Back-up ring for Link-Belt LS-98

The back-up ring, part number 1J939, serves as an auxiliary component within hydraulic sealing systems. Its primary function is to support the O-ring and prevent it from extruding into the clearance gap between mating surfaces when the system is under high pressure. By providing this structural support, the ring ensures the O-ring maintains its position and integrity, which is necessary for effective fluid containment in hydraulic circuits.

This component is specifically compatible with the Link-Belt LS-98 crawler crane. It is installed within the seal groove on the low-pressure side of the primary O-ring. Proper installation of this back-up ring is required to maintain the pressure-handling capabilities of hydraulic cylinders, pumps, and associated fluid power components used in this crane model.

In general engineering practice, back-up rings are used in hydraulic and pneumatic systems where high operating pressures or large clearance gaps exist. They are typically made from materials with higher hardness than the associated O-ring to resist deformation. The inclusion of a back-up ring prevents seal failure caused by the O-ring being forced out of its groove, which would otherwise lead to immediate fluid loss and potential system downtime.