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Details
The GAP series rotary shaft seals, also commercially known as reinforced pressure oil seals or BABSL type, are special dynamic seals designed to operate in the presence of internal circuit pressure. The profile features a short main sealing lip supported by a garter spring, together with an auxiliary front dust lip. The smooth rubber-covered outer casing ensures static sealing within the housing and counteracts internal hydraulic thrust.
Type GAP Standard
Double-lip profile, with a short spring-loaded sealing lip and an auxiliary dust lip without a spring. The outer diameter is made of completely smooth elastomer with an "L"-shaped structural reinforcement insert.
Type GAP/S Special
Variant with a modified dynamic lip or high-load spring, specifically designed for particularly high industrial rotational speeds and pressure peaks.
Materials and operating conditions
| Material / Compound | Peripheral speed | Temperature | Max pressure |
|---|---|---|---|
| NBR Nitrile rubber 70 / 80 ShA |
Up to 12.0 m/s | −30 / +100 °C |
Up to 1.0 MPa 10 bar continuous, depending on peripheral speed |
| FKM Fluoroelastomer / Viton |
Up to 35.0 m/s | −20 / +200 °C | — |
Internal structure
Mineral hydraulic oils, fluid gear lubricants, mineral and synthetic greases and, for the FKM/Viton version, special synthetic hydraulic fluids.
Main features
Short-section dynamic lip
Unlike standard oil seals, the GAP profile uses a short, rigid lip supported by the reinforcement. This geometry limits lip deflection under pressure and allows continuous pressures up to 10 bar (1.0 MPa).
Smooth rubber-covered static fit
The elastomer outer casing ensures static sealing against the housing. It compensates for structural thermal expansion of the metals and counteracts the axial thrust generated by internal hydraulic pressure.
Double hydrodynamic protection
The garter spring maintains a calibrated radial load on the shaft surface, while the front dust lip prevents abrasive dust and external moisture from reaching the primary sealing area.
Advantages of the GAP profile
Sealing under pressure
Allows use on rotating shafts where the internal fluid reaches high pressures, such as in front-mounted hydraulic pumps or hydraulic motors, reducing the need for complex external drainage circuits.
Controlled heat generation
The stability of the lip reduces the dynamic contact area under pressure, limiting localized overheating caused by friction and wear on the shaft surface.
Safe installation
The outer rubber coating reduces the mechanical force required during press-fitting and limits the risk of scratches or deformation in housings made from aluminium or light alloys.
Typical applications
- Front transmission shafts for hydraulic gear, vane or piston pumps
- Rotary hydraulic motors and oscillating hydraulic actuators exposed to return pressure
- Rotary screw air compressors, vacuum pumps and special industrial agitators
- Industrial gearboxes and speed reducers with internal air pressure or pressurized housings
- Transmission systems for mobile hydraulics, agricultural machinery and earthmoving equipment
International standards
Construction dimensions, geometric tolerances and installation dimensions in compliance with international standards and standardized tables for ISO 6194 hydraulic pumps and special BABSL-type high-pressure profiles.
Available configurations
Type GAP Standard
Reference configuration for standard hydraulic pumps and hydraulic motors operating in light- and medium-duty mobile hydraulics. It provides resistance to back-pressure and compatibility with mineral oils at medium temperatures.
Type GAP Premium
Specific configuration for applications with high peripheral speeds, up to 35 m/s, or subject to continuous operating temperatures up to +200 °C. The fluoroelastomer provides greater resistance to modern synthetic lubricants.
Market equivalents
| Manufacturer | Type GAP Standard - NBR | Type GAP Premium - FKM / Viton |
|---|---|---|
| Net Seals | Pressure Oil Seal Series BABSL / TCN / GAP | Viton Pressure Oil Seal Series BABSL / GAP FKM |
| Freudenberg (Simrit) | Simmerring® BABSL / 829N PR Profile | Simmerring® BABSL FKM Profile |
| Parker Prädifa | TCN / BP Profile | TCN (FKM) Profile |
| Kastas Sealing Technologies | K33 / K34 Profile | — |
| Corteco | BABSL High-Pressure Oil Seal Series | — |
| Dichtomatik | — | BABSL FKM Profile |
| SKF | — | Viton High-Pressure Seals (CRW5) |