FIELD OF INVENTION

This invention relates to an axel bush. More particularly, this invention relates to an axel bush. More particularly, this invention relates to an axel bush for attaching to an axel in situ. Still more particularly, this invention relates to an axel bush for an industrial wheel, particularly a multiple directional wheel.

BACKGROUND ART

The following references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the following prior art discussion does not relate to what is commonly or well known by the person skilled in the art, but assists in the understanding of the inventive step of the present invention of which the identification of pertinent prior art proposals is but one part.

Where it is not practical to form axel bushes in a complete cylindrical form because the section on which the axel bush is to be mounted on the axel is smaller in diameter than the diameter of the axel beyond the section, axel bushes must necessarily be either moulded on to the axel section or formed from longitudinal halves that may be joined together to form the bush on the axel. This may also be the case where the axel is non-removably mounted, so that the axel bush cannot be slid on to the axel mounting section as there is no access to the either end of the axel. Accordingly, there is a need for an improved axel bush that can be mounted to an axel where it is not possible to slide the axel bush on to the axel mounting section via either end of the axel. Prior art proposals have included forming the axel bush from two halves that can be joined together in siiu. However, such prior art bushes tend to fail along the join line, the so- called coin-purse split or separation of the components along the join line under pressure.

In discussing the word "axel" or "axel", it will be appreciated that the bush of the invention _. is adapted to attach to other shafts and rods for useful purposes

An object of the present invention is to ameliorate the aforementioned disadvantages of the prior art or to at least provide a useful alternative thereto.

STATEMENT OF INVENTION

The invention according to one or more aspects is as defined in the independent claims. Some optional and/or preferred features of the invention are defined in the dependent claims.

Accordingly, in one aspect of the invention there is provided: an axel bush formed by joining edges of component parts together to form a generally cylindrical bush by joining the component parts along the joinable edges, thejoinable edges following a line that is at least partially non-parallel to the longitudinal axis of the generally cylindrical bush,

In another aspect, the invention provides : an axel bush for mounting on a mounting section of an axel, the axel bush formed from multiple parts that are adapted to join along at least one longitudinal edge to form the axel bush, wherein the longitudinal edge is at least partially non-parallel to the longitudinal axis of the axel.

In another aspect, the invention provides:

Complementary component parts of a bush for an axel that fit together around the axel, the component parts each having at least one opposing joining edge following a substantially curved path.

Preferably, the component parts slide into engagement and are trapped together against radial parting, provided that the respective ends of the assembled bush are axially retarded to resist axial movement of the component parts relative to each other.

In another aspect, the invention provides: a split bush formed by joining component parts along at least one join line, characterised in that the join line follows a curved path.

The longitudinal edge of the parts of the axel bush may follow a curved or irregular line or a combination of both. The curved line may be helical, spiral, S-shaped, wavy and/or radiused. The irregular line may comprise straight sections connected by sharp angle transitions. The irregular line may be jagged, including having a Z- or V-shape, in which the sharp angle transitions are at least 90°.

Typically, the bush may be retained on an axel and trapped against longimdinal displacement of the component parts relative to each other.

Preferably, the join line is spiral or helically shaped. The curved join line is effective to resist splitting of the bush under pressure.

The present invention may be used where the axel configuration does not allow a bush to be placed on the axel, except where the bush is a split bush.The curved joining edges of the component parts may follow a spiral pathway so that the component part partially wraps around the axel. The semi-circular end wall of the component part at a first end may be offset by about 60° - 110° compared to a second opposed end. The component parts may comprise two joining walls. When viewed in end elevation, the extremity of a first joining wall at the first end may be close to the extremity of a second joining wall at the second end, so that the spacing between the extremities from an axial end view is smaller than the diameter of the axel. The spiral path of the joining walls may be sufficiently acute that each component part is adapted to wrap around the axel, so that the component cannot easily be removed from the axel by laterally moving the component part away from the axel but mamtaining the component part in coaxial relationship to the axel. The component part may only be removed by extricating one component part end, shifting the component part on an angle to allow the mouth defining the second end to release the axel from the second end mouth.

Locating protrusions may extend tangentially from each of the facing edges. The protrusions may form part of the wall of the bush components. The protrusions may have facing and abutting surfaces that are aligned parallel to one another. Each end of the bush component may be a semi-circular shape. Each semi-circular end may be adapted to engage with an opposed component part to form a complete circular end wall of a cylinder. The protrusions may extend towards the direction of approach of a complementary component part.

At least one section of the joining or longitudinal line may be an angled section set at an angle, preferably a sharp angle, relative to the curved joining edge. The angled section may be a flat section that may extend parallel to the longitudinal axis of the formed bush. The flat section of each component part may be effective to prevent counter-rotation of the component parts about the longitudinal axis, so that when the bush is assembled on an axel and is axially trapped, the component parts do not slide along the join line relative to each other and do not rotate relative to each other.

Preferably the flat section is at the end of the join line. Advantageously, each component part includes a fiat section adapted to oppose and abut a corresponding, complementary flat section of a complementary component part. The flat section may form part of the j oin line.

Alternatively, the join line may be wholly curved. Preferably, the flat section is adjacent to the curved join line.

The join line is preferably formed by opposing curved surfaces. The opposing surfaces preferably comprise laterally flat seats that follow the curved path. The opposing laterally flat, longitudinally curved, seats of each component part are adapted to abut to form complementary seats fox each other.

The component parts may each include an engagement section. The engagement sections may be complementary and adapted to engage an opposing engagement section of another component part. The engagement section may include a ramp section. The ramp section may comprise opposing and abutting surfaces that lie in planes between 0° and 110 ^* relative to the direction of approach of the opposing component part. In this way the ramp sections may slide passed each other as cam surfaces into abutment. The ramp sections may form part of head portions that are adapted to be trapped behind an opposing head in a recess of the other component part. The ramp sectons therefore engage each other with minimal distortion. The ramp sections do not snap into engagement but slide into abutment to create a resistant catch. However, due to the relative geometry of the spiral component part body that may be adapted to partially wrap around the axel, the engagement sections trap the component parts in engagement because the parts cannot be pulled laterally or radially away from each other as the angle of removal and the planes of the ramp sections are offset from the angle of withdrawal that would be necessary to separate the component parts.

The flat or ramp section may permit movement of the component parts of an assembled bush relative to each other under load. Permitting relative movement of the component parts whilst securely mamtaining their engagement enables the bush to distort under load without the component parts separating or the bush otherwise failing. If the component parts were positively engaged so that distortion of the engagement means and potential disengagement would result on application of heavy loads, the bush might fail or the engagement means might snap in and out of engagement under load, thereby causing an unwanted clicking noise.

Preferred embodiments of present invention may overcome this problem by allowing the bush to distort and shift slightly along the joining line without the component parts separating.

The ramp section may be effective to hold the component parts together at the join line against compression forces that would otherwise cause the component parts to split or separate. This is achieved by providing opposing surfaces that resist counter- rotation of the component parts about the longitudinal axis of the bush. The flat or ramp sections also act as a catch to hold the bush together by axially restriction of the bush at either end, so that the component parts cannot axially slide and rotate relative to each other.

A wheel member or tyre may be molded on to the bush after the bush has been assembled on an axel. The tyre may be a roller tyre. The roller may form part of a multiple directional wheel. However, other applications are envisaged as being within the scope of the invention. The generally cylindrical bush may include external surface features to assist in gripping the interior surface of a roller or other component to be molded thereto. The surface features may include undulations, protrusions, grooves, knobs or ridges, The ridges or grooves may follow a curved or irregular line or a combination of both. The curved line may be helical, spiral, S-shaped, wavy and or radiused. The irregular line may comprise straight sections connected by sharp angle transitions. The irregular line may be jagged, including having a Z- or V-shape.

Preferably the surface features comprise one or more longitudinal ridges. The longitudinal surface features may extend parallel to the longitudinal axis of the completed or generally cylindrical bush. The longitudinal surface features may be regularly ckcumferentially spaced from each other around the outer surface of the axel bush.

The external surface features may be in the form of protrusions or indentations. The external surface features may be effective to facilitate adherence of a mold material thereto. The protrusions are preferably longitudinal ribs. The longitudinal ribs may be ckcvunferentially spaced around outer surface of the barrel of the assembled bush. The component parts may comprise separate portions of the external surface features that align and are completed on joining the component parts. Thus each component part may include portions of a rib that is only completed on joining the component parts.

The contour of the longi dinal ribs preferably provide longitudinal structural strength. The longitudinal ribs are preferably configured to displace roller material so that less roller material is required to fill the space between the outer bush surface and the outer roller surface. The external surface features also permits careful control of the thickness of the roller wall molded onto the bush. This may be important with regard to performance characteristics, such as structural integrity during repeated, possibly high load, use, ride quality and/or noise rnmimisation of a wheel incorporating the bush.

Where one or more separate internal beating are required, these may be in the form of split bearings. The split bearings may comprise two or more bearing parts, such as a pair of halves, that together form the bearing. The internal surface of the bush may accommodate the bearings as a housing. The bush housing may provide means for permitting overmolding of the split bearings. The bearing may be accommodated by internal surface features, such as an annular seat groove formed in the internal wall of the bush. The internal surface features may be completed on assembly of the component parts. Portions of the internal suiface features may be located on separate component parts which align to complete the internal surface features when the bush is assembled. The internal surface features may be longitudinally spaced to effectively trap the bearings and ensure that they remain properly spaced along the length of the axel and the bush.

The bush may be formed from component parts that are hinged or connected along one or more permanent longitudinal joins, and are joinable together at another pair of opposed longitudinal edges circumferentially spaced from the permanent longitudinal joins. The component parts may comprise two parts. The two parts may be permanently hingedly connected, and have mating longitudinal edges cncumferentially spaced from the permanent longitudinal connections, The component parts may comprise two separate parts mateable or joinable together to form the generally cylindrical bush. The component parts may be identical and include mutually engageable complementary parts.

The joinable or mateable edges may form the mutually complementary engageable parts, such as male-female tongue and groove parts, protrusions and recesses for trapping the protruding parts: The engageable or joinable parts may include, in profile and extending longitudinally along the respective edges, a head, or bayonet or arrow head-shaped male mating or protruding portion having a protrading edge that transitions into a ramp surface of the ramp section. The ramp surface may be inclined at an angle to a radial line extending from the longitudinal axis of the completed bush cylinder. The ramp section may terminate with a detent wall in the form of a flat broad structure behind the head, bayonet or arrow head ramp section that directly faces an opposing broad flat surface on an opposing component part. The bayonet or arrow head or ramp section may be connected to a serni-cylindrical wall of a component part by a narrow neck, whereby a recess is defined by the flat broad detent wall, the internal surface of the bush facing towards the radial centre of the semi-cylindrical wall and forming part of the neck, and a broad face of the end wall of the cylindrical wall facing axially. These structural and surface features together define a recess for receiving and/or trapping a head portion, in profile, formed at the terminal edge of the joining edge of the opposed component part

Other male-female engageable or complementary, friction fit parts are envisaged as falling within the scope of the invention.

The axel bush may comprise an internal bore that includes internal surface features that are adapted to either engage with an axel for a driven roller or wheel, or may comprise a smooth bore to permit rotation of the bush relative to the axel.

The completed and assembled bush formed from the component parts may comprise a generally cylindrical core, pipe or tube and external surface features in the form of longitudinal ridges or ribs. The external surface features may have a greater radial height towards their middle centre and may taper towards the outer surface of the generally cylindrical core, pipe or tube. Accordingly, in side elevation the outline of the axel bush may be generally fusiform in silhouette.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be better understood from the following non-limiting description of preferred embodiments, in which:

Figures la- lb are perspective views of a first embodiment of an axel bush according to one aspect of the invention comprising a tongue and recess locating system, 16 outer ribs and a helical joining edge;

Figures 2a-2b are perspective exploded views of the embodiment shown in Figures la- lb;

Figure 3 is a perspective view of an axel bush made according to a third embodiment, comprising a bayonet catch, 16 outer ribs and a helical joining edge, that is mounted to an axel of a wheel frame of a multiple directional wheel;

Figures 4a-4b are end perspective views of the axel bush shown in Figure 3;

Figure 5a is a perspective view of the axel bush shown in Figure 3, removed from an axel;

Figure 5b is a perspective view of the axel bush shown in Figure 3 partially mounted the axel shown in Figure 5a;

Figure 6 is a perspective view of the axel bush shown in Figure 3 -5b mounted on an axel;

Figure 7 is an end perspective view of the axel bush shown in Figures 3 - 6 with its component parts separated;

Figure 8 is an end perspective view of the axel bush shown in Figures 3 - 7;

Figure 9 is an end perspective view of one component part of the axel bush shown in Figures 3 - 8;

Figure 10 is a perspective view of a part of a wheel frame on which are mounted axel bushes made according to a third embodiment comprising a smooth outer surface and Z-shaped joining edge;

Figures 11 a- 11 d are perspective views of a component part of an axel bush made according to a fourth embodiment comprising 8 ribs and a helical joining edge;

Figure 12 is a perspective view of two component halves of an axel bush made according to a fifth embodiment comprising a bayonet catch, 10 outer ribs and a Z- shaped joining edges;

Figure 13 is a side elevation of a component part of the axel bush shown in Fig. 12;

Figure 14a is a side elevation of the component part of the axel bush shown in Figure 13 mated to an identical part;

Figure 14b is an end elevation of the assembled axel bush shown in Figure 14a;

Figure 15 is an end elevation of a component part of an axel bush according to a sixth embodiment comprising a bayonet catch, 10 outer ribs and a helical joining edge;

Figure 16 is a side elevation of the component part shown in Figure 15; Figure 17 is a perspective view of the component part shown in Figures 13;

Figure 18 is a second perspective view of the component parts of the unassembled axel bush shown in Figure 12;

Figure 19 is a perspective view of an assembled axel bush formed from the component parts shown in Figures 12 and 18;

Figure 20 is a side view of the completed axel bush shown in Figure 19an assembled axel bush according to an eighth embodiment similar to that shown in Figur e 19, but comprising ribs having flat ends;

Figure 21 is a perspective view of an assembled axel bush according to an seventh embodiment similar to that shown in Figure 1 , but having ridges terminating in straight rather than angular ends;

Figure 22 is an end view of the completed axel bush shown in Figure 2 ;

Figure 23 is a side view of the completed axel bush shown in Figures 21 - 22;

Figure 24 is a side view of a completed axel bush according to an eighth embodiment featuring a bayonet catch, 8 longitudinal ridge outer surface features having straight edged tewninal ends and Z-shaped joining edges;

Figure 25 is a perspective view of the axel bush shown in Figure 24;

Figure 26 is a perspective view of an unassembled pah of component parts of the axel bush shown in Figures 21 - 23;

Figure 27 is an end view of the completed axel bush shown in Figures 24 - 25;

Figure 28 is a perspective view of an unassembled pair of component parts of the axel bush shown in Figure 24;

Figure 29 is a perspective view of an assembled axel bush made according to a ninth embodiment comprising a bayonet catch, 16 longitudinal ridge or rib portions on its outer surface, with the rib portions alternating between raised and lower profile rib portions and Z-shaped joining edges;

Figure 30 is an end view of the completed axel bush shown in Figure 29;

Figure 31 is a side view of the axel bush shown in Figures 29 and 30;

Figure 32 is a perspective view of the unassembled component parts of the axel bush W

shown in Figures 29 - 31;

Figure 33 is a perspective view of a bush according to a preferred embodiment;

Figure 34a is a perspective view of a cylindrical bush according to one embodiment;

Fure 34b is a perspective view of a component part of the bush embodiment shown in Figure 3 a from two different perspectives, emphasising that identical component halves form the bush of Figure 34a;

Figure 35a is a perspective view of a cylindrical bush according to another embodiment in which end flats and catches have been added to the embodiment shown in Fig.34a;

Fure 35b is a perspective view of a component part of the bush embodiment shown in Figure 35a noting that identical component halves form the bush of Figure 35a;

Figure 36a is a perspective view of a cylindrical bushwith an overmolded roller according to another embodiment in which ribs have been added to the embodiment shown in Fig. 35a;

Fure 36b is a perspective view of a component part of the bush embodiment shown in Figure 36a noting that identical component halves form the bush of Figure 36a;

Figure 37a is a perspective view of a cylindrical bush including axially spaced bearings according to another embodiment; and

Fure 37b is an exploded perspective view of the parts of the bush embodiment shown in Figure 37a noting that identical component halves form the bush of Figure 37a and provide a housing for the axally spaced split bearings.

DETAILED DESCRIPTION OF THE DRAWINGS

Preferred features of the present invention will now be described with particular reference to the accompanying drawings. However, it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention.

Figures 1 a - 2b show a first embodiment of the invention in the form of an axel bush 10 comprising a cylindrical core 12, a pair of identical component parts 14a,b mated or joined to each other along a pair of helically curved edges 16. The curved edges 1 comprise tongue and groove interconnecting parts 18a,b. An outer surface 13 of the cylindrical core 12 has sixteen longitudinally . aligned ribs 19. Each component part 14a, 14b comprises a pair of helically curving side edges 16 that are perfectly complementary to opposing helically curved edges on the other mating or joining component part 14a, 14b. Each component part 14a, 14b is identical. At one end of the component part 14a, 14b, adjacent the helically curved edge 16, there is a male protruding tongue 18b that extends beyond the flush surface of the helically curved edge 1 . At the opposed end of the component part 14a,b, the respective helically curved walls 16 tenninate witharecess 18athat is complimentaiyto me ro1rusion l8b, Both the protrusion 18b and the complementary recess 18a are adjacent the inner surface of the cylindrical core 12, The component parts 14a, 14b are held together in situ in an engaging or joinirig position by the . male and female engagement means, the tongue and recess parts 18a, b. The radial compressive forces caused by molding a roller thereon or thereabout the bush, so that the inward radial compressive force urges the component parts 14a, 14b to counter rotate relative to each other along their helical join lines, is resisted by the flat sections adjacent the tongue and recess parts that ensure that the component parts 14a,b the axel bush 10 does not counter rotate and remains assembled. The curved walls 16 of the respective component parts 14a, 14b therefore remain joined together whilst compressive forces are applied to the bush. These forces may be deflected and disseminated along the curved join line of the edges 16, so that localisation of loading at any one point along the edges 16 is reduced and failure of the axel bush 10 is minimized.

Figure 3 shows an axel bush 30 made according to a second embodiment mounted to a wheel frame manufactured and supplied by Rotacaster Wheel Limited. Prior to assembly, the bush 30 is comprised of two identical halves. The component halves are placed around a cylindrical axel 32 mounted and extending between wheel frame head posts 34. A roller (not shown) may then be moulded around the axel bush 30 as described in WO 2004014667, the entire contents of which are hereby imported herein.

Referring to Figures 4a-9, the second embodiment of the axel bush 30 comprises a pair of identical halves 44a, b that are adapted to engage together by allowing the engagement of bayonet or arrowhead, or abutting ramp members 38b that comprise an inner inclined ramp, surface 1 and a narrow neck 42 that connects the arrowhead or ramp member 38b to the wall of the semi-cylindrical core structure 43, The arrowhead structure or ramp member 38b is provided at the end of each component part 44a, b adjacent one longitudinal side or edge 45a of each component part. An opposed edge 45b to the edge 45a comprises complimentary engagement or joining structures 38a in the form of a substantially square shaped (in profile) head behind which extends an outwardly inclined recess surface 47 that is adapted to slidingly receive and trap the arrowhead ramp member 41, whilst the neck recess 48 defined by the arrowhead ramp member41, neck 42 and the end surface of the semi-cylindrical core wall 43, respectively receive and trap the square head 38a for an exceptionally strong, friction resistant engagement at both adjoining edges 45a, b of each of the component parts. Preferably, the material used to form the respective component parts 44a, b is typically acetal. Talcing into consideration the wall thickness and rib structures 39 and the rigidity to the bush structure imparted by the ribs 39 in the longitudinal direction, because the mating parts 18a,b are not positively engaged but merely form a resistance fit, the component parts 44a, b may be mounted on the axel 32 by hand. It is envisaged that the component parts 44a, b are made from extremely rigid material, such as steel, so that the mating of the component parts with a cam or ramp surface engagement allows the bush to be assembled without the need for a radially compressive tool to achieve the assembly of the axel bush 30 on the axel 32. It is noted that the rib structures 1 extend longitudinally along the outer surface of the axel bush 30 and provide . reinforcement to the overall structure of the core 43. To remove the bush from an axel, wherein the component parts 14a,b are axially trapped against counter rotation relative to each other, a tool may be helpful to urge the ramp sections 18a,b out of engagement, although this may be advantageously done by hand.

Referring to Figure 10, there is shown a third embodiment of an axel bush 50 that comprises a substantially cylindrical structure 52 formed of identical component parts 54a, b in which the joining line 56 therebetween is formed from a continuous curved edge. The exterior surface of the component parts shows the appearance of the end flat sections that transition between an intermediate angular section with shallow angled corners s 58.

It is noted that the third embodiment does not feature ribs longitudinally on the outer surface of the axel bush 50.

Figures 1 la- 1 lb show a fourth embodiment in the form of component parts 64 of a axel bush 60. The component part 64 is adapted to engage with an identical component part 64 along curved side walls 66 which together located and join into abutting relationship by tongue and recess guides 68a-b.

In Figures 12 - 14b there is shown a fifth embodiment in the form of an axel bush 70 comprising a pair of identical half component parts 74a, b that are adapted to mate together by engagement of bayonet engagement means or ramp sections 78a, b. The z-shaped outer side edges 76 comprise a middle inclined section 76b extending between outer straight edges 70a,c running substantially parallel to the longitudinal axis 71. However, preferably these straight edges obscure the curved joining edges or seats against which the component halves rest and abut when the bush is assembled.

The longitudinal ribs 79 feature a shallow arc shape in which the intermediate portion 71 shallowly rises relative to the respective end portion 31b and this follows the truncated fusiform shape of the rollers moulded thereon. The respective rib ends 72 comprise an inwardly inclined wall to form small, sharp angled protrusions whereby to better secure the roller molded thereon and thereabouts, so that some of the molded roller material extends radially inwardly relative to the outer most extent of the longitudinal rib 79.

Turning to Figures 15 and 16, there is shown a sixth embodiment in the form of an axel bush 80 in which only one component part 84 of a pair of component parts 84 is shown and demonstrates graphically the arrowhead or ramp engagement portion 88a and bulbous head portion 88b. In Fig. 15, the end elevation view illustrates that the opposed end portions 88a,88b almost completes a full wrap around an axel that has the same diameter as the internal diameter 81 of the part 84. A small opening 89 is provided that permits the single component part 84 to be mounted on to the axel. The component part 84 must be tilted at an angle offset to the axel axis to permit the part 84 to be mounted onto the axel. Once mounted, the part 84 hangs on to the axel in a lose resistance fit, but does require a small amount of force to be dislodged. However, if the part 84 is made sufficiently rigidly, it is not possible to remove the part 84 from an axel without tilting same relative to the axel axis.

Referring to Figures 21-23 and 26, there is shown an axel bush 90 comprising 10 outer longitudinal ribs 99 and a pair of identical component parts 94a, b joined along a curved joiriing surface obscured by the shallow z-shaped line of the outer edges 96a-c.

In Figures 24, 25, 27 and 28 there is shown an eighth embodiment in the form on an axel bush 100 comprising eight outer longi dinal ribs 109 and identical component parts showing a shallow z-shaped outer longitudinal edge 96 that obscures a spiral-shaped join line or seat. It is considered that the straight end walls 97 that extend normally to the longitudinal axis 101 facilitate the moulding process for the molding of a roller onto the axel bush 100 as all components, primarily the outer surface 107 of the cylindrical core 103 do not present any "cul- de-sacs" into which toiler moulded material must be forced or allowed to move over time.

In relation to Figures 29 - 32, there is shown a ninth embodiment in the form of an axel bush 110 comprising 8 large and radially tall longitudinal ribs 11 , altematingly interposed circtimferentially around the axel bush cylindrical core body 112 with low profile longitudirial ribs 129. The low profile ribs 129 extend a greater length along the outer surface 115 of the core 112 but their shallow height permits the outer profile of the roller to be tapered towards each end of the roller. The radially taller and circumferentially wider ribs 119 provide substantial rigidity and strength for the central region 126 of the core 112. The ends 132 of the low profile ribs 129 taper towards the outer surface 115, whereas the ends 134 of the tall ribs 119 end abruptly in an end wall 128 similar to the wall 108 of the eighth embodiment shown in Fig. 24. The inner surface 134 of the core 112 defines a cylindrical bore and snugly receives an axel whilst permitting rotation of the axel bush 110 relative to the axel 32.

The bayonet or arrow head or ramp section 118a extends radially at least two-thirds of the thickness of the core wall 112a. The core wall is preferably between 50 and 100%, preferably 60 - 80% of the radius of the borel 13. The neckl36 extending between the arrow head or ramp W

section 118a and the core wall 112a is radially about 30 to 80%, preferably 40 - 60%, of the thickness of the core wall 112a, and the bulbous head 118b is correspondingly or

complementarily so dimensioned whereby to be snugly trapped in the recess 117 defined by the arrowhead or ramp section 118a, the neck 136 and the broad end wall 112b of the core wall 112a.. The bayonet or arrow head or ramp section 118a includes a ramped surface that is inclined at an angle of about 30 - 70 ^s , preferably 40 - 50° relative to a radial line extending from the axel bush 110 axis 111.

Each component part 114a,b includes a pair of the Z-shaped joining side edges 116 that extend longitudinally and parallel to the bush axis 111 from the bayonet head 118a apex or tip 138 along a straight edge wall 116a at the side of the core wall 112a. The straight edge extends to a first corner point 140 past one end 128 of the tall ribs 119. The first corner point 140 provides the transition from an axially parallel wall edge 116a to an inclined edge wall 116b extending through an intermediate region of the side wall 116. This structure permits minor relative movement along the adjoining surfaces 116 and alleviates the focussing or localisation of such forces which would otherwise form fatigued and weak structural points, Yet the bush 110 retains its integrity due to the strong engagement of structures 118a,b.

The inclined intermediate joining edge 116b transitions at a second corner point 142 at the other end of the component part 114a,b into another axially straight edge 116c that is parallel to the first straight edge 116a,

Turning to Figure 33, there is shown an assembled roller 200 comprising a cylindrical bush 210 having eight external rib surface features 212 and an over-molded roller 230. The joining edge 214 of the opposing component parts 216,218 comprises, in axial end profile, aramp section 220 comprising a ramp surface 222, The ramp surfaces He in planes that are parallel or slightly offset by Γ - 20° to the direction or angle of approach of the respective opposed component part 216,218 immediately prior to engagement, so that the ramp surfaces 222 are adapted to slidingly engage across ramp surfaces in a resistance, rather than snap, fit. This arrangement forms a catch that will hold the part halves 216,218 together during an over-molding process as long as the ends of the bush are retarded against axial displacement. This achieves a resistant catch that does not have a '¾ard" snap feature.

The ramp 220 configuration allows the joined halves 216,21 to move when the bush 210 is under a load that causes distortion that would otherwise fail a "snap" design (one where mating parts must deflect or distort to permit engagement). The present embodiment eliminates the "clicking" sound that can be characteristic of bushings under load where the snap engagement continually fails and resets as the load shifts with transit.

With reference to Figures 34a-b ₃ there is shown a basic bush configuration 210a in which identical component halves 216a,218a combine to form the bushing 210a. This demonstrated by showing that component part 216a may be rotated to face "itself thereby presenting opposing parts that may be combined to form the cylindrical bushing 216a. The bushing 210a may be over-molded with roller material to achieve a split bushing 210a that does not "coin purse" apart under pressure.

In Figures 3 a - 35b, there is shown a more developed bushing 210b that is formed by the joining of two identical component halves 216b,218b that include, at their respective end joining surfaces, flat segments 224b adjacent the end of each helical seat 226b. The flat segments 224b are effective to resist counter-rotation of the component parts 216b,218b which would otherwise allow the parts to move longitudinally on each other. The flat segment 224b also contains resistance fit engagement features 228b,229b that temporarily hold the parts 2l6b,218b together prior to over-molding of the bushing 210b with roller material.

Figures 36a-36b show more elaborate bushing 210c over-molded with a roller 230c. The bush 210c has a contoured body featuring longitudinal ribs 232c that provide both strength as well as systematic displacement of roller material and roll thickness control of roller 230c material that is molded over the combined identical bush halves 21 c,218c,

Referring now to Figs. 37a - 37b, there is shown a bushing 210d that is used to provide a housing 210d where a series of split bearings 240d is required. The combined bush 210d comprises internally annular seats for the assembled bearings 240d. Not only does the bush 21 Od provide a housing, but also provides longi dinal strength, a means to keep the bearings 240d properly axially spaced and a means to provide over-molding of the roller material whilst keeping the split bearings240d together.

Throughout the specification and claims the word "comprise" and its derivatives are intended to have an inclusive rather than exclusive meaning unless the contrary is expressly stated or the context requires otherwise, That is, the word "comprise" and its derivatives will be taken to indicate the inclusion of not only the listed components, steps or features that it directly references, but also other components, steps or features not specifically listed, unless the contrary is expressly stated or the context requires otherwise.

In the present specification, terms such as "apparatus", "means", "device" and "member" may refer to singular or plural items and are terms intended to refer to a set of properties, functions or characteristics performed by one or more items or components having one or more parts. It is envisaged that where an "apparatus", "means", "device" or "member" or similar term is described as being a unitary object, then a functionaUy equivalent object having multiple components is considered to fall within the scope of the term, and similarly, where an

"apparatus", "assembly", "means", "device" or "member" is described as having multiple components, a functionally equivalent but unitary object is also considered to fall within the scope of the term, unless the contrary is expressly stated or the context requires otherwise, Orientational terms used in the specification and claims such as vertical, horizontal, top- bottom, upper and lower are to be interpreted as relational and are based on the premise that the component, item, article, apparatus, device or instrument will usually be considered in a particular orientation, It will be appreciated by those skilled in the art that many modifications and variations may be made to the methods of the invention described herein without departing from the spirit, and scope of the invention.

The invention can be described in terms of provisional claims that can assist the skilled reader in understanding the various aspects and preferments of the invention, However, these provisional claims are not to be construed as defining statements of the invention. It will b appreciated that other forms, aspects and preferred features of the invention and its

embodiments described herein may ultimately be included in the claims defining the invention in the specifications of complete, international or national applications (or their subsequent corresponding patent grants) that may claim priority from the provisional application accompanying this specification. In this context, the following non-limiting claims assist to better describe the invention: