Vehicles equipped with air brakes must have distinct braking systems for both routine stopping and emergency and parking braking. These systems are separately regulated. Service brakes are the brakes that are utilized for regular stopping. The brake chamber price also varies, The functioning and purpose of the service brake subsystem are described in this chapter. Note: The parts of the service braking system are shown in the circuit diagrams.
Use of the brake pedal
The brakes used for standard stopping are operated by depressing the brake pedal. The air pressure that is applied to the service brakes is managed by the brake pedal. Compressed air is provided to the brakes at the wheels as the brake pedal is depressed by passing via a valve linked to the pedal. The valve opens more when the brake pedal is depressed harder, sending more air pressure to the service brakes and enhancing braking power at the wheels.
The air is pulled from both the primary and secondary tanks and is sent to certain wheels on the vehicle since the majority of brake-system designs employ dual circuits. Depending on the car’s maker, different wheels may get air through the primary or secondary circuits. Because of the dual circuit architecture, the brakes will still function on the wheels attached to the other circuit even if one circuit fails.
hoses and tubes for brakes
A variety of flexible brake hoses and tubes are needed to provide compressed air to all air brake system components. These come in a variety of colors, sizes, and styles and are produced from a wide range of natural and synthetic materials. Every hose and tube needs to be the appropriate size and kind. Currently, manufacturers adhere to an industry color scheme, while older cars do not.
Each tire has an air brake chamber, which is a spherical metal container where compressed air is transformed into mechanical force to apply the brakes and stop the car. Service and spring brake chambers are the two types of air brake chambers.
A pushrod, a return spring, and a flexible rubber disc known as a diaphragm are all parts of a service brake chamber. Compressed air enters the service brake chamber as you depress the brake pedal, causing the diaphragm to move and force the pushrod out to apply the brakes (Diagram 3-1).
The chamber’s spring causes the pushrod to return to its initial position when air pressure is removed (Diagrams 3-2).
The brake chamber is connected to the brake system by a pushrod and a lever known as a slack adjuster (which contains the brake drum or disc). The slack adjuster advances when the brake pedal is depressed because the pushrod extends further from the brake chamber.
The brake assembly is moved by the slack adjuster, which then moves the brake shoes or pads into contact with the braking drum or disc.
Pushrod stroke refers to the movement of the pushrod as it extends from the brake chamber, and the stroke length is the distance that the pushrod moves out of the chamber. Some of the brake linkage, which connects the brake chamber to the brake assembly, is visible in the majority of brake designs. As a consequence, it is possible to gauge the pushrod’s stroke length and compare it to the permitted adjustment ranges for that size, style, and brake chamber type.
The pressure of the compressed air that enters the braking chamber affects the pushrod stroke. For instance, the stroke visibly increases when application pressure rises from 69 kPa (10 psi) to 552 kPa (80 psi).
Each brake chamber is only capable of accommodating a certain amount of pushrod stroke length before no braking force is generated. The brake linkage has a mechanism for adjusting the brake chamber’s position about the brake shoes’ location.
The linkage has to be adjusted when brakes deteriorate to guarantee that the pushrod stroke is always within the acceptable working range. Regular brake re-adjustments of this kind are necessary.
Brakes must be properly set to ensure the function is maintained since the loss in braking force when stroke exceeds a brake chamber’s adjustment limitations can be substantial. The brake-chamber pushrod stroke is rigorously governed by the Ontario Highway Traffic Act and its regulations. Any brake that deviates from the adjustment limit is defective and has to be fixed right away.
For both manual and automated slack adjusters, brake re-adjustments are only permitted by qualified technicians. See Chapter 11, Checking Air Brake Adjustment, for further details.
It is crucial to accurately identify the brake type and the chamber size to establish the appropriate brake adjustment limit since brake chambers are created in a range of designs, kinds, and sizes.
A type of braking chamber that is kept together by a clamp assembly is used in almost all commercial vehicles. Clamp-type brake chambers are what these are. Page 85 has an adjustment table for various kinds of chambers. However, certain automobiles could employ different kinds of braking chambers.