Rotary Shaft Seals

The area between the sealing edge and the shaft is most important. The sealing effect is achieved by preloading the sealing lip making its internal diameter slightly smaller than the shaft diameter. The garter spring ensures constant force to the shaft, flattening the edge to a defined width. The primary function of a rotary shaft seal is to retain the bearing lubricant and secondarily, to enhance the performance and life of the bearing by minimizing dirt, oil and water ingress that leads to damage and premature failure of the bearing and other components.

Rotary shaft seals are designed to seal fluids, oil, grease, oil mist or other media on rotating equipment, including rotating or oscillating shafts, rods or bores. In addition there are rotary seals that are specially designed for applications including, dry run, high pressure, low friction and low energy consumption, high temperature, high surface speeds, shaft misalignment and corrosive and aggressive media.

Rotary shaft seals are used in components with oscillating or rotating parts to keep lubrication fluids in while preventing ingress of mud and water. The market has on offer a wide range of rotary shaft seals for use in rotary applications; these range from traditional single or double lipped elastomeric configurations to PTFE based designs or a combination of both.

Rotary shaft seals are available in many different materials. These are with elastomeric based lips include Nitrile, Fluorocarbon, Carboxylated Nitrile, Hydrogenated Nitrile, Ethylene Propylene, Polyacrylate, Silicone and Neoprene. There are various different casings available for rotary seals and the most common include carbon steel and stainless steel. Depending on application criteria, other case materials include aluminium and zinc plated cold rolled steel.

Rotary applications need only one pneumatic seal. This seal is considered to be single acting because it can seal in one axial direction while the application is moving. On the other hand, a reciprocating application requires two pneumatics, or double acting seals. In this case, one seal is needed for each of the directions. Double acting pneumatics are more complicated than single acting ones. Pneumatic seals can be single or double acting. Single acting pneumatics are used for one axial direction only. Rotary shafts and pneumatics can be made of a variety of materials like Polyurethane, Nitrile, Viton, Silicone, EPDM and some PTFE. Composite seals composed of two or three different materials. Therefore, pneumatic seals are often found in products requiring one seal for many parts. Darcoid’s selection of products is the broadest offering in the industry for rotary shafts, pneumtic and hydraulic sealing systems.