04/01/2022
Q.No.(25) Describe the operation of anti-compounding relay valve!
Ans:- An Anti-Compounding valve is a relay valve with a double-check valve built into it. In some of the vehicles, both valves are fitted separately.
Uses - It is used in compressed air braking system of the heavy commercial vehicle.
Description- It is clear from its name that it does not allow two functions to be compound together at the same time. So that's why it's called anti-compound.
Application- Now, assume that a driver parked the vehicle on a slope by applying the parking brake. When he needs to move the vehicle then he will first press the foot brake pedal to apply the service brake and then release the parking brake (It is common operational behavior). Parking and service brakes are used simultaneously from this kind of operation. It leads to applied excessive forces on the slack adjusters and related components. Consequently, automatic slack adjusters could be flexed by the compounding forces upon the automatic slack adjuster, and this would allow the automatic adjuster to catch the next adjustment notch, even though it wasn't really needed. This resulted in automatic slack adjuster over-tightening, which was a real problem until anti-compounding valves came to the rescue.
Conclusion- The Anti-Compounding valve is fitted to parking brake circuits to prevent the service brake and parking brake from being applied simultaneously.
It prevents the mechanical components in the truck wheel brakes from being damaged if the driver brakes with the foot brakes while the parking brake is applied.
Note- For more information, visit the link mentioned below. Also, your comment is expected.
http://www.gonefcon.com/trucktcom/brakes_compounding.htm