WG9000360509 Relief Valve for Sinotruk HOWO

The WG9000360509 Relief Valve for Sinotruk HOWO is a China-made air brake system safety component offered by brand Skyond to global buyers, manufactured and supplied from its production base in Jinan. This valve is installed near the air reservoir or air dryer on HOWO trucks, activating automatically when system pressure exceeds the set limit to release excess air and prevent damage to piping or components from overpressure. It  fits HOWO, and other Sinotruk models. The thread matches factory ports directly, requiring no adapters or sealants for installation.

Product Specifications

Risks if a Relief Valve Fails

The relief valve is not a fast-wearing part, but when it fails, the consequences are direct and serious.

Valve stuck closed

The air reservoir continues to pressurise beyond design limits, potentially causing line or tank rupture and instant brake system pressure loss.

Valve opens prematurely or fails to seal fully

System hold pressure drops, the compressor cycles frequently (increasing fuel consumption), and brake pedal feel becomes hard with reduced braking force.

Spring fatigue causing pressure shift

The valve opens either below or above its set point, either bleeding off pressure too early (reducing brake reserve) or too late (keeping the system constantly overloaded).

For fleet operators, any delay in brake response caused by air pressure issues is a direct safety concern. The WG9000360509 Relief Valve for Sinotruk HOWO delivers consistent performance: calibrated to OEM pressure values, with springs engineered for long-term fatigue resistance, ensuring the valve opens and closes at the correct pressures.

How Does the Valve Work Internally?

The WG9000360509 Relief Valve for Sinotruk HOWO is a spring-loaded relief valve, consisting of four core components: body, spring, poppet, and seals.

Operating principle: System pressure acts on the bottom of the poppet through the inlet port. When pressure is below the spring set point, the spring holds the poppet tightly against the seat; the valve remains closed. When pressure reaches the set point, air force overcomes spring preload, lifting the poppet and discharging excess air through the exhaust port. As pressure drops, the spring pushes the poppet back to close the valve.

This cycle may occur hundreds of times during vehicle operation. The spring material and heat treatment determine fatigue life; seal material determines whether the valve deforms or hardens under low/high temperatures, affecting seal integrity; the poppet-to-seat fit precision determines zero-leak performance in the closed state.

Our design requirement: the valve must actuate within ±5% of the set pressure, with leak rate below specification after closing, and spring cracking pressure drift within 3% after 100,000 cycles.

Why Springs and Seals Are Critical for the Quality？

Failure points in a relief valve are concentrated in the spring and seals.

Spring: Made of alloy spring steel, quenched and tempered, with black oxide or zinc plating for corrosion resistance. Wire diameter, coil count, and free length are precisely calculated for each pressure rating to deliver accurate preload. Alloy spring steel offers higher elastic limit and fatigue strength than ordinary carbon steel, resisting plastic deformation or fracture under frequent cycling.

Seals: Nitrile butadiene rubber (NBR) with a working temperature range of -40°C to +100°C. NBR provides better tensile strength and abrasion resistance than standard rubber, resisting deformation or wear under high-pressure air impact. A dual-seal design combines an O-ring (dynamic sealing when the poppet moves) and a flat gasket (static sealing when the valve is closed) to achieve zero leakage in the closed state.

Body: Available in ductile iron or die-cast aluminium. Ductile iron offers high strength and impact resistance for heavy-load applications; aluminium is lighter with better heat dissipation where weight matters. Both materials receive anti-corrosion treatment, passing salt-spray tests of 72 hours minimum.

Inspection Process at Skyond

Each WG9000360509 Relief Valve for Sinotruk HOWO undergoes the following inspections before shipment:

1. Cracking pressure test. Using a dedicated pressure test bench with compressed air, pressure is gradually increased until the valve opens, recording the cracking pressure. For the 0.6MPa rating, the acceptable range is 0.58–0.62MPa; for 0.65MPa, it is 0.63–0.67MPa. Units outside this range are reworked.

2. Closing pressure and leak test. After opening, pressure is released until the valve reseats; the closing pressure is verified for stability. The valve is then held closed for 30 seconds while leak rate is measured. Standard requires leak rate ≤5mL/min after closing.

3. Spring compression test. Random samples of springs are tested for compression/rebound performance under simulated working conditions, verifying that free length and working height are within design tolerances.

4. Visual and thread inspection. Body surface is checked for sand holes or cracks; threads are verified with go/no-go gauges.

All inspection results are recorded per batch, with reports retained for traceability.

Installation Convenience 

The WG9000360509 Relief Valve for Sinotruk HOWO uses threads identical to original factory designs. Installation requires no adapters, thread tape, or liquid sealant.

Procedure: Locate the mounting port on the air reservoir or air dryer, hand-thread the valve until threads engage, then tighten with a standard wrench to the specified torque. The thread design is selfsealing – once torqued, the tapered or flat sealing surface forms a seal with the port, not relying on tape or paste to fill gaps.

Replacement process: Depressurise the air reservoir, remove the old valve, clean the mounting port threads and sealing surface, then install the new valve. Replacement time for a single valve is under 15 minutes.

OEM Customisation Capability:Manufacture to Drawings, Samples, or Special Requirements 

Skyond not only supplies standard catalogue products but also accepts OEM custom orders. For customers with special pressure settings, port sizes, or branding requirements, we provide end-to-end customisation from design to mass production.

Customisation process:Customer provides product drawings, samples, or detailed specifications.

Our technical team evaluates feasibility, confirming materials, pressure parameters, machining processes, and other critical aspects.

Samples are produced for customer testing and approval.

After sample approval, mass production begins with full quality control traceability.

Several overseas customers already cooperate with Skyond on OEM projects, with their own branding applied to product surfaces for local market sales. MOQ and lead time for OEM orders are negotiated based on product complexity.

Skyond’s Full Range of Sinotruk Parts Supply

The WG9000360509 Relief Valve for Sinotruk HOWO is just one product in Skyond’s portfolio. With 15 years of experience in the Sinotruk parts sector, Skyond offers a complete parts supply covering engines, transmissions, chassis, and body systems.

Engine parts: cylinder blocks, heads, pistons, piston rings, crankshafts, connecting rods, valves, fuel pumps, water pumps, turbochargers, etc.

Transmission parts: cases, gears, synchronisers, bearings, shift mechanisms, clutch discs and pressure plates, etc.

Chassis parts: frames, suspension, steering gears, tie rod ends, brake drums, brake discs, etc.

Maintenance parts: filters (oil, fuel, air), brake pads, belts, tensioners, etc.

All parts are available in both genuine OEM and high-quality aftermarket options to suit different market needs and procurement budgets. Volume orders receive better unit pricing – bulk orders are welcome.

Why Source Your HOWO Parts from Skyond?

1. Fifteen years of focused experience. Skyond has been operating in the heavy-duty truck and construction machinery parts sector for 15 years, building deep familiarity with Sinotruk's full product line from engine internals to chassis components and air brake system parts like the WG9000360509 relief valve. This means faster identification of the correct part for your vehicle and fewer ordering errors.

2. Located in Sinotruk's home city. Our factory and warehouse are based in Jinan, the headquarters city of Sinotruk. This gives us direct access to accurate specifications and original reference samples, and allows us to move inventory quickly with no long lead times caused by multi-tier distribution channels. Most orders ship within 7–45 days after payment.

3. Ready for global delivery. We export regularly to Russia, Central Asia, Southeast Asia, Africa, South America, and beyond. Our logistics team is experienced in container loading, customs documentation, and routing to major ports. Whether you need a single valve or a full container of mixed parts, we handle the shipping side so you don't have to.

4. One supplier, thousands of parts. Beyond the WG9000360509 relief valve, Skyond stocks and supplies engine parts, transmission components, chassis parts, filters, brake pads, belts, and more over 130,000 items in total. Ordering multiple part types from a single source reduces your procurement workload and consolidates shipments.

Straightforward after-sales. If a product arrives with a confirmed quality issue, we repair, replace, or refund. No arguments, no extended delays. We stand behind what we ship.