Biobased Lubricants for Tunnel Boring Machines

摘要

Special seal compounds have been developed over the last two decades based on the requirements of major Tunnel Boring Machine (TBM) manufacturers to help protect major rotating elements such as the TBM main bearing (front end of TBM) from water, mud and dust and to seal off the tail end of the TBM from the ingress of water. The main features of seal compounds are good water resistance and tackiness for maximum sealing capabilities as well as good pumpability and ease of product distribution. In addition, environmental friendliness along with fire resistance properties are highly desired. Front seal compounds provide also a lubrication function for the extra protection of the elastomer lip seals used for the rotary elements of most TBMs. Two products, based on biodegradable base oils, were developed for this purpose. Tested against conventional polymeric compounds in a major city subway tunneling system as well as in urban sewage networks, these products showed excellent sealing capabilities and outstanding lubrication performance leading to a tangible reduction in product consumption.