- ChangChun City, Jilin Province, China
by 
The FAW Transmission Top Cover Assembly serves as the kinetic interface between the driver and the 6G55 gearbox. Acting as the command module for torque management, this assembly houses the precise linkage mechanisms required to translate manual gear selection into internal fork movement. Maintaining the structural integrity of the FAW Transmission Top Cover Assembly is critical for ensuring smooth transitions and preventing drivetrain shock.
FAW Transmission Top Cover Assembly
In the heavy-duty logistics sector, transmission reliability is non-negotiable. The FAW Transmission Top Cover Assembly acts as the primary shield and control center for the transmission’s upper architecture. It is not merely a lid; it is a calibrated mechanical system that must endure millions of shift cycles. When a driver manipulates the gear stick, the force is routed directly into this assembly. The internal rocker arms and shafts must withstand high leverage forces without flexing. If the FAW Transmission Top Cover Assembly loses its dimensional stability due to fatigue or poor-quality casting, the result is “gear hunting” or an inability to fully engage a specific ratio.
Furthermore, this assembly plays a vital role in environmental isolation. The 6G55 transmission operates in grueling conditions, from dusty mines to rain-soaked highways. The FAW Transmission Top Cover Assembly utilizes a system of felt washers, dust cups, and precision-machined mating surfaces to create an impermeable barrier. This prevents abrasive silica dust and moisture from entering the gearbox oil. Contamination is the leading cause of premature bearing and gear failure. Therefore, the sealing capability of the FAW Transmission Top Cover Assembly is directly linked to the total lifecycle cost of the vehicle.
For fleet managers, understanding the breakdown of this component is essential for predictive maintenance. By treating the FAW Transmission Top Cover Assembly as a serviceable unit rather than a static part, technicians can identify wear in bushings and pins before they escalate into major transmission overhauls. The following sections detail the engineering logic and specific components that make this assembly a cornerstone of the FAW 6G55 transmission’s durability.
The engineering architecture of the FAW Transmission Top Cover Assembly prioritizes rigidity and friction management. The core of the system revolves around the Shift rocker axis (Part No. 6G55-8071) and the Select rocker axis (Part No. 6G55-8011). These axes are manufactured from high-grade steel, often subjected to induction hardening processes to resist surface wear. They rotate within specialized bushings, such as the Bush of shift rocker axis (Part No. 6G55-8084). This material pairing—hardened steel on a softer bushing—is a deliberate design choice within the FAW Transmission Top Cover Assembly to ensure that wear is concentrated on the replaceable bushing rather than the expensive shaft.
Precision kinematics are achieved through the Shift rocker arm (Part No. 6G55-8077) and the Select rocker arm (Part No. 6G55-8027). These components are forged to withstand the sudden torque application of a rapid gear change. The geometry of these arms in the FAW Transmission Top Cover Assembly is calculated to provide the optimal mechanical advantage, reducing the physical effort required by the driver while maximizing the force applied to the internal shift forks. Any deviation in the casting dimensions of these arms would result in a “notchy” or heavy shift feel, contributing to driver fatigue.
The assembly also integrates critical safety interlocks. The Pin of neutral position switch (Part No. 6G55-8955) is a prime example of electromechanical integration. This pin physically interacts with the neutral switch sensor, providing a signal only when the transmission is safely out of gear. This feature of the FAW Transmission Top Cover Assembly is crucial for the vehicle’s starting circuit logic, preventing the engine from cranking while in gear. Similarly, the Power switch of backup light (Part No. WK-118-6G55) is mechanically actuated by the internal rail movement, ensuring immediate illumination of reverse lights for job site safety.
Finally, the mounting strategy employs a high-density bolt pattern using fasteners like Bolt (Part No. Q150B1065) and Bolt (Part No. Q150B0850). The FAW Transmission Top Cover Assembly is subjected to intense high-frequency vibration from the diesel engine. To prevent self-loosening, these bolts are often paired with tensioning elements. The rigidity provided by this fastening system ensures that the shift rails remain perfectly parallel to the main shafts, preventing the dreaded “gear pop-out” phenomenon under load.
Below is the comprehensive parts catalog for the FAW Transmission Top Cover Assembly. This list includes all structural linkage, sealing elements, and fastening hardware required for a complete overhaul.
| No. | Code (Part No.) | Name | Number (Q’ty) |
|---|---|---|---|
| 1 | 6G55-8076 | Pin of shift rocker arm | 1 |
| 2 | Q340B10 | Nut | 2 |
| 3 | 6G55-8077 | Shift rocker arm | 1 |
| 4 | Q150B1065 | Bolt | 1 |
| 5 | 6G55-8023 | Dust cup | 1 |
| 6 | 28X42X11DC01-6G55 | Felt washer | 1 |
| 7 | 6G55-8084 | Bush of shift rocker axis | 1 |
| 8 | 6G55-8071 | Shift rocker axis | 1 |
| 9 | 6G55-8075 | Pushing Block | 1 |
| 10 | 6G55-8035 | Ring | 1 |
| 11 | 6G55-8021 | Shift rocker lid | 1 |
| 12 | 6G55-8022 | Shift rocker lid | 1 |
| 13 | 6G55-8025 | Cover board | 1 |
| 14 | Q40008 | Flap gasket | 4 |
| 15 | Q150B0816 | Bolt | 4 |
| 16 | 6G55-8053 | Positioning seat | 1 |
| 17 | WK-118-6G55 | Power switch of backup light | 1 |
| 18 | 6G55-8955 | Pin of neutral position switch | 1 |
| 19 | WTD25X18X1.5-6G55 | Drain plug gasket | 1 |
| 20 | WTM18X9-6G55 | Plug screw | 1 |
| 21 | Q901 | Ventilation plug | 1 |
| 22 | Q40008 | Flap gasket | 8 |
| 23 | Q150B0850 | Bolt | 8 |
| 24 | Q340B08 | Nut | 1 |
| 25 | 6G55-8027 | select rocker arm | 1 |
| 26 | 6G55-8921 | Pin of select rocker arm | 1 |
| 27 | Q150B1050 | Bolt | 1 |
| 28 | 6G55-8083 | Dust cup | 1 |
| 29 | 20X30X7DC01-6G55 | Felt washer | 1 |
| 30 | 6G55-8011 | select rocker axis | 1 |
| 31 | HK222812 | Bearing | 1 |
| 32 | 6G55-8085 | Pushing Block | 1 |
| 33 | Q43114 | Ring | 1 |
To fully understand the FAW Transmission Top Cover Assembly, we must analyze the specific role of its sealing infrastructure. The Felt washer (Part No. 20X30X7DC01-6G55) and Dust cup (Part No. 6G55-8023) form the first line of defense. Unlike rubber seals that may crack in extreme cold, felt retains oil, creating a self-lubricating barrier that traps fine particulate matter. If these components are neglected during a rebuild of the FAW Transmission Top Cover Assembly, the shift rails will ingest grit. This abrasive paste will score the shafts, leading to hydraulic leaks and a stiff, grinding shift action that infuriates drivers.
The structural rigidity of the assembly is maintained by the Positioning seat (Part No. 6G55-8053) and the Cover board (Part No. 6G55-8025). These static components provide the necessary abutment surfaces for the moving linkage. Over time, vibration can cause fretting wear at these contact points. A loose Cover board on the FAW Transmission Top Cover Assembly allows moisture ingress, which can rust the internal springs and detent balls. Therefore, inspecting these flat surfaces for pitting or warping is just as important as checking the moving gears.
The Pushing Block (Part No. 6G55-8085) is the critical translator of motion within the FAW Transmission Top Cover Assembly. It converts the rotational energy of the rocker axis into linear displacement. Because this block slides against the shift forks, it is a high-wear item. As the block wears down, the “throw” of the gear stick increases. Eventually, the driver may hit the physical stop of the stick before the gear is fully engaged inside the transmission. Replacing this block restores the crisp, short-throw feel that defines a well-maintained 6G55 unit.
Finally, the Bearing (Part No. HK222812) is a needle roller bearing designed for high radial loads in a compact space. Located at the pivot points of the axes, this bearing ensures friction-free rotation. If a technician uses a hammer to force the axis during disassembly, this delicate bearing can be crushed. A damaged bearing in the FAW Transmission Top Cover Assembly will cause the shift lever to bind or stick, making it difficult to find neutral. Professional installation using a press is mandatory to preserve the integrity of this component.
A proactive maintenance strategy for the FAW Transmission Top Cover Assembly begins with external inspection. Technicians should regularly check the condition of the Ventilation plug (Part No. Q901). This small breather allows the transmission to equalize pressure as it heats up. If it becomes clogged with mud or grease, internal pressure will build up, forcing oil past the Felt washer and gaskets. A simple cleaning of this plug during every oil change can prevent seal failure and extend the life of the entire assembly.
Fastener integrity is another pillar of maintenance. The FAW Transmission Top Cover Assembly is secured by multiple bolts, including Bolt (Part No. Q150B0816) and Nut (Part No. Q340B10). Due to the high-torque nature of the 6G55 transmission, chassis flex can cause these fasteners to back out over time. A loose top cover not only leaks oil but can also misalign the shift forks, leading to bent rails. We recommend checking the torque on these accessible bolts every 20,000 kilometers as part of a standard service loop.
When leaks do occur, the Flap gasket (Part No. Q40008) and Drain plug gasket (Part No. WTD25X18X1.5-6G55) are the usual culprits. These should be considered single-use items. Reusing a crushed gasket on the FAW Transmission Top Cover Assembly is a false economy that invariably leads to repeat repairs. Always keep a stock of these low-cost consumables to ensure that every time the cover is opened, it is resealed to factory specifications.
The market is flooded with aftermarket alternatives, but the FAW Transmission Top Cover Assembly requires the metallurgical precision that only genuine FAW parts can provide. An aftermarket Shift rocker arm may look identical, but if the steel lacks the correct heat treatment, it will wear prematurely or snap under heavy load. The downtime cost of a broken transmission far outweighs the savings of buying a generic component.
Furthermore, genuine parts guarantee geometric compatibility. The FAW Transmission Top Cover Assembly relies on the precise interaction of over 30 components. If the Ring (Part No. Q43114) or Pin of shift rocker arm (Part No. 6G55-8076) is out of tolerance by even a fraction of a millimeter, the entire shift linkage will feel loose and imprecise. Genuine parts ensure that the “click-clack” positive engagement of the 6G55 transmission is preserved.
By adhering to the parts list provided in this guide and insisting on genuine replacements, you ensure the longevity and safety of your fleet. Protect your investment by maintaining the FAW Transmission Top Cover Assembly with the same quality components used on the assembly line.
FAW parts, including the Cylinder Block Assembly, are packaged with care to ensure safe delivery. Each component is secured in protective materials to prevent damage during transit. The logistics network guarantees timely shipments worldwide, supporting efficient maintenance operations. Below is an image illustrating the standard packaging for FAW truck parts, showcasing the attention to detail in handling and storage.
This packaging approach minimizes the risk of corrosion or impact damage, ensuring that parts like the FAW Cylinder Block Assembly arrive in perfect condition. Customers can rely on FAW’s logistics for consistent quality and reliability.
FAW is one of China’s oldest and largest automotive manufacturers, with registered capital of RMB 35.4 billion yuan and total assets of RMB 457.83 billion yuan.
CHINA FAW GROUP CO., LTD. (short for FAW), formerly China First Automobile Works, can trace its roots back to Jul 15, 1953, when its first assembly plant started to be constructed. FAW is one of China’s oldest and largest automotive manufacturers, with registered capital of RMB 35.4 billion yuan and total assets of RMB 457.83 billion yuan.
China heavy truck sales global “five in a row”, heavy truck sales global “six in a row”, tractor sales for 16 consecutive years absolute leading industry.
