How does dripless shaft seal work?

Often referred to as dripless, face seals compress a fixed bearing against a collar that is attached to the shaft. A thin film of water forms on the interface between the stainless and the carbon, lubricating the seal. A hose connects the fixed bearing to the stern tube. This bellows should not contain any water.

What does the propeller shaft pass through?

The main engine of a ship is coupled to the propeller by means of a shaft. The translational motion of the pistons induces a rotatory motion on the crankshaft, which is in turn, coupled to the propulsion shaft. The shaft then passes through the stern tube.

What are dripless shafts?

Dripless shaft seals offer a dry bilge without the drip-per minute of the traditional stern gland. PBO checks out what’s available. The once-ubiquitous stuffing-box stern gland still has much in its favour – it’s simple, tried-and-tested and easy to repair and service.

How does a propeller shaft seal works?

A housing with series of seal rings clamped into position on the bush. Sterntube seals have to perform two separate functions, one is to ensure that water does not enter the engine room, the second one to allow the propeller shaft to rotate as smoothly and freely as possible.

What is a stuffing box on a boat?

Stuffing Box. If your boat has inboard power, odds are it is fitted with a stuffing box to provide a watertight seal for the propeller shaft. Stuffing boxes are also used to seal rudder stocks that penetrate the hull below the waterline. In principle a stuffing box is identical to the packing nut on a common faucet.

How long does a dripless shaft seal last?

As preventive maintenance, the bellows should be replaced no less than every six years, regardless of its apparent condition.” Lasdrop says of its shaft seals, “The Original Bellows and Generation II models will last as long as eight to 10 years before servicing…

What holds a propeller shaft?

The construction of the shaft bearings is important, as this holds the complete weight of the propeller shafts. There are two main types of bearings- the full case bearing located at the stern, and the half case bearing located at the other positions.

What does a gland nut do?

Gland. A gland is a general type of stuffing box, used to seal a rotating or reciprocating shaft against a fluid. The gland nut allows the packing material to be compressed to form a watertight seal and prevent water leaking up the shaft when the tap is turned on.