A combi oil seal is a rotary shaft seal that combines an oil-retaining sealing lip with an additional dust-exclusion or dirt-protection lip in one compact component. I use the term “combi” to describe this integrated sealing arrangement, which is designed to help retain lubricant on one side of the seal while limiting the entry of dust, mud, water spray, or other contaminants from the opposite side. The exact construction, material, dimensions, and performance depend on the equipment, shaft conditions, and seal design.
You can find more information on our web, so please take a look.
Unlike a basic single-lip oil seal, a combi oil seal provides two functional barriers within one housing position. This can be useful in gearboxes, agricultural machinery, construction equipment, electric motors, pumps, and other rotating assemblies that operate in contaminated environments. At TEBIETE, I help B2B buyers evaluate combi oil seals by looking beyond the part name and matching the seal to the shaft, lubricant, temperature, speed, and contamination level.
The primary sealing lip contacts the rotating shaft and helps prevent oil or grease from escaping from the housing. A garter spring is commonly used to maintain radial contact between the sealing lip and shaft, although the exact construction may vary by design. The outer sealing surface normally fits into a bore and helps prevent leakage around the outside diameter of the seal.
The secondary lip is positioned toward the contamination side and acts as a protective barrier. It may reduce the entry of dust, soil, moisture, or abrasive particles before they reach the primary oil-retaining lip. This arrangement does not make the assembly completely immune to contamination, but it can improve protection when the seal is correctly selected, installed, and lubricated.
A single sealing lip can be suitable for clean, controlled environments, but it may face greater contamination exposure in outdoor or industrial applications. When dirt reaches the main lip, it can increase wear on both the lip and shaft surface, potentially contributing to leakage. A combi oil seal separates the contamination-control function from the main lubricant-retention function, making the design more suitable for demanding service conditions.
However, the additional lip also creates another contact area and may increase friction compared with a simpler design. I therefore recommend evaluating heat generation, shaft speed, available installation space, and lubrication conditions instead of assuming that a combi seal is automatically the best choice for every rotating shaft.
These functions depend on more than the seal profile alone. Shaft roughness, shaft runout, bore condition, concentricity, installation quality, lubricant compatibility, and operating temperature all influence actual service performance. For this reason, I treat the combi oil seal as part of a complete sealing system rather than as an isolated replacement part.
Combi oil seals are commonly considered for equipment where lubrication must be retained and the external environment is not clean. Examples include agricultural transmissions, wheel hubs, construction machinery, industrial gearboxes, pumps, motors, axles, and material-handling equipment. They can be especially relevant where shafts rotate near soil, dust, water, metal particles, or washdown areas.
| Application condition | Why a combi seal may be considered | What the buyer should verify |
|---|---|---|
| Dust or soil exposure | The external lip adds a contamination barrier. | Dust type, ingress direction, shaft speed, and lip lubrication. |
| Oil-filled gearbox | The primary lip supports lubricant retention. | Oil type, temperature, pressure, and shaft surface condition. |
| Water spray or outdoor use | The protective lip can reduce direct contaminant access. | Water pressure, immersion risk, drainage, and material suitability. |
| High-cycle rotating equipment | Integrated sealing can provide a practical replacement format. | Speed, friction, heat dissipation, and expected service interval. |
A combi seal should not be treated as a universal solution for pressurized fluid systems, severe immersion, or chemically aggressive media without a specific design review. If the assembly experiences pressure, the seal profile and pressure-management features must be confirmed. In some cases, a mechanical seal, specialized high-pressure seal, or separate contamination shield may be more suitable.
Combi oil seals are available in different profiles, case constructions, lip arrangements, and elastomer materials. The correct choice depends on the medium, temperature, speed, contamination, and housing design. Common elastomer options include nitrile rubber, fluoroelastomer, and other application-specific compounds.
If you are looking for more details, kindly visit TEBIETE.
Nitrile rubber, often identified as NBR, is widely used for general mineral-oil applications because it offers a practical balance of sealing performance, cost, and availability. As a preliminary reference, many NBR formulations are considered for service around -30°C to 100°C, but the actual limit depends on the compound, lubricant, speed, and design. I recommend confirming the supplier’s technical range before approving the material for continuous operation.
Fluoroelastomer, commonly known as FKM, is often selected where higher temperature resistance or improved chemical resistance is required. Some FKM formulations are used in applications approaching 150°C or higher, while the permissible range depends on the compound and operating conditions. FKM may increase purchase cost, so it should be selected for a documented requirement rather than as a default upgrade.
Buyers should also review the metal case material, spring material, dust-lip geometry, shaft contact design, and whether the seal is intended for a dry or lubricated external lip. A protective lip that runs dry may generate additional friction and heat. If the shaft speed is near 10 m/s at the sealing diameter, I would treat that as a point requiring careful engineering review rather than relying only on a standard catalog selection.
The most important dimensions are usually shaft diameter, housing bore diameter, and seal width. These dimensions must correspond to the equipment drawing or the original seal identification, because a small dimensional mismatch can lead to poor retention, installation damage, or leakage. Buyers should also confirm the rotation direction, if the design is directional, and the correct orientation of the primary and secondary lips.
I recommend starting with the operating conditions instead of choosing a seal only by nominal size. First, record the shaft diameter, bore diameter, width, rotation speed, lubricant, temperature, pressure, and contamination exposure. Next, identify whether the seal is a replacement part, an original-equipment component, or a new design that may require profile optimization.
For replacement purchasing, compare the removed seal with the drawing, marking, dimensional specification, and application history. Leakage is not always caused by the seal itself; a worn shaft, excessive runout, incorrect installation, blocked vent, or incompatible lubricant can create the same symptom. Sending photographs, drawings, samples, and operating details to the supplier can reduce the risk of selecting a dimensionally correct but functionally unsuitable part.
At TEBIETE, I can support buyers with product selection, dimensional confirmation, material discussions, sample coordination, and production communication for combi oil seal requirements. The practical value of supplier support is not simply obtaining a part number; it is reducing uncertainty before production, especially when the application involves contamination, unusual temperatures, custom dimensions, or repeat purchasing.
A combi oil seal is the right starting point when your rotating assembly must retain lubricant while also limiting contamination from the outside. Its integrated two-function design can be practical for gearboxes, axles, agricultural machinery, construction equipment, motors, pumps, and other exposed applications. It is not automatically suitable for every pressure, speed, chemical, or immersion condition, so the design must be matched to the actual service environment.
As the next step, prepare the seal dimensions, lubricant type, operating temperature, shaft speed, pressure, contamination level, and equipment application. Share those details with TEBIETE along with a drawing, sample, or existing seal reference when available. I can then help evaluate the appropriate profile, material, customization requirements, sampling process, and repeat-supply plan for your combi oil seal project.
The company is the world’s best Combi Oil Seal supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.