Dongfeng FAST Gearbox Assy parts upper cover 12JS160T-1702012-Y

As a key structural component of the gearbox, this upper cover serves three core functions: protecting internal components, supporting the shifting mechanism, and enabling oil filling/inspection. Its integrated design incorporates multiple functional features:

Component Protection: The cover’s rigid structure forms a sealed barrier over the gearbox’s top cavity, shielding internal gears, bearings, and synchronizers from external dust, water, and debris—preventing premature wear caused by contamination.

Shifting Mechanism Support: The inner side of the cover is equipped with precision-machined guide grooves and mounting bosses for the gearbox’s shifting forks and linkage rods. These features ensure stable movement of the shifting components, reducing shifting backlash and improving gear engagement smoothness.

Oil Management: A built-in oil filling port (with a threaded cap and O-ring seal) allows easy gearbox oil replenishment, while an integrated oil level inspection window (made of high-transparency polycarbonate) enables quick visual checks of oil quantity—eliminating the need to disassemble the cover for routine maintenance

To withstand heavy-duty operating conditions, the upper cover uses high-quality materials and advanced manufacturing techniques:

Base Material: Made of high-strength aluminum alloy (ADC12)—a material chosen for its optimal balance of light weight (reducing overall gearbox weight by ~3% compared to cast iron covers) and mechanical strength (tensile strength: ≥220 MPa). ADC12 also offers excellent casting performance, ensuring complex internal structures (e.g., guide grooves, bosses) are formed with high precision.

Surface Treatment: The outer surface undergoes electrophoretic coating (thickness: 8-12 μm) with a black corrosion-resistant finish, which resists rust and chemical damage from road salt, oil, and engine coolant—extending the cover’s service life in harsh vehicle environments.

Precision Machining: Critical surfaces (e.g., flange mating face, shifting guide grooves) are processed via CNC milling, with dimensional tolerance controlled within ±0.05 mm and surface roughness (Ra) ≤ 1.6 μm. This ensures tight sealing with the gearbox body and smooth movement of the shifting components

The upper cover is designed to maintain reliable sealing and stability under high vibration and temperature fluctuations:

Flange Sealing: The cover’s bottom flange features a recessed groove for a nitrile rubber (NBR) sealing gasket (included with the assembly). When installed with the recommended torque (25-30 N·m), the gasket compresses evenly to form a leak-proof seal, preventing gearbox oil leakage (a common issue with poorly sealed covers) even under high internal oil pressure (up to 0.3 MPa).

Vibration Damping: The aluminum alloy material’s inherent damping properties, combined with the cover’s reinforced rib structure (distributed along the edges and around mounting bosses), reduce vibration transfer from the gearbox to the cover. This minimizes noise generated by component resonance and prevents loosening of mounting bolts over time.

Temperature Adaptability: The cover maintains structural integrity and sealing performance across a wide temperature range (-40℃ to 120℃)—covering extreme cold (e.g., northern winter operations) and high-temperature conditions (e.g., prolonged heavy-load driving, engine compartment heat)

The upper cover is primarily applied in Dongfeng FAST 12JS160T-equipped vehicles, including:

Dongfeng heavy-duty cargo trucks for long-distance intercity transportation (where reliable gearbox performance is critical for fuel efficiency and on-time delivery);

Tractor-trailers and semi-trailers used for bulk cargo transport (operating under continuous high-load conditions);

Specialized commercial vehicles such as concrete mixers and tankers (exposed to high vibration and frequent gear shifting).

In terms of installation, it offers distinct advantages:

Direct OEM Replacement: Matches the original upper cover’s dimensions, bolt hole positions, and functional features—no modifications to the gearbox body or shifting mechanism are required. Installation can be completed using standard hand tools (e.g., torque wrench, socket set) in 40-60 minutes.

Complete Assembly: The cover comes pre-fitted with the oil level inspection window, sealing gasket, and oil cap—eliminating the need to purchase and install separate components, and reducing the risk of compatibility issues with aftermarket parts.

Cost-Effective Durability: With a service life of over 100,000 km under normal use, the cover reduces the frequency of maintenance and replacement, lowering long-term operating costs for fleet operators and repair shops