Case Background: Sludge Transportation Challenges for Urumqi Municipal Sanitation Authorities. Located in the northwest cold region of China, Urumqi experiences winter temperatures as low as -30°C. In 2025, a local municipal sanitation department procured a batch of 24 m³ Sinotruk-based sludge self-dumping trucks to transport dewatered sludge from urban wastewater treatment plants. These vehicles must perform daily sludge transportation tasks under extreme low-temperature conditions, placing exceptionally high demands on cold-start capability, low-temperature hydraulic system stability, and overall winter operational reliability. According to local procurement practices, the budget for each vehicle was controlled within approximately RMB 509,000–622,000 per unit. Ultimately, Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as "Chengli") delivered five Sinotruk HOWO-based sludge self-dumping trucks, with a total contract value of approximately RMB 2.5 million (based on publicly available tender information). The vehicles comply with China VI emission standards; their superstructures feature Chengli’s independently developed sealed sludge tanks with an effective capacity of 24 m³, enabling single-trip transportation of approximately 15–18 tons of sludge. Core Requirements: Three Key Technologies for Low-Temperature Operation. Under Urumqi’s extreme climatic conditions, conventional sanitation vehicles frequently encounter difficulties such as hard starting, sluggish hydraulic response, and frozen seal failures. This procurement project specifically addressed the following three core technical challenges: 1. Cold-Start Performance. Chengli equipped these sludge trucks with an integrated fuel-heating system capable of preheating engine coolant and engine oil, ensuring successful first-time starts at -30°C. Additionally, the vehicles utilize low-temperature-specific batteries and preheating-type starters, complemented by Sinotruk’s factory-installed cold-start assist devices—significantly reducing winter starting failures. 2. Low-Temperature Hydraulic Stability. The hydraulic system is the core working component of sludge self-dumping trucks. Chengli adopted low-temperature hydraulic oil rated for operation between -40°C and +120°C, and insulated all hydraulic lines to prevent excessive oil viscosity at low temperatures—which otherwise causes slow lifting. Imported-brand hydraulic valve assemblies with low-temperature-rated seals were selected to ensure responsive actuation even under sub-zero conditions. 3. Winter Maintenance Program. Chengli’s after-sales team developed a customized winter maintenance plan for the Urumqi customer, including: changing low-temperature hydraulic oil every 500 operating hours; inspecting the heating system every 1,000 operating hours; and applying anti-freeze treatment to all vehicle seals prior to winter onset. Furthermore, chassis-related services leverage Sinotruk’s nationwide warranty network, while superstructure support—including lifetime service and 24-hour spare parts delivery directly to Urumqi—is provided by Chengli. Multi-Category Supply Capability: One-Stop Procurement Reduces Management Costs. Notably, the municipal sanitation department simultaneously procured other sanitation vehicles, including 5 m³ water-sprinkling trucks, 8 m³ compression garbage trucks, and 3 m³ vacuum sewage suction trucks. Leveraging its full-range product portfolio, Chengli supplied the following models in a single order: Sinotruk HOWO 24 m³ Sludge Self-Dumping Truck (Model CLW5250ZWXZ6): Used for sludge transportation, unit price approx. RMB 480,000; Dongfeng DOLICA 5 m³ Water-Sprinkling Truck (Model CLW5070GSSD6): Used for road dust suppression and greenery irrigation, unit price approx. RMB 110,000; Sinotruk HOWMAN 8 m³ Compression Garbage Truck (Model CLW5180ZYSZ6): Used for domestic waste collection