Case Background: Sewage Treatment Vehicle Procurement Requirement of a Municipal Sanitation Unit in Tianshui City. In winter 2024, a municipal sanitation department in Tianshui City, Gansu Province (hereinafter referred to as 'the municipal sanitation unit') urgently needed to procure a yellow-plated sewage treatment vehicle due to an upgrade and renovation project at its local wastewater treatment station—specifically to handle sewage collection and treatment tasks under low-temperature winter conditions. Through a public tender process, the unit selected Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as 'Chengli') to supply its CLW5180GSSD6 model sewage treatment vehicle. This article analyzes key aspects of the case based on publicly available tender information and Chengli’s delivery data, with emphasis on winter operation strategies—including maintenance, cold-weather starting, and freeze protection. According to local procurement practices, the unit’s budget was capped at approximately RMB 333,000, requiring the vehicle chassis to be from Dongfeng, compliant with China VI emission standards, and equipped with cold-start and freeze-protection capabilities. Chengli submitted a detailed technical proposal during bidding and ultimately delivered the vehicle at a unit price of approximately RMB 280,000 (per publicly disclosed tender information). Winter Operation Structural Analysis: Key Considerations for Northern Region Applications 1. Winter Maintenance Essentials for Northern Regions In the Tianshui area, winter temperatures frequently drop below −15°C, imposing severe demands on the hydraulic system, pump units, and piping of sewage treatment vehicles. Prior to project launch, the municipal sanitation unit rigorously evaluated Chengli’s maintenance solutions. The CLW5180GSSD6 model (official model number: CLW5180GSSD6) supplied by Chengli is equipped with antifreeze hydraulic oil and low-temperature-resistant sealing components, effectively preventing system failures caused by oil thickening at sub-zero temperatures. Per Chengli’s after-sales recommendations, hydraulic oil level and filter condition should be inspected every 30 days during winter to ensure no ice blockages occur in pipelines. Additionally, Chengli offers a lifetime service commitment for the vehicle’s superstructure, including free technical guidance and 24-hour direct shipment of spare parts. Customer feedback indicates that Chengli’s technical staff provided remote support via the toll-free hotline during winter maintenance, assisting users in optimizing pump freeze-protection measures. 2. Cold-Weather Starting Recommendations Engine starting difficulties are common under low-temperature conditions. To address this, Chengli Special Purpose Vehicle equipped the CLW5180GSSD6 model with a standard cold-weather preheating system and battery thermal insulation device. Following vehicle acceptance, Chengli sales manager Zhang Yue (phone: ) personally visited the site to guide the startup procedure: – Preheat for 10–15 seconds before starting; only initiate ignition after the instrument panel’s preheat indicator light extinguishes. – Use −35# diesel fuel to prevent wax precipitation and fuel line clogging. – If three consecutive start attempts fail, inspect battery voltage and fuel lines to avoid excessive power drain. In actual operation, the vehicle achieved successful first-time startup at −10°C without delay, earning high user satisfaction regarding starting performance. 3. Detailed Freeze-Protection Measures Sewage treatment vehicles operating in winter are prone to issues such as water tank freezing and pipeline rupture. Chengli incorporated the following freeze-protection features into the vehicle design: – Insulation cotton wrapping around water tanks and pipelines, with minimum thickness of 5 mm. – Installation of electric heating tapes, automatically activated at ambient temperatures down to −20°C. –