The type SB is a heavy duty single acting Rod seal with the advantage of an anti extrusion ring.
The seal comprises of a rubberized fabric which gives strength and durability to a nitrile energizer which is moulded . It needs a split housing.
The seal section is pre-loaded by the housing when installed to ensure effective sealing at low pressure increases, the nitrile energizes the fabric to increase the sealing area and hence the efficiency of the seal. The strength and durability of the rubberized fabric combines with its ability to retain lubricant keeping friction and wear to a minimum. A reinforced plastic anti-extrusion ring at the internal heel of the seal, to protect it against damage by extrusion, which enables the designer to use a large clearance between the rod and housing.