WO1994006710A1

WO1994006710A1 - Improvements in or relating to winches

Info

Publication number: WO1994006710A1
Application number: PCT/NZ1993/000081
Authority: WO
Inventors: Peter Lewis Owens; Graham James Marsh
Original assignee: Maxwell Winches Limited
Priority date: 1992-09-11
Filing date: 1993-09-09
Publication date: 1994-03-31
Also published as: AU4986893A

Abstract

A winch (1) particularly suitable as a yacht sheet line winch. In traditional manner the winch (1) preferably incorporates a cylindrically shaped drum (2) having a shoulder lower end section (2a), in use, the drum (2) being intended to be rotated, such as by handle (10), about a substantially vertically disposed axis. Longitudinal or axially extending recesses (3) are incorporated at radially spaced apart intervals about the drum (2) with the land sections (4a) therebetween maintaining the radius of curvature of the drum (2). The recesses (3) provide additional frictional grip on a sheet line (8) retained thereon. Preferably the recesses (3) terminate in adjacent spaced relationship to a shoulder end (2a) to provide a recess free zone (6). The recesses (3) are configured to provide an obtuse angle between a face (4) of the drum (2) and the adjacent intersection face (5) of a recess (3) this 'transition' angle being identified as angle 'X' on the accompanying drawings. Preferably both the depth and width of the recesses (3) and the diameter of the drum increase toward a top of the drum (2). This geometry of the recess (3) configuration and layout on a drum (2) tends to spread the frictionnally forces provided thereby away from a first turn (7) of sheet line (8) on the drum (2).

Description

TITLEJ IMPROVEMENTS IN OR RELATING TO WINCHES TECHNICAL FIELD

This invention relates to winches and in particular is concerned with an improved drum for a yacht sheet winch.

BACKGROUND ART

Traditionally winches have a drum with an essentially cylindrically shaped central section often with diametrically enlarged end sections to facilitate retaining a line thereon. With some winches, particularly those intended, in situ, to rotate about a substantially vertically disposed axis such as a yacht sheet winch, the drum is marginally tapered to provide an increase in diameter toward an upper end thereof.

Most such winch drums have a smooth line or sheet gripping drum face although it is known to increase the frictional grip character thereof by providing an irregular drum face. A draw-back with such an arrangement tends to be excessive wear and tear on an associated sheet on line. This can be particularly so with a yacht sheet winch where there is a need to allow for both controlled and forced slippage of a sheet line about a drum such as when paying-out. Further with a sheet winch while increased grip circumferentially is desirable increased grip axially is not as this tends to prevent the desirable axial displacement of the coils along a drum. Some known grip enhancing means increase both the circumferential and the axial grip substantially equally and this is considered undesirable.

An object of this invention is to provide a winch drum with a line gripping face thereof that incorporates a particular form of irregular surface which it is envisaged will enhance the gripping characteristics of the drum but which will not cause excessive and unacceptable wear and tear on an associated line.

DISCLOSURE OF THE INVENTION

According to a first aspect of this invention there is provided a cylindrically shaped winch drum characterised in that axially extending recesses are incorporated at radially spaced apart intervals about a line gripping face thereof, the recesses being separated from one another by land sections of the drum.

According to a second aspect of this invention there is provided a winch drum as described in the preceding paragraph wherein the radius of curvature of the line gripping face is maintained over the face of the land sections.

According to a third aspect of this invention there is provided a winch drum as described in either of the two preceding paragraphs incorporating a lower shoulder end section of a diameter substantially larger than the remainder of the drum, the drum being intended, in situ, to have an axis of rotation disposed essentially vertically.

According to a fourth aspect of this invention there is provided a winch drum as described in the preceding paragraph wherein the recesses terminate in adjacent spaced relationship from the commencement of the shouldered end section to form a recess free zone.

According to a fifth aspect of this invention there is provided a winch drum as described in the preceding paragraph wherein the diameter of the drum marginally increases over substantially the complete length of the section thereof above the shouldered end section with a line of least diameter of the drum falling within the recess free zone.

According to a sixth aspect of this invention there is provided a winch characterised by the incorporation therein of a winch drum as described in any one of the five preceding paragraphs.

According to a seventh aspect of this invention there is provided a winch intended, in situ, to have an axis of rotation disposed substantially vertically, characterised in that a cylindrically shaped drum thereof has axially extending recesses incorporated at radially spaced apart intervals about a line gripping face thereof, the recesses being separated from one another by land sections of the drum and the diameter of the drum increases over substantially the complete length thereof with a line of least diameter being adjacent to a lower end of the drum.

BRIEF DESCRIPTION OF THE DRAWINGS In further describing the invention reference is made to the accompanying drawings of a preferred embodiment wherein:

Fig 1 is a side elevation of a winch incorporating a drum as characterised by this invention, with a first turn of a line (depicted in broken line) thereon, and Figs 2-4 inclusive are cross-sectional detail views through a recess on lines a-a, b-b and c-c respectively on Fig 1. BEST MODE FOR CARRYING OUT THE INVENTION

A manually operable winch 1 incorporates a cylindrical shaped drum 2 intended, in situ, to be rotated, such as by handle 10 about an essentially vertical axis, such as a yacht sheet winch, is adapted in accordance with the invention. Preferably the diameter of the drum 2 marginally increases toward an upper end thereof. For example, the drum 2 incorporates a two (2) degree taper relative to the axis of rotation.

A plurality of recesses 3 are incorporated in a line gripping face 4 of the drum 2, the recesses 3 being disposed at radially spaced apart intervals thereabout. The recesses 3 are formed such as by milling the face 4 of the drum 2 to a depth of a few millimetres. In the preferred embodiment, the recesses 3 are of a concave or "bull-nose" cross-sectional shape, as depicted on Figs 2- 4 inclusive.

More particular the shaping of a recess 3 at a point about mid-way (depicted in Fig 3) of the length thereof is such as to provide an obtuse angle in the region of 135 degrees, between the face 4 of the drum 2 and the adjacent intersecting face 5 of a recess 3. Referring to Figs 2-4 inclusive this angle is identified as "X" thereon with its corresponding angle indicating the degrees of the angle. For convenience angle "X" is called the "transition" angle.

Preferably the depth of a recess 3 is not constant with preferably the depth reducing at about half the rate (ie. on a one degree taper) to the tapering reduction in diameter of the drum 2. Thus, the depth of a recess 3 is less toward a shouldered or lower end 2a of the drum 2 and increases toward the top of the drum 2. Consequentially the transition angle "X" alters with preferably the transition angle "X" at an upper end of a recess 3 being about 30 degrees less than at a lower end of a recess 3. Preferably the land sections 4a between the recesses 3 retain the radius of curvature of the drum 1.

Preferably the recesses 3 are formed at about 10 degree intervals about a drum face 4. The width of a recess 3 and the number of recesses 3 on a drum 2 are selected to provide that about 50% of a drum face 4 remains as land sections 4a between the recesses 3. Preferably the recesses 3 are marginally tapered along their length to become narrower toward the lower end thereof. These changes in width, depth, and the transition angle "X" are depicted in Figs 2-4 inclusive, Fig 3 depicting essentially a mid-point as aforesaid and Figs 2 and 4 depicting essentially upper and lower points respectively along the length on a recess 3.

The recesses 3 extend longitudinally or axially of a drum 2 preferably at least over that section of the drum 2 above a line f-f of least diameter of the drum 2. Thus a zone 6 of a drum face 4 where the shouldered lower end 2a commences is preferably free of any recesses 3. In the case of a tapered drum 2 the line of least diameter f-f of a drum 2 falls within this zone 6.

Thus where the line gripping face 4 of a drum 2 blends with the lower shouldered end section 2a thereof the effect of the recesses 3 is minimal. It is in this zone 6 that, in use, a first turn 7 of a sheet line 8 seats and thus the recesses 3 offer little resistance to slippage of line 8 on a drum 2. It is estimated that a first turn 7 of a sheet line 8 about a drum 2 takes a high proportion (possibly up to 75%) of the load to be borne by a winch 1 thus the recesses 3 have minimal effect on the wear and tear on a sheet line. It follows that with application of a second turn 9 and subsequent turns the frictional grip effect of the recesses 3 on a line 8 substantially increases. Put another way, the geometry of the recess 3 configuration and the layout thereof on a drum 2 spreads the additional frictional grip provided by the recesses 3 away from a first turn 7 of a line 8 thereon.

Claims

1. A cylindrically shaped winch drum characterised in that axially extending recesses are incorporated at radially spaced apart intervals about a line gripping face thereof, the recesses being separated from one another by land sections of the drum.

2. A winch drum as claimed in claim 1 wherein the radius of curvature of the line gripping face is maintained over the face of the land sections.

3. A winch drum as claimed in either of the preceding claims wherein the faces of the recesses intersect the face of the drum at an obtuse angle.

4. A winch drum as claimed in any of claims 1 to 3, incorporating a lower shoulder end section of a diameter substantially larger than the remainder of the drum, the drum being intended, in situ, to have an axis of rotation disposed essentially vertically.

5. A winch drum as claimed in claim 4 wherein the recesses terminate in adjacent spaced relationship from the commencement of the shouldered end section to form a recess free zone.

6. A winch drum as claimed in claim 5 wherein the diameter of the drum marginally increases over substantially the complete length of the section thereof above the shouldered end section with a line of least diameter of the drum falling within the recess free zone.

7. A winch drum as claimed in any one of the preceding claims wherein the depth of the recesses decreases toward a lower end of the drum.

8. A winch as claimed in any one of the preceding claims wherein the width of the recesses decreases toward a lower end of the drum.

9. A winch drum as claimed in either claim 7 or claim 8 wherein the faces of the recesses intersect the face of the drum at an obtuse angle throughout their length, this transition angle of intersection varying over substantially 30 degrees and having a medium of substantially 135 degrees.

10. A winch drum as claimed in any one of the preceding claims wherein the number of recesses and their width are selected to provide that about 50% of a drum face remains as land sections between the recesses.

11. A winch characterised by the incorporation therein of a winch drum as claimed in any one of the preceding claims.

12. A winch intended, in situ, to have an axis of rotation disposed substantially vertically, characterised in that a cylindrically shaped drum thereof has axially extending recesses incorporated at radially spaced apart intervals about a line gripping face thereof, the recesses being separated from one another by land sections of the drum.

13. A winch as claimed in claim 12 incorporating a lower shoulder end section of a diameter substantially larger than the remainder of the drum and wherein the diameter of the drum marginally increases over substantially the complete length of the section thereof above the shouldered end section and the recesses terminate in adjacent spaced relationship from the commencement of the shouldered end section to form a recess free zone with a line of least diameter of the drum falling within the recess free zone.