SET

The present invention relates to a multi-part connector for a modular construction set.

Construction sets are known in various forms for constructing assemblies or subassemblies in which the constituent parts have differing angular and rotational relationships so as to form complex modular structures in two and three dimensions. Assemblies or subassemblies of that kind can be, for example, essentially static constructions such as models, support structures and mounts or movable or mobile constructions such as robotic assemblies and fabrication tools or self-propelled robots for various purposes. A construction set focussed on enabling creation of assemblies and subassemblies with these capabilities is disclosed in International Patent Specification WO 2008/093028, a core component of this set being represented by a connector in the form of a drum with at least one circular flange. The drum is provided with connecting means at each of its ends, whereby another such connector can be coupled thereto in orthogonal or axial relationship. In this manner it is possible to create a modular structure composed of a multiplicity of the connectors and other component types, the latter attachable to the connectors peripherally and/or integrated within an assembled line of connectors. A disadvantage of formation of a structure in this way from a multiplicity of generally identical connectors is that a substantia) number of separate components is required, with a consequent penalty in terms of mass and weight and inevitably a degree of redundancy at least insofar as utilisation of the flanges of all of the connectors is concerned. Unused flanges may represent a source of interference with other parts of the structure and a potential snag with features of an environment.

It is therefore the principal object of the present invention to provide a component connector which by comparison with known connectors is capable of enhanced flexibility in the context of assembly of modular structures, especially through rationalisation of the connector construction in such a way that there is scope for providing extended connector axial lengths without concomitant disadvantages with respect to redundant parts and associated weight and mass penalties.

A subsidiary object is provision of a connector construction capable of variation in disposition of features according to the specific requirements of a particular assembly. Other objects and advantages of the invention will be apparent from the following description.

According to a first aspect of the present invention there is provided a multi-part connector for component connection in a construction set, the connector comprising a drum and an annular flange constructed separately therefrom and detachably connectible therewith to extend around the drum circumference, the drum being provided on its circumferential surface with a set of recesses substantially lying on a circular path around the drum circumference and the flange being provided at the inner circumference thereof with a plurality of projections engageable in at least some of the recesses of the set to detachably connect the flange with the drum.

Such a connector has the advantage of dissociation of the drum and flange in terms of construction, so there is no longer the constraint of constructing a modular assembly solely by employing connectors which are identical in dimensions or, in the alternative, by employing connectors which have to be produced in their entirety with different dimensions. In particular, a flange of standard form can be combined with a drum of selectable length, in which case it can be advantageous to provide, for example, a selection of drums with lengths differing by a given increment. In this way connectors can be provided which can individually span a greater length than prior art connectors, a number of which may have to be joined together to achieve the same length with consequent reduction in overall rigidity and inclusion of flanges which may in part remain unused for connecting or other purposes. The possibility also arises of including drums without flanges to extend the length of part of a structure.

The recesses of the set are preferably substantially equidistantly spaced around the drum circumference, which represents a precondition for convenient fitting of the flange without requiring a specific or unique rotational orientation. Equally, it is possible to provide different rotational relationships of the drum and flange. It is also advantageous if the number of recesses in the set is the same as the number of projections, so that optimum rigidity of the interconnection of drum and flange is provided. Alternatively, the number of recesses in the set is even and the number of recesses is an even-number quotient thereof, in which case a lesser number of projections can be formed on the flange without loss of the capability of selection of different rotational relationship of drum and flange. Accordingly, it is an advantageous feature if the projections of the flange are selectively engageable in the recesses in dependence on a selectable one of a plurality of different rotational orientations of the flange relative to the drum.

For preference, the projections of the flange are engageable in and disengageable from recesses of the set under resilient deflection of at least one of the flange and the drum. It is preferable to construct the flange from material, particularly plastics material, with a limited degree of resilience, but equally the drum can be constructed from the same or similar material, particularly if the drum is hollow with a relatively thin wall.

The drum is preferably provided on the circumferential surface thereof with guide slots communicating with the recesses to guide movement of the projections of the flange to and from the recesses in the circumferential direction of the drum. Thus, for the purpose of fitting to the drum the flange can be manipulated so that the projections travel, under pressurable engagement with the bases of the slots, until they snap into place in the recesses. This which provides a particularly positive and defined relative position of the drum and flange in the assembled state. Disengagement of the projections from the recesses is accordingly resisted in the absence of application of a suitably directed force, optionally in conjunction with resilient deflection of relevant parts of the drum and/or flange, to move the projections out of the recesses and into the slots.

For the purpose of assembly and disassembly of the drum and flange it is advantageous if the flange is rotatable relative to the drum for engagement of the projections of the flange in or disengagement of the projections of the flange from recesses of the set. This represents a particularly simple procedure for fitting and removal of the flange, rotation of the flange being assisted if the projections thereof are substantially convex or trapezium- shaped in cross-section in the axial end aspect of the flange. The projections can thereby more easily enter the slots or otherwise run on the circumference of the drum.

For preference, the drum is provided on its circumferential surface with axially extending grooves defining pathways for guidance of the projections of the flange into the region of the recesses of the set under axial movement of the flange along the drum. Such grooves allow the flange to be slid along the drum until the desired position of the flange is achieved. In that case, the grooves preferably extend between the ends of the drum so that the flange can be mounted on and demounted from the drum at either one of its ends. Location of the flange in the desired position can be assisted if the grooves contain overridable detents defining a position of radial alignment of the flange with the recesses. Such detents can be, for example, small elevations which can be overridden by the projections, when sliding in the grooves, by application of a relatively low force, the resistance to movement of the projections nevertheless being sufficient to signal to the user that the flange is appropriately positioned.

The grooves are preferably dished, for example substantially convex in cross-section, which assists movement of the projections out of the grooves in circumferential direction towards the respective recesses. It is also particularly advantageous if the grooves are so arranged in pairs on either side of each recess that the flange is rotatable relative to the drum in either one of two mutually opposite senses of rotation for the engagement and disengagement of the projections. Consequently, a specific alignment of multiple flanges can be maintained in an assembly with a plurality of axially connected connectors or the flange alignment can vary if required.

In the case of, especially, engagement of the projections in and disengagement of the projections from the recesses by relative rotation of the drum and flange it is advantageous if the flange is of integral construction. This ensures optimum rigidity and thus strength of the flange. In an alternative flange configuration, however, the flange is of multi-part construction, each flange part consisting of at most substantially one half of the flange in circumferential direction. In that case the flange parts, preferably flange halves, can be fitted to and removed from the drum without the need for, for example, access to the drum ends. Consequently, the flange can be fitted to and removed from a connector drum in situ in a modular structure incorporating the connector, which enhances the flexibility of the connector with respect to design and construction.

With regard to detail construction of such a multi-part flange, the flange parts are preferably constructed to adjoin in the regions of projections of the flange, each projection where the flange parts adjoin being formed with half on one flange part and half on the other or another flange part. The process of engagement of the projections in the recesses therefore entails joining the flange parts together by the common association of each pair of projection halves engaged in a single recess. In addition, each of the flange parts is preferably provided with one of the projections in a location intermediate the ends of the flange part, the said one projection being shaped for pressurable frictiona) contact with surfaces bounding a recess in which it is engaged. This particular projection can be formed with, for example, a slot dividing the projection into two arms which resiliently move towards one another on engagement in the associated recess thereby to generate the pressurable frictional contact. Consequently, a particularly firm seating of the flange parts on the drum is achieved.

Moreover, the flange parts can be provided with interengaging orienting means to align the flange parts in a common plane, for example interengaging male and female parts which co-operate to constrain the flange parts into the intended alignment when the projections are engaged in the recesses. Further assistance in that respect can be provided if drum is provided on its circumferential surface between the recesses with locating slots and each flange part is provided at the inner circumference thereof with ribs engageable in the locating slots to axially locate the flange parts relative to the drum. The engagement of the ribs in the locating slots contributes to rigid positioning of the flange parts on the drum.

In a simple embodiment particularly for a small axial length of the drum the set of recesses is disposed substantially equidistantly from the ends of the drum. The flange is therefore positionable on the drum symmetrically between its ends. In a developed embodiment, however, the drum is preferably provided with a plurality of the sets of recesses and the projections of the flange are engageable in recesses of a selectable one of the sets. It is thus possible to locate the flange at different positions along the drum depending on the number of sets of recesses and their disposition along the drum, for which reason the sets are preferably disposed at predetermined spacings from one another and the ends of the drum. The predetermined spacings can be, for preference, equidistant.

In the case of multiple sets of recesses it is then possible for the connector to comprise at least one further flange detachably connective with the drum by way of a selectable one of the sets of recesses. This provides considerable enhancement of the versatility of the connector, since in the case of a connector with, for example, four sets of recesses two or more flanges can be fitted to the connector at desired positions in correspondence with the requirements of the modular structure being constructed. This is merely an example and various permutations of numbers of sets of recesses and numbers of flanges are possible.

In conformity with the connecting requirements embodied in the afore-mentioned prior art connection the drum is preferably provided at at least one axial end thereof with connecting means for connection with another component of the construction set. In addition, the drum can be provided in the region of the connecting means with apertures for receiving locking projections of locking means for locking a connected component in place. The provision of connecting means and optionally also apertures for locking projections of locking means enables the connector to suitably co-operate with other components by way of known connecting procedures, so that the connector is usable with, for example, prior art connectors of integral construction. The connecting means preferably comprises at least one transverse groove for receiving the other component, whereby the other component may be coupled in, for example, an orthogonal relationship and preferably also locked in place by the locking means. The range of coupling relationship can be extended if the connecting means comprises two such grooves in mutually orthogonal relationship and further extended if the connecting means comprises two pairs of mutually parallel grooves, the two pairs being in mutually orthogonal relationship. In the case of such a connecting means, the other component can be, for example, the annular flange of a further connector.

Additionally or alternatively the connecting means can comprise a recess for receiving an axial coupling component of the construction set and preferably also a hollow centre post for centring the axial coupling component and for receiving a further axial coupling component of the construction set. Such axial coupling components can be, for example, an adapter for axial coupling of two connectors, the adapter being receivable in part in the recess of one connector and in part in the recess of the other connector, and a peg for both axial coupling and strengthening of the coupling, the peg being receivable in part in the post of one connector and in part in the post of the other connector. Such a post arrangement offers the additional possibility of transmission of electric current between the connector and a connected component if the post has mutually insulated electrically conductive tracks respectively at the inner circumferential surface thereof and the outer circumferential surface thereof. In a particularly advantageous construction the post can comprise electrically insulating material and the tracks can be formed by coatings of electrically conductive material on the inner and outer circumferential surfaces of the post. It is then additionally advantageous if the inner and outer circumferential surfaces of the post taper towards one another in the direction of the respective end of the drum to provide friction coupling means for internal and external frictional and electrical coupling with complementary electrically conductive surfaces of the axial coupling components. The axial coupling components, such as the afore-mentioned adapter and peg, can be similarly constructed from electrically insulating material with coatings of electrically conductive material in selected locations.

In one preferred embodiment the connecting means is _. formed on a removable cap insertable into an interior space of the drum. This represents a particularly versatile construction, since the drum can be, for example, a simple hollow cylindrical component which is integrally furnished with recesses and optionally grooves, slots and detents as mentioned above, but which is equipped with the connecting means by way of a separate part, namely the removable cap. This opens up the possibility of providing caps of different construction for different connecting purposes. The drum is preferably provided in the interior space with securing means for securing the inserted cap against rotation relative to the drum and the cap is, for preference, frictionally engageable with the drum to resist withdrawal therefrom. These features ensure firm fitting of the cap in the drum, with the option of also locking the cap to the drum by, for example, a locking clip which utilises an appropriately located set of recesses unoccupied by a flange and which engages in openings in the cap or against a shoulder of the cap.

It is equally possible, however, for the connecting means to be formed integrally with the drum so that a simple and more rigid configuration can be achieved.

It is also possible for the drum itself to be of multi-part construction, preferably divided into the parts along a central axial plane thereof. The drum thus essentially consists of two halves which can be of identical construction. This may allow simplification of tooling, especially an injection-moulding tool, and less involved moulding procedures. The drum parts can be conveniently assembled to form the drum if the parts of the drum are provided at longitudinal edges thereof with interengageable connecting elements for interconnecting the parts.

The invention embraces further aspects employing the connector as a core component. Thus, in a second aspect of the invention there is provided an axle assembly comprising an axle formed by such a connector and a hub detachably mountable on the drum of the connector. Such an assembly provides a means by which running gear can be incorporated in a modular structure to achieve mobility, whether by wheels or by endless tracks. The hub, when mounted, preferably bears against the flange or at least one of the flanges of the connector, which provides a defined axial location of the hub on the axle. For preference, the hub and drum comprise co-operable securing means for securing the hub and drum against relative rotation so that rotational drive imparted to the drum is directly transmitted to the hub. It is then advantageous, in a case where the drum has the afore-mentioned axially extending grooves on its circumferential surface, if the co-operable securing means are provided by those grooves and by inwardly directed protrusions provided at the inner circumference of the hub and engageable in the grooves. The hub can, in detail construction, be conveniently formed by at least one hub insert mountable on the drum and a surround mountabie on the insert or inserts. The surround can then carry, for example, a wheel with a tyre or a sprocket for a track.

According to a third aspect of the invention there is provided a connector according to the first aspect, particularly a connector with the afore-mentioned post with electrically conductive tracks, and a power supply unit posit/onable in the drum and electrically connectible at each of two terminals thereof with a respective one of the conductor tracks. The connector can thus be integrated in a power supply module for the supply of electrical power to electrically driven elements, such as movable arms or rotary components, of a modular structure. The power supply unit preferably comprises a battery holder for holding a battery or batteries, the holder being removably insertable into the drum so that the battery or batteries can be conveniently fitted and replaced.

According to a fourth aspect of the invention there is provided a drive module comprising a connector according to the first aspect and a drive unit positionable in the drum of the connector, the drive unit comprising drive output means locatable at an end of the drum. The drum of the connector thus advantageously serves as a housing for the drive unit, with a drive output available at an end of the drum. For preference, the drive unit comprises a drive and a drive holder holding the drive, the holder being removably insertable into the drum, whereby the drive can be conveniently fitted in the connector and removed for repair or replacement if required. The drive preferably comprises a motor and a transmission, in which case the drive output means can comprise a drive shaft of the transmission, a rotary drive element being mounted on the shaft to be secure against rotation relative thereto.

Preferred embodiments of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of a first connector, in disassembled state, embodying the invention;

Fig. 2 is a perspective view of a second connector, in partly assembled state, embodying the invention;

Fig. 3 is an end view of the connector of Fig. 1 or Fig. 2, in assembled state; Fig. 4 is a perspective view of two interconnected connectors corresponding with that of Fig. 2;

Fig. 5 is a perspective view of a third connector, in partly assembled state, embodying the invention;

Fig. 6 is a schematic sectional view of the connector of Fig. 5, in assembled state; Fig. 7 is a perspective view of a multi-part drum, in disassembled state, of a fourth connector embodying the invention;

Fig. 8 is a perspective view of the drum of Fig. 7 in assembled state; Fig. 9 is a perspective view of an end cap fittable to the drum, such as that of

Figs. 7 and 8, as a further part of the connector;

Fig.10 is a perspective view of a multi-part end cap fittable to the drum, such as that of Figs. 7 and 8, as a further part of the connector;

Fig. 1 1 is a perspective view of an insert part of the cap of Fig. 0; Fig. 12 is a perspective view of a connecting part of the cap of Fig. 10; Fig. 13 is a perspective view of a locking ring intended for integration in the cap of

Fig. 10;

Fig. 14 is a perspective view of an axle assembly, in disassembled state, composed of the connector of Fig. 2 and a wheel insert of a hub mountable on the connector;

Fig. 15 is a perspective view of the axle assembly of Fig. 14, in assembled state;

Fig. 16 is a perspective view of the axle assembly of Fig. 5 with a hub completed by two surrounds mounted on the insert;

Fig. 17 is a perspective view of a power transmission module, composed of a connector (shown partly assembled) with an end cap the same as or similar to that of Fig. 9 oR Fig. 10 and an electrically conductive centre post fitted in the cap;

Fig. 18 is a perspective view of a battery holder locatable in the connector of the module of Fig. 17;

Fig. 19 is a perspective view of part of the connector of the module of Fig. 17, showing the battery holder in place;

Fig. 20 is a perspective view of a drive module in disassembled state, composed of a connector (shown partly assembled) and a drive unit;

Fig. 21 is a perspective view of the drive module of Fig. 20 in assembled state, together with an end cap the same as or similar to that of Fig. 9 or Fig. 10; and

Fig. 22 is a perspective view of the drive unit by itself and without a rotary drive element of the unit.

Referring now to the drawings there is shown in Figs. 1 to 3 a connector 10 intended for component connection in a modular construction set, the purpose of which, such as the construction of assemblies and subassemblies including robots and other mobile and static structures, has been indicated in the introduction. An example of such a subassembly is shown in Fig. 4. The connector is intended to be compatible with connectors of known kinds particularly such as disclosed in WO 2008/0932028 and to cooperate not only with those connectors and connectors embodying the present invention, but also other types of components, especially axial coupling components and locking rings and clips for locking together interconnected components.

Whereas known connectors of the kind mentioned have an integral construction and are generally injection-moulded as a single part from plastics material, the connector of the present invention is of multi-part construction, whereby advantages with respect to dimensional change of individual connectors and reduction of part numbers in modular structures can be achieved. The connector 10 accordingly comprises, as basic elements, a hollow cylindrical drum 11 and an annular flange 12 intended to be detachably mounted on the drum to extend around the drum circumference such that a length portion of the drum is engaged in the opening of the flange and two further length portions extend on either side of the flange. The drum and flange are constructed separately from each other by injection-moulding from plastics material, particularly a material imparting to the drum and/or flange a limited amount of resilience to assist the process of mounting the flange on or demounting the flange from the drum as described further below.

The drum 11 is provided on its circumferential surface with at least one set of equidistantly spaced recesses 13 lying on a circular path and serving for fixing the flange 12 to the drum as described further below. The drum can be of a desired axial length, preferably one of several predetermined lengths differing from one another by a fixed amount so that the drum lengths increase by a given increment from a smallest to a largest size; accordingly, a construction set containing connectors 10 can include drums in a range of sizes. Depending on the length of the drum, a greater or lesser number of sets of recesses 13 can be present to permit mounting of the flange 12 in a variable position and also to permit mounting of additional flanges. In the embodiment shown in Fig. 1 , two sets of recesses 13 respectively adjacent to the two axial ends of the drum are provided, in company with a single flange. In the embodiment of Fig. 2, four sets of recesses and two flanges are present. A wide range of permutations is thus possible, from a single set of recesses and a single flange to multiple sets of recesses with the same or lesser number of flanges. Considerable flexibility is thus afforded to the user, who, in given circumstances, can select a drum of desired length and fit one or more flanges in a selectable position or selectable positions depending on the requirements of the structure being constructed. The selected configuration can also be subsequently changed if this proves desirable or necessary. The drum 11 and flange 12 are also capable of use as individual components, in which respect Fig. 4 by way of example shows two flanges in a connecting function connecting two connectors, but not themselves associated with a drum.

To enable detachable mounting of the flange 12 or the drum 1 1 and thus assembly of a connector 10 the flange is provided on its inner circumference with four equidistantly spaced projections 1 each engageable in a respective one of the recesses 13 of the set or of a selected set. A lesser number of projections, provided the number is an even- number quotient of the number (which itself is even) of recesses in the set, can also be provided. Although as evident from Fig 1 the flange 12 is of symmetrical form with respect to its axis, it will be apparent that the flange 12 can be mounted on the drum 1 1 in a selectable one of a plurality (here four) of rotational settings with respect to the drum.

In the embodiments of Figs. 1 and 2 the flanges are of integral construction. In order to permit mounting of the flange on the drum the latter is provided on its circumferential surface with a plurality of grooves 15 of concave section extending axially of the drum between its ends and forming pathways for the projections 14. Consequently, the flange 12 can be mounted on the drum 1 1 from either end by alignment of the flange projections 1 with and engagement of the projections in the grooves 15, which are spaced from one another in correspondence with the mutual spacing of the projections, and by then sliding the flange 12 along the drum 11 until the projections are aligned with the or a selected set of the recesses. In the embodiment of Fig. 2, this process of alignment with the recesses is assisted by overridable detent elevations 16 provided in each of the grooves 15 in the vicinity of the recesses 13, so that an increasing and decreasing resistance as a projection passes over a detent communicates to the user a signal that the flange is appropriately positioned.

Mounting is then completed by relative rotation of the drum 1 and flange 12 so that the projections 14 move in circumferential direction of the drum out of the grooves 15 and into the respectively adjacent recesses. This movement is assisted firstly by provision of guide slots 17 which communicate with the recesses and thus each provide an entry/exit to the associated recess, secondly by appropriate shaping of each projection, which in cross- section in the axial end aspect of the flange is convex or part-circular in Fig. 1 and trapezium-shaped in Fig. 2, and thirdly by the concavely curved surfaces of the grooves. The curved or inclined surfaces of the projections act as cams to ease the projections out of the concave grooves 15 and into the guide slots 17 and ultimately the recess under relative rotation of the drum and flange by a force sufficient to induce a slight resilient flexing of the drum and/or flange as the projections enter and travel along the guide slots 17. Consequently, the projections 14 will snap into the recesses 3 to provide a firm seating of the flange on the drum, which nevertheless remain separable by relative rotation with application of a suitable level of force.

As evident in Figs. 1 and 2 the grooves 15 are, in fact, arranged in pairs with the grooves of each pair on either side of an associated recess of the set or axially aligned recesses of all sets, so that the flange 12 can be rotated relative to the drum 1 1 , for engagement of the projections 14 in the recesses 13, in either one of two mutually opposite senses of rotation. The relationship of the grooves 15, the projections 14 and the recesses 13 is particularly clear in the schematic sectional view of Fig. 3.

The flange 12 can also be of multi-part construction, as in the case of that shown in Fig. 5. In this instance the flange consists of two halves 12a and 12b which combine to form a flange substantially the same as that of the embodiments of Figs. 1 to 3. By contrast with the flange of integral construction, the multi-part flange can be mounted on the drum 11 - which can be the same as that shown in Figs. 1 to 3 - by fitting the halves 12a and 12b individually to the drum, each half being pushed laterally onto the drum substantially in the plane containing the set or a selected set of the recesses 13. It thus does not matter if the drum is already connected at its ends in such a way as to block access to the grooves 15.

The two flange halves 12a and 12b are provided at each of their mating regions with male and female orienting means 18 for orienting the flange halves in a common plane, the orienting means comprising a protrusion 16a on one half engageable in a notch 18b at the other half. The projection 14 at each of those regions consists of two halves 14a and 14b respectively on the two flange halves 2a and 12b, such that when the projection halves 14a and 14b are together engaged in a respective single recess 13 the two flange halves are locked together and firmly mounted on the drum 11. Mounting of each flange half 2a and 12b is enhanced by construction of the intermediate projection in bifurcated form with two stiff, but slightly resilient, arms which on insertion into an associated recess 13 are squeezed slightly together and thereafter remain in pressurable frictional contact with boundary walls of the recess.

The construction of the flange halves 2a and 12b allows mounting on the drum with utilisation of a resilient flexural property of each flange half. Thus, each flange half is pushed laterally onto the drum until the intermediate projection 14 engages partly in an intended recess and the projection halves 14a and 14b align with the guide slots of respectively associated recesses, whereafter further pressure can be applied to the flange half concerned to drive its intermediate project/on and projection halves into the recesses under resilient expansion of the flange half, i.e. spreading apart of the arcuate portions thereof on each side of the intermediate projection 15. In this embodiment it may be advantageous if for the purpose of, in particular, detaching the flange halves the drum 1 1 has a thin-walled resilient construction.

In order to enhance the rigidity of the connection of the flange halves 12a and 12b with the drum 1 the former can be provided on the inner circumferences thereof and between the projections 15 with ribs (not shown) engageable in locating slots formed in the drum circumferential surface in Jine with the recesses 13 and between the grooves (cf. Figs. 7 and 8).

The drum 1 is additionally provided with connecting means at each of its axial ends, the connecting means in the case of the embodiments of Figs. 1 to 3 being formed integrally of the drum and comprising, firstly, two pairs of parallel transverse grooves 19, the grooves of each pair extending perpendicularly to those of the respective other pair. The width of each groove 19 substantially corresponds with the thickness or axial length of the flange 12, whereby the flange of another such connector, a flange by itself as shown in Fig. 4, or the flange of a connector of the kind described in WO 2008/093028 is receivable in the groove, preferably by an interference fit providing a frictional couple so that such a flange is connectible to the connector 10 in orthogonal relationship. Secondly, the connecting means comprises a recess 20 which is provided in the end of the drum and which incorporates parts of the grooves, the recess serving to receive an axial coupling element such as an adapter (not illustrated) for axial coupling of another connector or component. Thirdly, the connecting means comprises a hollow centre post 21 for receiving another form of axial coupling element such as a peg (not illustrated) for axial coupling with another connector or component and/or stabilising a connection provided by the adapter. The post 21 , which can - as shown - be internally splined for coupling purposes, can optionally be a separate component detachably fixed to the drum by internal radial fixing webs thereof, the webs engaging in slots of the post on its outer circumferential surface (cf. Fig. 10). If the post is not separable, it can be formed integrally with such webs. Axial coupling elements of the kinds mentioned can be those present in construction sets of the prior art.

Also present at each axial end of the drum 1 , in particular between the transverse grooves 19, are locking apertures 22 for reception of locking projections of locking clips or rings (not shown) embracing the drum. The locking projections of such locking dips or rings extend through the apertures 22 and into the transverse grooves 19 and thus, necessarily also, the recess 20, so as to lock in place a received flange of another connector or an axial coupling element received in the recess. Such locking clips or rings and the co-operation thereof with the locking apertures are also aspects of prior art construction sets and consequently not described in more detail at this point. However, the construction and operation of an integrated locking ring are described further below in connection with Figs. 10 to 13.

The flange 12, for its part, is provided around its circumference with a plurality - in this instance eight - of equidistantly spaced radial slots 23 and on mutually opposite faces with two concentric channels 24. The slots 23 and channels 24 participate in the orthogonal connecting process of connectors, in particular when a flange 11 of one connector is engaged in a transverse groove 19 of the drum 1 1 of another connector, by entry of a locking projection of a locking ring or clip into a slot 23 and then rotation of the flange about its axis so that the locking projection travels from the slot 23 into a channel 24 to retain the flange in the groove 19. This connecting procedure is also an aspect of prior art construction sets and consequently not described in more detail.

Figs. 7 to 22 show further or optional features of the connector 10 and also assemblies or modules incorporating the connector.

Referring firstly to Figs. 7 and 8, an alternative embodiment of the drum 1 1 is shown which is of multi-part construction and dispenses with integral connecting means at its axial ends. The drum 1 , which is shown without a flange or flanges, in this case comprises two drum halves 1 a and 1 1 b which are provided along the longitudinal edges thereof with detent projections 1 1 c interengageable to interconnect the two halves and thereby form the drum. The interconnection can be assisted or, if so desired, alternatively realised by, for example, gluing or ultrasonic welding. The two drum halves are of identical construction, which means that the drum as a whole can be produced by a simpler mould tool. Apart from the divided construction and the absence of integrated connecting means at the axial ends the drum substantially corresponds with the drum of the embodiments of Figs. 1 to 3. The locating slots for the afore-mentioned ribs of the halves of the multi-part flange are shown in Figs. 7 and 8 and referenced 25. The drum of Figs. 7 and 8, like the drums in Figs. 1 to 3, is usable with flanges of either integral construction or multi-part construction .

Although Figs. 7 and 8 show a divided construction of the drum, the drum could equally well be of the same form as shown in Fig. 8, but of integral construction. In either case, the provision of connecting means at the or each axial end of the drum 11 can be achieved by way of a detachable end cap 26 as shown in Fig. 9. The end cap 26 has an insert portion 26a insertable into either one of the - here - open ends of the drum 1 1 and a connecting portion 26b, which is formed with connecting means substantially identical with the connecting means provided on the drum of Figs. 1 and 2, thus transverse grooves 19, recess 20 and hollow centre post 21 , and locking apertures substantially identical in disposition and purpose with the locking apertures 22 provided in the drum of Figs. 1 and 2. Accordingly, a more detailed description of the connecting portion 26b is not necessary. The insert portion 26a has friction surfaces 26c for frictional engagement with inner circumferential surface portions of the drum to resist withdrawal of the inserted cap and axially extending and circumferentially spaced apart securing arms 26d which co-operate with shallow, axially extending ridges at the inner circumference of the drum to secure the cap and drum against relative rotation.

Although the connecting means of the connecting portion 26b of the cap 26 as illustrated correspond with those integrally formed on the drum in the embodiments of Figs. 1 and 2, the use of a separable cap affords scope for variation of the connecting means by furnishing a range of caps differing from one another with respect to the form of connecting means. In one variation, the hollow centre post 21 is constructed to be removable and is designed not only for transmission of axial coupling force, but also electrical current, such a form of post being shown in Fig. 17. The separately constructed post, which has slots slidably receiving free end portions of radially extending fixing webs in the interior of the cap in a firm, interference fit, is made of electrically insulating material, for example plastics material, and provided with mutually insulated electrical conductor tracks at its inner and outer circumferential surfaces. These tracks can be conveniently formed by metal coating the post as a whole and removing the metal coating at the axial end faces of the post. The fixing webs of the cap should, of course, also electrically isolate the post from the rest of the connector. By contrast with the post in Figs. 1 and 2 with a splined interior surface, the post in Fig. 17 is smooth-bored and is constructed so that its inner and outer circumferential surfaces taper towards one another in direction towards the free end of the post so as to provide friction coupling surfaces for fractional engagement with correspondingly tapered surfaces of electrically conductive components respectively insertable into the post and mountable on the outside of the post. Power supplied to the conductor tracks of the post from positive and negative poles can thus be transmitted to these frict/onally and electrically connected components.

Further forms of cap can be optimised for co-operation with various elements required for supply or transmission of power or data and drive and it is equally possible for the drum of Figs. 1 and 2, with integral connecting means, to be provided with variant forms of the connecting means, including differently constructed and optionally separable posts in place of the illustrated integral post 21.

As already mentioned, the end cap 26 includes locking apertures 22, in similar manner to the drum 1 1 of Fig. 1 or Fig. 2, for receiving locking projectors of locking clips or a locking ring applied around the end portion of the drum or, in the present case, around the end cap. If the locking ring is of integral construction this can be incorporated in the end cap by constructing the insert portion and connecting portion as separate parts. An example of such a two-part end cap, designated 27, with integrated locking ring 28 of integral construction is illustrated in Figs. 10 to 13. The cap 27 thus comprises an insert part 27a and a connecting part 27b constructed separately therefrom, the insert part 27a and connecting part 27b generally corresponding with, respectively, the insert portion 26a and connecting portion 26b of the integrally constructed end cap 26 of Fig. 9. In distinction from the end cap 26 of Fig. 9, however, the end cap 27 has a configuration appropriate for a separate centre post (not shown in Figs. 10 to 13). Clearly evident in Fig. 10 are the radially extending fixing webs, which are four in number, for the interference fit in the slots of the centre post, each web being formed by a web part 27a' of the insert part 27a of the cap 27 and a web part 27b' of the connecting part 27b of the cap, the two web parts aligning in the assembled state of the cap to form a complete web. The webs can also have an additional supporting function, as described further below.

The locking ring 28 comprises an annular body 28a with equidistantly spaced radially inwardly extending locking projections 28b captively located in the locking apertures 22 in the assembled state of the caps, the annular body 28a being mounted on the cap to be capable of rotation relative to the cap within limits defined by contact of the projections 28b with boundary edges of the apertures 22. The dimension of each aperture 22 in the circumferential direction of the cap 27 is thus larger than the corresponding dimension of the associated locking projection 27b. The locking ring 27 is intended particularly for locking interengagement with an axial coupling component (not shown) receivable by a flange thereof in the recess 20, the flange, when so received, being supported on the fixing webs formed by the web parts 27a', 27b'. The flange is slotted so that on insertion into the recess 20 the slots allow the locking projections 28b to pass through the flange to a position of alignment with a face of the flange remote from the webs. On rotation of the locking ring 28 relative to the end cap 27 from an unlocking position to a locking position, which is possible in either one of two mutually opposite senses of rotation from a starting point of each locking projection 28b in the centre of the respective locking aperture 22, the locking projections 28b move into engagement with the aligned face of the flange to prevent withdrawal of the flange - and thus the axial coupling components having the flange - from the recess 20. The engagement of the locking projections 28b with the flange face in this manner can be pressurable, for example by forming the projections to be capable of slight resilient deflection, so as to enhance the security of fixing of the axial coupling component in the locking position of the ring. In addition, the inner circumference of the locking ring and the outer circumference of the cap can be provided with mutually co-operable detents interengaging in and thus defining the unlocking position of the locking ring. The detents preferably comprise detent nubs on the ring and detent depressions on the cap such that when the ring is turned from the unlocking to the locking position the detent nubs, or at least half of them if the cap and ring can be relatively rotated in either one of two opposite senses of rotation to attain the locking position of the ring, pressurably bear on the outer circumferential surface of the cap to assist maintenance of the ring in that position.

As evident from Fig.12, each locking aperture 22 is formed in part by an axially extending access channel in a plug extension of the cap connecting part 27b so that the ring can be fitted onto that part from an axial end of the extension. The plug extension is then inserted into a socket of the insert part 27a of the cap so as to complete the cap and at the same time close the access channels and form a final boundary of each locking aperture 22, the locking ring 28 thus being captively sandwiched between the two parts 27a and 27b, but remaining rotatable relative to the drum. Subassemblies which can be constructed with use of the connector 10 including various permutations of the drum 1 1 are shown in Figs. 14 to 22. Figs. 14 to 16 show an axle assembly 30 in which a connector 10, in this instance corresponding with that of Figs. 2 (albeit with a single flange 12), but equally capable of being realised by any one of the previously described forms of connector drum and flange, forms an axle of the assembly. Detachably mounted on the drum 1 1 of the connector 10 to be secure against rotation relative thereto is a hub insert 31 of a hub for a wheel, a wheel with tyre or a sprocket or other cogged rotary drive element for a track of the kind employed in a track-laying vehicle. The hub insert 31 is provided on its inner circumference with inwardly directed locating protrusions in the form of ribs 32 slidably engageable in the axially extending grooves 15 present on the outer circumference of the drum 1 1 so as to secure the hub insert and drum against relative rotation. The hub insert 31 is slid onto the drum at one end thereof and moved into abutment with the flange 12. If appropriate, flanges 12 can be provided on either side of the hub insert 31. The hub is then completed by a surround 33 mountable on the hub inserts. In the illustrated embodiment of the axle assembly, two such hub inserts 31 are mounted on the drum at an axial spacing and the surround 33 is of such a size as to encompass both inserts 31 and is secured against rotation relative thereto by engagement of axially protruding dogs 34 at the periphery of an axial end face of the insert in corresponding notches 35 in an internal step of the surround. The assembly procedure comprises fitting one insert 31 on the drum, mounting the surround 33 on that insert and fitting the other insert 31 on the drum. Flanges 12 are applied to the drum 1 on either side of the two inserts 31. As shown in Fig. 15, the insert 31 has two dogs 34 at one axial end face, but complementary notches at the other end face, so that two such inserts can also be mounted in axial abutment on the drum and secured by engagement of the dogs 34 of the insert in the notches of the other insert against relative rotation.

Figs. 17 to 19 illustrate another subassembly in the form of a power supply module 40 structured on the basis of a connector 10 with an open-ended drum 11 , such as shown in Fig. 8, of integral or multi-part construction and an end cap 26 with connecting means incorporating a removable centre post 21 with internal and external electrical conductor tracks as previously described. The flange of the connector is not illustrated. Arranged in the interior of the drum is a power supply unit with two terminals respectively connected with the two tracks. The power supply unit comprises a battery holder 41 , shown by itself in Fig. 18, removably inserted in the drum and provided with four receptacles each for a respective one of four serially connected batteries (not shown). Fig. 19 shows the inserted holder 41 and Fig. 17 the module consisting of drum, inserted holder and fitted end cap 26 with the centre post 21 for power transmission from the power supply unit to coupled axial coupling elements, such as an electrically conductive adapter and an electrically conductive peg. The connector can, of course, be fitted with the end cap 27 with integrated locking ring 28 instead of the end cap 26.

Finally, Figs 20 to 22 show a drive module 50 which again has a connector 10 as core component and which again utilises a drum of the kind shown in Fig. 8, i.e. without integrated connecting means. The module 50 further comprises a drive unit which is positionable in the drum and has drive output means at one end of the drum, the other end being fitted with an end cap 26 (as shown in Fig. 21 ) or an end cap 27. The drive unit comprises a drive holder 51 which is removably mounted in the drum and which holds a drive 52 consisting of a motor and a transmission, for example a 30 watt electric motor with integrated planetary speed-reduction transmission. The drive holder 51 can have the form of a simplified apertured end cap with locating arms engageable in the drum. The drive output means comprises a keyed drive shaft of the transmission, on which is detachably mounted a rotary drive element 53 to be secure against rotation relative thereto. The drive element 52 is provided at its periphery with radial protrusions shaped and arranged for engagement in the circumferential recesses formed in an end face of the drum 11 or cap 26 or 27 of another connector 10, in particular recesses defined by the junctions of the transverse grooves 19 of the connecting means. Drive can thus be transmitted to that other connector, which is thus able to act as an axle as in the case of the axle assembly 30.

The connector hereinbefore described in basic and variously developed forms exhibits a considerably enhanced level of flexibility by comparison with prior art connectors and has the significant advantage of being able to be constructed from a standard flange, whether of integral or multi-part construction, and a drum which can, if desired, be selected from a range of graduated lengths according to requirements. This provides advantages with respect to parts saving in a modular construction, reduction in the number of possibly unused flanges and variable numbers and positioning of flanges per connector.