一、概况北京市城区有下水道近1300公里,小管径约占一半。十几年来市政处职工自己动手搞技术革新。1970年开始制做了机动绞车;1974年研制出能抽泥、水冲两用的真空吸泥车;1978年在市政研究所协助下制出了下水道低压射水冲洗车;1980年初使用了下水道高压射水冲洗车。目前养护城区下水道的专 I. Overview The urban area of ​​Beijing has a sewerage system of nearly 1300 kilometers, with a small diameter of about half. For more than a decade, staff of the Municipal Services Department have started to make technological innovations. In 1970, a mechanical winch was started; in 1974, a vacuum suction dredger capable of extracting mud and water was developed; in 1978, a sewer low-pressure jet flushing vehicle was manufactured under the assistance of the municipal institute; in 1980, a sewer high pressure was used. Jet flusher. The current maintenance of urban sewers