CDL Exam Prep
What does Rearward Amplification case?
"Rearward amplification" causes the crack-the-whip effect. Figure 6.1 shows eight types of combination vehicles and the rearward amplification each has in a quick lane change. Rigs with the least crack-the- whip effect are shown at the top and those with the most, at the bottom. Rearward amplification of 2.0 in the chart means that the rear trailer is twice as likely to turn over as the tractor. You can see that triples have a rearward amplification of 3.5. This means you can roll the last trailer of triples 3.5 times as easily as a five-axle tractor.
Motor carriers must not allow nor require drivers to use a hand-held mobile telephone while driving. Employers may also be subject to civil penalties in an amount up to $_____________.
$11,000
What is the purpose of a bicycle lane?
- Bicycle lanes are designed to separate bicycle traffic from normal vehicle traffic. - It is illegal to drive in these lanes except to enter or leave the road or to prepare for a turn. -Yield the right-of-way to approaching bicyclists. When the bicycle lane is clear, signal your intention to turn and then move into the bicycle lane before making the turn.
What is involved in a Final Air Brake Check (instead of a hydraulic brake check?)
- Test Low Pressure Warning Signal - Check That Spring Brakes Come On Automatically - Check Rate of Air Pressure Buildup - Test Air Leakage Rate - Check Air Compressor Governor Cut-in and Cut-out Pressures - Test Parking Brake - Test Service Brakes
What are the three different braking systems in Air brakes?
- service brake - parking brake - emergency brake
What are some general tips and tricks to avoid rollovers?
-Steer gently and smoothly when you are pulling trailers. -If you make a sudden movement with your steering wheel, your trailer could tip over. -Follow far enough behind other vehicles (at least 1 second for each 10 feet of your vehicle length, plus another second if going over 40 mph). -Look far enough down the road to avoid being surprised and having to make a sudden lane change. -At night, drive slowly enough to see obstacles with your headlights before it is too late to change lanes or stop gently. -Slow down to a safe speed before going into a turn.
If you are found to have a blood alcohol concentration of .____________percent or more while operating a NON-COMMERCIAL vehicle, your Class D driving privileges will be revoked.
.08% or more
You will lose your CDL for at least one year for a first offense if You drive a CMV when your blood alcohol concentration is ____________ percent or more.
0.04% If your blood alcohol concentration is less than 0.04 percent but you have any detectable amount, you will be put out of service for 24 hours.
If you are found to have a blood alcohol concentration of .08 percent or more while operating a non-commercial vehicle, your Class D driving privileges will be revoked and you will be disqualified from driving CMVs for at least ____________ year.
1 year
You will be disqualified from operating a commercial motor vehicle for ______________________ if, during any three-year period, you are convicted of three or more railroad grade crossing violations arising from separate incidents.
1 year
You will lose your CDL for at least ____________ year(s) for a first offense if you drive a CMV under the influence of alcohol or a controlled substance (for example, illegal drugs).
1 year
You will lose your CDL for at least ________________ year for a first offense if You commit an offense in another state that would be grounds for disqualification in Minnesota.
1 year for a first offense
Test Your Knowledge
1. What is a dual air brake system? 2. What are the slack adjusters? 3. How can you check slack adjusters? 4. How can you test the low pressure warning signal? 5. How can you check that the spring brakes come on automatically? 6. What are the maximum leakage rates?
Test Your Knowledge
1. Why should you be in the proper gear before starting down a hill? 2. What factors can cause brakes to fade or fail? 3. The use of brakes on a long, steep downgrade is only a supplement to the braking effect of the engine. True or False? 4. If you are away from your vehicle only a short time, you do not need to use the parking brake. True or False? 5. How often should you drain air tanks? 6. How do you brake when you drive a tractor- trailer combination with ABS? 7. You still have normal brake functions if your ABS is not working. True or False?
What are the 5 substances that are tested via urine? (drug tests)
1.Marijuana (THC metabolite) 2.Cocaine 3.Amphetamines 4.Opiates (including heroin) 5.Phencyclidine (PC) If you refuse to submit to a chemical test, you will be disqualified from operating a commercial motor vehicle for a period of one year and your driver's license will be revoked for one year.
Test Your Knowledge
1.Why must air tanks be drained? 2.What is a supply pressure gauge used for? 3.All vehicles with air brakes must have a low air pressure warning signal. True or False? 4.What are spring brakes? 5.Front wheel brakes are good under all conditions. True or False? 6.How do you know if your vehicle is equipped with anti-lock brakes?
Before driving a vehicle with a dual air system, allow time for the air compressor to build up a minimum of ____________psi pressure in both the primary and secondary systems.
100 psi Watch the primary and secondary air pressure gauges (or needles, if the system has two needles in one gauge). Pay attention to the low air pressure warning light and buzzer.
If you have committed three serious traffic violations while operating a CMV within a three-year period, you will lose your CDL for at least _________________ days.
120 days
You will be disqualified from operating a commercial motor vehicle for _________________ days if, during any three-year period, you are convicted of two railroad grade crossing violations arising from separate incidents.
120 days
The Safety valve is usually set to open at ______________ psi.
150 psi
_____________ disqualifying offenses will result in losing your CDL privileges for life.
2 disqualifying offenses
A driver's CDL will be disqualified after __________ or more convictions of any state law on hand-held mobile telephone use while operating a CMV.
2 or more
The spring brakes will come on when the air pressure drops into the range of _________ to ________ psi.
20 to 45 psi.
When passing, the law requires at least ____________ feet between the side of your vehicle and the bicyclist.
3 Feet of Space -When approaching turns, be sure to check side mirrors for bicyclists.
If a first disqualifying offense occurs while you are operating a CMV that is placarded for hazardous materials, you will lose your CDL for at least _____________ years.
3 years
You may not drink alcohol while you are on-duty or consume any alcoholic beverage within ____________ hours before you go on duty.
4 hours
Research commissioned by FMCSA shows that the odds of being involved in a safety-critical event(e.g., crash, near-crash, unintentional lane deviation) is ___________ times greater for CMV drivers who engage in dialing a mobile telephone while driving than for those who do not.
6 times greater
If you have committed two serious traffic violations while operating a CMV within a three-year period, you will lose your CDL for at least _______________ days.
60 days
You will be disqualified from operating a commercial motor vehicle for ________________ days if you are convicted of a railroad grade crossing violation.
60 days
Dual Air System: The warning light and buzzer should shut off when air pressure in both systems rises to a value set by the manufacturer. This value must be greater than ____________ psi.
60 psi The warning light and buzzer should come on before the air pressure drops below 60 psi in either system. If this happens while driving, you should stop right away and safely park the vehicle. If one air system is very low on pressure, either the front or the rear brakes will not be operating fully. This means it will take you longer to stop. Bring the vehicle to a safe stop, and have the air brakes system fixed.
On large buses it is common for the low pressure warning devices to signal at _______-_______ psi.
80-85 psi.
Where are Modulating Control Valves located?
A control handle on the dash board that is used to apply the spring brakes gradually. It is spring-loaded so you have a feel for the braking action. The more you move the control lever, the harder the spring brakes come on.
When is a Low Air Pressure Warning required?
A low air pressure warning signal is required on vehicles with air brakes. A warning signal you can see must come on before the air pressure in the tanks falls below 60 psi. (Or one half the compressor governor cutout pressure on older vehicles.) The warning is usually a red light. A buzzer may also come on.
How does the computer within ABS work?
ABS helps you avoid wheel lock up. The computer senses impending lockup, reduces the braking pressure to a safe level, and you maintain control. You may or may not be able to stop faster with ABS, but you should be able to steer around an obstacle while braking, and avoid skids caused by over braking. Having ABS on only the tractor, only the trailer, or even on only one axle, still gives you more control over the vehicle during braking. Brake normally.
What is the purpose of ABS?
ABS is an addition to your normal brakes. It does not decrease or increase your normal braking capability. ABS only activates when wheels are about to lock up. ABS does not necessarily shorten your stopping distance, but it does help you keep the vehicle under control during hard braking.
What do Air Storage Tanks do?
Air storage tanks are used to hold compressed air. The number and size of air tanks varies among vehicles. The tanks will hold enough air to allow the brakes to be used several times, even if the compressor stops working.
How do Supply Pressure Gauges work?
All vehicles with air brakes have a pressure gauge connected to the air tank. If the vehicle has a dual air brake system, there will be a gauge for each half of the system (or a single gauge with two needles). These gauges tell you how much pressure is in the air tanks.
What is a Wig Wag?
Another type of warning is the "wig wag." This device drops a mechanical arm into your view when the pressure in the system drops below 60 psi. An automatic wig wag will rise out of your view when the pressure in the system goes above 60 psi. The manual reset type must be placed in the "out of view" position manually. It will not stay in place until the pressure in the system is above 60 psi.
What is ABS?
Antilock Braking Systems ABS is a computerized system that keeps your wheels from locking up during hard brake applications. Vehicles with ABS have yellow malfunction lamps to tell you if something isn't working.
What is the Stab Braking method?
Apply your brakes all the way. Release brakes when wheels lock up. As soon as the wheels start rolling, apply the brakes fully again. It can take up to one second for the wheels to start rolling after you release the brakes. If you re-apply the brakes before the wheels start rolling, the vehicle won't straighten out.
Why is the manual adjustment of automatic slack adjusters dangerous?
Because it may give the driver a false sense of security regarding the effectiveness of the braking system. The manual adjustment of an automatic adjuster should only be used as a temporary measure to correct the adjustment in an emergency situation, as it is likely the brake will soon be back out of adjustment since this procedure usually doe snot fix the underlying adjustment problem.
What should be checked on Brake Drums (or discs), Linings and Hoses?
Brake drums (or discs) must not have cracks longer than one half the width of the friction area. Linings (friction material) must not be loose or soaked with oil or grease. They must not be dangerously thin. Mechanical parts must be in place, not broken or missing. Check the air hoses connected to the brake chambers to make sure they aren't cut or worn due to rubbing.
Where are Brake Drums located?
Brake drums are located on each end of the vehicle's axles. The wheels are bolted to the drums. The braking mechanism is inside the drum.
How to brakes work?
Brakes are designed so brake shoes or pads rub against the brake drum or disks to slow the vehicle. Braking creates heat, but brakes are designed to take a lot of heat. However, brakes can fade or fail from excessive heat caused by using them too much and not relying on the engine braking effect.
What are the main differences between Combination Vehicles and Single Commercial Vehicles?
Combination vehicles are usually heavier, longer, and require more driving skill than single commercial vehicles. This means that drivers of combination vehicles need more knowledge and skill than drivers of single vehicles.
Air brakes use ________________________________ to make the brakes work.
Compressed Air
How can you Check That Spring Brakes Come On Automatically?
Continue to fan off the air pressure by stepping on and off the brake pedal to reduce tank pressure. The tractor protection valve and parking brake valve should close (pop out) on a tractor-trailer combination vehicle and the parking brake valve should close (pop out) on other combination and single vehicle types when the air pressure falls to the manufacturer's specification (20 - 45 psi). This will cause the spring brakes to come on.
Disqualification is ______________ days for the second offense within 3 years and _________________days for three or more offenses within 3 years.
Disqualification is 60 days for the second offense within 3 years and 120 days for three or more offenses within 3 years. In addition, the first and each subsequent violation of such a prohibition are subject to civil penalties imposed on such drivers, in an amount up to $2,750.
When should you not use the parking brakes?
Don't use the parking brakes if the brakes are very hot (from just having come down a steep grade), or if the brakes are very wet in freezing temperatures. If they are used while they are very hot, they can be damaged by the heat. If they are used in freezing temperatures when the brakes are very wet, they can freeze so the vehicle cannot move. Use wheel chocks on a level surface to hold the vehicle. Let hot brakes cool before using the parking brakes. If the brakes are wet, use the brakes lightly while driving in a low gear to heat and dry them.
What is the purpose of a Stop Light Switch?
Drivers behind you must be warned when you put your brakes on. The air brake system does this with an electric switch that works by air pressure. The switch turns on the brake lights when you put on the air brakes.
What is the defined as Driving?
Driving means operating a commercial motor vehicle on a highway, including while temporarily stationary because of traffic, traffic control device, or other momentary delays. Driving does not include operating a commercial motor vehicle when the driver has moved the vehicle to the side of, or off, a highway and has halted in a location where the vehicle can safely remain stationary.
What are the restrictions around hand-held mobile telephones?
Effective January 3, 2012, a commercial motor vehicle (CMV) driver is restricted from: -holding a mobile telephone to conduct a voice communication -dialing a mobile telephone by pressing more than a single button. Hands-free use is allowed via either an earpiece or the speakerphone function of the mobile telephone.
Automatic air tanks are available with ______________________________________. These help prevent freezing of the automatic drain in cold weather.
Electric Heating Devices
What does ENS an abbreviation for?
Emergency Notification System Every highway-rail crossing has an Emergency Notification System (ENS) sign that provides a 24/7/365 telephone number to call to report problems or emergencies at the railroad location.
What is brake fade?
Excessive use of the service brakes results in overheating and leads to brake fade. Brake fade results from excessive heat causing chemical changes in the brake lining, which reduce friction, and also causing expansion of the brake drums. As the overheated drums expand, the brake shoes and linings have to move farther to contact the drums, and the force of this contact is reduced. Continued overuse may increase brake fade until the vehicle cannot be slowed down or stopped. Brake fade is also affected by adjustment. To safely control a vehicle, every brake must do its share of the work. Brakes out of adjustment will stop doing their share before those that are in adjustment. The other brakes can then overheat and fade, and there will not be enough braking available to control the vehicle(s). Brakes can get out of adjustment quickly, especially when they are hot. Therefore, check brake adjustment often.
Zipper Merge True or False: When you see the "lane closed ahead" sign in a work zone, slow quickly and move to the lane that will continue through the construction area immediately.
FALSE -When you see the "lane closed ahead" sign and traffic is backing up, stay in your current lane up to the point of merge. Then take turns with other drivers to safely and smoothly ease into the remaining lane. -When most drivers see the first "lane closed ahead" sign in a work zone, they slow quickly and move to the lane that will continue through the construction area. This can cause dangerous lane switching that is unexpected to other drivers, serious crashes and road rage.
True or False: You will lose your CDL for at least THREE YEARS for a first offense if you refuse to submit to an alcohol or drug test.
FALSE 1 YEAR
True or False: It is ok to alter any driver's license or Minnesota identification card.
FALSE This is unlawful, and would be a misdemeanor.
True or False: It is okay for a person to display or have in possession any fictitious or altered driver's license or Minnesota identification card.
FALSE This is unlawful, and would be a misdemeanor.
True or False: It would be considered legal to lend your driver's license or Minnesota identification card to any other person.
FALSE This is unlawful, and would be a misdemeanor.
True or False: You are allowed to take any part of the driver's license examination for another person, or allow another person to take the examination for you.
FALSE This is unlawful, and would be a misdemeanor.
True or False: A person may display as a valid driver's license any canceled, revoked or suspended driver's license.
FALSE This is unlawful, and would be a misdemeanor. (A person whose driving privileges have been withdrawn may display a driver's license only for identification purposes.)
True or False: Leaving the scene of an accident involving a CMV that you were driving will NOT cause you to lose your CDL for at least one year for a first offense.
FALSE. You will lose your CDL for at least one year for a first offense if You leave the scene of an accident involving a CMV that you were driving.
True or False: The most common type of Foundation Brake is the Disc Brake.
False The most common type is the s-cam drum brake. Foundation brakes are used at each wheel.
True or False: It is sometimes okay to not apply parking brakes or chock the wheels while unattended.
False Never leave your vehicle unattended without applying the parking brakes or chocking the wheels. Your vehicle might roll away and cause injury and damage.
True or False: You should brake differently when driving a tractor-trailer combination with ABS.
False When you drive a tractor-trailer combination with ABS, you should brake as you always have. In other words: -Use only the braking force necessary to stop safely and stay in control. -Brake the same way, regardless of whether you have ABS on the tractor, the trailer, or both. -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.
_____________ wheel braking is good under all conditions.
Front wheel braking Tests have shown front wheel skids from braking are not likely even on ice. Make sure the control is in the "normal" position to have normal stopping power.
What should you do if the Low Air Pressure warning comes on?
If the low air pressure warning comes on, stop and safely park your vehicle as soon as possible. There might be an air leak in the system. Controlled braking is possible only while enough air remains in the air tanks.
What is the Implied Consent Law?
If you drive a CMV on public roads in the state of Minnesota, you have automatically given your consent to a test of your blood, breath or urine to determine alcohol and/or drug concentration. If you refuse to submit to a chemical test, you will be disqualified from operating a commercial motor vehicle for a period of one year and your driver's license will be revoked for one year.
What does it indicate when the pushrod stroke exceeds the legal brake adjustment limit in a vehicle equipped with automatic adjusters?
In a vehicle equipped with automatic adjusters, when the pushrod stroke exceeds the legal brake adjustment limit, it is an indication that a mechanical problem exists in the adjuster itself, a problem with the related foundation brake components, or that the adjuster was improperly installed.
How do Disc Brakes work?
In air-operated disc brakes, air pressure acts on a brake chamber and slack adjuster, like s-cam brakes. But instead of the s- cam, a "power screw" is used. The pressure of the brake chamber on the slack adjuster turns the power screw. The power screw clamps the disc or rotor between the brake lining pads of a caliper, similar to a large c-clamp. Wedge brakes and disc brakes are less common than s-cam brakes.
Who has the right of way in a multiple lane roundabout?
In multiple lane roundabouts, if two vehicles with a total length in excess of 40 feet, a total width of 10 feet, or any combination of vehicles, approach and drive through at approximately the same time, the vehicle on the right must yield the right of way to the vehicle on the left and, if necessary, reduce speed or stop.
How do you put on the parking brakes in newer vehicles with air brakes?
In newer vehicles with air brakes, you put on the parking brakes using a diamond-shaped, yellow, push-pull control knob. You pull the knob out to put the parking brakes (spring brakes) on, and push it in to release them. On older vehicles, the parking brakes may be controlled by a lever. Use the parking brakes whenever you park.
How can you tell if an older vehicle is equipped with ABS?
In the case of towed units manufactured before it was required by the Department of Transportation, it may be difficult to tell if the unit is equipped with ABS. Look under the vehicle for the electronic control unit (ECU) and wheel speed sensor wires coming from the back of the brakes.
How do Wedge Brakes work?
In this type of brake, the brake chamber push rod pushes a wedge directly between the ends of two brake shoes. This shoves them apart and against the inside of the brake drum. Wedge brakes may have a single brake chamber, or two brake chambers, pushing wedges in at both ends of the brake shoes. Wedge type brakes may be self-adjusting or may require manual adjustment.
What should you do if your vehicle becomes stalled on railroad tracks and a train is approaching?
Leave the vehicle. To avoid being struck by debris from the collision keep a safe distance from the tracks. Walk quickly in a 45 degree angle away from the tracks in the direction from which the train is approaching.
What action can cause the trailer to turn over via the "crack-the-whip" effect?
Making a quick lane change Trucks with trailers have a dangerous "crack-the- whip" effect. When you make a quick lane change, the crack-the-whip effect can turn the trailer over. There are many crashes where only the trailer has overturned.
What are the two types of drain valves in air tanks?
Manually operated by turning a quarter turn or by pulling a cable. You must drain the tanks yourself at the end of each day of driving. See Figure 5.1. Automatic--the water and oil are automatically expelled. These tanks may be equipped for manual draining as well.
What do automatic front wheel limiting valves do?
Many vehicles have automatic front wheel limiting valves. They reduce the air to the front brakes except when the brakes are put on very hard(60 psi or more application pressure). These valves cannot be controlled by the driver.
What are the two Dual Air Brake systems?
One system typically operates the regular brakes on the rear axle or axles. The other system operates the regular brakes on the front axle (and possibly one rear axle). Both systems supply air to the trailer (if there is one). The first system is called the "primary" system. The other is called the "secondary" system.
How do you check the Slack Adjusters on S-cam Brakes?
Park on level ground and chock the wheels to prevent the vehicle from moving. Release the parking brakes so you can move the slack adjusters. Use gloves and pull hard on each slack adjuster that you can reach. If a slack adjuster moves more than about one inch where the push rod attaches to it, it probably needs adjustment. Adjust it or have it adjusted. Vehicles with too much brake slack can be very hard to stop. Out-of-adjustment brakes are the most common problem found in roadside inspections. Be safe. Check the slack adjusters.
What is factored into the Total Stopping Distance?
Perception Distance + Reaction Distance + Brake Lag Distance + Braking Distance = Total Stopping Distance The air brake lag distance at 55 mph on dry pavement adds about 32 feet. So at 55 mph for an average driver under good traction and brake conditions, the total stopping distance is over 450 feet.
How do you activate the parking brakes?
Pull the parking brake control knob out to apply the parking brakes, push it into release. The control will be a yellow, diamond- shaped knob labeled "parking brakes" on newer vehicles. On older vehicles, it may be a round blue knob or some other shape (including a lever that swings from side to side or up and down).
How do you Check Air Compressor Governor Cut-in and Cut-out Pressures?
Pumping by the air compressor should start at about 100 psi and stop at about 125 psi. (Check manufacturer's specifications.) Run the engine at a fast idle. The air governor should cut-out the air compressor at about the manufacturer's specified pressure. The air pressure shown by your gauge(s) will stop rising. With the engine idling, step on and off the brake to reduce the air tank pressure. The compressor should cut-in at about the manufacturer's specified cut-in pressure. The pressure should begin to rise. If the air governor does not work as described above, it may need to be fixed. A governor that does not work properly may not keep enough air pressure for safe driving.
How do you make a normal stop using air brakes?
Push the brake pedal down. Control the pressure so the vehicle comes to a smooth, safe stop. If you have a manual transmission, don't push the clutch in until the engine rpm is down close to idle. When stopped, select a starting gear.
How do you test the Low Pressure Warning Signal?
Shut the engine off when you have enough air pressure so that the low pressure warning signal is not on. Turn the electrical power on and step on and off the brake pedal to reduce air tank pressure. The low air pressure warning signal must come on before the pressure drops to less than 60 psi in the air tank (or tank with the lowest air pressure, in dual air systems). If the warning signal doesn't work, you could lose air pressure and you would not know it. This could cause sudden emergency braking in a single- circuit air system. In dual systems the stopping distance will be increased. Only limited braking can be done before the spring brakes come on.
What kinds of vehicles have Front Brake Limiting Valves?
Some older vehicles (made before 1975) have a front brake limiting valve and a control in the cab. The control is usually marked "normal" and "slippery." When you put the control in the "slippery" position, the limiting valve cuts the "normal" air pressure to the front brakes by half. Limiting valves were used to reduce the chance of the front wheels skidding on slippery surfaces. However, they actually reduce the stopping power of the vehicle.
What types of brakes are usually used to meet the emergency brakes and parking brakes needs of needing to be held on by mechanical force?
Spring Brakes All trucks, truck tractors, and buses must be equipped with emergency brakes and parking brakes. They must be held on by mechanical force (because air pressure can eventually leak away). Spring brakes are usually used to meet these needs.
What step during the Pre-Trip Inspection should the Air Compressor Drive Belt be checked?
Step 2: Engine Compartment Checks Check Air Compressor Drive Belt (if compressor is belt-driven). If the air compressor is belt-driven, check the condition and tightness of the belt. It should be in good condition.
How do you Test Parking Brake?
Stop the vehicle, put the parking brake on, and gently pull against it in a low gear to test that the parking brake will hold.
Describe the function and purpose of the Air Compressor.
The air compressor pumps air into the air storage tanks (reservoirs). The air compressor is connected to the engine through gears or av-belt. The compressor may be air cooled or may be cooled by the engine cooling system. It may have its own oil supply or be lubricated by engine oil. If the compressor has its own oil supply, check the oil level before driving.
Why should you never push the brake pedal down when spring brakes are on?
The brakes could be damaged by the combined forces of the springs and the air pressure. Many brake systems are designed so this will not happen. But not all systems are set up that way, and those that are may not always work. It is much better to develop the habit of not pushing the brake pedal down when the spring brakes are on.
Why is it so important for spring brakes to be in adjustment?
The braking power of spring brakes depends on the brakes being in adjustment. If the brakes are not adjusted properly, neither the regular brakes nor the emergency/parking brakes will work right.
What does the Emergency Brake System do?
The emergency brake system uses parts of the service and parking brake systems to stop the vehicle in a brake system failure.
What tank is the Safety Release Valve installed in?
The first tank the air compressor pumps air to.
What are some things you can do to prevent rollover?
The following two things will help you prevent rollover--keep the cargo as close to the ground as possible, and drive slowly around turns. Keeping cargo low is even more important in combination vehicles than in straight trucks. Also, keep the load centered on your rig. If the load is to one side so it makes a trailer lean, a rollover is more likely. Make sure your cargo is centered and spread out as much as possible. Rollovers happen when you turn too fast. Drive slowly around corners, on ramps, and off ramps. Avoid quick lane changes, especially when fully loaded.
Describe the function and purpose of the Air Compressor Governor.
The governor controls when the air compressor will pump air into the air storage tanks. When air tank pressure rises to the "cut-out" level(around 125 pounds per-square-inch or "psi"), the governor stops the compressor from pumping air. When the tank pressure falls to the "cut-in" pressure (around 100 psi), the governor allows the compressor to start pumping again.
What does the Parking Brake System do?
The parking brake system applies and releases the parking brakes when you use the parking brake control.
What is the role of a Safety valve in an air brake system?
The safety valve protects the tank and the rest of the system from too much pressure. If the safety valve releases air, something is wrong. Have the fault fixed by a mechanic.
What does the Service Brake System do?
The service brake system applies and releases the brakes when you use the brake pedal during normal driving.
What is "Brake Lag"?
The time required for the brakes to work after the brake pedal is pushed. With hydraulic brakes (used on cars and light/medium trucks), the brakes work instantly. However, with air brakes, it takes a little time (one half second or more) for the air to flow through the lines to the brakes.
What is the proper braking technique?
The use of brakes on a long and/or steep downgrade is only a supplement to the braking effect of the engine. Once the vehicle is in the proper low gear, the following is the proper braking technique: 1. Apply the brakes just hard enough to feel a definite slowdown. 2. When your speed has been reduced to approximately five mph below your "safe" speed, release the brakes. (This application should last for about three seconds.) 3. When your speed has increased to your "safe" speed, repeat steps 1 and 2.
Why is it bad for air brake systems when water and compressor oil collect in the bottom of the air tank?
The water can freeze in cold weather and cause brake failure. Be sure that you drain the air tanks completely. Each air tank is equipped with a drain valve in the bottom.
What does the Application Pressure Gauge show?
This gauge shows how much air pressure you are applying to the brakes. (This gauge is not on all vehicles.) Increasing application pressure to hold the same speed means the brakes are fading. You should slow down and use a lower gear. The need for increased pressure can also be caused by brakes out of adjustment, air leaks, or mechanical problems.
What is the purpose of Modulating Control Valves?
To control the spring brakes if the service brakes fail. When parking a vehicle with a modulating control valve, move the lever as far as it will go and hold it in place with the locking device.
What is the purpose of an alcohol evaporator to put alcohol into the air system in air brakes?
To help to reduce the risk of ice in air brake valves and other parts during cold weather. Ice inside the system can make the brakes stop working. Check the alcohol container and fill up as necessary, every day during cold weather. Daily air tank drainage is still needed to get rid of water and oil. (Unless the system has automatic drain valves.)
What happens to the brake shoes and linings when the brake is pushed?
To stop, the brake shoes and linings are pushed against the inside of the drum. This causes friction, which slows the vehicle (and creates heat). The heat a drum can take without damage depends on how hard and how long the brakes are used. Too much heat can make the brakes stop working.
How can you tell if a vehicle is equipped with ABS?
Tractors, trucks, and buses will have yellow ABS malfunction lamps on the instrument panel. Trailers will have yellow ABS malfunction lamps on the left side, either on the front or rear corner. Dollies manufactured on or after March 1, 1998 are required to have a lamp on the left side. 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.
More than half of truck driver deaths in crashes are the result of ________________________________________________________.
Truck Rollovers When more cargo is piled up in a truck, the "center of gravity" moves higher up from the road. The truck becomes easier to turn over. Fully loaded rigs are ten times more likely to roll over in a crash than empty rigs.
What vehicles are required to have ABS?
Truck tractors with air brakes built on or after March 1, 1997, and other air brakes vehicles, (trucks, buses, trailers, and converter dollies) built on or after March 1, 1998, are required to be equipped with antilock brakes. Many commercial vehicles built before these dates have been voluntarily equipped with ABS. Check the certification label for the date of manufacture to determine if your vehicle is equipped with ABS.
True or False: Bicycles are legal vehicles on Minnesota roads and they share the same rights and responsibilities as other vehicles.
True
True or False: Using a CMV to commit a felony will result in losing your CDL for at least one year for a first offense.
True
True or False: You will lose your CDL for at least one year for a first offense if you cause a fatality through negligent or criminal operation of a CMV.
True
True or False: You will lose your CDL for at least one year for a first offense if: You drive a CMV under the influence of alcohol or a controlled substance (for example, illegal drugs).
True
True or False: You will lose your CDL for life if you use a CMV to commit a felony involving a controlled substance.
True
True or False: During low air pressure, It is much safer to stop while there is enough air in the tanks to use the foot brakes.
True A heavily loaded vehicle will take a long distance to stop because the spring brakes do not work on all axles. Lightly loaded vehicles or vehicles on slippery roads may skid out of control when the spring brakes come on.
True or False: Tractor and straight truck spring brakes will come fully on when air pressure drops to a range of 20 to 45 psi (typically 20 to 30 psi).
True Do not wait for the brakes to come on automatically. When the low air pressure warning light and buzzer first come on, bring the vehicle to a safe stop right away, while you can still control the brakes.
True or False: The manual adjustment of an automatic adjuster to bring a brake pushrod stroke within legal limits is generally masking a mechanical problem and is not fixing it.
True Further, routine adjustments of most automatic adjusters will likely result in premature wear of the adjuster itself. It is recommended that when brakes equipped with automatic adjusters are found to be out of adjustment, the driver take the vehicle to a repair facility as soon as possible to have the problem corrected.
True or False: Pressing and releasing the pedal unnecessarily can let air out faster than the compressor can replace it.
True If the pressure gets too low, the brakes won't work.
True or False: The ENS is for those emergencies that would require stopping train traffic due to an obstruction or any other problem at the crossing.
True The blue colored ENS sign is located on the railroad crossing posts or the metal control box near the tracks. By providing the DOT number on the sign, the dispatchers know exactly where the grade crossing is and can notify trains moving in that direction to either come to a stop or be placed on a speed restriction.
True or False: Without ABS, you still have normal brake functions.
True If your ABS malfunctions, you still have regular brakes. Drive normally, but get the system serviced soon.
True or False: It is unlawful for any person to give a name and date of birth of another person, or give a fictitious name and date of birth to a police officer for the purpose of falsely identifying yourself.
True This would be a GROSS misdemeanor.
True or False: It is unlawful for any person to make a counterfeit driver's license or Minnesota identification card.
True This would be a GROSS misdemeanor.
True or False: It is unlawful for any person to use another name or a fictitious name and date of birth on any application for a driver's license or Minnesota identification card.
True This would be a misdemeanor.
True or False: It is unlawful to use another person's driver's license or Minnesota identification card.
True This would be a misdemeanor.
How do you Test Service Brakes.
Wait for normal air pressure, release the parking brake, move the vehicle forward slowly (about five mph), and apply the brakes firmly using the brake pedal. Note any vehicle "pulling" to one side, unusual feel, or delayed stopping action. This test may show you problems, which you otherwise wouldn't know about until you needed the brakes on the road.
How do Spring Brakes work?
When driving, powerful springs are held back by air pressure. If the air pressure is removed, the springs put on the brakes. A parking brake control in the cab allows the driver to let the air out of the spring brakes. This lets the springs put the brakes on. A leak in the air brake system, which causes all the air to be lost, will also cause the springs to put on the brakes.
What happens when only the tractor has ABS?
When only the tractor has ABS, you should be able to maintain steering control, and there is less chance of jackknifing. But, keep your eye on the trailer and let up on the brakes (if you can safely do so) if it begins to swing out.
What happens when only the trailer has ABS?
When only the trailer has ABS, the trailer is less likely to swing out, but if you lose steering control or start a tractor jackknife, let up on the brakes (if you can safely do so) until you gain control.
How can you Check Rate of Air Pressure Buildup?
When the engine is at operating rpms, the pressure should build from 85 to 100 psi within 45 seconds in dual air systems. (If the vehicle has larger than minimum air tanks, the buildup time can be longer and still be safe. Check the manufacturer's specifications.) In single air systems (pre-1975), typical requirements are pressure build up from 50 to 90 psi within 3 minutes with the engine at an idle speed of 600-900 rpms. If air pressure does not build up fast enough, your pressure may drop too low during driving, requiring an emergency stop. Don't drive until you get the problem fixed.
How do S-cam Brakes work?
When you push the brake pedal, air is let into each brake chamber. Air pressure pushes the rod out, moving the slack adjuster, thus twisting the brake camshaft. This turns the s- cam (so called because it is shaped like the letter "S"). The s-cam forces the brake shoes away from one another and presses them against the inside of the brake drum. When you release the brake pedal, the s-cam rotates back and a spring pulls the brake shoes away from the drum, letting the wheels roll freely again.
How do you Test Air Leakage Rate?
With a fully-charged air system (typically 125 psi), turn off the engine, chock your wheels if necessary, release the tractor protection valve and parking brake (push in), and time the air pressure drop. The loss rate with no brakes applied should be less than two psi in one minute for single vehicles and less than three psi in one minute for combination vehicles. Then fully apply the foot brake and hold it for one minute. After the initial pressure drop, check the air gauge to see if the air pressure drops more than three pounds in one minute (single vehicle) or four pounds in one minute (combination vehicle). If the air pressure falls more than three psi in one minute for single vehicles (more than four psi for combination vehicles), the air loss rate is too much. Check for air leaks and fix before driving the vehicle. Otherwise, you could lose your brakes while driving.
What is the Controlled Braking method?
With this method, you apply the brakes as hard as you can without locking the wheels. Keep steering wheel movements very small while doing this. If you need to make a larger steering adjustment or if the wheels lock, release the brakes. Re-apply the brakes as soon as you can.
Do you have to do anything differently if your vehicle does not have automatic air tank drains?
Yes If your vehicle does not have automatic air tank drains, drain your air tanks at the end of each working day to remove moisture and oil. Otherwise, the brakes could fail.
Do Automatic Slack Adjusters need to be checked during a Pre-Trip Inspection?
Yes. All vehicles built since 1994 have automatic slack adjustors. Even though automatic slack adjustors adjust themselves during full brake applications, they must be checked. Automatic adjusters should not have to be manually adjusted except when performing maintenance on the brakes and during installation of the slack adjusters.
What does it mean if the yellow malfunction lamp stays on after the bulb check, or goes on once you are under way?
You may have lost ABS control at one or more wheels.
What is the penalty for driving with a revoked, suspended, canceled, denied or disqualified CDL.
You will lose your CDL for at least one year for a first offense A second disqualifying offense will result in losing your CDL privileges for life.
What may happen if you brake hard on slippery surfaces in a vehicle without ABS?
Your wheels may lock up. When your steering wheels lock up, you lose steering control. When your other wheels lock up, you may skid, jackknife, or even spin the vehicle.
There is an emergency exception that allows CMV drivers to use their hand-held mobile telephones if necessary to communicate with _______________________________ or __________________________________________.
law enforcement officials or other emergency services.
When must you stop your vehicle at least 15 feet and no more than 50 feet from the nearest railroad track approaching a railroad grade crossing? (3 instances)
•A clearly visible electric or mechanical signal device warns of the immediate approach of a railroad train. •An approaching railroad train is plainly visible and is in hazardous proximity. •A flag person is signaling the approach or passage of a train or when a crossing gate is lowered.
The following vehicles are required to stop at all railroad grade crossings:
•Buses carrying passengers •School buses (whether carrying passengers or not) •Placarded vehicles
