Snap-in wiper seals
Snap-in wiper seals are designed without any metal component and are easy to install without any special equipment.
A common problem with snap-in wiper seals is that they become loose in the housing resulting in poor static sealing on the outside surface and reduced preload on the dynamic wiper seal lip (fig. 1). Furthermore, if the inside edge of the wiper seal could contact the rod, it may become an unintended sealing lip (fig. 1) and could trap pressure between the rod and wiper seal. Therefore, SKF snap-in wiper seals have special sealing and venting features to help ensure proper operation.
DTW profilesfig. 2) have a single-lip design and a radial static seal lip on the outside surface that maintains a positive sealing contact. An axial static seal lip on the external side face keeps the wiper tight in the housing and also serves as an additional static seal. During operation the inside edge of the wiper seal could contact the rod, for example during rod extension. In this case and in the event the rod seal has become damaged or exceeded its service life, notches on the inside edge prevent the wiper seal trapping pressure or being pushed out by pressure. These profiles are available in metric (→ Size list [pdf]) and inch sizes (→ Size list [pdf]). For additional information, refer to DTW profile data.
DX wiper seals (fig. 3) have a patented profile with a single external lip design and vented inside edge. These profiles incorporate a rubber O-ring that maintains a robust static sealing contact in the housing. The O-ring also serves as an energizer to provide consistent long term preload on the dynamic lip. In case of radial misalignment, the entire TPU wiper ring follows these radial movements (“floating” design) as the relatively soft and flexible rubber O-ring energizer deforms to compensate.
When the wiper lip encounters resistance from contaminants adhered to the retracting rod (e.g. tree sap or frozen rain), the profile reacts by twisting to increase the preload on the dynamic wiper lip.
Therefore, DX profiles include the functionality of press-in wiper seals as well as the convenience of snap-in wiper seals. These profiles are available in inch sizes (→ Size list [pdf]). For additional information, refer to DX profile data.