Zhongtong Bus Four Circuit Protection Valve Air Brake System Manifold 4 Way

Zhongtong Bus Four Circuit Protection Valve

Four circuit protection valve for Zhongtong city buses and coaches. The valve splits the compressed air supply from the compressor into four independent circuits - typically front service brake, rear service brake, parking brake and auxiliary circuits - and protects each one with its own pressure limiting and check function. If one circuit loses pressure through a leak or a burst line, the other circuits stay charged and the bus can still brake and be driven to the depot safely.

Product Highlights

• Four independent circuits - front brake, rear brake, parking brake and auxiliary supply
• Circuit isolation on failure - a leaking circuit is cut off and the remaining circuits hold pressure
• Pressure limiting per circuit - keeps each circuit inside its design pressure range
• Integrated check valves - stops back flow between circuits
• Anodised aluminium body - corrosion resistant in humid and coastal service
• Direct replacement fit - port layout and mounting holes match the original valve

Technical Specifications

Fault Signs of a Failed Protection Valve

• Air pressure builds slowly, or one circuit never reaches working pressure
• Pressure drops overnight with no visible leak at the pipes
• Low pressure warning buzzer or lamp stays on after start up
• Air escaping from the valve body or at a delivery port
• Brake performance uneven between front and rear axle

Installation Notes

1. Drain the air system completely and confirm zero pressure before removing any pipe.
2. Mark each pipe position before removal so the four delivery lines go back to the correct ports.
3. Fit the new valve with new sealing washers, then tighten the unions to the specified torque.
4. Refill the system, check for leaks at every port and confirm all circuits reach working pressure.
5. Carry out a brake test and check the low pressure warning function before the bus returns to service.

Packing and Supply

Each valve is protected with port caps, wrapped in anti-rust paper and packed in an export carton. Neutral packing and mixed container loading with other Zhongtong air brake parts are available.

Order Support

Send us a photo of the original valve with the port layout, and we will confirm the matching version, thread sizes and price within one working day.