CDL Exam Prep

By Douglas Reese

THE ONLY GUIDE YOU'LL NEED TO PASS THE CDL EXAM ON YOUR FIRST TRY 

• Are you looking for a study guide to help you pass the Commercial Driver's License Exam?
• Do you lack direction and feel overly anxious about your impending Commercial Driver's License test?

 

We have the perfect solution for you! Our +800 Q&A guide it's by far the most complete on the market and will help you pass with flying colors!

 

In this CDL Exam Prep, you will find:

 

• The essential material gathered in a few focused, well-organized, and concise chapters.
• Review material and test-taking strategies so that you can feel confident and prepared when it comes time to take the actual exam.
• More than 800 insightful questions and responses to help you reflect on your learning.
• 3 Full-Length Exams for All Classes
• 2 Hazardous materials tests, 2 School bus tests, 2 passenger vehicle tests, 2 air-break tests, 4 Combination vehicle tests, 2 tanker vehicle tests, 2 pre-inspection tests
• 3 Practice tests specific to the new ELDT regulations

 

You don't want to spend weeks or months studying for this exam. You want to get it done and move on with a new chapter of your life. That's why our guide is so valuable, it will help you pass quickly and easily. You can have everything you need for success right at your fingertips. 

 

You won't find anything better out there. Purchase our CDL study guide today!

 

About us 

The Driving School is the leading authority when it comes to preparing for the driving test. Our study guides are designed to help students pass their exams with ease. We take pride in our guides because they combine both theory and test questions. At The Driving School, we do not just compile test questions; we compile the same number of questions as the real exams, in the same format. This has been a great help for past students because they were able to simulate the real exam while studying.

 

We have helped thousands of students pass their DMV and CDL exams, and we can help you too!

• Language: English
• Publisher: Valentino Chiavarini
• Release date: Nov 17, 2022
• ISBN: 9798215547700

Book preview

PART TWO

STUDY GUIDE

CHAPTER 3

AIR BRAKES

The air brake on a truck is one of the most crucial components when a driver is transporting thousands of pounds of weight. It is a braking system that uses compressed air to slow or stop a vehicle. Besides their use in railroad trains and light aircraft, air brakes are also used in large, heavy vehicles, particularly those with many trailers that need to be connected to the brake system, such as trucks, buses, trailers, and semi-trailers. Large vehicles depend on air-powered brakes because air is cheap and accessible, whereas hydraulic fluid may leak and endanger drivers and other road users.

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George Westinghouse first developed air brakes for use in railway service. Impressed by the effectiveness of air brakes in the railway sector, truck and heavy vehicle manufacturers adopted and implemented them in heavy commercial vehicles. Rather than hydraulic fluid, pressurized air is used to operate air brakes on trucks. Drum brakes, disc brakes, or a combination can be used as air brakes. Typical operating pressure is between 100 and 120 psi, or 6.9 to 8.3 bars or 690 to 830 kPa. The supply and control systems comprise a compressed air brake system.

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Unlike traditional hydraulic brakes, which use hydraulic fluid to apply pressure to the brakes, air brakes use compressed air. This makes them more reliable in cold weather, as hydraulic fluid can freeze and cause brakes to fail. The brake is, by default, in the released position in a conventional braking system and is only activated when the braking fluid is compressed. However, triple-valve system air brakes are always activated and can only be released under pressure from compressed air. The compression starts when the vehicle is started, and when the vehicle is placed in motion, the brakes are released. As a result, the brakes return to their default, active position in the event of a leak or even a full failure of the compression mechanism, which brings the vehicle to a stop.

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Air brakes are also less likely to leak, making them ideal for large vehicles that travel long distances. Air brakes are very reliable and require little maintenance. As a result, air brakes have become the standard brake system for commercial vehicles.

COMPONENTS OF AIR BRAKES IN BUSES AND TRUCKS

Air reservoir tanks: Air reservoir tanks are essential to any air brake system. These tanks store compressed air generated by the compressor. This compressed air is then used to power the brakes. The air tank size will determine how much-compressed air is available for braking. A larger air tank will provide more compressed air and, therefore, more braking power.

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Air compressor: Air compressors are an essential part of air brake systems. They work by pressurizing air and storing it in a tank. This air can be released when the brakes are applied, providing extra stopping power. Air compressors are typically connected to the engine through a v-belt or gears. This can be air-cooled by an engine cooling system and lubricated by the engine oil, which helps ensure that the air compressor is always operating at peak efficiency. Understanding how air compressors work can help keep your air brake system in top condition.

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Slack Adjuster: The slack adjuster is a mechanical device used in air brakes to maintain the correct amount of slack in the brake system. The slack adjuster is located between the pushrod and the brake shoes, consisting of the adjusting screw and the yoke. The adjusting screw is used to adjust the amount of slack in the system, while the yoke connects the adjusting screw to the pushrod. The yoke also contains a ratchet mechanism that prevents the slack adjuster from being over-tightened. While inspecting or adjusting the slack adjuster, it is important to follow the manufacturer's instructions carefully to avoid damaging the brakes.

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Brake Chambers: Each wheel has an air brake chamber and a cylindrical metal container where compressed air is converted into mechanical force to apply the brakes and stop the vehicle. The brake chamber is where the slack adjuster, which moves the diaphragm, is located.

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Push Rod: Push rod is a steel rod that resembles the piston that connects the slack adjuster and the brake chamber in some ways. The brakes are instantly released when the rod is depressed. The brakes are automatically applied when the push rod is extended.

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Air Compressor Governor: The purpose of an air compressor governor is to regulate the flow of air from the compressor based on the system's needs. The reservoirs are typically pumped with air when the compressor is loaded. The compressor pumps the necessary air between the two cylinders while it is not loaded. It doesn't supply air to the reservoirs at that point. The governor stops the air pumping when the air pressure in the tank reaches the cut-out level (125 psi). The governor permits it to pump air at the cut-in pressure (100 psi). When an air compressor is used in an air brake system, the governor must be properly adjusted so that the correct amount of air flows into the system. If too much or too little air is supplied, it can cause problems with braking performance.

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Foot Valve: The foot valve is an important part of the air brake system, as it allows the brake pedal to control airflow into the system. Without it, the brake system would not be able to function properly. The brake pedal in an air brake system is connected to a foot valve by a linkage. The foot valve is a small, cylindrical valve located at the end of the brake pedal. When the brake pedal is depressed, the foot valve opens, allowing air to flow from the compressor into the brake system. The compressed air applies pressure to the brake shoes, which causes them to press against the drum. This action slows or stops the drum rotation and, ultimately, the vehicle.

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Drain Valves: The drain valves in an air brake system are responsible for draining air from the system. This is necessary to prevent moisture from building up and causing corrosion. The drain valves are typically located at the bottom of the air tanks, where they can gravity-drain the air. In some cases, the drain valves may also be located near the compressor, where they can remove condensation from the Air Lines. It is important to check the drain valves regularly to ensure they are clear and functioning properly. If the drain valves become clogged, it can cause serious damage to the air brake system.

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Brake Shoe: The Brake Shoe in an air brake system is the part that contacts the Brake Drum to create friction and slow the wheel. The Brake Shoe consists of two metal plates with a friction material bonded to the surface. The return spring is a stiff spring essential to the braking system. When the diaphragm or the S-Cam does not spread the brakes, it connects to the brake shoes and returns them to the proper open position. When the air pressure is applied to the Brake Shoe, it causes the Brake S-Cam to rotate. This rotation forces the Brake Shoe against the Brake Drum, which slows the wheel. The Brake Shoe is also responsible for holding the Brake Linings in place. The Brake Linings are what create the friction against the Brake Drum. Without the Brake Lining, the Brake Shoe would not be able to create enough friction to slow the wheel.

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Safety Valve: The function of the safety valve in an air brake system is to protect the entire brake system against excessive pressure. When the working pressure in the system rises to the level required to open the safety valve, the valve opens and allows air to escape. This relieves the pressure in the system and prevents damage to components. The safety valve can be manually operated, or it can be automatic. In either case, it is an important component of an air brake system, and its function is essential for the safe operation of the system.

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Alcohol Evaporator: Alcohol evaporators are used in some air brake systems. In colder regions, this is helpful. It reduces the chance that the air brake valves will frost over. To maintain the brakes functional during cold weather, you must inspect the alcohol container daily and fill it up if necessary. Unless the air tank has automated drain valves, you must empty the air tank every day to remove the water and oil from the evaporator.

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Air Tank Drains: In an air brake system, the air tank drains remove oil and water from the air tanks. There are two air tank drains - manual drains and electric heating drains. Manual drains are operated by a lever, while electric heating drains are automatically activated when the air temperature reaches a certain level. Both types of air tank drain help to keep the air brakes in good condition and prevent corrosion.

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Spring Brakes: The primary function of the spring brakes is to provide the mechanical force to stop air leakage from the system. This mechanical force is generated by the tension in the springs between the two halves of the spring brake. When the spring brakes are applied, the tension in the springs increases, increasing the mechanical force exerted on the air brake system. As a result, the Spring Brakes help keep the air brake system functioning properly by preventing air leakage.

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Parking Brake Controls: The parking brake control in an air brake system is used to engage the parking brakes. The control knob is usually located on the dash, near the steering wheel. You pull the yellow push/pull control knob out to engage the parking brakes. This will cause the brakes to engage and remain engaged until you push the control knob back in. The parking brakes are typically used when you want to park the vehicle on an incline or when you need to secure the vehicle while it is not in use. When the parking brakes are engaged, the vehicle will not roll away.

HOW AIR BRAKES WORK

The air brake system in a vehicle uses air pressure to apply the brakes. Air compressors generate air pressure, which is stored in reservoirs. The air brake system is often used in trucks and buses because it can provide more stopping power than a hydraulic brake system. It is also less likely to overheat, making it ideal for vehicles that are used for long periods.

Let’s study in detail the working of the air brakes.

First, the air is pumped into the reservoirs or storage tanks for air under the vehicle by the air compressor. After that, the air is forced through the air brake lines until it reaches the air brake. When a commercial motor vehicle brakes, air pressure pushes a rod out and moves the slack adjuster. This is how most standard S-Cam braking systems work. The slack adjuster is a component of the air brake system that adjusts the tension on the brake cables, ensuring that there is always enough pressure on the brake liners to stop the truck.

The spring moves the S-cam due to air passing through the nozzle and into the air brake chamber. The brake shoe lining is forced apart by the S-cam and pressed against the braking drum. This generates the friction and pressure required to slow the wheel down. Similarly, when you let go of the brake pedal, the S-cam rotates back, forcing the spring to pull the same brake liner away from the brake drum, eliminating friction.

Similar to brake pads, brake liners also deteriorate over time, especially under pressure from pushing the brake pedal excessively or frequently. According to safe operating procedures, commercial drivers and the company that manages CMVs must keep the thickness of their brake shoes at a minimum of 1/4 inch. Truck drivers and the companies they drive for must continually and routinely inspect the air brake system to ensure that there are no dangerous or malfunctioning parts of the system because both the brake liner and the brake drum deteriorate with time and with excessive heat/wear.

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An air brake system is a combination of 3 different braking systems: Service Brake, Parking Brake, and Emergency Brake.

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Service Brake: When traveling slowly or needing to stop, you use this braking mechanism. To use it, depress the brake pedal and direct the air to the braking chamber of the car at a pressure of between 100 and 120 psi. This will activate the brake, slowing or stopping the vehicle.

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Parking Brake: When you apply the parking brake control, this part of the air braking system is activated. The parking brake system has an engineered drum or disc so that spring pressure can maintain it in the applied position.

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Emergency Brake: If the brake system fails, the vehicle will come to a stop using this brake system, also referred to as a c-brake or hand brake. The pressure in the pipes connecting the brakes and the compressed air storage tank is released when this system is activated. This activates the parking brake right away. As a result, your vehicle has a braking system to let you stop it whenever you want and avoid unnecessary accidents. In addition to being used in emergencies, it can also be employed to keep parked vehicles immobile.

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What is the Wig wag device in the Air Brake system?

The wig wag device is a low air pressure warning device in the air brake system. When the air pressure in the system drops below a certain level, the wig wag device will activate and warn the truck operator of the low air pressure. The wig wag device is an important safety feature in the air brake system and helps to prevent accidents. Without it, the air pressure in the brakes could get too low.

The compressed air brake system is divided into two categories:

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Supply System

Air compressor (1) is controlled by the engine either directly from the engine timing gears or indirectly through a crankshaft pulley and a belt. Normally, the engine's cooling and lubrication systems lubricate and cool it. However, other systems use self-lubricating or air-cooled compressors. A governor controls the system pressure between a minimum, and maximum value;[5] the governor unloads the compressor when the system pressure reaches its highest setpoint and loads it when it drops below its minimum setpoint.

Once the compressor is loaded, compressed air is initially sent through a cooling coil and into an air dryer (3), which eliminates moisture and oil contaminants and may also include a pressure regulator (2), safety valve, and smaller purge reservoir (4). An oil separator and anti-freeze device can be added to the supply line in place of the air dryer.

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After that, the compressed air is kept in a supply reservoir (6), also known as a wet tank, where most of the oil and water from the compressor congregate. The service reservoir, located further down, is the main source for brake operation. If the compressor breaks down or the engine stops, the supply and service reservoirs are sized to allow different service brake applications. A four-way protection valve (5) is used to transport compressed air from the service reservoir into the primary reservoir (the rear brake reservoir), the secondary reservoir (the front/trailer brake reservoir), a parking brake reservoir, and an auxiliary air supply distribution point.

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Control System

The control system is divided into two service brake circuits, a parking brake circuit, and a trailer brake circuit.

For additional security in the case of an air leak, the dual-service braking circuits are further divided into front- and rear-wheel circuits, each receiving compressed air from its supply reservoir. The service brakes are activated through a brake pedal air valve (9) that regulates both circuits. When the brake pedal is depressed, compressed air from the corresponding supply reservoirs enters each service brake chamber (10 & 12), and the service brakes are actuated. When the brake pedal is released, the supply reservoirs are disconnected, the service brakes are released, and the compressed air that actuated them is released into the atmosphere. The governor will load the compressor again if the service brakes are used repeatedly because this will reduce the pressure in the air reservoir.

Relay valves are used to improve brake response with long lines. The lines for the rear and trailer service brakes are plumbed directly to the service reservoir through a local relay valve (11), and the line from the brake pedal air valve is used to actuate the relay valve rather than the service brakes because doing so would cause the service brakes to act too slowly. Similarly, when the brakes are released, quick-release valves close to each set of brakes enable the air to be exhausted more quickly.

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The parking brake is an air-operated spring brake that uses spring pressure in the spring brake cylinder (12) to apply the brake and compressed air to release it through a hand-control valve (7).

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The supply line and the separate control or service line make up the direct two-line system that makes up the trailer brake. A park brake relay valve transfers air from the prime mover park brake air tank to the supply line, and a trailer-brake relay valve controls airflow to the control line. The prime mover park brake hand control, the trailer service brake hand control, and the prime mover brake-pedal air valve all supply the operational signals for the relay.

DUAL AIR BRAKES

Dual air brakes are used on heavy trucks and buses to enhance their safety features. They consist of two separate air brake systems that work together to stop the vehicle. Each system has separate air tanks, hoses, lines, etc. The standard brakes on the rear axle or axles are normally operated by one system. The other system controls the front axle's regular brakes (possibly one rear axle). The trailer receives air from both systems (if there is one). The primary system is the first system. The secondary system is the other. This creates more braking power than a single air brake system and helps to distribute the weight more evenly, which makes stopping shorter and more controlled. Dual air brakes are typically used on vehicles that carry heavy loads or tow trailers, as they provide greater stopping power and control than a single system.

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Allow enough time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems before operating a vehicle with a dual air system. Try to keep an eye on the primary and secondary air pressure gauges. Pay close attention to the buzzer and warning light for low air pressure. When the air pressure in both systems rises to a preset level determined by the manufacturer, the warning light and buzzer should turn off. This number needs to be higher than 60 psi.

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Before the air pressure in any system falls below 60 psi, the warning light and buzzer should activate. If this occurs while driving, you need to stop and park the vehicle in a secure location. The front or rear brakes won't work properly if one air system is low in pressure. As a result, stopping will take longer for you. Stop the vehicle safely, then get the air brake system fixed.

ADVANTAGES OF AIR BRAKES OVER HYDRAULIC BRAKES

Though hydraulic brakes are the most common braking system used in cars and light trucks, air brakes are slowly gaining popularity due to their superior performance. Hydraulic brakes transfer pressure from the brake pedal to the brake shoe using the hydraulic fluid. Due to their reliability, air brakes are employed in heavy commercial vehicles. They have several advantages for large multi-trailer vehicles. Here are just a few advantages that air brakes have over hydraulic brakes:

Air brakes are much more powerful, which is especially important for large vehicles like buses and semi-trucks. In emergencies, air brakes can stop a vehicle up to 30% faster than hydraulic brakes.

Air brakes are also more resistant to fade, meaning they maintain their power even after extended use. This is because they are not reliant on brake fluid, which can start to break down when it gets hot.

Since there is an endless supply of air, the air braking system will never run out of operating fluid, unlike hydraulic brakes.

Compared to the Hydraulic lines, the Air line couplings are easier to connect and disconnect, and the risk of air getting into a hydraulic fluid is eliminated. Trailer air-brake circuits are simple to attach and detach.

The system's inherent compressed air can be utilized for accessories like air horns, seat adjustments, and trolleybus and bus doors for which hydraulics are ineffective.

Air brakes are less likely to leak than hydraulic brakes. This is because the Air lines used in an air brake system are enclosed, whereas the Brake lines in a hydraulic system are exposed. As a result, air brake systems tend to be much more reliable and require less maintenance.

For these reasons, air brakes quickly become the preferred choice for many commercial vehicles. So if you're in the market for a new braking system, consider the many benefits of air brakes.

DISADVANTAGES OF AIR BRAKES

Air brakes have a few disadvantages:

Generally, air brakes are more expensive. Air-brake systems compress the air, creating moisture that air dryers must remove. This adds to the cost of the air-brake systems and can result in greater maintenance and repair expenses, especially in the first five years.

In cold climates, defective air dryers cause the air-brake system to freeze. The brakes may not work properly if the air pressure gets too low.

Air brakes can be more difficult to maintain than other types of brakes. It could be difficult to locate and fix a leak if one occurs in the system. Also, an air brake system might freeze up if water enters the system through a leak.

Air brakes can be noisy (ranging from 95–115 dB), which can be annoying for both the driver and the people around the truck. The sound is created when compressed air confined inside the brake chamber is released.

While air brakes have some drawbacks, they are still widely used because of their effectiveness.

AIR BRAKES INSPECTION

Drivers are required to perform a full air brake inspection at the beginning of each day and after any period of extended use. The inspection includes a check of the air compressor, reservoir, and all lines and hoses for leaks. The brakes themselves should be checked for wear and proper operation. If any problems are found, the vehicle should not be driven until the repairs have been made. By performing a daily inspection, drivers can help to ensure that their air brakes are in safe working condition.

The following should be included in the checklist:

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Air Compressor Drive Belt: If the compressor in your vehicle is belt-driven, check this belt. Make sure it is tight and in good condition overall.

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Slack Adjusters: The slack adjusters are located on the vehicle's S-cam brakes. Park the car somewhere on level ground, and make sure it stays there while you inspect the adjusters. Make sure that the vehicle remains still while you check it. Release the parking brakes to make the slack adjuster movable. While wearing hand gloves, firmly pull each slack adjuster.

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If a slack adjuster moves more than an inch from the point of attachment to the push rod, adjustments may be required. Adjust it if you can. If not, leave the adjustment in the hands of a professional. If the brake is excessively loose, stopping the vehicle could be challenging. Misalignment is the most prevalent issue with brakes. This emphasizes how crucial it is to ensure your brakes are properly adjusted.

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Any vehicle manufactured after 1994 is equipped with automatic slack adjustors, which start working as soon as the brakes are completely applied. However, routinely inspecting the slack adjusters can make it easier for you to spot problems with the adjusters and fix them before it's too late.

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Brake Discs or Drums, Hoses, and Linings: Cracks may exist in brake drums or discs. However, there should be cause for concern if the cracks are longer than half the breadth of the areas permitted for friction. The longer crack may hinder the drums' or discs' functionality, decreasing the effectiveness of the brake system. Pay attention to the materials that create friction as well. They must not be overly thin, loose, or drenched in grease or oil.

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Additionally, the air hoses attached to the brake should be examined. Rubbing is a problem that needs to be resolved immediately since it might lead to wearing or cutting out.

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Air Leakage Rate: You can do this test when the air system is fully charged, or roughly 125 psi. After shutting the engine off, release the parking brake. Keep track of how quickly the air pressure is dropping. A problem exists if the loss rate for a single vehicle exceeds 2 psi per minute. It shouldn't be less than 3 psi/minute for combination vehicles.

Use the brake pedal to apply no less than 90 psi. After the initial decrease, the air pressure must not go below 3 psi per minute for single vehicles. It cannot exceed 4 psi in combination vehicles. Look for air leaks or other sources of air loss in the vehicle. Fix any issues you detect before starting the vehicle. If not, a braking issue could occur while driving.

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Test Low-Pressure Warning Signal: When the air pressure is sufficient, and the low-pressure warning signal is not on, turn the engine off. To lower the pressure in the air tank, turn on the electric power and step on and off the brake pedal. Before the pressure in the air tank (or tank with the lowest air pressure in dual air systems) drops to less than 60 psi, the low air pressure warning signal must activate.

If the warning indicator is ineffective, you could lose air pressure without even knowing it. A single-circuit air system can experience abrupt emergency braking due to this. The stopping distance will be longer in dual systems. Before the spring brakes engage, only a small amount of braking is possible.

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Verify that Spring Brakes come on Automatically: Keep stepping on and off the brake pedal to fan off the air pressure to reduce tank pressure. When the air pressure drops to the manufacturer's recommended level (20-45 psi), the tractor protection valve and parking brake valve should close (pop out) on a tractor-trailer combination vehicle, and the parking brake valve should do the same on other combination and single vehicle types. The spring brakes will activate as a result of this.

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Check the Rate of Air Pressure Buildup: In dual air systems, the pressure should increase from 85 to 100 psi within 45 seconds of the engine reaching operating rpm. If the vehicle has air tanks greater than the required size, the buildup time can be extended while being safe. Examine the manufacturer's requirements. The standard requirement for single-air systems (existing before 1975) is a pressure buildup of 50 to 90 psi in 3 minutes with the engine at an idle speed of 600 to 900 rpm.

If air pressure does not rise quickly enough, it may fall critically low while driving and force you to make an emergency stop. Drive only after the issue has been resolved.

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Test Parking Brake: To see if the parking brake will hold, stop the vehicle, engage the parking brake, and then gently pull against it while in a low gear.

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Test Service Brakes: Wait for normal air pressure, release the parking brake, move the vehicle forward at a gentle 5 mph, then firmly press the brake pedal to stop the vehicle. Wait for normal air pressure. Any pushing to one side, off-normal sensation, or delayed halting action should be noted. If you take this test, it can reveal issues that you wouldn't otherwise be aware of until you need your brakes.

PREVENTIVE MAINTENANCE OF AIR BRAKE

To keep your air brakes in top condition, it is recommended that you perform a daily visual inspection. This should include checking for leaks, ensuring that the brake pads are not worn down, and ensuring that the airlines are properly connected. In addition, you should bleed the brakes every six months to remove any moisture or debris from the system. By following these simple preventive maintenance measures, you can help to ensure that your air brakes will be there when you need them.

Verify that the mounting is secure and look for wear, leaks, corrosion, and damage.

Check for leaks in the air system, damaged parts, and loose, cracked, or broken air hoses.

Check that the brake hoses and cables are secured properly.

Check for enough clearance to enable the full caliper movement during normal operation to ensure proper brake pad wear.

Inspecting the spring brake chambers ensures that the parking springs are not caged in the released position. Ensure that the dust plugs are correctly placed.

Ensure that the vent holes in the air brake chamber are not obstructed by snow, ice, or mud.

At each brake pad change, inspect the wheel-bearing unit for grease leaks.

Examine the brake assembly for oil or grease contamination (e.g., pads, rotor, etc.).

Make sure all the dust caps and boots are in fine condition.

Conduct general safety checks regularly in compliance with any applicable rules.

After the first 100 miles of operation, and subsequently, at each normal service period, the wheel nuts must be re-tightened to the appropriate torque level.

CHAPTER 4

HAZARDOUS MATERIALS

Hazardous materials are substances or items that risk public safety and the environment. Common examples of hazardous materials include chemicals, oil, gasoline, and radioactive materials. Special care must be taken when these materials are transported to ensure they are not released into the environment. There are strict laws and regulations governing the transportation of hazardous materials, and companies that violate these rules can be subject to heavy fines. Individuals who plan to transport hazardous materials must obtain the proper training and certification. In addition, all vehicles used for transportation must be properly labeled and equipped with the necessary safety equipment. By taking these precautions, we can help to ensure the safe transportation of hazardous materials.

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If you're looking to get your commercial driver's license (CDL) to transport hazardous materials, you may need to get a hazmat endorsement. This allows you to transport hazardous materials, defined as any flammable, poisonous, corrosive, or explosive materials. There are three hazmat endorsements: X, N, and H.

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The H endorsement is for drivers transporting hazardous materials in a commercial vehicle. N endorsement is required to drive a tanker transporting a minimum of 119 gallons of liquid gas or other hazardous liquids. The X endorsement is a combination endorsement for both tank vehicles and hazardous materials. You'll need to