How to troubleshoot a hard-to-push brake footvalve on an 88 International single axle dump truck

Question:

The 88 International single axle dump truck has a firewall-mounted brake footvalve with a plunger connected to the pedal. Lately, the pedal has been difficult to push for effective braking despite good brakes and properly adjusted maxis. Research indicates that the valve may be in "emergency mode," where the secondary inlet valve opens only with significant force applied through the footpedal, plunger, and primary piston. Troubleshooting is needed to address this issue. The truck features two reservoir gauges, possibly for accessories. Before dismantling the valve, it is crucial to gather as much information as possible to avoid overlooking other potential problems. Seeking recommendations for a reliable airbrake system diagnostic website to assist with the troubleshooting process.

Top Replies

The under dash linkage on these vehicles can be challenging to maintain. It's essential to remove the Treadle Valve from the firewall and thoroughly clean up the linkage, which is classified as an E-7 type. When taking your Driver License exam, you may encounter questions about the dual air supply system. In this system, the red supply is for the front axle, while the green supply is for the rear axle. This separation is crucial as it ensures that one supply can still function in case of a mass leak, allowing the vehicle to stop safely. While some may think pressure gauges are necessary, they are often just an unnecessary distraction on large car dashboards. This system is known as a dual-circuit air system according to SGI standards.

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Frequently Asked Questions (FAQ)

FAQ: 1. What could be causing the brake footvalve on my 88 International single axle dump truck to be hard to push?

Answer: Answer: The valve may be in "emergency mode," where the secondary inlet valve opens only with significant force applied through the footpedal, plunger, and primary piston.

FAQ: 2. How can I troubleshoot a hard-to-push brake footvalve on my truck?

Answer: Answer: Before dismantling the valve, it is important to gather as much information as possible to avoid overlooking other potential problems. Seeking recommendations for a reliable airbrake system diagnostic website can assist with the troubleshooting process.

FAQ: 3. What should I check if my brake pedal is difficult to push despite having good brakes and properly adjusted maxis on my dump truck?

Answer: Answer: It is recommended to investigate the possibility of the valve being in "emergency mode" and the secondary inlet valve requiring significant force to open through the footpedal, plunger, and primary piston.

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