N4M type back-up ring, also named support ring, is an auxiliary anti-extrusion part matched with O-rings, piston seals and rod seals in hydraulic sealing assemblies. Installed on the low-pressure side of the main seal, the N4M support ring fills the metal clearance gap. It blocks soft elastomer seals from being squeezed into the gap under high hydraulic pressure, effectively avoiding extrusion tearing and premature seal failure.
Made of high-strength reinforced PTFE or nylon composite material, the N4M back-up ring features high rigidity, low friction coefficient and excellent wear resistance. It maintains stable dimensional accuracy under continuous high pressure and cyclic pressure surges, and offers good chemical compatibility with various hydraulic fluids. It can operate reliably within temperature range from -30℃ to 120℃, greatly boosting the pressure-bearing capacity of the whole sealing set.
Compatible with mineral hydraulic oil and most conventional hydraulic media, N4M support rings are widely applied in excavators, loaders, injection molding machines and other heavy-duty hydraulic cylinders. It conforms to standard groove dimensions for easy installation and direct replacement. By protecting primary sealing elements and extending service life of the sealing system, the N4M back-up ring provides an essential anti-extrusion support solution for high-pressure hydraulic equipment.
Original text from: Hydraulic and Pneumatic Seals https://www.bszzseal.com/
