WO2008066397A1

WO2008066397A1 - Roof rack accessory clamp

Info

Publication number: WO2008066397A1
Application number: PCT/NZ2007/000350
Authority: WO
Inventors: Peter Douglas Hubbard
Original assignee: Hubco Automotive Limited
Priority date: 2006-12-01
Filing date: 2007-11-29
Publication date: 2008-06-05
Also published as: NZ573922A

Abstract

A roof rack accessory clamp including: first and second bearing parts, the first bearing part being constrained to movement solely along a linear actuation axis and said second bearing part being constrained to movement solely orthogonally to said actuation axis; a first linear actuation mechanism capable of reversibly moving said first bearing part along said linear actuation axis; a first housing at least partly enclosing the bearing parts and the linear actuation mechanism. Both the bearing parts include an inclined bearing face confronting each other in at least partially in intimate contact in a common plane orientated at a non-orthogonal angle to said actuation axis, such that in use, reversible linear movement of the first bearing part by the linear actuation mechanism forces the second bearing part to reversibly slide along said bearing face displacing the second bearing part along a clamping axis orthogonal to the actuation axis to reversibly apply a clamping force to a cross bar or roof rail.

Description

TITLE: ROOF RACK ACCESSORY CLAMP TECHNICAL FIELD

The present invention relates to a roof rack accessory clamp to secure items to a vehicle roof rack.

BACKGROUND ART

Roof racks are a ubiquitous means for vehicular transport of a variety of loads. The popularity of sporting activities such as kayaking, skiing/snowboarding, mountain biking and the like has created a burgeoning market for activity-specific roof rack accessories to transport the necessary equipment. Many such users place a high emphasis on performance and functionality, not only for their sporting equipment, but also on their vehicles and ancillary transportation equipment, e.g. the roof rack and fittings.

As is well established, increasing the perpendicular height of a transported item above the vehicle roof increases aerodynamic drag and decreases stability.

Consequently, there is a continual desire to reduce the overall height of a roof rack and associated clamps, whilst retaining practicality and ease of use. This requires the transported item to be readily secured to, and unloaded from the roof rack without undue complication or hindrance. Roof rack accessories are typically clamped to removable roof rack cross bars or factory fitted roof rails. Applying sufficient clamping force to secure the load typically requires some form of vertical acting clamping mechanism which requires the presence of sufficient space below the cross bar to prevent the clamp impinging on the roof and to enable satisfactory securing/releasing operation. This increases the minimum overall height of the roof rack, exacerbating the above described drawbacks.

It is thus desirable to produce a roof rack accessory clamp which enables secure attachment and release of a mounting accessory used to transport a load item without impinging on the vertical space between the cross bar/roof rail and the vehicle roof.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

It is acknowledged that the term 'comprise' may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term 'comprise' shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term 'comprised' or 'comprising' is used in relation to one or more steps in a method or process.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF INVENTION

According to one aspect of the present invention there is provided a roof rack accessory clamp for clamping said accessory to a roof rack cross bar or roof rail, said clamp including:

first and second bearing parts, said first bearing part being constrained to movement solely along a linear actuation axis and said second bearing part being constrained to movement solely orthogonally to said actuation axis;

- a first linear actuation mechanism capable of reversibly moving said first bearing part along said linear actuation axis;

a first housing at least partly enclosing said bearing parts and said linear actuation mechanism;

characterised in that;

both said bearing parts include an inclined bearing face confronting each other in at least partially in intimate contact in a common plane orientated at a non- orthogonal angle to said actuation axis, such that in use reversible linear movement of the first bearing part by the linear actuation mechanism forces the second bearing part to reversibly slide along said bearing face displacing the second bearing part along a clamping axis orthogonal to the actuation axis to reversibly apply a clamping force to a cross bar or roof rail.

* The linear actuation mechanism may take any convenient form including, but not limited to, a manually rotatable male screw threaded element passing through a complementary female threaded aperture in the first bearing part, an over centre lever and cam assembly, and/or any other mechanical, electromechanical, hydraulic or pneumatic actuator capable of effecting reversible linear movement of the first bearing part.

As used herein, the term 'bearing part' is used broadly to encompass any element, member, or component, whether solid, hollow, or part hollow, framed or part framed, moulded or machined or any other type of construction and configuration, provided the bearing parts possess said mutually complementary inclined bearing faces (which need not necessarily be solid) and a means of coupling with said linear actuation mechanism to permit reversibly linear movement.

Similarly, the terms roof rack cross bars, roof rail and the like are to be interpreted broadly to include any load carrying apparatus configured to be releasably clamped or attached to a support structure.

According to a further aspect of the present invention, the first and second bearing parts are slidably coupled together, allowing relative movement between both parts in the plane of said bearing faces. The slidable coupling may take any convenient form, including interlocking slots and protrusions aligned to permit sliding movement in the common plane of the inclined bearing faces. Such a coupling prevents the second bearing part becoming detached from the first bearing part and thus not retracting into the housing when releasing the clamp.

It will be appreciated that the movement of the second bearing part along the clamping axis may be used to bear directly or indirectly on the roof rail or the like to effect a clamping action. It will be further readily appreciated by one skilled in the art that a portion of the clamp (hereinafter referred to as the retaining portion) must at least partially engage with a bearing surface of the cross bar or roof rail portion such that at least a portion of the cross bar or roof rail is interposed along the clamping axis between the retaining portion and the second bearing part. This configuration allows a compressive clamping action to be reversibly applied by the second bearing part on the roof rail/cross bar by actuation of the linear actuation mechanism.

In one embodiment, the clamp further includes a secondary housing attachable to said first housing and incorporating said retaining portion.

In one embodiment, the secondary housing is configured with a hollow central passageway with a cross-section configured to accept a roof rail or cross bar, said passageway orientated substantially orthogonal to the clamping axis, said secondary housing being configured to encircle said roof rack or roof bar and allow insertion of same via a pivotable door section placed in an open position, wherein when said door section is placed in a closed position, said movement of the second bearing part towards said passageway acts to apply compressive pressure to portions of the secondary housing adjacent the door section, thereby acting to secure the door from opening. Alternatively, portions of the second bearing part may be configured to interlock with mating portions of said door section in said closed position to prevent opening.

In a further embodiment, said roof bars are of square or rectangular cross-section and accordingly, said secondary housing is formed as three sides of a square or rectangle and said pivotable door section comprises the remaining side.

According to one aspect of the present invention, said retaining portion is formed by the second housing. In another aspect, said retaining portion is formed as an extrusion (e.g. with a T-shape or rectangular cross-section or the like), shaped to engage with one or more inner surfaces of a cross bar or roof rail. Preferably, said retaining portion is releasably attachable to said first housing, though in an alternative embodiment, the retaining portion may be integrally formed with the first housing.

According to a further aspect of the present invention, said secondary housing is configured as an independent fastener attachable to said first housing and preferably incorporating said retaining portion. The fastener thus provides a further means of attaching one or more said accessories to a roof rack, cross bar, roof rail or a variety of objects, e.g. storage racking, train/aircraft freight storage fittings. According to one embodiment, said fastener includes: - a second linear actuation mechanism capable of reversibly moving at least one pawl along a second linear actuation axis;

- a fastener housing at least partly retaining said second linear actuation mechanism and pawl;

- at least one tensioning element with an engagement portion configured to engage with said pawl to produce unidirectional movement therebetween upon activation of said second linear activation mechanism.

According to a further aspect, said fastener includes an attachment portion, preferably capable of releasably attaching or retaining a tensioning element. However, it will be readily appreciated that the attachment portion may be used to attach the fastener to a variety of objects including, but not limited to, straps, tethers, rods, roof rack/rails, cross bars, and/or other fixed surfaces and the like.

As used herein, the tensioning element may be a strap, band, tether, rod, strut or any other practical object capable of co-operative engagement with said pawl.

As used herein, the term pawl includes ratchet teeth or tooth, castellations, male threads, chain cogs, gears and/or any mechanical configuration capable of engaging with the engagement portion of the tensioning element and being capable of creating mutual relative unidirectional movement therebetween. In a preferred embodiment, said pawl and engagement portion are a set of ratchet teeth and a series of saw-toothed serrations respectively. For the sake of clarity, the invention will be predominately described with respect to such an embodiment, though it will be readily appreciated that the invention is not limited to same.

In a preferred embodiment, a single elongate tensioning element is provided having two distal ends with said engagement portion being located at one said distal end. The tensioning element is attached at one distal end to the fastener at said attachment portion, and releasably attached at the other distal end via engagement of said pawl with the engagement portion.

The attachment of the tensioning element to the fastener may be by an enlarged portion at the opposing distal end to the engagement portion and a suitably dimensioned slot or aperture as said attachment portion. Thus, the tensioning element strap passing through the attachment portion aperture will eventually be restrained by said enlarged strap portion.

Thus a tensioning element in the form of a strap attached at one end to the attachment portion may be wrapped around a given object (e.g. a roof bar) before being engaged with the fastener pawl. Activation of the second linear activation mechanism pulls the strap towards the fastener, tightening the fastener to the object. As the strap may be readily formed with a flexible/semi-flexible construction, it may be wrapped around a variety of object shapes. The fastener may thus be used with a greater variety of roof bar profiles for example, in comparison to the purpose-made secondary housing such as the above-described configured for square-section roof rails.

In one preferred embodiment, the fastener also includes said retaining portion. For example, the upper portion of the second housing/fastener may be configured with an inverted T-shaped slot to accommodate the accessory clamp as hereinbefore described.

However, it will be readily appreciated by one skilled in the art that the fastener may be used independently from the above-described accessory clamp, either in combination with alternative types of accessory clamps, or formed integrally therewith. In the former case, said secondary housing and second linear activation mechanism are more appropriately re-termed as 'fastener housing' and 'fastener linear activation mechanism' respectively. Thus, according to a further aspect of the present invention, there is provided a fastener including:

- a fastener linear actuation mechanism capable of reversibly moving at least one pawl along a fastener linear actuation axis;

- a fastener housing at least partly retaining said fastener linear actuation mechanism and pawl;

at least one tensioning element with an engagement portion configured to engage with said pawl to produce unidirectional movement therebetween upon activation of said fastener linear activation mechanism.

It will be readily appreciated that all the above-described features and various embodiments pertaining to the fastener as a secondary housing are equally applicable when said fastener is used independently of the above-described accessory clamp.

According to preferred aspects of the present invention, the clamp may further include an activity-specific fitting, attached to, or incorporated in said first housing. The activity-specific fitting may be releasably attachable to, or formed integrally with, the first housing and may take many forms including, but not limited to, bicycle holders, ski/snowboard racks, kayak holders, ladder holders and so forth.

According to a further embodiment, the linear actuation mechanism may also releasably clamp the activity-specific fitting in a fixed position. Preferably, the activity-specific fitting is clampable in a range of positions. Thus, for example, a kayak holder may be attached to the first housing by a fitting, pivotal about the actuation axis and which may be releasably clamped by operating the actuation mechanism, e.g. tightening a bolt passing through the first housing and the kayak holder fitting. The ability of the present invention to apply a clamping force via the linear actuation axis orthogonally into the clamping axis enables the whole clamp to be mounted on roof bars/rails closer to the vehicle roof (and thus provides less aerodynamic drag) without adding the inconvenience of side-acting operation of the clamping/unclamping action.

BRIEF DESCRIPTION OF DRAWINGS

Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which:

Figure 1 shows an exploded view of a roof rack assembly clamp according to one preferred embodiment of the present invention;

Figure 2a-b shows a perspective side elevation of the assembled roof rack holder shown in figure 1 ;

Figure 3a-b shows a section through a side elevation of the clamp shown in figure 1 ;

Figure 4a-c shows an enlarged perspective view of first and second bearing parts of the clamp shown in figure 1 ;

Figure 5a shows the clamp of figure 1 in use with a roof rack crossbar inserted into a secondary housing portion with a hinged door portion in an open position;

Figure 5b shows the clamp shown in figure 5a with a hinged door portion in the closed position;.

Figure 6a shows a perspective exploded view of a further preferred embodiment of a clamp for attachment to a roof rail; Figure 6b shows the clamp of figure 6a assembled and fitted to a roof rail;

Figure 7 shows a further preferred embodiment of the present invention in the form of a ski/snowboard holder, and

Figure 8 shows a further preferred embodiment of the present invention in the form of a cycle holder.

Figure 9 shows a further preferred embodiment of the present invention in the form of fastener shown as an exploded view of the fastener components;

Figure 10 shows a perspective side elevation view of the fastener in figure 9 in use, and

Figure 11 shows a side elevation section through the plane AA' shown in figure 10.

BEST MODES FOR CARRYING OUT THE INVENTION

Figures 1-6 show preferred embodiments of the present invention in the form of a roof rack accessory clamp for clamping an accessory to a roof rack crossbar or roof rail. The construction and means of attaching a roof rack crossbar or roof rails to a vehicle is well-known in the art, and is not described in detail further.

Figures 1 -6 illustrate a roof rack accessory clamp in the form of a kayak holder clamp (1 ), typically used in two mirror image pairs on two roof rails/crossbars. The following description displays a single kayak holder clamp (1 ), though it will be readily appreciated that this is exemplary only.

Referring to the exploded clamp (1 ) view shown in figure 1 and the assembled clamp (2) illustrated in figures 2 a-b), the clamp (1 ) comprises generally a first housing in the form of main body (2), enclosing a clamping mechanism comprised of first and second bearing parts (3, 4) and a linear actuation mechanism in the form of bolt (5) and knob (6).

The clamp (1 ) further includes an activity-specific fitting in the form of kayak holder (7) releasably attached to the main body (2) by a partially pivotal fitting (8) coupled to the main body (2) via the bolt (5). The orientation of the kayak holder (7) may be adjusted by pivoting the fitting (8) about the actuation axis (12). Operating the actuation mechanism, i.e. tightening the knob (6) and bolt (5) thus also clamps the kayak holder (7) in position in addition to clamping the clamp (1 ) to the roof rack crossbar or roof rail, as described below.

The clamp (1) further includes means to engage with a roof rail or crossbar, in the form of a secondary housing (9) attached to the main body (2) and releasably attachable to a crossbar / roof rail. It will be appreciated that in alternative embodiments (not shown) the secondary housing (9) may be formed integrally with main body (2), or alternatively be releasably detachable to the main body (2).

In more detail (and with particular reference to figures 3a-3b), the operation of the clamp (1 ) in use is as follows:

The first bearing part (3) is formed as a block with a central passageway (10) with an internal female thread (11 ) which mates with an external male thread on bolt

(5). Rotating the knob (6) causes the first bearing part (3) to travel linearly along the longitudinal axis of the bolt (5) (hereinafter referred to as actuation axis (12)).

The first bearing part (3) includes an inclined bearing face (13). The second bearing part (4) is formed with a complementary inclined bearing face (14) orientated in a confronting arrangement with the first bearing part bearing face (13) in a common inclined plane. The allowable movement of the second bearing part is constrained within the first housing (2) solely in an axis (hereinafter referred to^' as the clamping axis (17)) orthogonal to the actuation axis (12). Consequently, as a user turns the knob (6), rotating bolt (5) to move the first captive bearing part (3) along the actuation axis (12) towards the second bearing part (4), the two bearing parts (3, 4) push against each other in the common plane of their respective bearing faces (13, 14). As a consequence of the mechanical interaction of the two inclined bearing faces (13, 14) and the constraint on allowable movement direction of the second bearing part (4) by the main body, (2) the second bearing part is forced downwards.

As may be most clearly seen from figures 4a -c) showing the two bearing parts (3, 4) in greater detail, the two bearing faces (13, 14) are slidably coupled together by projecting lugs (15) projecting from the first bearing face (13) and interlocking with complementary slots (16) in the second bearing face (14). The lugs and slots (15, 16) allow sliding movement in the plane of the bearing faces (13, 14) and prevents the second bearing part (4) from becoming detached from the first bearing part (3).

The movement of the second bearing part (4) along the clamping axis (17) is typically orientated vertically for a conventional roof rack application, thus orientating the actuation axis horizontal (12) for use of operation by a user standing aside a vehicle clamping an item with the present invention. The characteristic of the present invention to effectively translate movement in the actuation axis (12) from the horizontal plane into the vertical plane of the clamping axis (17) avoids the clamping mechanism of a clamp operating entirely vertically from encumbering the load. Moreover, it enables the height necessary between the roof rail / crossbar and the vehicle roof (needed to accommodate the clamp (1 )) to be minimised thus reducing aerodynamic drag of the roof mounted load.

The lowermost portions of the second bearing part (4) are formed as elongated legs (18) which may apply a compressive force to the crossbar/roof rail either directly or indirectly (though an intermediate structure or element. In the embodiment shown in figures 1- 5, the clamp (1 ) includes a secondary housing (9) in the form of a square cross-sectioned structure with three substantially rigid parallel wall sections (19) and a pivotable door section (20) completing the open- ended box-shape configuration. The secondary housing (9) includes a hollow central passageway (21 ) orientated orthogonally to the clamping axis (17) with a cross-section configured to accept a roof rack crossbar (22).

The secondary housing (9) is configured to encircle the roof rack crossbar (22) (as shown in figures 5a-b)) by insertion of the bar (22) via the pivotable door section (20) placed in an open position (figure 5a). When the door section (20) is pivoted into a closed position (figure 5 b), the legs (18) of the second bearing part (4) are forced downwards (by operation of knob (6) and bolt (5)) into contact with the secondary housing (9).

In one embodiment as shown in figures 5a - b), this movement of the second bearing part (4) towards the roof rack bar (22) acts to bring the tips of the legs (18) to engage with corresponding mating portions (23) (shown in figure 5a) of said door section (20) in the closed position to prevent unintentional re-opening.

The above described embodiment shown in figures 1 -5 releasably attaches the secondary housing (9) to the first housing (2) by an interlocking element (24) with dovetail portions configured to interlock complementary portions of the first and second housings (2, 9).

In a further embodiment (shown in exploded form in figure 6a) and assembled form in figure 6b)), the clamp (1 ) is attached to a roof rail (25). The lower dovetail portion of the interlocking element (24) is configured as an inverted T-shaped extrusion and may be slid into a corresponding recess (26) in the roof rail (25). In such, an embodiment, the interlocking element (24) fulfils the role of both the secondary housing and the retaining element.

Figures 7 and 8 respectively show further embodiments of the present invention in the form of a ski/snowboard rack holder (27) and a cycle holder (28). The ski/snowboard rack holder (27) incorporates two separate clamp assemblies inside respective main housings (200, 201 ), each including a first and second bearing part (not shown) configured and operable as described in the preceding embodiments. The embodiment shown in figure 7 utilises an interlocking element

(24) attached to each main housing (200, 201 ) to fit the holder (27) to a roof rail

(25). The clamping mechanisms are activated as previously described by rotating the knobs (6).

A lockable hinge ski/snowboard fitting (29) partially encloses the housings (200, 201 ) such that the knobs (6) are unable to be rotated once the hinge cover (30) is locked in position.

This provides a measure of security deterring unauthorised removal of any clamped skis/boards. It also prevents the inadvertent release of the clamping face by knobs (6) vibrating loose.

The cycle holder shown in figure 8 is also attached to a pair of roof rails (25) via the insertion of an interlocking T-slot element (24) into corresponding recesses (26). The cycle carrier (28) is comprised of an elongated support section (31) spanning the two roof rails (25) and clamped thereto via two separate clamps contained within individual main bodies (300, 301 ), each containing individual first and second bearing parts (not shown) configured to operate in the previously described manner.

Figures 9 - 11 show a further aspect of the present invention in the form of a fastener (100). In the embodiment shown in figures 9 - 11 , the fastener (100) is also a further embodiment of the secondary housing (9) shown in the previous embodiments. It will be readily appreciated that the fastener (100) may in alternative embodiments (not shown), be used independently from the clamp (1) or be formed as an integral component (not shown) with the clamp (1 ).

The fastener (100) shown in figures 9-11 is attachable to said first housing main body (2) via an inverted T-section slot (126) configured to accept a T-section interlocking element such as T-slot element (24), which in itself interlocks with the first housing main body (2). The fastener (100) thus provides a further means of attaching one or more said accessories (via the clamp (1) to a wide variety of objects including roof racks, cross bars, roof rails or indeed many other objects, e.g. storage racking, train/aircraft freight storage fittings. The fastener (100) generally comprises;

- a second linear actuation mechanism in the form of;

^■ a male threaded bolt (105) manually rotatable by a knob (106) attached at one end of the bolt (105);

■ a captive pawl (107) apertured with a female thread to accept the bolt (105);

a fastener housing (101 ) enclosing and retaining the bolt (105) and pawl (107),and

at least one tensioning element in the from of an elongated, semi-flexible strap (108) having two distal ends.

An engagement portion, in the form of a series of saw-toothed serrations (109) is located at one distal end of the strap (108), while an enlarged portion in the form of transverse bar (110) is located at the opposing distal end of the strap (108). The strap (108) is attached to the fastener housing (107) by an attachment portion in the form of a slot (112) through which the strap (108) is passed until further passage is impeded by the transverse bar (110).

In use, the strap (108) is wrapped about a chosen strongpoint (e.g. roof rail, storage rack or the like) before the free distal end with the toothed serrations (109) is re-inserted into an aperture in the housing (101 ) to engage with the pawl (107). The pawl (107) and serrations (109) are profiled such that relative movement therebetween is only unidirectional, i.e. a ratchet. Thus, rotating knob (106) to rotate bolt (105) causes the captive pawl (107) to travel along the bolt (105) thread pulling the strap (108) into the fastener housing (101), thereby tightening the strap (108) about the chosen strongpoint.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.

Claims

1 . A roof rack accessory clamp for clamping said accessory to a roof rack cross bar or roof rail, said clamp including:

- first and second bearing parts, said first bearing part being constrained to movement solely along a linear actuation axis and said second bearing part being constrained to movement solely orthogonally to said actuation axis;

a first linear actuation mechanism capable of reversibly moving said first bearing part along said linear actuation axis;

- a first housing at least partly enclosing said bearing parts and said linear actuation mechanism;

characterised in that;

both said bearing parts include an inclined bearing face confronting each other in at least partially in intimate contact in a common plane orientated at a non-orthogonal angle to said actuation axis, such that in use reversible linear movement of the first bearing part by the linear actuation mechanism forces the second bearing part to reversibly slide along said bearing face displacing the second bearing part along a clamping axis orthogonal to the actuation axis to reversibly apply a clamping force to a cross bar or roof rail.

2. A roof rack accessory clamp as claimed in claim 1 , wherein said linear actuation mechanism is selected from the group including, but not limited to, a manually rotatable male screw-threaded element passing through a complementary female threaded aperture in the first bearing part, an over- centre lever and cam assembly, and/or ^' any other mechanical, electromechanical, hydraulic or pneumatic actuator capable of effecting reversible linear movement of the first bearing part.

3. A roof rack accessory clamp as claimed in claim 1 or claim 2, wherein the first and second bearing parts are slidably coupled together, allowing relative movement between both parts in the plane of said bearing faces.

4. A roof rack accessory clamp as claimed in any one of claims 1 - 3, wherein the movement of the second bearing part along the clamping axis is capable of bearing directly or indirectly on said roof rail or roof bar to effect a clamping action.

5. A roof rack accessory clamp as claimed in any one of the preceding claims, wherein a portion of the clamp (hereinafter termed "retaining portion") is capable of at least partially engaging with a bearing surface of a cross bar or roof rail portion such that at least a portion of the cross bar or roof rail is interposed along the clamping axis between the retaining portion and the second bearing part allowing a compressive clamping action to be reversibly applied by the second bearing part on the roof rail/cross bar by actuation of the linear actuation mechanism.

6. A roof rack accessory clamp as claimed in claim 5, further including a secondary housing attachable to said first housing and incorporating said retaining portion.

7. A roof rack accessory clamp as claimed in claim 6, wherein the secondary housing is configured with a hollow central passageway with a cross-section configured to accept a roof rail or cross bar, said passageway orientated substantially orthogonal to the clamping axis, said secondary housing being configured to encircle said roof rack or roof bar and allow insertion of same via a pivotable door section placed in an open position, wherein when said door section is placed in a closed position, said movement of the second bearing part towards said passageway acts to apply compressive pressure to portions of the secondary housing adjacent the door section, thereby acting to secure the door from opening.

8. A roof rack accessory clamp as claimed in claim 6, wherein the secondary housing is configured with a hollow central passageway with a cross-section configured to accept a roof rail or cross bar, said passageway orientated substantially orthogonal to the clamping axis, said secondary housing being configured to encircle said roof rack or roof bar and allow insertion of same via a pivotable door section placed in an open position; and wherein portions of the second bearing part are configured to interlock with mating portions of said door section in said closed position to prevent opening.

9. A roof rack accessory clamp as claimed in claim 7 or claim 8, wherein said roof bars are of square or rectangular cross-section and accordingly, said secondary housing is formed as three sides of a square or rectangle and said pivotable door section comprises the remaining side.

10. A roof rack accessory clamp as claimed in any one of claims 5 - 9, wherein said retaining portion is formed by the second housing.

11. A roof rack accessory clamp as claimed in any one of claims 5 - 10, wherein said retaining portion is formed as an extrusion, shaped to engage with one or more inner surfaces of a cross bar or roof rail.

12. A roof rack accessory clamp as claimed in claim 10 or claim 1 1 , wherein said retaining portion is releasably attachable to said first housing.

13. A roof rack accessory clamp as claimed in any one of claims 5 - 9, wherein the retaining portion is integrally formed with the first housing.

14. A roof rack accessory clamp as claimed in any one of claims 1-5, wherein said secondary housing is configured as an independent fastener attachable to said first housing.

15. A roof rack accessory clamp as claimed in claim 14, wherein said secondary housing incorporates said retaining portion.

16. A roof rack accessory clamp as claimed in claim 14 or claim 15, wherein the fastener includes:

- a second linear actuation mechanism capable of reversibly moving at least one pawl along a second linear actuation axis;

a fastener housing at least partly retaining said second linear actuation mechanism and pawl;

at least one tensioning element with an engagement portion configured to engage with said pawl to produce unidirectional movement therebetween upon activation of said second linear activation mechanism.

17. A roof rack accessory clamp as claimed in any one of claims 14 - 16, wherein said fastener includes an attachment portion capable of releasably attaching or retaining a tensioning element.

18. A roof rack accessory clamp as claimed in claims 16 - 17, wherein said pawl and engagement portion are a set of ratchet teeth and a series of saw-toothed serrations respectively.

19. A roof rack accessory clamp as claimed in claims 16 - 18, wherein a single elongate tensioning element is provided having two distal ends with said engagement portion being located at one said distal end.

20. A roof rack accessory clamp as claimed in claim 19, wherein the tensioning element is attached at one distal end to the fastener at said attachment portion, and releasably attached at the other distal end via engagement of said pawl with the engagement portion.

21. A roof rack accessory clamp as claimed in claims 17 - 20, wherein said attachment of the tensioning element to the fastener is performed via by an enlarged portion at the opposing distal end to the engagement portion and an aperture dimensioned to accommodate said attachment portion.

22. A roof rack accessory clamp as claimed in any one of claims 14 - 21 , wherein said fastener includes said retaining portion.

23. A roof rack accessory clamp as claimed in claim 22, wherein the upper portion of the fastener is configured with an inverted T-shaped slot capable of accommodating the accessory clamp.

24. A roof rack accessory clamp as claimed in any one of the preceding claims, further including an activity-specific fitting, attached to, or incorporated in said first housing.

25. A roof rack accessory clamp as claimed in any one of the preceding claims, wherein the linear actuation mechanism is configured to releasably clamp the activity-specific fitting in one or more fixed position(s).

26. A fastener including:

a fastener linear actuation mechanism capable of reversibly moving at least one pawl along a fastener linear actuation axis;

a fastener housing at least partly retaining said fastener linear actuation mechanism and pawl; at least one tensioning element with an engagement portion configured to engage with said pawl to produce unidirectional movement therebetween upon activation of said fastener linear activation mechanism.

27. A roof rack accessory clamp substantially as hereinbefore described, and as shown in the attached drawings.

28. A fastener substantially as hereinbefore described, and as shown in the attached drawings.