Spring Body Ball Cap nut The following explains the additional components of a basic air brake system. S-cam Brake with Automatic Slack Adjuster Automatic slack adjusters adjust themselves during brake applications to accommodate for brake lining and drum wear. 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. If the warning signal does not work, you could lose air pressure and not know it. If the safety valve releases air, something is wrong. What is the main cause of brake failure? Compounding is the combination of two forces: the force applied by the spring brakes and the service brake.
Loss of Reservoir Air Pressure 28 21 In this illustration the pressure has been lowered to approximately 45-20 psi and the tractor protection system has closed automatically, placing the trailer brakes into an emergency position. What is the purpose of having more than one reservoir? Further, routine adjustment of most automatic adjusters will likely result in premature wear of the adjuster itself. Compressor and Warning Devices Check · Start the engine and run at fast idle to build air pressure. One of the most important phases of any investigation into a traffic crash is that which is conducted at the scene. The driver has full control of the braking force as the air control section modulates the boost pressure in proportion to the master cylinder pressure.
The Components of an Air Brake System A basic air brake system capable of stopping a vehicle has five main components: 1. They use hydraulic brakes at each wheel with their reliable self adjusters and limited maintenance. The manual adjustment of automatic slack adjusters is dangerous because it may give the driver a false sense of security regarding the effectiveness of the braking system. The braking power of spring brakes depends on the brakes being in adjustment. It is important to understand that pedals and the gearbox system use compressed air to amplify and assist the input of the driver.
These tanks may be equipped for manual draining as well. If the brake application is held, the air pressure in the tractor system will lower to a dangerously low level and then the tractor protection system will place the trailer brakes into an emergency application. A safety valve is normally set at 150 psi. The parts of these systems are discussed in greater detail in the following paragraphs. Disc Brake Adjustment There are a number of makes and models of air disc brakes, each with a different adjustment procedure. . You should know how it passes through filters and dries before it is stored in the main reservoir.
If a slack adjuster moves more than about one inch where the push rod attaches to it, it probably needs adjustment. When is the compressor able to accomplish most of its cooling? Too much heat results in brake damage and possible failure. Hand Valve Application 30 26 31 In this illustration with the foot valve 31 released and the hand valve 30 opened, application air is directed from the hand valve through a two-way check valve 26 , to the brake chambers. Verify that the system is at full pressure, charge the trailer by opening the trailer supply valve, make a brake application and hold it, use a hand brake valve if alone. Most vehicles are equipped with more than one reservoir. Stop fanning to see if the governor has placed the compressor in the loading stage the reading on the air gauge should increase.
As an automatic slack adjuster ages in service, the components wear that sense when an adjustment is required. In fact, replacement of a kidney, cornea, heart or liver is no longer considered an experiment but a treatment choice. Bring the vehicle to a safe stop, and have the air brakes system fixed. · Gently tug against the spring parking brakes in low gear, it should hold the vehicle. How is the heat that is generated by the brakes dissipated? Letting up on the brake pedal reduces the air pressure and releases the brakes. Slack adjuster Diaphragm 16 Clevis and pin Diaphragm return spring Push rod A brake chamber 11 14 32 is a circular container divided in the middle by a flexible diaphragm.
Any time a trailer brake application is made using the hand valve, the driver may depress the foot valve treadle. Dollies manufactured on or after March 1, 1998 are required to have a lamp on the left side. Check the air hoses connected to the brake chambers to make sure they are not cut or worn due to rubbing. When air enters, the pressure protection part of the trailer spring parking brake valve opens, allowing the air to fill the trailer reservoirs. These springs are under extreme pressure and could cause serious personal injury if disassembly is attempted by anyone not experienced in servicing these units. With the air pressure at maximum pressure cut-out , begin slowly pumping the brake pedal to reduce the air tank pressure. Most air gauges measure in imperial units.
For more information, please see. Air Brake Endorsement · permits the holder to drive vehicles equipped with air brakes in class of vehicle for which the driver is licenced. Wedge brakes may have a single brake chamber, or two brake chambers, pushing wedges in at both ends of the brake shoes. It is in this reservoir that most of the water is condensed from the incoming air. This is important as it prevents an automatic application of the trailer spring brakes if one of the reservoirs were to lose air pressure.