Hydraulic Guide Rings & Wear Rings

Guide rings—also called wear rings, bearing bands or guide strips—are rigid rings or strips installed in grooves on the piston and/or cylinder head. Their primary function is to prevent metal-to-metal contact between the piston and bore and between the rod and head. By absorbing radial side loads caused by weight, misalignment or external forces, guide rings protect the elastomer seals from extrusion and the cylinder surfaces from scoring. They also improve cylinder alignment, reduce friction and extend the life of the entire seal package. PTFE filled with bronze is the most common guide ring material for high-performance hydraulic cylinders. It offers extremely low friction, good wear resistance, high compressive strength and compatibility with virtually all hydraulic fluids. Bronze-filled PTFE guide rings are typically supplied as cut-to-length strips or spiral-wound rings that are installed in rectangular grooves. Phenolic fabric guide rings provide higher load capacity and rigidity for heavy-duty mobile equipment and large-bore cylinders. POM guide rings are used where high stiffness and low cost are required. Guide rings are dimensioned by groove width, groove depth and ring thickness. The ring must be slightly thinner than the groove width to allow for thermal expansion and fluid film formation. Standard guide strip thicknesses include 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm and thicker. For pistons, guide rings are often placed at both ends of the piston to maximize stability. For rods, a single guide ring in the head supports the rod against side loads. Our guide ring range includes PTFE-bronze strips, phenolic fabric rings and POM wear rings for bore diameters from 20 mm to over 1000 mm. We supply standard cut-to-length strips and custom-machined rings from drawing. Proper guide ring selection depends on load, speed, fluid compatibility, temperature and whether the application is piston or rod side.