Guide rings and guide strips
In hydraulic cylinders the most commonly used guides are guide rings and guide strips. They accommodate radial loads of forces acting on the cylinder assembly and guide the rod in the cylinder head as well as the piston in the cylinder bore (fig. 1).
Guides are made of polymer materials and prevent metal-to-metal contact between moving parts in a working hydraulic cylinder. Compared to metal guides, polymer guides provide the following advantages in hydraulic cylinders:
- significantly longer service life
- work more smoothly against the cylinder bore and the sealing surfaces
- avoid wear of cylinder surfaces despite the presence of contamination particles
- high resistance to insufficient lubrication at low speeds
- larger contact area (fig. 2, fig. 3 and fig. 4) due to higher degree of elastic deformation distributes the load and reduces stress to counter-surface
- certain self-lubricating properties
SKF supplies different precision machined guide rings with different polymer materials and sizes, which make them appropriate for a wide variety of operating conditions and applications.
Guides of PTFE are also available for applications where start-up friction must be minimized. PTFE guides have limited load carrying capability and should only be used in applications with light loads.