Case Study and Bid-winning Solution Analysis of the National VI Dongfeng 3308 mm Wheelbase Sewage Treatment Vehicle Procurement in Shijiazhuang Shijiazhuang, located in North China, experiences winter temperatures as low as -15°C to -20°C, imposing stringent requirements on specialized vehicles’ hydraulic systems, engine starting performance, and sewage treatment efficiency. In late 2025, a municipal sanitation department launched a procurement initiative for sewage treatment vehicles to replace aging equipment and enhance urban sewer network maintenance efficiency. This article deconstructs the procurement case, focusing on why Chengli Special Purpose Vehicle (CLW)’s National VI Dongfeng 3308 mm wheelbase sewage treatment vehicle secured delivery of six units—and details its targeted design features for frost-resistant starting, low-temperature hydraulic stability, and winter maintenance. I. Pain Points of Aging Equipment: Vulnerabilities in Low Temperatures The department previously operated three aging sewage vehicles, all over eight years old. During winter operations, they frequently encountered the following issues: - Difficult Starting: Below -10°C, diesel engines suffered from intake manifold frost formation or battery discharge, requiring multiple preheating cycles before successful startup—delaying emergency response operations. - Hydraulic System Failure: At low temperatures, hydraulic oil viscosity increased significantly, causing sluggish operation—or even complete failure—of suction pumps and pipeline directional valves; in extreme cases, hydraulic oil solidified. - Sewage Freezing: Tanks and pipelines lacked thermal insulation, resulting in residual wastewater freezing after operations, leading to pipe blockages and increased maintenance costs. These issues directly compromised the timeliness of urban sewage cleanup—especially following heavy snowfall or ice storms—severely limiting emergency response capability. II. New Requirements Survey: Emphasis on “Winter Adaptability” In November 2025, the department formally initiated a procurement needs survey. Referencing publicly available tender information, the total budget was set at approximately RMB 831,000–942,000 for six vehicles (i.e., RMB 120,000–140,000 per unit). Key technical requirements included: - Chassis: Dongfeng 3308 mm wheelbase, National VI emission standard, compliant with Shijiazhuang’s environmental regulations. - Tank: Effective capacity of 4–6 m³; insulated tank body to prevent freezing during winter. - Hydraulic System: Equipped with low-temperature startup assistance (e.g., electrically heated hydraulic lines). - Engine: Fitted with an engine preheater or cold-start assist system. - After-sales Service: Chassis covered under nationwide warranty; superstructure supported by lifetime service; supplier required to provide a dedicated winter maintenance plan. After comparative evaluation of multiple vendors, the department issued the official tender notice in December 2025—with special emphasis on bidders submitting a “Winter-Specific Technical Proposal.” III. Chengli’s Solution Match: Targeted Design to Overcome Low-Temperature Challenges Chengli Special Purpose Vehicle Co., Ltd. (hereinafter “Chengli”), leveraging extensive experience in sanitation vehicle development—particularly customized solutions for northern Chinese markets—submitted a tailored sewage treatment vehicle solution based on the National VI Dongfeng 3308 mm wheelbase chassis (reference model: CLW5070GSSD6, per official announcement parameters). Key highlights of the solution include: 1. Frost-Resistant Starting Design The vehicle is equipped with a fuel-fired heater and battery thermal insulation system, enabling rapid engine preheating even at -15°C. The engine—selected from Dongfeng’s National VI series (e.g., D20TCIF11)—delivers rated power of 70–85 kW and integrates a cold-start assist system, ensuring reliable ignition down to -20°C.