Air Brake 18 Wheeler Accident Lawyer

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18 Wheeler Accident Lawyer Reshard Alexander is licensed to drive big trucks and understands the cause when you are injured in a commercial motor vehicle wreck.

Air Brakes 18 Wheeler Accident Lawyer

Seeking a Free Consultation with one of Texas’ 18 wheeler accident lawyers? Call the Big Rig Bull Texas Truck Accident Lawyer Reshard Alexander today at 713.766.3322.

18 wheeler accident lawyer Reshard Alexander is dedicated to holding professional truck drivers and trucking companies accountable for their negligence.

An air brake or, more formally, a compressed air brake system, is a type of friction brake for vehicles in which compressed air pressing on a piston is used to apply the pressure to the brake pad needed to stop the vehicle. Air brakes are used in large heavy vehicles, particularly those having multiple trailers which must be linked into the brake system, such as trucks, buses, trailers, and semi-trailers, in addition to their use in railroad trains. George Westinghouse first developed air brakes for use in railway service.^[1] He patented a safer air brake on March 5, 1872.^[2]^[3] Westinghouse made numerous alterations to improve his air pressured brake invention, which led to various forms of the automatic brake. In the early 20th century, after its advantages were proven in railway use, it was adopted by manufacturers of trucks and heavy road vehicles.

Design and function

Air brakes are typically used on heavy trucks and buses. The system consists of service brakes, parking brakes, a control pedal, and an air storage tank. For the parking brake, there is a disc or drum arrangement which is designed to be held in the ‘applied’ position by spring pressure. Air pressure must be produced to release these “spring brake” parking brakes. For the service brakes (the ones used while driving for slowing or stopping) to be applied, the brake pedal is pushed, routing the air under pressure (approx 100–120 psi or 690–830 kPa or 6.89–8.27 bar) to the brake chamber, causing the brake to be engaged. Most types of truck air brakes are drum brakes, though there is an increasing trend towards the use of disc brakes. The air compressor draws filtered air from the atmosphere and forces it into high-pressure reservoirs at around 120 psi (830 kPa; 8.3 bar). Most heavy vehicles have a gauge within the driver’s view, indicating the availability of air pressure for safe vehicle operation, often including warning tones or lights. A mechanical “wig wag” that automatically drops down into the driver’s field of vision when the pressure drops below a certain point is also common. Setting of the parking/emergency brake releases the pressurized air in the lines between the compressed air storage tank and the brakes, thus allowing the spring actuated parking brake to engage. A sudden loss of air pressure would result in full spring brake pressure immediately.

A compressed air brake system is divided into a supply system and a control system. The supply system compresses, stores and supplies high-pressure air to the control system as well as to additional air operated auxiliary truck systems (gearbox shift control, clutch pedal air assistance servo, etc.).

Supply system

Highly simplified air brake diagram on a commercial road vehicle (does not show all air reservoirs and all applicable air valves).

The air compressor is driven by the engine either by crankshaft pulley via a belt or directly from the engine timing gears. It is lubricated and cooled by the engine lubrication and cooling systems. Compressed air is first routed through a cooling coil and into an air dryer which removes moisture and oil impurities and also may include a pressure regulator, safety valve and smaller purge reservoir. As an alternative to the air dryer, the supply system can be equipped with an anti-freeze device and oil separator. The compressed air is then stored in a supply reservoir (also called a wet tank) from which it is then distributed via a four-way protection valve into the primary reservoir (rear brake reservoir) and the secondary reservoir (front/trailer brake reservoir), a parking brake reservoir, and an auxiliary air supply distribution point. The system also includes various check, pressure limiting, drain and safety valves.

Air brake systems may include a wig wag device which deploys to warn the driver if the system air pressure drops too low.

Control system

The control system is further divided into two service brake circuits, the parking brake circuit, and the trailer brake circuit. The dual service brake circuits are further split into front and rear wheel circuits which receive compressed air from their individual reservoirs for added safety in case of an air leak. The service brakes are applied by means of a brake pedal air valve which regulates both circuits. The parking brake is the air operated spring brake type where its applied by spring force in the spring brake cylinder and released by compressed air via a hand control valve. The trailer brake consists of a direct two line system: the supply line (marked red) and the separate control or service line (marked blue). The supply line receives air from the prime mover park brake air tank via a park brake relay valve and the control line is regulated via the trailer brake relay valve. The operating signals for the relay are provided by the prime mover brake pedal air valve, trailer service brake hand control (subject to local heavy vehicle legislation) and the prime mover park brake hand control.

Trailer Control Valve
Spring brake cylinder
Air brake foot valve
Trailer brake relay valve
Truck air compressor
Air dryer
Air brake relay valve
Four-way protection valve

Advantages

Air brakes are used as an alternative to hydraulic brakes which are used on lighter vehicles such as automobiles. Hydraulic brakes use a liquid (hydraulic fluid) to transfer pressure from the brake pedal to the brake shoe to stop the vehicle. Air brakes are used in heavy commercial vehicles due to their reliability. They have several advantages for large multi-trailer vehicles:^[4]

The supply of air is unlimited, so the brake system can never run out of its operating fluid, as hydraulic brakes can. Minor leaks do not result in brake failures.
Air line couplings are easier to attach and detach than hydraulic lines; the risk of air getting into hydraulic fluid is eliminated, as is the need to bleed brakes when they are serviced. Air brake circuits on trailers can be easily attached and removed.
Air not only serves as a fluid for transmission of force, but also stores potential energy as it is compressed, so it can serve to control the force applied; hydraulic fluid is nearly incompressible. Air brake systems include an air tank that stores sufficient energy to stop the vehicle if the compressor fails.
Air brakes are effective even with considerable leakage, so an air brake system can be designed with sufficient “fail-safe” capacity to stop the vehicle safely even when leaking.
The compressed air inherent in the system can be used for accessory applications that hydraulics are not appropriate for. For example, air horns and seat adjusters.

Disadvantages

Although air brakes are readily considered the superior braking system for heavy vehicles, generally those with a maximum gross vehicle weight rating (GVWR) of 26,000 to 33,000 pounds or more, which would overload hydraulic brakes, they also have the following disadvantages, when compared to hydraulic braking systems:

Air brakes generally cost more.^[5]
Air brake systems compress air, which results in moisture that requires air dryers to remove, which also increases the price for air brake systems and can contribute to higher maintenance and repair costs, particularly in the first five years.^[5]
In the U.S. commercial drivers are required to obtain additional training and licensing, known as an “endorsement,” in order to legally drive any vehicle using an air brake system. The Federal Motor Carrier Safety Administration (FMCSA), which regulates the trucking industry in the U.S., requires that drivers who operate a vehicle equipped with air brakes take their driving test in one.^[6]
Learning to operate air brakes smoothly has a learning curve, as they are difficult to operate smoothly.^[5]
Also, since air brakes must be operated differently from hydraulic systems, driving a vehicle with air brakes requires knowledge of proper maintenance. A driver is required to inspect the air pressurization system prior to driving and make sure all tanks are in working order.
As noted by the Insurance Corporation of British Columbia (ICBC), “Operating commercial vehicles or vehicles equipped with air brakes requires special knowledge and skill, and the cost of a mistake can be very high. When large vehicles are involved in crashes, the damage—to vehicles, cargo and human lives—can be catastrophic.” [7]

Semi-trucks use air pressure, rather than hydraulic fluid, to actuate the brake. The use of air hoses allows for ease of coupling and uncoupling of trailers from the tractor unit. The most common failure is brake fade, usually caused when the drums or discs and the linings of the brakes overheat from excessive use.

The parking brake of the tractor unit and the emergency brake of the trailer are spring brakes that require air pressure in order to be released. They are applied when air pressure is released from the system, and disengaged when air pressure is supplied. This is a fail-safe design feature which ensures that if air pressure to either unit is lost, the vehicle will stop to a grinding halt, instead of continuing without brakes and becoming uncontrollable. The trailer controls are coupled to the tractor through two gladhand connectors, which provide air pressure, and an electrical cable, which provides power to the lights and any specialized features of the trailer.

Glad-hand connectors (also known as palm couplings) are air hose connectors, each of which has a flat engaging face and retaining tabs. The faces are placed together, and the units are rotated so that the tabs engage each other to hold the connectors together. This arrangement provides a secure connection but allows the couplers to break away without damaging the equipment if they are pulled, as may happen when the tractor and trailer are separated without first uncoupling the air lines. These connectors are similar in design to the ones used for a similar purpose between railroad cars. Two air lines typically connect to the trailer unit. An emergency or main air supply line pressurizes the trailer’s air tank and disengages the emergency brake, and a second service line controls the brake application during normal operation.

Another braking feature of semi-trucks is engine braking, which could be either a compression brake (usually shortened to Jake brake) or exhaust brake or combination of both. However, the use of compression brake alone produces a loud and distinctive noise, and to control noise pollution, some local municipalities have prohibited or restricted the use of engine brake systems inside their jurisdictions, particularly in residential areas. The advantage to using engine braking instead of conventional brakes is that a truck can descend a long grade without overheating its wheel brakes. Some vehicles can also be equipped with hydraulic or electric retarders which have an advantage of near-silent operation.

There are an estimated 500,000 truck accidents in the U.S. each year. Nearly 5,000 of these result in fatalities. The remainder often results in injuries of varying degrees. With four major interstates running through Houston — I-45, I-10, US-290, and I-69 — Texans see more than their fair share of trucking accidents. Unfortunately, many of these accidents are caused by the negligence of truck drivers or trucking companies.

Seeking a Free Consultation with one of Texas’ 18 Wheeler accident lawyers? Call the Big Rig Bull Texas Truck Accident Lawyer Reshard Alexander today at 713.766.3322.

A lot of professional truck drivers work for big motor carrier companies who have law firms ready to fight the moment a driver is involved in a truck wreck. It isn’t unusual for a representative (safety director) of their company to arrive on the scene of an accident to solicit signatures from the injured parties to decrease their liability. If you’re involved in an accident with a large truck, then it is important to keep in mind that you shouldn’t sign anything placed in front of you from the professional driver, the driver’s employer or the insurer of the driver. In the event that you or a loved one was hurt in a collision between a large truck, you want an experienced truck accident attorney that will fight for you.

18 wheeler accident lawyer Reshard Alexander understands exactly what it takes to fight the legal teams of big trucking firms. I help families and their loved ones in a dire time of need. Time is of the essence in these kinds of cases, therefore it is important to call a lawyer versed in this area of law immediately. It is best to consult an experienced Houston truck accident attorney to get help in seeking the claim. Call 18 wheeler accident lawyer Reshard Alexander to request a free case evaluation.