FAW Valves, Hoses And Fittings Assemblies: A Comprehensive Focus on 24 Critical Pneumatic Parts

Welcome to this comprehensive technical guide on the FAW Valves, Hoses And Fittings Assemblies, the complete pneumatic control “logic” system for the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor. This system is the “brains” that controls the “muscle” of the transmission’s range shifter.

The FAW Valves, Hoses And Fittings Assemblies are a critical, chassis-mounted system. It is responsible for taking the driver’s electronic “high/low range” command, passing it through a set of electro-pneumatic valves, and then routing high-pressure air through a specific set of hoses to the transmission’s sub-box shift cylinder.

This in-depth guide is an essential resource for professional technicians and parts specialists. We will deconstruct the entire FAW Valves, Hoses And Fittings Assemblies system into its 24 serviceable components, including the main control valves, the air filter, the high/low gear hoses, and all the brackets and fittings.

The “Brains”: Control Valves (1702355AA9P & 1702255AA9P)

The “logic” of the FAW Valves, Hoses And Fittings Assemblies resides in its main control valves. The parts list identifies a ‘Pneumatic directional valve’ (1702355AA9P) and a ‘Control valve assembly’ (1702255AA9P). These are the electro-pneumatic “logic gates” of the system.

These valves are effectively electronic solenoids. When the driver flips the range selector switch (from Low to High), a low-voltage electrical signal is sent to these valves. This signal energizes an electromagnet, which pulls a “spool” or “poppet” valve open. This action, in turn, releases high-pressure (100+ PSI) air from the truck’s main air system and directs it into a specific port.

This is the “logic”: a small electrical signal from the driver is used to control a large, powerful pneumatic force. These valves are the heart of the FAW Valves, Hoses And Fittings Assemblies. They are sealed to their mounting bracket by the ‘Gasket-control valve’ (1702281AA9P), which is a critical seal. A leak here will cause the system to lose air pressure and fail to shift. A failure in the electronic solenoid will also render the FAW Valves, Hoses And Fittings Assemblies inoperable.

The “Piping”: High & Low Gear Hoses (1702431AA9P / 1702441AA9P)

Once the control valves have directed the air, the “Hoses” component of the FAW Valves, Hoses And Fittings Assemblies takes over. The parts list specifically calls out an ‘Intake hose-low gear’ (1702431AA9P) and an ‘Intake hose-high gear’ (1702441AA9P).

These two hoses are the primary “actuation” lines. The “low gear” hose connects to the “push” side of the transmission’s shift cylinder, and the “high gear” hose connects to the “pull” side (or vice-versa). When the control valve sends air down the ‘Intake hose-high gear’, it pressurizes the cylinder, physically moving the shift fork and engaging the high-range synchronizer.

These are part of a larger network of ‘Intake hoses’ (1702451AA9P, 1702421AA9P, 1702411AA9P) and ‘Elbow joints’ / ‘Pipe joints’ (1702245AA9P, 1702365AA9P, 1702265AA9P, 1702235AA9P, 1702295AA9P). This entire pneumatic “piping” system is the muscle of the FAW Valves, Hoses And Fittings Assemblies.

A crack, split, or loose fitting in any of these high-pressure hoses is a critical failure. It will create a high-pressure air leak, which not only prevents the transmission from shifting ranges but also puts a constant, parasitic drain on the truck’s main air brake system, which is a major safety hazard. The integrity of every component in the FAW Valves, Hoses And Fittings Assemblies is vital.

The “Lungs”: Air Filter (1702380-A7G) & Breathers (1702165-A8L)

The pneumatic valves in the FAW Valves, Hoses And Fittings Assemblies are high-precision components with very tight tolerances. They cannot be fed the “raw” air from the main tanks, which often contains small amounts of rust, moisture, and compressor oil.

The ‘Air filter & joint assembly’ (1702380-A7G) is the “lung” of the system. This is a final, in-line “polishing” filter. It is placed just before the control valves to trap any fine debris or moisture, protecting the solenoids from sticking or failing. This small filter is a key part of the FAW Valves, Hoses And Fittings Assemblies‘ long-term reliability.

Conversely, the two ‘Breather plug assembly’ (1702165-A8L) units are the “exhaust” ports. When the driver shifts from “High” to “Low,” the high-pressure air in the “High” hose must be vented *out* to allow the piston to move. These breathers allow the air to escape quickly and silently, while their internal filters prevent dirt and water from being ingested back into the clean side of the FAW Valves, Hoses And Fittings Assemblies.

The “Fittings”: Brackets, Clamps, and Hardware

The “Fittings” portion of the FAW Valves, Hoses And Fittings Assemblies refers to the complete mounting system. The ‘Welded bracket assembly’ (1702385AA9P) is the main structural foundation. It is a heavy-gauge steel bracket that bolts to the transmission housing or chassis. This bracket provides a rigid, secure platform to mount the control valves and filters.

This bracket, and all its associated plumbing, is secured with high-tensile fasteners designed to resist vibration. This includes ‘Hex flange bolts’ (Q1841020, Q1840660S), ‘Hex head bolts’ (CQ1500435), ‘Inner hex socket head cap screws’ (Q02180620), and ‘Light spring gaskets’ (Q40404, Q40406).

Finally, the hoses are secured with ‘Worm Drive Hose Clamps’ (CQ67622B, CQ67640B) and ‘Hose clamps’ (1702391-A7G). These are critical for creating an air-tight seal at all “push-on” hose connections. A single loose clamp will cause the entire FAW Valves, Hoses And Fittings Assemblies to fail. This robust hardware is what makes the FAW Valves, Hoses And Fittings Assemblies a durable, truck-grade system.

FAW Valves, Hoses And Fittings Assemblies Parts List (1/2)

The following table provides the complete, detailed breakdown of all 24 components for the FAW Valves, Hoses And Fittings Assemblies.

Technical Specifications and Assembly Context

The specifications for the FAW Valves, Hoses And Fittings Assemblies are defined by its function as the pneumatic control system for the transmission’s range shifter. The FAW Valves, Hoses And Fittings Assemblies system is a critical logic controller.