FIELD OF THE INVENTION The present invention relates to mechanisms for displacing a load, or placing tension on a strap, rope, or wire. More particularly, the invention relates to mechanisms useful in replacing those of standard winches,

BACKGROUND TO THE INVENTION

Drive mechanisms are used in a variety of settings, typically for displacing a load. For example, an elevator system includes a drive mechanism to transport the car between the floors of a building. Conveyors utilize a drive mechanism to move goods from one location another. Drive mechanisms may also be used for tensioning wire, ropes and the like

Drive mechanisms are commonly used in winch devices which may be manually operated, or driven by an engine, motor, hydraulics, pressurized air or other means. For example, hand operated winches are often used to pull small watercraft onto a trailer or erect a mast structure. Motorized winches may be used in elevators, or for cranes

A winch typically comprises an axle-mounted drum to which wire is attached. Rotation of the drum winds the wire onto the drum, with any load attached to the wire being drawn toward the drum. Winches are typically equipped with a gearing system, often to convert a highspeed low force electric motor output onto a low-speed high torque pulling force.

Winches of the prior art have a number of problems. Firstly, they are only capable of displacing a load in one direction. While a standard winch can be used to pull a boat onto a trailer and to disengage the drive and allow the boat to roll back, it is not possible to use the winch to actively pull it in the opposite direction. Thus, load can only be taken in one direction.

A further problem is that the effective diameter of the drum increases as the wire is would up onto the drum. This decreases the efficiency of the winding, leading to fatigue for a manual operator or increased stress on the engine or motor in a powered winch.

Another type of drive mechanism is the griphoist (also termed a tirfor), which reties o two sets of cam-type grippers or cleats that alternately grip the wire rope with each cycle of the l handle. This apparatus is only useful for tensioning cables, and is not useful for moving or lifting loads. Furthermore, many parts {including the grippers or cleats) are fabricated from steel leading to corrosion problems. Yet a further problem is the high wear rate on the rope or wire used.

Winches and griphoists have a further problem in that they may be very slow, especially when operated manually.

Drive mechanisms may also be used in means for transporting or placing parts and products in a manufacturing setting. In some applications, rapid movement of goods is required. Again, a lack of speed can be an issue with prior art drive mechanisms. It is an aspect of the present invention to overcome of ameliorate a problem of the prior art by providing an improved drive mechanism.

It is a further aspect to provide an alternative to drive mechanisms of the prior art. The discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application

SUMMARY OF THE INVENTION

In one aspect the present invention provides a drive mechanism comprising: (i) first and second rotating components, the rotating components comprising formations on their surfaces, the rotating components being positioned relative to each other such that there is at least some meshing between the formations, and

(ii) an elongate flexible load or tension bearing means, wherein the formations are shaped and dimensioned to aliow the load or tension bearing means to be interposed between the first and second circular components such that in use, when the first and/or second rotating components is/are driven, the load or tension bearing means is displaced longitudinally. In one embodiment the formations are regularly spaced about the edge of the circular rotating component.

In one embodiment the rotating components are substantially circular and the formations are 80 regularly spaced on the circumferential surfaces of the rotating components.

In one embodiment the formations are configured to frictionally engage with the load or tension bearing means to cause the longitudinal displacement of the load or tension bearing means.

85

In one embodiment the rotating components are generally cog-fike in appearance or generally gear-like in appearance.

In one embodiment the drive mechanism comprises 3. 4, 5, 6 _S 7, 8, 9, 10 or more rotating 90 components.

In one embodiment the rotating components are in a planetary arrangement.

In one embodim ent the central rotating component of the planetary arrangement is driven.

95

In one embodiment the drive mechanism comprises 4 peripheral rotating components and 1 central rotating component, the centres of the peripheral rotating components being disposed at the vertices of a square, with the centre of the central rotating component being disposed at the centre of the square.

100

In one embodiment the rotating components are configured to turn clock-wise and anticlockwise such that the load or tension bearing means can be displaced or tensioned bi- direciionaily.

105 In one embodiment the formations are substantially triangular.

In one embodiment any corners on the formations are rounded, and/or any valleys between the formations are rounded.

110 In one embodiment part of all of the rotating components are fabricated from a non-ferrous material. In one embodiment part or all of the rotating components are fabricated from a plastic.

115 In one embodiment the load or tension bearing means is a strap or a rope.

In one embodiment the load or tension bearing means is resistant to stretching.

In one embodiment the load or tension bearing means is configured so as to f fictionally 120 engage with the formations of the rotating components.

In one embodiment the load or tension bearing means is fabricated from a polyester.

In one embodiment the drive mechanism is capable of displacing a load of at least about 500 125 kg.

In a second aspect the present invention provides a winch device comprising a drive mechanism as described herein.

130 In a third aspect the present invention provides a conveyer device comprising a drive mechanism as described herein.

In a fourth aspect the present invention provides a tensioning device comprising a drive mechanism as described herein.

135

In a fifth aspect the present invention provides a placement or a positioning device comprising a drive mechanism as described herein.

In a sixth aspect there is provided a method for winching, conveying, tensioning or placing 140 an item, the method comprising the steps of: providing the winch device as described herein,

the conveyer device as described herein,

the tensioning device as described herein,

145 or the placement or positioning device as described herein, and actuating the winch device, or the conveyer device, or the tensioning device, or the placement or positioning device, 150 BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1 is a diagrammatic lateral view of a drive mechanism of the present invention having 5 rotating components, each component having 10 formations.

155 Fig. 2 is a diagrammatic perspective view of the drive mechanism shown in Fig. 1 ,

Fig, 3 is a perspective view of a drive mechanism of the present invention having 5 rotating components, each component having Θ formations. The central rotating component has an integral drive member. No strap is shown in this drawing.

160

Fig. 4A is an elevated perspective view of the drive mechanism shown in Fig. 3. Panel B is a second housing part. No strap is shown in this drawing.

Fig. 5A is ah end-on view of the drive mechanism and housing parts shown in Fig 4, shown 265 as assembled. No strap is shown in this drawing. Panel B is a perspective view of the assembled drive mechanism shown in Fig, 4. No strap is shown in this drawing.

Fig. 6 is a diagram of an embodiment having a locking ratchet mechanism. No strap is shown in this drawing.

170

Fig. 7 is a perspective view of an embodiment having a locking/ratchet mechanism, and also gearing.

DETAILED DESCRIPTION OF THE INVENTION

175

After considering this description it will be apparent to one skilled in the art how the invention is implemented in various alternative embodiments and alternative applications. However, although various embodiments of the present invention will be described herein, it is understood that these embodiments ar presented by way of example only, and not 180 limitation. As such, this description of various alternative embodiments should not be construed to limit th scope or breadth of the present invention. Furthermore, statements of advantages or other aspects apply to specific exemplary embodiments, and not necessarily to all embodiments covered by the claims. 185 Throughout the description and the claims of this specification the word "comprise" and variations of the word, such as "comprising" and "comprises" is not intended to exclude other additives, components, integers or steps.

Reference throughout this specification to "one .embodiment ⁰ or "an embodiment" means that 190 a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may.

195 In a first aspect the present invention provides a drive mechanism comprising:

(i) first and second rotating components, the rotating components comprising formations on their surfaces, the rotating components being positioned relative to each other such that there is at least som meshing between the formations, and

200

(ii) an elongate flexible load or tension bearing means, wherein the formations are shaped and dimensioned to allow the load or tension bearing means to be interposed between the first and second circular rotating components such that 205 in use, when the first and/or second rotating components is/are driven, the load or tension bearing means is displaced longitudinally.

The load or tension bearing means (which is typically a strap) is disposed between the two rotating components and in contact with some of the surface formations at any given point in 210 time. Rotation of the first and second components acts to move the strap in the direction of rotation (i.e. longitudinally with respect to the strap). Typically, the first rotating component is driven (by a hand crank or electric motor, for exampie) in one direction with the meshing between the formations and the interposed strap causing contra-rotation of the second rotating component.

215

Applicant has discovered that a significant load can be displaced with the present drive mechanism. For example, a load attached to a strap may be lifted with a winch incorporating a drive mechanism of the present invention.

220 The present mechanism is a significant departure from prior art drives which utilize a drum about which a rope is spooled and taken up by rotation of the drum. This arrangement is used extensively in winches and associated devices. By contrast, the drive mechanism of the present invention relies on the interaction between the formations and the strap, and also the movement of the formations to continuously displace the strap.

225

A significant advantage of the present mechanism is the avoidance of a drum. As discussed in the Background section herein, the effective diameter of the drum increases as more wire is wound on. Thus, the drum requires the application of greater torque as the winding proceeds, this causing a user to rapidly tire (where the manual winding is used) or placing 230 greater stress on a motor. The present mechanism is not reliant on a rotating drum, and is instead reliant on the engagement of the formations with the strap to directly displace the strap and any associated load.

For reasons of economy at least, drums are typically fabricated from steel (as are any 235 associated gears) and are therefore prone to corrosion especially when in a marine environment or otherwise exposed to weather. Some, most or all components of the present mechanism may be fabricated from non-metallic materials such as plastics which are non- corroding, or from corrosion-resistant metals such as aluminium.

240 Furthermore, drums (being essentially hollow) may also distort during use, especially where significant load is being displaced. The present mechanism by contrast can be fabricated from essentially smaller, solid structures and are therefore less easily deformable. Thus, greater loads may be assumed with a lower risk of damage to the mechanism.

245 The rotating components may be mounted in any manner deemed suitable by the skilled person, and are typically mounted on a plate, frame or within a housing. For ease of construction and reaso of economy the mounting arrangement may be a simple axial protuberance extending from the centre of the rotating component. The protuberance may insert into a recess or aperture in a housing wall so as to be able to rotate substantially

250 freely. In more sophisticated embodiments, the rotating components may be mounted on bearings, however this is not essential.

As used herein the terms "first" and "second" when used to describe the rotating components is used only to denote the separate nature of the components. The terms "first" 255 and "second" are not to be construed to denote importance, size, timing or any other consideration. The rotating components are typically circular and generally disc shaped (discounting the formations), however it is to be understood that other configurations are contemplated. For 260 example, a rotating component may be a caterpillar track-like contrivance with formations extending from the track. Thus, two tracks may be placed side-by-side with an elongate load bearing means disposed between such that the formations act to push the bearing means through the mechanism.

265 In another alternative, the rotating components may be hexagonal, with the vertices of the hexagon acting as the formations of the components.

Given the benefit of the present specification the skilled person wiil be enabled to routinely conceive of other variations, all of which are included in the scope of the present invention. 270 As wiil be apparent from the foregoing, the protrusions are the components of the mechanism which contact the strap, and responsibie (upon driving one or both of the rotating components) for the feeding to the strap through the drive mechanism. The formations ar typicaily disposed in a linear manner and regularl spaced so as to achieve the meshing relationship required between the formations of the first and second rotating components.

275

In some embodiments of the mechanism, the rotating components and formations are generally cog-like or gear-like in appearance.

The formations may be shaped in any manner capable of achievin the desired result within 280 the context of the invention, and may have a profile being substantially tooth-like, saw- toothed, triangular, rectangular, square, semicircular, conical, frustoconical, pyramidal, or mound-like.

Typically, the formations of the first rotating component are substantialiy identical to those of 285 the second rotating component.

The distance between the axes of rotation of tie first and second rotating components may be influenced to an extent by the distance by which the formations protrude. The converse is also a possibility, in that that the distance by which the formations protrude may influence 290 the distanc between the axes of rotation of the first and second rotating components. The degree of meshing can be characterised by the maximum amount of overlap between the formations of the first and second rotating components. In turn, the maximum amount of overlap may be characterized by reference to the distance by which the formations protrude. For example, where the formations of both the first and second rotating components 295 protrude by 10 mm, and where the rotating components are turned such that maximum overlap between the formations is achieved, and where the formations overlap by 5 mm then the amount of overlap is 50%.

The amount of overlap between the first and second formations may be selected from the 300 group consisting of greater than about 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, and 95%. in some embodiments, the amount of overlap between the formations is from about 40% to about 50%. Where a particularly thin strap is used, the amount of overlap may be permitted to be greater than where a thicker stra is used.

305

In some embodiments, one formation is continuous with the next, there being no intervening space of the surface of the rotating component. In other embodiments, there is a defined area between formations.

310 The formations are preferably shaped so as to minimise damage to the strap of the mechanism, this providing for greater longevity of the mechanism, it has been found that the use of sharp corners is to be avoided given the potential for the strap to be worn or even severed by contact with the formations. Accordingly, where the formation has an apex it is preferred for the apex to be rounded.

315

Moreover, sharp internal corners may be avoided in the valleys between formations, and again preferably rounded to allow the strap to easily conform without the necessity for sharp bends to be made in the strap during operation.

320 A function of the formations is to engage with the strap (and preferably frictionally engage), and so materials used and the finish of the formation surfaces may be selected to be conducive to that function. Materials which are substantially rigid and capable of withstanding the forces occasioned on the formations in operation are typically used. The surface finish of the formations may be engineered to, on the one hand, provide sufficient

325 frictional engagement to efficiently move the strap through the mechanism (preferably without any slippage), but to also minimise damage to the strap which may be occasioned by highly frictional surfaces.

Given the benefit of the present specification, the skilled person is enabled to select an appropriate material and finish for the formations. The rotating components may be 330 fabricated form any suitable material, the suitability of any material being apparent to the skilled person having the benefit of the instant specification, and in light of the varying structural and functional requirements detailed herein. The components may be fabricated from a plastic by injection molding or other suitable technique from commercially-available material such as a nylon, thermo plastic polyurethane (TPU); ionomer resin; ethylene vinyl

335 acetate (EVA); thermo plastic styrenics (TPS); polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC); acrySonitrile-butadtene-styrene terpolymer (ABS); a polycarbonate and acrylonitrile-butadiene-styrene copolymer blend (PG/ABS); polymethylmethacrylate (PM A, marketed as "PERSPEX" by ICI Acrylics, inc.); other acrylics; metal .(e.g., stainless steel, aluminium, copper); wood; or any combination thereof.

340 Other suitable materials and forming methods will be apparent to those skilled in the art. It is preferred that the rotating component is fabricated from a nylon, and more preferably an acetylated nylon.

The same material used for the formations may also be used for the entire rotating 345 component. In some embodiments, more than one material is used to form a composite component. For example, the major portion of the component may be fabricated from a first plastic, and the formations from a second plastic.

Specific engineering consideration may be given to the driven rotating component, given the 350 propensity for significant torque forces being applied to the component by a drive shaft.

Where the mechanism is a manually driven winch device for example, the driven rotating component may be subject to significant torque where the user exerts their weight on the crank handle or uses a lever extension bar to increase the force applied to the handle. Accordingly, in some embodiments the driven rotating component may be fabricated from a 355 non-plastic material such as a metal or an alloy. Given the higher cost of metal components, the second rotating component may be fabricated from a plastic.

In some embodiments, both the first and second rotating components are driven. Driving both components may be necessary or desirable where a certain speed of displacement of 360 the strap is required, or where a load is particularly heavy.

While the preceding description refers to embodiments having first and second rotating components, while operable such embodiments will be inferior in performance to drive mechanisms having a third, fourth, fifth, six, seventh, eighth, ninth or tenth rotating 365 component. Where multiple rotating components are included, each component may be positioned in the device so as to best engage with and displace the strap.

370 A preferred arrangement is a planetary-type arrangement whereby a central rotating component is surrounded by multiple peripheral components. As a simple example, a central rotating component may be surrounded by four peripheral components, the centres of each of the peripheral rotating components being disposed at the vertices of a square, with the centre of the central rotating component being disposed at the centre of the square.

375 In such arrangements (as shown in Figs. 1 to 8 herein), it is typical for the central rotating component to mesh with each of the peripheral components, but there be no meshing between any of the peripheral components. The central component is typically the driven component, and may be driven anti-clockwise. Given the meshing with the peripheral components, the peripheral components are caused to rotate clockwise. The strap is drawn

380 into the device while the central driven rotating component is turned. The strap is interposed between the central component and all peripheral components and thus almost completely encircles the central component. Reference is made to Fig. 1 and 2 showing that arrangement.

385 As will be clear from the foregoing, the elongate flexible load or tension bearing means may be a strap. As used herein, the term "strap" is intended to include any broad, thin structure having sufficient flexibility and strength to allow for engagement with the formations of the rotating components. Typically the strap has a width about equivalent or less than the width of the formations. The strap is generally sufficiently thin so as to allow interposition between

390 the first and second rotating components, but not so thin such that the strap does not properly engage with the formations.

As will be appreciated, some flexibiiity is required to allow for the stra to assume a substantially concave configuration when disposed over a formation. Resilience may also 395 be required such that the strap returns substantially to its original (flat) formation upon exit from the device. Stretch in the strap is to be generally avoided.

The strength (i.e. resistance to breakage in use) of the strap will be determined by a consideration of at least the expected loads or tensions placed on the strap under normal 400 operating conditions. As a starting point, the strap alone may be tested for an ability to support the expected load or tension. In addition to that test, furthe consideration may be had to any compression, stretching, or friction applied to strap by the formations when the drive is in operation. 405 While the strap may be fabricated form any suitable material, synthetic materials are preferred fro reason of at least cost or durability. In one embodiment, the strap is fabricated from a woven polymer such as a polyester or a polyethylene. The strap may be UV stabilized or coated to exclude moisture, modify surface frictiona! properties to better engage with the formations, and the like.

410

Where the strap is woven, it is preferred for a longitudinal weave to be avoided. Preferred weave patterns are where the weave is on the bias, or more preferably where the weave is directly across the log axis of the strap. Without wishing to be limited by theory, it is proposed that a lateral weave provides the necessary flexibility, but without the negative 415 effects of stretching.

In some embodiments, the strap has a width to thickness ratio of at least about 5:1 , 10.1 , 15:1, 20:1 , 25:1 , 30:1, 35:1 , 40:1, 45:1 , 50:1, 55:1, 60:1 , 65:1 , 70:1 , 75:1 , 80:1 , 85:1 , 90:1 , 95:1 or 100:1.

420

The thickness of the stra may be selected by reference to the amount of overlap between formations (the calculation of which is disclosed elsewhere herein). In some embodiments, the thickness of the strap (in mm) is between about 20% and about 40% the amount of overlap (in mm) between the formations.

425

It will be apparent to the skilled person that other load or tension bearing means will have utility. For example, a rope or rope-like contrivance may be useful. The rope may have a diameter to allow for some compression when passed between the first and second rotating components, such that frictional engagement is not lost.

430

Preferably the load or tension bearing means has surfaces which are substantially flat and devoid of any ribbing, depression, aperture, tooth, formation, undulations or the like which may interfere with efficient engagement with the formations. For the same reason, the means is preferably substantially continuous, and devoid of any links, joins, connections and 435 the like.

The components of the present drive can be configured in terms of number, size, shape, or material in order to assume any expected load or tension, or any torque applied to the driven components). For example, where the load or tension is expected to be large, the diameter 440 of the driven rotating component (and optionally the depth) may be increased. The width or thickness of the strap may also be increased. The strap and/or formations may be configured so as to provide greater frictionai engagement thereby minimising slippage in the direction of the load.

445 The ability to assume significant load or tension is a significant advantage of the present mechanism, rendering suitability in many applications. In some embodiments, the drive mechanism is configured to be operable under a load of at least about 500 kg, 1000 kg, 1500 kg, 2000 kg, 2500 kg, 5000 kg, 7500 kg, or 10000 kg. It is emphasized that still greater loads may be lifted by the present drives with there being no theoretical or practical upper

450 limit known to the inventor at the filing date of this specification. For example, the use of larger rotating components and/or fabrication of the rotating components from a metal (such as steel) and/or the use of thicker and wider straps are contemplated to be useful approaches in increasing the load capacity of the present drive mechanism.

455 The present drive mechanisms may include ratchet means to lock the drive in position. The ratchet means may only need to act on a single rotating component given the meshing relationship between components. A significant advantage o the present drive mechanism is an ability to drive bi-directionally, and accordingly a ratchet means capable of acting in either direction is provided for. Further disclosure regarding this embodiment is found infra

460 in the preferred embodiments section, and reference is made to Figs. 6 and 7 herein.

The present drive mechanisms may further comprise gearing, in addition to the cog-like or gear-like structures (having formations) which are responsible for displacing the strap. For example, where the mechanism is driven manually and the toad is significant, gearing to

465 increase torque on the driven rotating component may be incorporated. As another example, where the mechanism is driven by an electric motor, speed reduction gears may be incorporated into the mechanism to provide greater control over the rate of displacement of the belt. The skilled person is familiar with gearing means for obtaining any mechanical advantage required, and is enabled to implement same in the context of this invention

470 through routine means only. An exemplary embodiment of a geared drive mechanism is shown in Fig. 7 herein.

It will be appreciated that the present invention is disclosed mainly by reference mainly to manual and power driven winch devices. However, it will be appreciated that the invention is 475 useful in other applications. Non-limiting applications include mechanisms for hoists and other types of lifting equipment, communication and boat masts, precision placement devices, conveyer equipment, tensioning devices and the like. It should be appreciated that in the description of exemplary embodiments of the invention 480 herein, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof, for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects, This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the 485 following ciaims reflect, inventive aspects He in less than ail features of a single foregoing disclosed embodiment. Thus, the ciaims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as falling within the scope of the invention.

The present invention will now be more fully described by reference to the following non- limiting preferred embodiments.

PREFERRED EMBODIMENTS OF THE INVENTION

510

Reference is made to Figs. 1 and 2 showing an embodiment of the invention having a central rotating component 10, and 4 peripheral rotating components 12, 14, 16 and 18. Each rotating component has 10 formations. For clarity, 2 formations are marked 20 on component 16. Each formation has a rounded apex 26 and is separated from adjacent 515 formations by a discrete area of circumferential surface marked 24. A strap 28 is interposed between the central rotating component 10 and the peripheral components 12, 14, 16 and 18. The strap 28 is engaged with the meshing formations 20, and in operation is moved through the mechanism by turning of the central rotating component 10, via the drive shaft 30, The drive shaft 30 extends outwardly from the non-visible side of component 10, this

520 providing the advantage that the drive can be driven from either side.

Upon rotation of the component 10 anti-clockwise (as shown by the broad arrow superimposed over component 10), the peripheral rotating components 1 , 14 and 16 rotate clockwise due to the meshing arrangements between the formations of the 5 rotating 525 components. The direction of movement of the strap 28 into and out of the mechanism is indicated by the adjacent arrows.

The embodiment shown in Figs 3 to 5 illustrates an embodiment having a central rotating component 40, with 4 peripheral components 42, 44, 46, and 48. The central component 530 has a drive shaft 54 which is adapted to be operatively connected to a handle or motor (not shown). Each rotating component has 6 formations, each peripheral component 42, 44, 46, 48 in meshing relationship with the central component 40.

Figure 3 shows a partially disassembled drive mechanism embodiment consisting of a first 535 housing portion 60. Each peripheral component has an axial flange 52 on both sides (the underside not shown) adapted to insert into apertures in the lower housing portion 58, to allow rotation about their central axes. The central rotating component has a drive shaft 54. The first housing portion 60 includes two shafts 56 for the insertion of fasteners to secure the second housing portion to the first.

540

Fig. 4 shows the assembly of the first housing portion 60 (and having disposed thereupon the 5 rotating components) with the second housing portion 62. It will be noted that the second housing portion 62 has a centra! aperture 88 to accept the drive shaft 70 of the central rotating component, the aperture being sized so as to allow entry of the axta! flange. 545 Very little play is allowed between the axial flange and the side wall of aperture 68 to ensure the components is not allowed to significantly move in a manner other than axial rotation. Similarly, the axial flanges 64 of the peripheral components insert into apertures 66, again with very little free play.

550 Fig. 5 shows the assembled device (although with the strap), and demonstrating more fully the base 80 formed by the assembly of the two housing portions 60 and 62. Fig. 6 is an embodiment having a ratchet mechanism, consisting of an arm 94 allowing for movement of the ratchet mechanism about the axis 96 fully to the left (as drawn) such that

555 the nub 104 sits between two formations 106 of rotating component 110, thereby locking that component in position. When the rotating component 110 is turned anti-clockwise, the nub 104 travels up and over the formation 106, and subsequent formations until the rotation ceases, at which time the spring 118 maintains the nub 104 in the valley between two formations thereby causing the component 110. to lock. Because of the meshing

560 relationship between components 110 and 100, and the meshing relationshi between component 100 and components 114 and 116, all rotating components are locked. A strap (not shown) interposed between the central rotating component 1 Q0 and peripheral components 110, 112, 114, 116, will also be locked and unable to slip through the drive mechanism.

565

When the arm 94 is moved to an upright position, the nubs 104 are clear of all rotating components which are thereby allowed to turn freely.

When the arm 94 is moved completely to the right, the nub 120 is urged by the spring 118 to 570 sit between two formations of the rotating component 112, thereby locking it. Again, this prevents movement of a strap (not shown) within the drive mechanism when the drive is not being operated.

To control movement, the ratchet mechanism has a locating member 90 which travels within 575 the elongate aperture 92.

As discussed elsewhere herein, the present drive mechanism can displace the strap bi- directionally. The ratchet mechanism disclosed supra is capable of acting to lock the movement of the strap through the drive mechanism selectively and in either direction.

580

Fig 7 shows an embodiment having a ratchet mechanism 130, 4 peripheral rotating components 132 and a central rotating component 134, The component 134 is mounted on a first toothed gear 136 which meshes with a second toothed gear 138 having a drive shaft 140. The gears 138 and 136 provide a mechanical advantage to the drive mechanism 585 overall. Where the mechanical advantage is not required the central rotating component 134 can be driven directly Some components such as the housing, strap, ratchet spring and the like are not shown in the drawing, it should be noted that the strap is not interposed between gears 138 and 136, but travels only around the central rotating component 134.