Power Transmission Seals

Power Transmission Seals

Power transmission seals — rotary shaft seals, oil seals, and lip seals — are the components that keep oil and grease in (and contaminants out) of gearboxes, pumps, motors, and power transmission equipment. A good seal protects bearing life and keeps lubricant where it belongs; a failed seal lets oil leak out and dust in, damaging bearings within hours. AIMS Industrial stocks power transmission seals for industrial maintenance, OEM repair, and engineering applications.

The seal types we stock

• Single-lip oil seals — the most common rotary shaft seal, for general industrial applications
• Double-lip seals — primary lip plus dust lip, for environments with airborne contamination
• Spring-loaded seals — garter spring inside the lip for consistent contact with the shaft
• PTFE-lipped seals — for high-temperature, dry-running, or chemical-resistant applications
• V-rings and axial seals — for environments where radial seals can't fit
• Specialist seals — labyrinth seals, bearing isolators, and high-speed seals for specific applications

Seal materials

• Nitrile (NBR) — the everyday material; suits oil, hydrocarbon, and general industrial fluid service up to about 100°C
• Viton (FKM) — fluoroelastomer for higher temperature (up to 200°C) and aggressive fluids
• Silicone — for high-temperature dry running and food-grade applications
• PTFE — chemical resistance, low-friction, dry-running tolerance — at higher cost
• Polyacrylate (ACM) — for hot oil applications where Viton would be over-spec

Sizing — bore × shaft × width

Rotary shaft seals are sized by housing bore diameter, shaft diameter, and seal width — typically given as e.g. "30 × 47 × 7" (30mm shaft, 47mm bore, 7mm width). All three dimensions must match the application; substituting any one is rarely workable. Seal manufacturers' catalogues list standard sizes with type designations (TC, TB, etc.) that describe lip configuration.

Common seal failures and causes

• Oil leaking from new seal — usually shaft surface finish issues (scoring, roughness), or incorrect size
• Premature lip wear — shaft hardness too low, or shaft surface finish too rough; consider hardening or polishing
• Lip cracking — usually material incompatibility (wrong elastomer for fluid type) or excessive temperature
• Garter spring missing or displaced — installation damage; the spring must be in place for proper sealing

Installation practice

Use a proper seal installation tool (or a flat-faced fitting that matches the seal's outer diameter); never hammer directly on the seal face. Lubricate the lip lightly with the oil it will be sealing — installation dry tears the lip on first rotation. Check shaft surface finish and remove any score marks before fitting the new seal. For gear oil seals, ensure the seal is installed with the lip facing the oil side (the spring side faces inboard).

Brands stocked at AIMS

Power transmission seals are stocked from quality manufacturers — including the seal lines associated with our bearing brands (NSK, NTN, Koyo) and dedicated seal specialists. We can match by size or by OEM equipment part number — bring us the existing seal designation or a sample, and we'll cross-reference.

Need help with seal selection or sourcing? contact our team — we'll work through the application.