Cangzhou Dongfeng Double-Cab Sludge Suction Truck (Blue License Plate, 3 m³) Government Procurement Case: Winter Operation Performance and Winning-Bid Solution Analysis In northern China—especially cities like Cangzhou—low winter temperatures impose stringent operational challenges on municipal sludge suction vehicles. At the end of 2024, a municipal sanitation department conducted an open tender to procure a batch of blue-plate sludge suction trucks suitable for complex winter operating conditions. This article analyzes, based on this procurement batch and Chengli Special Purpose Vehicle Co., Ltd. (www.clspecial.com)'s Dongfeng double-cab blue-plate 3 m³ sludge suction truck solution, key aspects including winter-optimized structural design, maintenance guidelines, cold-start recommendations, freeze-protection measures, and Chengli’s service commitments—to serve as a reference for similar procurement entities. I. Case Background: Procurement Requirements of a Municipal Sanitation Department in Cangzhou Located in North China, Cangzhou experiences winter temperatures frequently dropping below −10°C, and its urban drainage networks contain high-silt, high-sand-content sludge with significant freezing risks. In November 2024, a municipal sanitation department issued a procurement notice seeking five blue-plate sludge suction trucks meeting the following core requirements: • Blue license plate classification, operable with a Class C driver’s license—facilitating operation by frontline drivers; • Chassis must be Dongfeng double-cab configuration, balancing crew capacity and operational workspace; • Tank effective volume: 3 m³—sufficient for routine pipeline cleaning and sludge transport; • Equipped with a winter anti-freeze system, including engine pre-heating for cold starts and insulated piping. According to publicly available tender information, the total budget for this batch was capped at approximately RMB 567,000 (≈RMB 100,000 per unit). Chengli Special Purpose Vehicle Co., Ltd. secured the contract by leveraging comprehensive official announcement parameters (e.g., chassis basis for model CLW5070GSSD6) and extensive service experience across northern regions. Five units were successfully delivered and are now in active service with a street-level environmental maintenance unit in Cangzhou. II. Core Considerations for Winter Operation: Key Maintenance Practices and Cold-Start Recommendations To address Cangzhou’s harsh winter climate, Chengli’s technical team provided detailed winter operation guidelines upon delivery. Key points include: 1. Winter Maintenance Guidelines for Northern Regions • Coolant Replacement: Use −35°C antifreeze coolant to prevent pipe cracking due to freezing. While the original Dongfeng chassis supplied by Chengli comes standard with factory coolant rated for −25°C, customer feedback indicates upgrading to higher-grade coolant for extreme Cangzhou weather conditions. • Engine Oil Selection: Recommend 5W-30 low-temperature engine oil to ensure adequate lubrication during cold starts. Per local procurement practice, Chengli pre-installed winter-grade engine oil prior to delivery. • Battery Maintenance: Battery capacity drops ~30% in low temperatures; electrolyte density should be checked regularly. Chengli sludge suction trucks come standard with maintenance-free batteries, but weekly charging is advised. • Hydraulic Oil Replacement: The hydraulic system requires low-temperature hydraulic oil (e.g., HS-32) to prevent oil gelling and subsequent lifting mechanism failure. 2. Cold-Start Recommendations • Preheating System: Chengli offers optional intake air preheating devices, capable of rapidly raising engine intake temperature even at −15°C. As specified in the CLW5070GSSD6 official announcement, this feature is available as an optional upgrade. • Starting Procedure: Turn the ignition key to the ON position and wait 10 seconds until the preheat indicator light extinguishes before cranking the en