technique should be used on icy roads? And why?
You should use extremely light pressure on the brakes. This will stop the wheels locking up. It is better to have a spinning wheel than a locked wheel.
When should you put on tire chains?
After you install them, and begin driving, what should you do?
Before a snowy or icy slope.
Check them at the first safe opportunity, for tightness.
On a hill, what are some notes to remember regarding gears? (2)
You should use a lower gear when descending, than you would for ascending.
Never change DOWN gears on a downslope; UNLESS you can control the speed with retarder or engine compression.
How can you ensure that you won’t need to use the service brakes when descending a hill?
Ensure that you keep an appropriate, safe speed and low gear and use the retarding device.
If you haven’t been able to control the speed down a hill, what should you do?
Brake gently to reduce the speed by 10-15km/hr
Downshift to a lower main gear.
(Be careful using this procedure on icy roads)
Explain what to do if you need to drive through a pool of water on the road.
Slow down. Put foot over the brake. When driving through the water put a slight but constant drag on the brakes. After the pool, apply a gentle constant pressure again, for a short distance, to dry out the brakes.
Wha can cause jack-knifing?
Improper braking technique, and improper use of retarders.
What are some things to remember with EMERGENCY Braking?
-Apply firm, hard continuous pressure to the brake pedal until the vehicle stops.
• Don’t pump the brakes — this turns the system on and off.
• Don’t be alarmed by brake noise, pedal movement or shudder. This is normal. Keep applying firm pressure.
• Be extremely cautious when steering around obstacles. Remember that steering and handling characteristics will be affected by the size and load of
the vehicle you’re driving, and by the trailer you may be towing.
• When you operate combination vehicles, make sure you know which of the units have ABS. If the tractor and trailers do not all have ABS, apply the
brakes as if you were operating a combination without ABS.
Explain ATC and how it works.
Automatic Traction Control - works by sensing if one wheel is spinning and braking that wheel, transferring power to the other side.
