Wear Rings and Guide Rings for Cylinders

In a cylinder, the load on the rod is rarely perfectly in line. Side forces from mounting misalignment, worn pivot pins, uneven loads or gravity push the piston and rod sideways. Without a wear ring, the metal parts would touch, causing scoring, galling and rapid damage to seals. The wear ring takes the side force and spreads it across a bearing surface that is softer than the metal.

Wear rings do not seal. They are installed next to a seal (see Piston Seals and Rod Seals), and are often replaced when the seals are replaced. Typical symptoms of a worn wear ring are bore scoring, uneven seal wear, and rod seal extrusion. Wear rings are separate parts from Backup Rings, which support seals against extrusion. The family overview is on Hydraulic Seals.

Wear strips (cut to length)

A flat strip supplied in lengths and cut to fit the groove. Used on pistons and in glands. The ends are cut with a small gap to allow for thermal expansion and installation, and the gap can be angled.

Split (single-cut) rings

Pre-formed rings with a single cut, springing into the groove. Convenient for closed grooves and quick installation.

Endless (solid) rings

Continuous rings that must be stretched or pressed into the groove. Offer a cleaner running surface but demand groove accessibility.

Guide bushes and bearing rings

Machined bushes pressed into the gland, used in large cylinders where bearing area is critical.

Wear bands for piston rods (rod guide rings)

Placed in the gland ahead of the seals, take rod side load and protect the rod seal.

Pneumatic wear bands

Lower-load bands in light plastic, used in air cylinders.

These notes are typical and general. Load, temperature and fluid limits vary widely by grade. Always confirm against the manufacturer's data for your application.

• Phenolic resin with fabric reinforcement: a standard hydraulic wear ring material. Strong, stable and economical, but can absorb some moisture and requires a fluid it tolerates.
• Bronze-filled PTFE: low friction, good for high loads and dry running, sometimes used with water-based fluids. Check bronze compatibility with the fluid.
• Glass or carbon-filled PTFE: improved wear in different fluids and for chemical resistance.
• Nylon (polyamide): economical, used in lower-load applications, but absorbs moisture and swells in water.
• POM (acetal): stiff, dimensionally stable and low friction, for precise guidance with moderate loads.
• PEEK and other engineering plastics: for high-load and high-temperature work, with higher cost.

1. Measure the groove diameter, width and depth, and the rod or bore diameter. Check against the hydraulic seal measuring guide.
2. Estimate the side load. Heavy, off-centre or long-stroke cylinders need more bearing area.
3. Choose the material for the load, fluid and temperature.
4. Choose the form: strip, split or endless, based on the groove and how easily you can fit it.
5. Check the clearance. The ring should stand slightly proud of the groove so that the metal parts do not touch, but not so much that it binds.
6. Replace with the seals. Worn rings change the seal position and wear.

• Groove diameter, width and depth, and bore or rod diameter
• Existing ring thickness, width and material, if known
• Cylinder make, model and application
• Estimated side load and mounting arrangement
• Fluid and temperature
• Piston or rod location
• Quantity, and strip length if applicable

Genuine wear rings are supplied by the cylinder maker or major seal brands. Compatible wear rings and strip are common, since the dimensions are often to well-known sizes. The difference is in the material grade. Resin content, filler quality and thickness tolerance affect load capacity and wear life, so for heavy-duty applications ask for material details.

You can enquire about genuine or compatible wear rings for equipment from manufacturers such as Hallite, Trelleborg and Freudenberg/Simrit.

Wear strip by the metre and standard rings can be suitable for online ordering where listed.

• Buy online: where a product is listed in the online shop with a confirmed price, you can order directly. Products are being added to the shop progressively, so not every item will be listed yet.
• Request a quote: for custom, bulk, unpriced or repeat-order requirements, send us a quote request with your details.
• Technical review: if you cannot identify the part, or the application is demanding, use Find My Seal or upload a drawing and our team will review it with you.

You can also call head office in Johannesburg on 011 079 6033, or WhatsApp 079 508 0989, or email info@globseals.com.

These guides support measuring and diagnosis.

• How to measure a hydraulic seal: measure the groove and bore correctly
• Common causes of seal failure: recognise wear-ring wear, scoring and misalignment
• Pump and seal maintenance guide: alignment checks that reduce side load