Marine propulsion – With indicator
Patent
1997-02-03
1998-08-18
Basinger, Sherman
Marine propulsion
With indicator
440 83, 440112, B63H 2336
Patent
active
057951985
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
On the leisure boats with inboard engine and shafting line, stuffing boxes are usually employed to prevent water from entering through the interstice between the outstanding propeller shaft and the hull opening, said stuffing boxes comprising one or more ring-shaped packings made of graphite-asbestos and being contained in a body that is concentrical with and pressed against the rotating propeller shaft.
In order to reduce the overheating caused by the friction between the packing and the rotating propeller shaft, and to allow the packing to be cooled, a certain amount of water ought to flow between these two members. This water penetrating into the hull is then to be drained away.
Another drawback of the stuffing box appears upon terminating navigation: the packing must be tightened very firmly in order to prevent it from continuously dripping, otherwise--in case of a prolonged stop--the boat would become filled with water, with the obvious consequences.
A further very important problem is the power consumption as a consequence of the rubbing between the packing and the propeller shaft: the bigger models have a cooling system. The friction thus caused produces an axle braking action that takes up a large amount of driving power, thereby increasing fuel consumption and causing a loss of speed. Differently said, it would be like driving a car with the hand-brake applied.
The rubbing between the packing and the propeller shaft causes moreover a premature wear of the shaft which, after a certain time length, is to be substituted.
Furthermore it is to be noted that mounting the stuffing box requires a perfect aligning of the propeller shaft along the outer propeller mounting bracket, the engine and the stuffing box; this gives rise to high assembly expenses.
Moreover, the stuffing box, being rigidly mounted on the hull, transmits all the vibrations of the propeller shaft to the same hull.
For a good operation quality, the three supports of the propeller shaft, i.e. the engine coupling, the stuffing box and the propeller mounting bracket are to be perfectly aligned.
Since such a structure is not a single block that is machined in one run to form a single length, a perfect aligning is almost impossible to be achieved; consequently, the transmission shaft never works in the optimum condition, whereby it exhibits a great rotational resistance, said resistance being due not only to the braking action of the packing, but also to the forcing of the transmission as a consequence of the impossibility to achieve a perfect alignment.
Another sealing device that is often used on certain boats consists of a rotating joint comprising a disk that rotates with the shaft, said disk being pushed by a spring against another disk that is coated with a friction-reducing material (graphite and alike), this latter disk being fixed to the hull.
The most serious problem is that all types of rotating joint--with rings integrally fixed to the axle, such as the one known from GB-A-2251273 having the features according to the preamble part of claim 1--do not allow the shaft to axially slip, with the consequence that in case of a commonplace (and rather frequent) accident like a line winding on the propeller that pulls rearwards the propeller shaft which in turn is fixedly connected to the engine, one or more engine mountings can be broken and the engine displaced rearwards. This causes the rotating joint to be broken with the consequent opening of a large water flow passage and creates a shipwreck risk.
Further problems associated with such a rotating joint consist in the friction races being degraded--also by action of the sodium chloride crystals--with the consequent leakage of water into the hull, both when the shaft is rotating and when it is at rest.
A problem shared by all the stuffing boxes and rotating joints is that they cannot be operated without water (for example in the case of a high speed forming a water pocket in front of the propeller, or in case of an obstructed sea--water intake, and so on) b
REFERENCES:
patent: 3565447 (1971-02-01), Goetze et al.
patent: 3625523 (1971-12-01), Gardner et al.
patent: 3844247 (1974-10-01), Collis et al.
patent: 4174672 (1979-11-01), Cox
LandOfFree
Floating seal for high rotational speed propeller shafts with in does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Floating seal for high rotational speed propeller shafts with in, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Floating seal for high rotational speed propeller shafts with in will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1109997