A bolted bearing end cap seated in a heavy cast axle housing

It leaks

Sealing

A felt seal works by being squeezed. Cut a little larger than the groove it sits in, it compresses on assembly and keeps pushing back for the life of the part.

Because felt has no weave, a ring or washer cut from it has no grain and no seam for anything to travel along. It can be cut in any direction and will not fray at the edge, which is why a felt washer behaves the same whichever way it came off the sheet.

Wool felt recovers after being compressed rather than taking a permanent set the way a soft gasket does. It keeps its load as the joint settles and as the shaft wears, so it goes on sealing without a spring behind it.

It also holds oil, so a felt seal on a slow-turning shaft is doing two jobs at once: keeping grit and dust out, and keeping a film of lubricant on the shaft as it turns.

Where it is used

Already doing this job

Felt rarely appears on a drawing by name. These are the places it is already fitted, doing exactly this.

01
Textile looms and spinning frames
End seals on bearing housings, keeping cotton fly and dust out of the bearing.
02
Electric motors and gearboxes
Shaft seals and end-cap washers where a lip seal would drag or run hot.
03
Agricultural and earth-moving plant
Dust excluders on pivots and slow shafts working in grit.
04
Pumps, blowers and fans
Washers under covers, inspection plates and bearing caps.
05
Glass and ceramic handling
Soft seals and pads where a hard gasket would mark the surface.