stuffing box

A Stuffing box is a type of gland seal. It is used to prevent leakage of fluid, such as water or steam, between sliding or turning parts of machine elements.

Applications

Boats

A stuffing box, or packing gland, is used around a propeller shaft at the point it exits a boat's hull underwater. It is the most common method for preventing water from entering the hull while still allowing the propeller shaft to turn.

In a conventional stuffing box, the seal itself is provided by packing rings, or a square cross-sectioned rope, made of greased flax, which is packed or wound tightly around the propeller shaft, and compressed in place with a threaded nut and spacer. The box may also be fitted with an opening for periodic insertion of grease between the rings, and sometimes with a small grease reservoir.

A stuffing box packed with flax rings is designed to leak a small amount of water, a few drops per minute, when the shaft is turning; this helps keep it lubricated. This amount of leakage is seldom a problem. Dripless seals, like a mechanical face seal, or lip seal use materials more technologically advanced than flax. The more successful dripless seals are made from Carbon or PTFE (Teflon).

The stuffing box is usually attached with hose clamps to a short piece of heavy-duty rubber hose, which is then clamped around the propeller opening in the boat's hull.

Steam engines

In a steam engine, where the piston rod reciprocates through the cylinder cover, a stuffing box provided in the cylinder cover prevents the leakage of steam from the cylinder

See also

• Compression seal fitting
• Journal bearing

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References

• Calder, Nigel (2005). Boatowner's mechanical and electrical manual. Camden, Maine: International Marine/McGraw-Hill. ISBN 0-07-143238-8

External links

• Stuffing Box FAQ by Aloha Owner's Association
• Construction of stuffing box