Marine propulsion – Screw propeller – Self-clearing
Patent
1988-06-23
1990-07-03
Peters, Jr., Joseph F.
Marine propulsion
Screw propeller
Self-clearing
416146R, B63H 516
Patent
active
049387243
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to line cutting devices of the type adapted to be mounted on the propeller shaft of a water-borne vessel for the purpose of cutting lines, ropes, nets, plastic bags or other debris which may foul the blades of a propeller on the shaft.
BACKGROUND OF THE INVENTION
Such a device is disclosed in British Patent Specification No. GB-A-2139169, and comprises a stationary blade projecting radially from a ring and restrained against rotation by cooperation with a propeller shaft bearing, and a pair of diametrally opposed rotatable blades projecting radially from another ring to be secured to the propeller shaft. The blades have straight cutting edges on both sides lying radially to the rings, so that the width of the blades increases radially outwardly to form fan-shaped or dovetailed blades. At the distal or radially outward free end of each blade integral ear portions project forwardly and rearwardly, in the direction of rotation. Thus the ear portion on the leading edge of a rotating blade engages the ear portion on the opposed edge of the stationary blade before the cutting edges co-operate to shear a line therebetween. The intention of the ear portions is to prevent jamming of the blades as they wear. As the cutting edges approach during rotation, a line caught in the space therebetween tends to slide radially outwardly along the cutting edges until stopped by the ear portions, so that cutting usually takes place with the line at the distal or radially outward ends of the cutting edges. The moment of the cutting forces when cutting takes place there is greater than if it takes place closer to the rings. In addition, cutting takes place through the full width of a line in one action and this may prove difficult or impossible with large lines.
THE INVENTION
The object of the invention is to overcome this problem by providing a progressive cutting of fouled lines which enables even large diameter lines to be successfully cut without jamming.
According to the invention, there is provided a line cutting device for mounting around a propeller shaft between a shaft bearing and a propeller comprising a rotatable cutting blade assembly mountable for rotation with the propeller shaft and including at least one rotatable cutting blade extending generally radially of the propeller shaft and having a cutting edge provided between an axially directed face and a circumferentially directed face; and a stationary cutting blade assembly adapted to be restrained against rotation by co-operation with the shaft bearing and including a stationary cutting blade extending generally radially of the propeller shaft, having a cutting edge provided between an axially directed face and a circumferentially directed face and arranged for cutting action of its cutting edge with the cutting edge of the rotatable cutting blade on rotation of the propeller shaft with the axially directed faces passing opposite each other during such rotation; wherein the cutting edge of the or each rotatable cutting blade and/or the cutting edge of the stationary cutting blade is/are provided with serrations, and the cutting edges are shaped for cutting action of inner ones of the serrations prior to such action of outer serrations on continued rotation of the propeller shaft.
The serrations tend to grip a fouled line and if it is larger than can be fully cut by the first engaged serration(s), the outer serrations are engaged sequentially, progressively cutting the line.
Preferably, the axially directed faces of the stationary and rotatable cutting blades are flat and the respective circumferentially directed face(s) is/are provided with a tooth formation, whereby the said cutting edge(s) is/are provided with the said serrations.
The tooth formation is conveniently of saw-tooth shape and the circumferentially directed face(s) having this tooth formation is/are raked back from its cutting edge, whereby the cutting edge(s) is/are provided with points.
Although cutting edges are preferably provided on both edge
REFERENCES:
patent: 732568 (1903-06-01), Lee
patent: 756031 (1904-03-01), Lee
patent: 1214238 (1917-01-01), Taubert
patent: 1272168 (1918-07-01), Youngren
patent: 1390397 (1921-09-01), Svenson
patent: 1649657 (1927-11-01), Blake
patent: 1813540 (1931-07-01), Laska
patent: 2666485 (1954-01-01), Antosh
patent: 3371720 (1968-03-01), Blanchard
patent: 4211515 (1980-07-01), Henrich
patent: 4447215 (1984-05-01), Govan
patent: 4507091 (1985-03-01), Govan
Peters Jr. Joseph F.
Sotelo Jesus D.
LandOfFree
Line cutting device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Line cutting device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Line cutting device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1887864