A004200184 Brake valve OE number by MERCEDES-BENZ

A004200184 Brake valve OE number by MERCEDES-BENZ 

1.Quick Notice

A004200184 brake valve for Mercedes-Benz commercial vehicles. This is a genuine OE number, typically functioning as a brake pedal valve or foot brake valve (often referred to as a "brake valve" in truck pneumatic systems). Direct replacement component for the air brake actuation system. No mounting hardware or fitting seals included. Verify the valve port configuration and thread types before ordering. Professional installation is mandatory.

2.Description

The A004200184 brake valve is a pneumatic component designed for Mercedes-Benz trucks, likely from the Actros, Axor, or Atego series. In heavy-duty commercial vehicles, the foot brake valve converts the mechanical force from the brake pedal into a proportional air pressure signal, which is then sent to the brake chambers via relay valves [citation:1]. This valve is central to the vehicle's safety system.

Construction: The housing is typically made of high-strength aluminum alloy or reinforced plastic with a corrosion-resistant coating to withstand underbody conditions, including road salt and moisture. The valve includes a plunger mechanism, return springs, and rubber diaphragms that are sensitive to contamination.

Operation (Pneumatic Foot Brake Valve): When the driver presses the brake pedal, a pushrod compresses the internal spring. This force opens an inlet valve, allowing compressed air from the reservoir (Port 1) to flow to the brake circuits (Port 2). The pressure output increases proportionally with the pedal stroke. When the pedal is released, the valve closes the inlet and opens an exhaust port to vent the brake line pressure to the atmosphere [citation:1]. This valve usually manages two separate circuits (dual-circuit) for redundancy.

This specific part number (A004200184) replaces previous versions or is superseded by later numbers depending on the chassis generation. Compatibility is strictly defined by the vehicle identification number (VIN). It is not interchangeable with standard pneumatic valves due to specific pedal ratio and pressure characteristic curves.

Suitability: This replacement valve is suitable if the original unit exhibits signs of brake drag (valve not exhausting), hard pedal feel (internal binding), hissing from the exhaust port (internal leakage), or visible corrosion of the aluminum body.

3.Parameter Table

4.Custom Content

Important Fitment Notes:
This part number must be matched to the specific chassis number. The brake valve is one of the most safety-critical components on a truck. Do not rely solely on the part number printed on the old valve, as Mercedes-Benz often supersedes numbers or uses variant-specific characteristics (e.g., different pedal travel to pressure ratios). Provide the vehicle's VIN to the parts supplier to verify that A004200184 is the exact match for the specific truck model and year.

Pre-Installation Checks:
Before installing the new valve, inspect the condition of the compressed air supply. Water or oil contamination from the air tanks is the primary cause of premature brake valve failure. If the old valve was contaminated, the air dryer and tanks must be serviced to prevent damage to the new unit. Check the actuation pushrod for straightness and wear where it contacts the valve plunger.

Installation Guidance:
Depressurize the air system completely before removal. Open the drain valves on the air tanks. Visually confirm that the old fitting seals (copper washers or O-rings) are not seized in the ports. Install new seals on the new valve, if applicable. Apply a small amount of non-hardening thread sealant or use the specified thread paste for metric brake threads to ensure a dry connection. Do not use Teflon tape on tapered threads inside a brake system.

Post-Installation Procedure:
After installation, pressurize the system and conduct a thorough leak test using soapy water at all port connections and the exhaust port. The internal exhaust port should not emit air when the brake is released. Perform a brake function test in a safe, low-speed environment to ensure the pedal feel is correct and the brakes release fully.

5.FAQ (Q&A Format)

Q1: Which Mercedes-Benz trucks use the A004200184 brake valve?
A1: This part number is specific to certain generations of Mercedes-Benz heavy trucks, including Actros (MP1, MP2, MP3) and Axor models. Fitment depends entirely on the VIN and chassis configuration due to different pedal assemblies.

Q2: What is the difference between A004200184 and the previous part number?
A2: The differences are usually internal. Mercedes-Benz may have revised the supercession to improve seal durability or change the pressure curve slightly. Externally, the port orientation is often identical, but the internal calibration (load sensing or pressure reduction) may vary.

Q3: Why does my new brake valve hiss from the exhaust port continuously?
A3: This is usually not a fault with the new valve. If the exhaust port hisses without the brake being pressed, it indicates that the valve is "cracked" open. This often points to improper pushrod adjustment (it is too tight, preloading the valve) or a lack of free play in the brake pedal linkage.

Q4: Does this valve include the mounting bracket or pedal pushrod?
A4: No. The A004200184 is typically the valve body only. The mounting bracket, pedal pushrod, and clevis are separate components that must be reused from the original vehicle or ordered separately.

Q5: Can I rebuild this brake valve instead of replacing it?
A5: While repair kits are available for some truck brake valves, OE manufacturers and most safety regulations strongly recommend complete replacement. Wear inside the aluminum bore and corrosion on the plunger often make rebuilding unreliable. Replacing the entire valve is the safest option for a brake system component.

Q6: What torque should I apply to the air line fittings?
A6: Torque depends on the thread size. For M22x1.5 metric threads, the typical torque range is 40 to 50 Nm. Overtightening can crack the valve housing. Always use a torque wrench and ensure the threads are clean and dry or lightly lubricated with brake system paste.