Marine propulsion – Screw propeller
Patent
1994-09-21
1996-05-07
Basinger, Sherman
Marine propulsion
Screw propeller
416204R, 416244B, 440 80, B63H 114
Patent
active
055140114
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a propeller arrangement for a marine propulsion unit, comprising at least one propeller shaft which carries a propeller hub, said hub presenting a sleeve member secured to the shaft so as to rotate therewith, which sleeve member is axially located on the shaft by means of both a nut abutting the sleeve member and cooperating with an external thread on the shaft, and a screw which is screwed into a threaded bore in the shaft, with the head of the screw abutting the nut.
A propeller arrangement of this type is already known in which the nut is tightened with a high tightening torque using a first tool so as to axially secure the propeller hub. A screw is screwed into the bore at the shaft's end and tightened using another tool so as to lock the nut. When the propeller is to be removed, the screw must first be loosened with the one tool and the nut loosened with the second before the propeller can be slid off the shaft. Should the propeller need to be exchanged when the boat is in water, then it is disadvantageous to require several tools and fasteners, since objects which may be dropped in the water during this operation are virtually impossible to find.
OBJECTS AND SUMMARY
It is therefore an object of the present invention to provide a propeller arrangement of the type mentioned in the introduction, which has a lock-nut arrangement which effectively locks the propeller whilst no more than one tool is needed for the fitting and removal of the propeller.
This object is achieved in accordance with the present invention by means of a propeller arrangement of the type mentioned in the introduction, in which the screw is tightened so that the head of the screw exerts an axial force on the nut which unloads the nut and changes the loading of the nut thread on the shaft thread to the opposite thread flank on the shaft thread.
In engineering terms, this means that, compared to the previously known arrangement, the screw is upgraded in order to be able to accommodate greater loads. During the fitting of the propeller, in principle it is sufficient that the nut be tightened by hand to take up any free play and to centre the hub on the shaft, whereafter the screw is firmly tightened with a tool so that the thread of the nut exerts a force on the opposite thread flank on the shaft.
In a further development of the propeller arrangement according to the invention, a flange is provided around an entrance to the bore through the nut on the surface of the nut facing the screw head, which flange, after insertion of the screw in the nut, is caused to deform inwardly to reduce the diameter of the entrance to the bore. Such a reduction of diameter can be advantageously used to hold the screw and nut together so that during removal of the propeller the screw and nut can be handled as a single component. Once the screw has been loosened with a tool, the nut can be loosened by hand, with the screw being held by the nut so that no risk of dropping the screw arises.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in greater detail with reference to the embodiment shown in the attached drawings, in which
FIG. 1 is a longitudinal sectional view of an embodiment of a propeller arrangement according to the invention and its communication with the lower stern region of a stern-drive unit;
FIG. 2 is a perspective view of a lock nut, and
FIG. 3 is a longitudinal sectional view through the nut of FIG. 2 with an enlargement of the circled region.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, reference numeral 1 denotes a lower wall region of a stern-drive unit, for example of the Aquamatic.RTM. type, which is connected to a not-shown internal combustion engine. A first tubular propeller shaft 2 and a second propeller shaft 3 are concentrically rotatably supported in the drive unit and connected to a drive shaft in a known manner via a not-shown conical gear arrangement so that the propeller shafts are driven in opposite directions. Each pro
REFERENCES:
patent: 2351356 (1944-06-01), Meyer
patent: 3444932 (1969-05-01), Wlezien
patent: 4897058 (1990-01-01), McCormick
patent: 5022875 (1991-06-01), Karls
patent: 5154559 (1992-10-01), Wagner
Hallenstvedt Oddbjorn
Johansson Stig
Rodskier Christian
AB Volvo Penta
Basinger Sherman
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