US3368797A

US3368797A - Sheave

Info

Publication number: US3368797A
Application number: US591653A
Authority: US
Inventors: Gross Seymour
Original assignee: Navy Usa
Current assignee: US Department of Navy
Priority date: 1966-11-02
Filing date: 1966-11-02
Publication date: 1968-02-13
Anticipated expiration: 1985-02-13

Description

Feb. 13, 1968 s. GROSS SHEAVE 5 Sheets-She et 1 Filed Nov. 2, 1966 56W GIZVENTOR. 002 055 8Y p33 /5. I firm/ways s. GROSS SHEAVE Feb. 13, 1968 3 Sheets-Sheet 2 Filed Nov. 2, 1966 "'i ll llu u S. GROSS Feb. 13, 1968 SHEAVE 5 Sheets-Sheet 5 Filed Nov. 2. 1966 5 GIgVENTOR if/vaz/e ass Unite 3,368,797 Patented Feb. 13, 1968 3,368,797 SHEAVE Seymour Gross, New London, Cnn., assignor to the United States of America as represented by the Secretary of the Navy Filed Nov. 2, I966, Ser. No. 591,653 6 Claims. (Cl. 254-190) ABSTRACT 6F THE DISCLOSURE A tiltable sheave for a faired towline comprising a continuous loop section consisting of a non-circular track bearing V-shaped sheave segments which are rollably mounted on the track. The track is mounted on the inner one of a pair of concentric rings, the outer ring forming a track upon which the inner ring can rotate. The plane of the rings is transverse to the plane of the sheave so that transverse movements of the towline force the inner ring to move transversely, whereby the sheave is also forced to move transversely and to tilt.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to an improved sheave and especially to an improved marine towing sheave.

In marine towing applications such as the towing of sonar equipment housed in a torpedo-like casing at various depths in the ocean, the bulk and weight of the towed body require towing lines of large diameter. In addition, the towing lines are frequently covered with fairings to reduce water drag.

The large diameters of towed lines and the presence of fairing structures do not permit sharp bending of the lines; it is thus required that the sheave over which the line is payed out over the stern have a large radius of curvature. However, because of the competition for space at the stern of a towing vessel and for ease of handling and mounting of the sheave, it is desirable to reduce the size of towing sheaves without reducing the effective radius of curvature.

A second problem which occurs during the towing of bodies behind ships involves the sideways shifts in position of the towed bodyand consequently of the towline. If the sheave is fixed in position in a vertical plane, the line scrapes against the sides of the sheave and there is a good possibility that the line may be damaged. It is therefore desirable to have a sheave which is movable transversely as well as one which tilts to both sides of its vertical position to accommodate the sideways movements of the towing line in response to the sideways swings of the towed body.

An object of this invention is to reduce the size of a sheave without reducing its effective radius of curvature.

Another object is to provide a sheave which accommo dates itself to sideways shifts in the position of a towed object without damage to the towing line.

Other objects and advantages will appear from the following description of an example of the invention, and the novel features will be particularly pointed out in the appended claims.

In the accompanying drawings:

FIG. 1 is an isometric front view of an embodiment of the invention, the view being taken from a position above the middle line;

FIG. 2 is an isometric right-side view taken at an angle of about 45 from the front;

FIG. 3 is a partial section taken through the sheave and transverse track; and

FIG. 4 is a partial section showing details of the tilting means for the sheave and the'manner in which the tilting means is mounted to the transverse track.

FIG. 1 shows an isometric front view of an embodiment of the invention. A tow line (not shown) passes over the segmented sheave 10 which is secured to the inner ring 14 of the tilting means 12 for the sheave 10. The inner ring 14 is rotatable on roller bearings 15 along the outer ring 16 so that the sheave 10 can be tilted from its vertical position (see FIG. 4).

The outer ring 16 is secured to and supported by the tilting means mount 18 which is slidable along a transverse track 20, and the transverse track 20 is supported at its ends by a pair of deck-

mounting members

22 and 24 which are secured to the deck ofthe towing ship at its stem.

The sheave 10 itself consists of a continuous, movable linkage of towline-bearing sheave segments 26, each of which is mounted on a pair of rollers 28 (see FIGS. 3 and 4), and a pair of spaced parallel tracks 30. (A single track may be used, if desired.) The shape of the tracks 30, as is evident in FIG. 3, is not circular. However, the radius of curvature along the top edge is suflicient to prevent the towline from being bent too sharply, but this radius of curvature does not have to be maintained elsewhere along the track. Thus, the bottom of the track is flattened out and a good deal of weight and space is thereby saved. This space can be used for stowage of the towed body When it is hauled out of the water and taken aboard the ship.

The plane of the sheave 10 is defined herein as a plane passing through the middle of the sheave 10 from front to back, the front being the view of the sheave seen in FIG. 1. The plane of the sheave in FIG. 1 is therefore a vertical plane orthogonal to the plane of the drawing. The maximum tilt or swing of the plane of the sheave 10 in this particular embodiment of the invention is about 30 to each side of the vertical, as is indicated by line 36 in FIG. 4.

The shape of a segment 26 of the sheave is approximately rectangular when viewed from the side and approximately V-shaped with flared tips when viewed from the front (see FIG. 4). The manner in which the towline fits into a segment is illustrated in FIG. 4 which shows a cross-section of a towline 32 and its associated fairing 34.

The means by which the individual sheave segments are linked permits the segments to move with respect to each other as they traverse sections of the track along which the radius of curvature changes. It should be noted that the individual segments do not necessarily have to be linked together to form a chain, as is the case in this particular embodiment, but could be placed on the track separately, with a mechanical means such as a tongue and groove arrangement provided to prevent them from falling off the track along the bottom edge.

In operation, the towline is brought over the sheave from a drum behind the sheave and attached to the towed body. The latter is lowered into the water behind the ship and the towline is payed out the required amount. Sideways movements of the towed body cause the sheave to respond by tilting and by transverse movements which act to prevent damage to the towline and its fairings when the towed body is being let out and pulled in.

It will be understood that various changes in the details, materials, and arrangements of parts (and steps), which have been herein described and illustrated in order to explain the nature of invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

I claim:

1. A sheave for a towline comprising in combination:

a track in the form of a continuous loop;

a plurality of towline-bearing segments movably mounted on the outer periphery of said track and sufiicient in number to cover the periphery of said track, the segments also being movable with respect to each other; and

means for supporting said track, said means for supporting said track including transverse track means for permitting said sheave to be moved transversely to the normal vertical position of its plane in response to sideways movements of the towline.

2. A sheave as specified in claim 1, each said sheave segment having a cross-section shaped substantially like the letter V with flared tips, said sheave further including a plurality of wheels, each said sheave segment being mounted on a pair of said wheels,

said wheels being mounted so as to roll along the outer periphery of said track.

3. A sheave as specified in claim 1, each said sheave segment having a cross-section shaped substantially like the letter V with flared tips, said sheave further including a plurality of wheels, each said sheave segment being mounted on a pair of said wheels,

4. A sheave as specified in claim 3, said track being noncircular in shape but having a sufficient radius of curvature along its upper edge and side to avoid damaging the towline because of a sharp bend therein.

5. A sheave for a towline comprising in combination:

a track in the form of a continuous loop;

a plurality of towline-bearing segments movably mounted on the outer periphery of said track and sutlicient in number to cover the periphery of said track, the segments also being movable with respect to each other; and

means for supporting said track, said means for sup porting said track including arcuate means mounted transversely to the plane of said track and movably supporting said track for movement transversely to its plane in response to transverse movements of the towline.

6. A sheave as specified in claim 5, said arcuate means comprising a pair of concentric rings, the inner ring supporting said track and being rotatable within the outer ring so that transverse movements of the towline act to rotate said inner ring thereby tilting said track as well as moving it transversely.

References Cited UNITED STATES PATENTS 1,552,161 9/1925 Houghton 254l90 2,802,639 8/1957 Troyer 254-190 FOREIGN PATENTS 1,303,096 7/1961 France.

RICHARD E. AEGERTER, Primary Examiner.

H. C. HORNSBY, Assistant Examiner.