Project Background and Requirements: Sewage Treatment Vehicle Procurement for High-Altitude Low-Temperature Environments. In 2025, a municipal sanitation department in Xining planned to procure a batch of sewage treatment vehicles for routine maintenance of urban sewer networks and septic tanks. The project budget was capped at approximately RMB 1.652 million, with an intended purchase of five units at around RMB 300,000 per unit (based on publicly available tender information). Due to Xining’s location on the Qinghai-Tibet Plateau—where winter temperatures can drop below -20°C—the buyer specifically emphasized requirements for frost-proof engine starting capability, low-temperature hydraulic system stability, and detailed winter maintenance guidance from the supplier. This procurement attracted bids from multiple manufacturers, including Chengli Special Purpose Vehicle Co., Ltd., Zoomlion, and Foton Auman. Ultimately, Chengli Special Purpose Vehicle Co., Ltd. successfully delivered five units of its Dongfeng Yizhan-style sewage treatment vehicle (model CLW5070GSSD6), along with its supporting service package. Customer feedback confirmed stable operation under low-temperature conditions and a low failure rate. Major Bidding Brands and Models Key bidding brands and models included: Chengli Special Purpose Vehicle (CLW5070GSSD6): Built on a Dongfeng chassis, fully compliant with national certification requirements; the superstructure features a wing-type design for convenient inspection and maintenance. Zoomlion (ZLJ5070GSSDFE5): A well-established brand; however, it uses a non-Dongfeng chassis, and after-sales service coverage in Qinghai Province is limited. Foton Auman (BJ5084GSS-AA): Features a high-specification chassis, but its superstructure offers only average thermal insulation performance and carries a relatively higher price. Comparative Analysis of Advantages and Disadvantages The following comparison evaluates key criteria: frost-proof starting performance, low-temperature hydraulic stability, winter maintenance support, pricing, and after-sales service. Comparison Criteria | Chengli Special Purpose Vehicle (CLW5070GSSD6) | Zoomlion (ZLJ5070GSSDFE5) | Foton Auman (BJ5084GSS-AA) ---|---|---|--- Frost-Proof Starting Performance | Standard low-temperature preheating system enables normal startup at -25°C (verified via customer testing) | Heating device optional; adds approx. RMB 5,000 to cost | Standard equipment, but longer startup time Low-Temperature Hydraulic Stability | Uses low-temperature hydraulic oil; hydraulic lines insulated with thermal wrap—stable operation down to -20°C | Hydraulic system not specially modified; oil viscosity increases significantly at low temperatures | Partial improvements implemented, but insufficient insulation thickness Winter Maintenance Support | Free winter inspection (including antifreeze, battery, and piping); lifetime technical support | Provides only basic maintenance manual—no dedicated winter service | Winter maintenance package available only as paid add-on Unit Price (per publicly available tender data) | Approx. RMB 295,000/unit | Approx. RMB 320,000/unit | Approx. RMB 310,000/unit After-Sales Service | Nationwide Dongfeng chassis warranty; lifetime superstructure service; spare parts shipped within 24 hours | Limited service network in Qinghai; slow response times | Broad service coverage, but higher service fees Delivery Lead Time | 7–15 days (zero-inventory direct shipment) | Over 30 days | 15–20 days Why Chengli Prevailed Following comprehensive evaluation, Chengli Special Purpose Vehicle earned the buyer’s approval based on the following strengths: Outstanding frost-proof starting performance: The CLW5070GSSD6 model comes standard with a low-temperature preheating system, enabling reliable startup at -25°C—performance verified through field testing and superior to competing models. The buyer conducted evaluati