I. Case Background: In 2025, a municipal sanitation department in Zunyi City procured the 3308 wastewater treatment vehicle. To address high-load wastewater treatment demands during the rainy season, the Urban Management Bureau of a district in Zunyi City, Guizhou Province, launched a public tender for a batch of 3308-type wastewater treatment vehicles (model EHY5045TWCE6). These vehicles are primarily used for sewage suction, discharge, and purification in urban drainage networks, industrial zones, and residential areas—with particular emphasis on long-term operational stability under hot and humid conditions. According to publicly available tender information, the budget was capped at approximately RMB 394,000, requiring vehicles equipped with high-efficiency vacuum pumps, corrosion-resistant tanks, and intelligent control systems. Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as 'Chengli')—as one of the primary bidders—leveraged its extensive chassis selection expertise (covering Dongfeng, Sinotruk, Foton, FAW Jiefang, and Shaanxi Automobile chassis) to propose multiple configuration options. Ultimately, a supplier selected the Dongfeng chassis solution and won the bid, delivering two units currently in operation; customer feedback indicates excellent performance during high-load rainy-season operations. II. Chassis Selection Analysis: Comparative Differences Among Dongfeng, Sinotruk, Foton, and FAW Jiefang Chassis For the EHY5045TWCE6 wastewater treatment vehicle, chassis selection is critical to determining load capacity, off-road capability, and maintenance convenience. Below is a comparative analysis of common chassis options (based on Chengli’s product database and MIIT announcement parameters, e.g., CLW5070GSSD6): Comparison of Chassis Options for EHY5045TWCE6 (Reference: Chengli Special Purpose Vehicle Announcement Parameters) Chassis Brand | Wheelbase (mm) | Engine Power (kW) | Load Capacity (tons) | Approach/Departure Angle | Maintenance Convenience | Typical Application Scenarios Dongfeng | 3308 | ~95–105 | 4.5–5.5 | 20°/18° | Nationwide warranty coverage with dense service network | Urban roads, rainy-season operations Sinotruk | 3280 | ~100–115 | 5–6 | 22°/20° | Slightly fewer service stations, but higher chassis strength | Heavy-duty applications, complex road conditions Foton | 3360 | ~90–100 | 4–5 | 19°/17° | Lower maintenance costs and broad service network coverage | Cost-sensitive procurement FAW Jiefang | 3300 | ~95–110 | 4.8–5.5 | 21°/19° | Strong presence in Northeast China; relatively limited coverage in southern regions | Conventional sanitation operations In the Zunyi case, the winning bidder selected the Dongfeng chassis, primarily based on the following considerations: Load Capacity and Off-Road Capability: The Dongfeng 3308-wheelbase chassis offers a load capacity of 4.5–5.5 tons, meeting the weight requirements of the fully loaded EHY5045TWCE6 wastewater treatment vehicle. Its approach angle of 20° and departure angle of 18° ensure good maneuverability on urban roads and narrow rural lanes—particularly suitable for Zunyi’s mountainous, hilly terrain. Maintenance Convenience: Dongfeng chassis enjoys a dense service network across Southwest China—including Guizhou Province—ensuring rapid after-sales response. Chengli provides lifetime upper-structure service support, while Dongfeng offers nationwide factory warranty coverage and 24-hour direct shipment of spare parts, effectively reducing operational and maintenance costs. Anti-Corrosion Coating and Sealing Component Durability in Hot-Humid Environments: To address Zunyi’s hot-humid climate (annual average humidity exceeding 80%), Chengli applied anti-corrosion coatings to the tank and piping system, along with sealing components specifically engineered for long-term durability under such conditions.