Tianjin Municipal Government Procurement Case of Dongfeng Dual-Cab Sewage Suction Truck (Blue License Plate, 3 m³): Analysis of Heavy-Duty Operation and Low-Temperature Winter Solutions In municipal sanitation systems across northern Chinese cities, sewage suction trucks are critical for routine maintenance of urban drainage networks, rivers, and residential septic tanks. As a coastal city, Tianjin’s harsh winter temperatures impose stringent requirements on vehicle starting performance and hydraulic system stability. This article analyzes a real-world procurement case involving Chengli’s Dongfeng dual-cab sewage suction truck (blue license plate, 3 m³) by a municipal sanitation department, focusing on equipment fatigue management under high-load operation, cold-start reliability, and winter maintenance strategies — offering practical insights for peer procurement decisions. I. Procurement Background and Operational Requirements In 2025, the Urban Management Bureau of a district in Tianjin planned to procure a batch of lightweight sewage suction trucks to address frequent blockages in aging residential drainage networks within its jurisdiction. According to publicly released tender documents, key requirements included: blue license plate classification (drivable with C1 driver’s license), tank capacity of 3 m³, integrated high-pressure cleaning, suction, and unloading functions, and full operational capability at Tianjin’s minimum winter temperature of -15°C. The procurement budget was capped at approximately RMB 226,000 per unit, with an expected unit price around RMB 180,000 (based on local procurement norms). Ultimately, Chengli Special Purpose Vehicle Co., Ltd. delivered four units of the Dongfeng D6-series dual-cab sewage suction trucks (model reference: CLW5070GSSD6, based on similar chassis design). The chassis features a Dongfeng Dorcen dual-cab cab with high load-bearing capacity and compliance with China VI emission standards. Customer feedback stated: “This model demonstrates outstanding cold-start performance and hydraulic system stability during winter, significantly reducing unplanned downtime and repair needs.” II. Heavy-Duty Operational Design: Addressing High Load and Fatigue Sewage suction trucks operate under intense daily workloads—especially during rainy seasons or emergency clearance operations—often running continuously for 8–12 hours. To meet such demanding usage, Chengli implemented the following heavy-duty enhancements: Chassis Reinforcement: The Dongfeng dual-cab chassis is equipped with a Yunnan YN4102 turbocharged diesel engine (95 hp, China VI compliant), paired with a 5-speed manual transmission. Its rear axle load capacity reaches 3.5 tons—sufficient to transport a fully loaded 3 m³ tank (approx. 4.5 tons). The chassis employs reinforced leaf springs and hydraulic power steering to mitigate metal fatigue during prolonged operation. Tank and Hydraulic System: The tank is fabricated from 6 mm-thick Q235 carbon steel with internal anti-corrosion coating, ensuring durability against aggressive media. The hydraulic system features dual-circuit cylinders (lifting force ≥ 8 tons) for smooth, stable unloading; the hydraulic pump uses low-temperature hydraulic oil (ISO VG 32 grade), maintaining fluidity down to -20°C and preventing hydraulic line rupture. Cold-Start Capability: Standard equipment includes a fuel heater and battery insulation cover, ensuring >95% cold-start success rate at -15°C. Customer feedback noted: “Last winter, when ambient temperatures dropped to -10°C overnight, the vehicle started reliably on the first attempt—no external power source required.” III. Winter Maintenance Protocols and After-Sales Support To address Tianjin’s low-temperature conditions, Chengli provides a dedicated winter maintenance program: Hydraulic Oil Replacement: Recommend replacing hydraulic oil every 1,000 operating hours or quarterly to prevent viscosity-related sluggishness in actuator respons