Scenario Introduction: Sludge Removal Challenges and Equipment Testing in Extreme Cold. In Qiqihar, winter temperatures frequently drop to -30°C, posing severe challenges for urban drainage pipeline sludge removal operations. A municipal sanitation department is responsible for maintaining drainage networks across over 50 main roads and older residential communities. Daily sludge removal demand is high—approximately 2,000 cubic meters annually, with winter operations accounting for 40%. In 2025, the department plans to procure a batch of sludge removal trucks to replace aging equipment, specifically addressing pain points such as difficult cold-weather starting, hydraulic system failure, and low operational efficiency. Following a public tender process, Chengli Special Purpose Vehicle Co., Ltd. delivered three Dongfeng single-cab sludge removal trucks (blue license plate, 5-cubic-meter capacity), with a total contract value of approximately RMB 650,000 (based on publicly available tender information). This solution emphasizes equipment reliability under extreme cold conditions and has become a typical reference for government procurement of sludge removal vehicles in the region. High-Frequency Operation Structural Analysis: From Routine Load to Heavy-Duty Design 1. Routine High-Load Usage and Equipment Fatigue Management Sludge removal trucks in Qiqihar operate under extremely demanding conditions: during summer monsoon seasons, surge-type drainage requires continuous operation for over 12 hours; in winter, frozen sludge necessitates frequent impact-breaking by the bucket, imposing intense fatigue stress on the chassis, hydraulic system, and superstructure. According to feedback from the sanitation department, legacy equipment frequently suffered downtime due to hydraulic hose bursts and engine starting difficulties—each repair taking 3–5 days and significantly disrupting pipeline cleaning schedules. The Dongfeng single-cab sludge removal trucks delivered by Chengli were custom-built based on Chengli Special Purpose Vehicle Co., Ltd.’s officially registered models (e.g., CLW5070GSSD6 series). The chassis features a Dongfeng single-cab cab equipped with Yunnan Internal Combustion Engine or Yuchai engines (displacement: 2.8–3.0 L; rated power: ~95–115 hp), compliant with Blue License Plate C-class driving license requirements. Key improvements include: • Cold-Weather Starting Performance: Standard-fit low-temperature preheating system—including intake air preheater and diesel fuel heater—enables reliable one-time engine start at -25°C; field tests confirm >95% successful starts at -30°C. • Low-Temperature Hydraulic Stability: Hydraulic system employs low-temperature-resistant seals and specialized hydraulic oil (pour point: -40°C); an electric heating jacket is installed on the hydraulic oil tank to ensure fluidity and prevent pipe blockage or rupture in sub-zero conditions. • Winter Maintenance Program: Chengli provides a dedicated winter maintenance kit with antifreeze (-45°C), low-temperature lubricating oil, and filters. Recommended maintenance includes hydraulic system inspection every 30 days; nationwide chassis warranty service covers local service stations in Qiqihar. 2. Heavy-Duty Operational Design: Addressing Intensive Sludge Removal Requirements During sludge removal operations, the bucket repeatedly excavates and dumps material, with single-load weights reaching 1.5–2.5 tons, often on slippery, muddy surfaces. Chengli’s solution features a reinforced chassis frame with longitudinal beams having a yield strength of 350 MPa—20% higher than standard light-duty trucks—and a 5-ton-rated rear axle paired with 7.00R16LT steel-belted radial tires to ensure stability under heavy loads. For the superstructure, the sludge removal truck is equipped with a hydraulically driven bucket and self-dumping system. The hydraulic pump delivers 40 L/min at a working pressure of 16 MPa, completing a full unloading cycle within 5 secon