GB2121471A

GB2121471A - Snap hook systems

Info

Publication number: GB2121471A
Application number: GB08315819A
Authority: GB
Inventors: John A Bakker; Gilbert Solarz
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 1982-06-10
Filing date: 1983-06-09
Publication date: 1983-12-21
Also published as: JPH0463252B2; IT8321539A0; AU557302B2; DE3321141A1; ES279044Y; DK267283A; KR840005010A; FR2528507B1; FI832061L; ES279044U; SE8303180D0; AU1564583A; GB2121471B; IT1168706B; FR2528507A1; FI832061A0; JPS5954810A; DK267283D0; CA1189687A; KR900005494B1

Abstract

A snap hook 41 comprising a bi- ended base portion 43, a blade portion 45, a re-entrant portion 50 and a latch portion 47 is disclosed. The blade 45 is integral with a first end of the base, through the re- entrant portion, thereby providing the snap hook with an aperture 51 intermediate the base and the blade. The aperture has a mouth 55 and two integrally formed lips 53. The aperture is adapted to receive a substantially cylindrical portion of a retainer 59 therein. The latch 47 is integral with the second end of the base and thereby provides the snap hook with a hook 63 at the junction thereof. A free end 65 of the blade and a free end 67 of the latch are in distal relation to the base. A relaxed condition for the snap hook (full lines Figure 1) is defined to be when the distal end 65 of the blade is above the distal end 67 of the latch, in relation to the base. A locked condition for the snap hook (phantom lines Figure 1) is defined to be when the distal end 65 of the blade is positioned beneath the distal end 67 of the latch, in relation to the base. The lips 53 are adapted to lockingly retain the above-mentioned substantially cylindrical portion of the retainer 59 while the snap hook is in the locked condition and the blade 45 is in biased engagement with the latch 47. A ring 97 is selectively permitted to be secured to or released from the hook 63 by manipulation of the blade 45. <IMAGE>

Description

SPECIFICATION Snap hook systems including snap hooks, retainers and rings The present invention relates not only to snap hook systems but also to individual snap hooks and their combination with retainers and/or rings.

According to the present invention, a snap hook system comprises: a first means including a base having a hook-shaped end and a second end, with a blade portion extending from said second end for selectively controlling access to and from said hook-shaped end; and a second means including a substantially cylindrical portion to be confined at said second end of said first means and a further portion for securing a strap thereto.

The fact that said substantially cylindrical portion of said second means is actually confined at said second end of said first means helps to maintain said first means in a fixed spatial position with respect to said second means and to the strap to be secured to said second means.

Said second means may be selected from a plurality of predetermined sizes of said second means wherein each size corresponds to a predetermined width of strap. Moreover, there may be a third means including a first portion to be held by said hook-shaped end of said first means and a further portion for securing a strap thereto. Said third means may again be selected from a plurality of predetermined sizes of said third means wherein each size corresponds to a predetermined width of strap.

It will be appreciated that in practice said first means is constituted by a snap hook said second means is constituted by a retainer, and said third means is constituted by a ring.

The retainer and the ring are in practice secured to different straps, or different parts such as the ends of the same strap, with the snap hook being located between the retainer and the ring to form the sequence strap, retainer, snap hook ring, strap.

It will be appreciated that in practice the substantially cylindrical portion of the retainer remains secured to the snap hook while the blade portion of the snap hook can be manipulated to permit the ring to be secured to, and subsequently released from, the hook-shaped end of the snap hook.

The snap hook, for which independent protecton is being sought, may comprise: a biended base portion, a blade portion, a re-entrant portion and a latch portion; a first end of said base portion being integral with said blade portion through said re-entrant portion thereby providing said snap hook with an aperture which is located intermediate said base portion and said blade portion, is accessible through a mouth of restricted depth and is for receiving a substantially cylindrical portion of a retainer, a second end of said base portion being integral with said latch portion thereby providing said snap hook with a hook; a free end of said blade portion being in distal relation to said base portion, a free end of said latch portion being in distal relation to said base portion, a relaxed condition of said snap hook being defined when said distal end of said blade portion is positioned above said distal end of said latch portion in relation to said base portion, a locked condition for said snap hook being defined when said distal end of said blade portion is positioned beneath said distal end of said latch portion in relation to said base portion; said mouth being adapted to lockingly retain said substantially cylindrical portion of said retainer within said aperture when said snap hook is in said locked condition, and said snap hook being maintained in said locked condition by a biased engagement between said distal end of said blade portion and said distal end of said latch portion.

Preferably: said base portion and said latch portion form a substantially V-shaped hook at the junction thereof; said re-entrant portion has a generally tubular shape and is split along its length at said mouth; said mouth is defined by and lies between a pair of opposed lips; said re-entrant portion and said aperture provided thereby are substantially wider than and project laterally to both sides of said base portion and said latch portion; said re-entrant portion is strengthed by a reinforcing rib; said distal end of said blade portion, said distal end of said latch portion and said base portion are substantially parallel when viewed in transverse cross-section;; said distal end of said blade portion includes a first plurality of projecting surfaces and said distal end of said latch portion includes a second plurality of projecting surfaces, said first plurality of projecting surfaces extending outwardly from said distal end of said blade portion and interfitting with said second plurality of projecting surfaces when said snap hook is in said locked condition, whereby lateral or transverse movement of said distal end of said blade portion with respect to said dismal end of said latch portion is substantially limited; and said blade portion converges in width along its length towards said distal end thereof.

In the combination of the snap hook and the retainer, for which independent protection is being sought, the snap hook may be formed as described hereinabove, and the retainer may include a substantially cylindrical portion confined in said aperture provided by said re-entrant portion of said snap hook and a further portion for securing a strap thereto.

Preferably: said retainer has a generally rectangular shape; each end of said substantially cylindrical portion of said retainer is bounded by a stop extending outwardly of said substantially cylindrical portion whereby longitudinal movement of said substantially cylindrical portion of said retainer with respect to said aperture provided by said re-entrant portion of said snap hook is substantially limited; there is a plurality of different sizes of said retainers corresponding to a plurality of different widths of strap with a selected one of said retainers being secured to said snap hook; and each of said plurality of different sizes of said retainers is of a different colour.

In the combination of the snap hook and the ring, for which independent protection is being sought, the snap hook may be formed as described hereinabove, and the ring may include a first portion through which said latch portion of said snap hook has been inserted and a further portion for securing a strap thereto.

Preferably: said ring has a generally triangular shape which may be that of an isosceles triangle or that of an equilateral triangle; or said ring has a generally rectangular shape defining a slot through which a strap may be inserted as well as a separate hole through which said latch portion of said snap hook has been inserted; there is a plurality of different sizes of said rings corresponding to a plurality of different widths of strap with a selected one of said rings being secured to said snap hook; and said plurality of different sizes of said rings is of a different colour.

Naturally, the combination of the snap hook and the retainer may itself be combined with the combination of the snap hook and the ring with the snap hook being common to both combinations.

The individual snap hooks, retainers and rings may each be integrally formed of a suitably resilient and durable synthetic substance, such as being moulded of a plastics material, thus permitting the avoidance of sharp edges, rust and other corrosion, and the need for an external coating of aesthetic purposes.

General advantages are the ease of engagement of the ring with the snap hook and the ease of subsequent disengagement of the ring from the snap hook because location of the blade portion of the snap hook is straight forward, even after relaxing of any initial tension in the snap hook system.

Various snap hooks, retainers and rings according to the present invention, and thus various snap hook systems according to the present invention, will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of an integrally formed snap hook incorporating features of the present invention; Figure 2 is a right-end view (reduced in size) of the snap hook of Figure 1; Figure 3 is a top view (also reduced in size) of the snap hook of Figure 1; Figure 4 is a fragment of the view of Figure 1, partially in section, and including a sectional view of a cylindrical portion of a retainer approaching the aperture of the snap hook; Figure 5 shows the cylindrical retainer portion negotiating the lips of the aperture while the snap hook is in a relaxed condition;; Figure 6 shows the position after the cylindrical portion of the retainer has been pushed past the lips of the aperture and the snap hook is being moved from the relaxed condition to the locked condition; Figure 7 is the side view of another embodiment of the snap hook of the present invention; Figure 8 is a sectional view taken generally along the line 8-8 of Figure 7 showing one embodiment of a locking feature of the blade portion of the snap hook; Figure 9 is an end view taken generally along the line 9-9 of Figure 7; Figure 10 is a sectional view taken generally along the line 10-10 of Figure 7 showing a complementary feature of the latch portion of the snap hook; Figure 11 is a perspective view, partially in section, illustrating another embodiment of the locking feature of the blade and latch portions of the snap hook;; Figure 12 is an assembled side view of the embodiment of Figure 11; Figure 1 3 is a perspective view, partially in section, illustrating yet another embodiment of the locking feature of the blade and latch portions of the snap hook; Figure 14 is an assembled side view of the embodiment illustrated in Figure 13; Figure 1 5 is a side view of one embodiment of a retainer adapted to be used in combination with the novel snap hook of this invention; Figure 1 6 is an end view, partially in section, taken generally along the line of 1 6-1 6 of Figure 15; Figure 1 7 is a bottom view of the snap hook retainer of Fig. 15; Figure 1 8 is an end view of yet another embodiment of such a retainer; ; Figure 1 9 is a front view of one embodiment of a ring-like member adapted to be claspable by the snap hook of the present invention; Figure 20 is a side view, partially in section, taken generally along the line 20-20 of Figure 19; Figure 21 is a front view of yet another embodiment of such a ring-like claspable member; Figure 22 is a front view of still another embodiment of such a ring-like claspable member; and, Figure 23 is a perspective view of one embodiment of the snap hook system of the present invention as used in combination with a pair of webbing ends.

Referring to the drawings, and initially to Figure 1, an integrally formed one-piece snap hook referred to generally by the reference numeral 41, will now be discussed. The snap hook 41 comprises a bi-ended base portion 43, a blade portion 45, a re-entrant portion 50, and a latch portion 47.

With reference to Figures 1 and 7, it will be seen that the blade 45 is integral with a first end 49 of the base 43 through the re-entrant portion 50. Referring to Figure 3, it will be seen that the dimensions of the blade 45 converge outwardly from the re-entrant portion 50. In the embodiments presented in Figures 1, 4-6 and 7, it will be seen that the re-entrant section or portion 50 is generally C-shaped (when the snap hook 41 is viewed from the side). It also will be seen that the re-entrant portion 50 thus provides the snap hook 41 with an aperture 51. A preferred shape for the aperture 51 is a cylindrical surface of curvature having a substantially circular cross section, as presented in Figures 1, 6 and 7.

It can be seen, in Figures 1 and 7, that the aperture 51 has a mouth (referred to generally by the reference numeral 55) and two distally positioned and integrally formed lips 53. Referring to Figures 4-6, it will be seen that the aperture 51 is adapted to receive a cylindrical portion or section 57 of a retaining member or ring 59 which has been pushed past these lips 53 and into the aperture 51. Referring to Figures 4-6, it will also be seen that the cylindrical portion 57 of the retainer 59 has an outside diameter which is less than the inner diameter of the aperture 51, which thus permits the cylindrical portion 57 of the retainer 59 to freely pivot or turn within the aperture 51.

Referring to Figures 1 and 7, it will be seen that the latch 47 is integral with a second end 61 of the base 43. For the preferred embodiments of the present invention (presented in Figures 1 and 7), the latch 47 of the snap hook 41 is reversely bent toward the blade 45 at the second end 61 of the base 43 thereby providing the snap hook 41 with a pocket or corner (referred to generally by the reference numeral 63). The corner 63, together with the cooperation between the blade 45 and the latch 47, provides the snap hook 41 with the quality of being usable for clasping a wide variety of co-operating rings or like members. In the embodiments presented in Figures 1 and 7, the corner 63 is smooth and rounded; and the latch 47 and the second end 61 of the base 43 are joined thereat thereby providing the snap hook 41 with a substantially V-shaped clasping portion.It can be seen, when viewing Figures 1 and 7, that such clasping portion extends substantially from a distal end 67 of the latch 47 to the corner 63; and further includes substantially all of the base 43.

Referring to Figure 1, it will be seen that a distal end 65 of the blade 45 is resiliently movable in relation to the base 43 of the snap hook 41: it will further be seen that the re-entrant portion 50 flexes as the snap hook 41 is moved from the "relaxed" to the "locked" condition. On the other hand, the distal end 67 of the latch 47 remains fixed in relation to the base 43. The resilently movable feature of qualities of the blade portion 45 and the re-entrant section 50 thus provide the snap hook 41 with a "springy" quality. The snap hook 41 is preferably made of a suitably resilient and sufficiently durable substance, such as a plastic, thereby providing principally the blade 45 and the re-entrant 50 portions of the snap hook 41 with this springy quality.A preferred material for the manufacture of the snap hook 41 is a strong, hard, resilient, highly crystalline thermoplastic commercially known as acetal resin. In addition to acetal resin, however, it can be appreciated that the snap hook 41 can be molded from any suitably tough, resilient, plastic material.

Moreover, it can be appreciated that the springy quality of the snap hook 41 can otherwise be adjusted by altering the dimensions of the Cshaped re-entrant portion 50 surrounding the aperture 51, by altering the dimensions of the blade 45, by altering the type of plastic used to manufacture the snap hook 41 or by altering the amount of plasticizer used in the compositional make-up or recipe of such a plastic (if such a plastic requires use of such a plasticizer). For example, referring to Figure 7, it can be seen that the C-shaped re-entrant portion 50 (surrounding the aperture 51) can include another section or portion 71 formed integral therewith for increasing the force-resistive or resilient qualities of the re-entrant portion 50.

In one embodiment of the snap hook 41, presented in Figures 2 and 3, the distal end 65 of the blade 45, the distal end 67 of the latch 47 and the base 43, are substantially co-planar. Thus, when the re-entrant section 50 is subjected to a first force (a component of such a force being generally co-linear to the base 43) and the corner 63 is subjected to a second force, oppositely directed to the first, lateral movement of the distal end 65 of the blade 45 in relation to the distal end 67 of the latch 47 is substantially eliminated.

When the distal end 65 of the blade 45 is above the distal end 67 of the latch 47, as presented in Figures 1 and 7, the snap hook 41 is in a "relaxed condition". The hook 41 is in a "locked condition", as will be seen by referring to Figures 1 and 7, when the distal end 65 of the blade 45 is snapped beneath the distal end 67 of the latch 47. The preferred embodiment of the snap hook 41 is manufactured with the parts or sections being in the relaxed condition.

The snap hook 41 is adapted to be normally used in combination with the retainer 59.

Referring to Figures 1 5-17, a first embodiment of such a retainer 59 is seen to be a generally rectangular ring having a first longer side 72, a second longer side (which is opposed to the first side 72) and which comprises end portions 74 integrally formed at respective ends of the cylindrical portion 57 of the retainer 59. The retainer 59 further includes a pair of integrally formed shorter sides 76 which join paired ends of the first and second longer sides 72 and 74.

Furthermore, such a retainer 59 is provided with a substantially rectangular slot 78 through which an end of belting, strapping, webbing or the like can be secured. Referring to Fig.18, it will be seen that a second embodiment of such a retainer 59 can be manufactured to have such components.

As noted above, the aperture 51 of the snap hook 41 and the cylindrical portion 57 of the retainer are adapted to have a complementary geometry. The unique relationship between the portion or section 57 of the retainer 59 and the aperture 51 of the snap hook 41 will next be discussed.

Briefly, referring to Figures 4--6, it will be seen that the C-shaped re-entrant section 50 resiliently flexes whereupon the mouth 55 closes slightly thereby bringing the lips 53 toward one another when the snap hook 41 is moved from the relaxed condition to the locked condition.

Furthermore, the snap hook 41 is specifically adapted to be used in combination with the retainer member 59, two embodiments of such a retainer 59 being presented in Figures 1 5-1 8, whereby the retainer 59, in turn, can be connected to an end of a strap or belt or other similar element (as illustrated in Fig. 23). The retainer 59 is cooperatively assembled with the snap hook 41 by snapping the cylindrical portion or section 57 of the retainer 59 past the lips 53 and into the aperture 51. This action is presented inFigures4-6.

More specifically, while the snap hook 41 is in the relaxed condition, the cylindrical section 57 of the retainer 59 will be seen (referring to Figure 4) approaching the lips 53 of the aperture 51.

Reference to Fig. 5 presents the cylindrical section 57 of the retainer 59 engaging the lips 53 (while the snap hook 41 is in the relaxed condition) and the retainer 59 being pushed past the lips 53 and into the aperture 51. As soon as the cylindrical section 57 of the retainer 59 is snapped past the lips 53, the snap hook 41 can be moved into the locked condition by moving the blade 45 around the latch 47 and positioning the blade 45 therebelow in a biased manner, as can be seen by referring to the phantom lines in Figures 1 and 7. Such a biassed engagement is made between the distal end 65 of the blade 45 and the distal end of the latch 47.

In Figure 6, the co-operation between the cylindrical section 57 of the retainer 59 and the aperture 51 of the snap hook 41 will be seen while the snap hook 41 is in such a locked condition. As the lips 53 are brought toward one another when the snap hook 41 is moved into the locked condition, it can further be appreciated by referring to Figure 6, that the lips 53 thus cooperate to lockingly retain the cylindrical section 57 of the retainer 59 within the aperture 51.

If desired, the retainer 59 can be removed from the aperture 51 of the snap hook 41 by reversing the procedure set forth above.

Referring to Figures 7-10, several features of a second embodiment of the invention will now be discussed.

It has previously been noted that the C-shaped re-entrant portion 50 can include the integrally formed section 71 for increasing the forceresistive or resilient qualities of the snap hook 41.

The second embodiment will also be seen to include a plurality of projections 73, 75 and 77 specifically adapted to prevent both lateral and longitudinal movement of the distal end 65 of the blade 45 in relation to the distal end 67 of the latch 47 (while the snap hook 41 is in the locked condition). With the snap hook 41 in the locked condition, the projections 73 and 75 extend away from the distal end 65 of the blade 45 and also extend in the direction of the distal end 67 of the latch 47. The projection 77 extends away from the distal end 67 of the latch and in the direction of the distal end 65 of the blade 45, where it interfits with the projections 73 and 75. The projection 77 thus fits between the projections 73 and 75, and lateral movement of the distal end 65 of the blade 45, in relation to the distal end 67 of the latch 47, is effectively eliminated.The second embodiment of the snap hook 41 (Figure 7), is thus highly resistant to disengagement of the blade 45 from the latch 47 while the snap hook 41 is in such a locked condition.

Referring to Figures 11-14, two more embodiments of this latch-locking feature will now be discussed.

Referring to Figures 11-12, it will be seen that such projections can take the form of interlocking blocks 81,83, 85, 87 and 89. The substantially rectangularly-shaped blocks 81,83 and 85 will be seen to extend outwardly from the distal end 65 of the blade 45 and to interfit with the substantially rectangularly-shaped blocks 87 and 89 of the distal end 67 of the latch 47.

Referring to Figures 1 3-14, it will be seen that such a latch-locking feature can also take the form of an extension 91 adapted to fit into a slot 93 between two projections 95. The substantially rectangularly-shaped extension 91 will be seen to extend outwardly from the distal end 67 of the latch 47 and to fit into the substantially rectangularly-shaped slot 93 formed between the two curled projectiohs 95 which extend away from the distal end 65 of the blade 45. These are but a few of the embodiments that the latchlocking feature of the snap hook 41 can assume.

A variety of ring-like members, referred to generally by the reference numeral 97 and adapted to be clasped by the snap hook 41, will next be discussed.

Referring to Figures 1 9-20, it will be seen that one such claspable member 97A can be a triangular ring 99. The triangular ring 99 is integrally formed of a suitable plastic. The ring 99 is an isosceles triangle having legs 101 and a base 103. The triangular ring member 99 is normally clasped by the snap hook 4-1 by inserting the distal end 67 of the latch 47 through an open portion or hole 109 of the triangular ring 99 with the corner 63 of the snap hook 41 clasping an apex 104. The open portion or hole 109 is seen to be of a size and shape sufficient to accommodate an end of webbing or the like.

A second embodiment of a ring-like member 97B will be seen, by referring to Figure 21, to be an equilateral triangle ring-like member 105 having sides 108. The triangular ring member 105 is normally clasped by the snap hook 41 by inserting the distal end 67 of the latch 47 through the open portion or hole 109 of the triangular ring 105 with the corner 63 of the snap hook 41 clasping any apex 106.

Referring to Figure 22, it will be seen that a third embodiment of such a ring-like member 97C is a rectangular ring 107 having a longer side 121, an opposite longer side comprising a circular portion 123 (approximately located in the middle of such opposed longer side) and shorter sections 125 extending outwardly from the circular portion 123, and shorter sides 127 which connect the longer side 121 to the opposed longer side. The rectangular ring 107 includes a slot 110 sufficient in size and shape to accommodate an end of webbing or the like. The rectangular ring 107 further includes a hole 129 centrally located within the circular portion 123. The rectangular ring 107 is normally clasped by the snap hook 41 by inserting the distal end 67 of the latch 47 through the hole 129 with the corner 63 of the snap hook 41 clasping the circular portion 123.

Referring to Figure 23, it will be seen that the ring-like member 97 can be adapted to assume a shape consistent with a use therefor. The snap hook 41 is presented as holding a free end 111 of a piece of webbing 113 in fixed relation to another free end 11 5 of a second piece of webbing 116.

Moreover, the retainer 59 can assume a variety of shapes. Although the preferred embodiment of the retainer 59 is the substantially rectangular ring illustrated in Figures 15-18, and 23, it will be appreciated that only the cylindrical portion or section 57, bounded by the end portions 74, is a critical element of the retainer 59. Referring to Figures 1 5 and 16, it will be seen that the end portions 74 are adapted along an edge 117 to be substantially greater in linear dimension than is the diameter of the cylindrical portion or section 57 of the retainer 59 thereby retaining the cylindrical portion 57 within the aperture 51. The preferred retainer 59, moreover, is adapted at the edges 1 17 to substantially prevent free longitudinal movement of the cylindrical portion or section 57 as such pivots or turns within the aperture 51.

Thus, a snap hook system, as contemplated by this invention, comprises the snap hook 41, and the retainer member 59 (which is adapted to engage with the aperture 51 and thereby cooperate with the snap hook 41). Moreover, such snap hook system further includes the ringlike member 97 adapted to permit quick and easy engagement with (or disengagement from) a clasping portion or corner 63 of the snap hook 41.

From this it can be seen that a single snap hook 41 may be used with various sizes of retainers 59 and ring-like members 97. Clearly, when various sizes of straps are used a complementary sized retainer 59 and ring-like member 97 should be used therewith. The advantage of the instant snap hook system being not only the novel construction of the component parts but the interchangeability of a single snap hook with preselected retainers 59 and ring-like members 97 of different sizes. For example, a one inch wide strap may be attached to a two inch wide strap or a three inch wide strap may be attached to a three inch wide strap, etc., where the retainer and ringlike member are properly sized for each respective strap, using the snap hook system of the instant invention.It should be evident that a single snap hook may be packaged with a plurality of different sizes of retainers 59 and ring-like members 97 giving the user the capabilty of attaching different pairs of straps where each pair is of a particular size as well as straps of different sizes with a single universal snap hook as described herein. It can be appreciated that the cooperation between the retainer 59 and the snap hook 41 aperture 51 provides a means for positively locating the snap hook 41 in relation to the cylindrical section or portion 57 of the retainer member 59 while the cylindrical portion 57 is engaged in the aperture 51 and the snap hook 41 is in the locked condition.

It is further contemplated that such a snap hook system can be advantageously used in combination with ends of belting, strapping, webbing or the like, but that the usefulness of the invention is not limited to combinations therewith.

The preferred snap hook system is made from a single durable and resilient substance such as the commerically available plastic described above, thereby avoiding costs resulting from manufacturing the snap hook system from dissimilar materials.

The term straps is clearly intended to be generic to belts, webbing or the like.

Claims

1. A snap hook system comprising: a first means including a base having a hook-shaped end and a second end, with a blade portion extending from said second end for selectively controlling access to and from said hook-shaped end; and a second means including a substantially cylindrical portion to be confined at said second end of said first means and a further portion for securing a strap thereto.

2. A snap hook system according to claim 1, in which said second means is selected from a plurality of predetermined sizes of said second means wherein each size corresponds to a predetermined width of strap.

3. A snap hook system according to claim 1 or claim 2, in which a third means includes a first portion to be held by said hook-shaped end of said first means and a further portion for securing a strap thereto.

4. A snap hook system according to claim 3, in which said third means is selected from a plurality of predetermined sizes of said third means wherein each size corresponds to a predetermined width of strap.

5. A snap hook comprising: a bi-ended base portion, a blade portion, a re-entrant portion and a latch portion; a first end of said base portion being integral with said blade portion through said reentrant portion thereby providing said snap hook with an aperture which is located intermediate said base portion and said blade portion, is accessible through a mouth of restricted depth and is for receiving a substantially cylindrical portion of a retainer, a second end of said base portion being integral with said latch portion thereby providing said snap hook with a hook; a free end of said blade portion being in distal relation to said base portion, a free end of said latch portion being in distal relation to said base portion, a relaxed condition for said snap hook being defined when said distal end of said blade portion is positioned above said distal end of said latch portion in relation to said base portion, a locked condition for said snap hook being defined when said distal end of said blade portion is positioned beneath said distal end of said latch portion in relation to said base portion; said mouth being adapted to lockingly retain said substantially cylindrical portion of said retainer within said aperture when said snap hook is in said locked condition, and said snap hook being maintained in said locked condition by a biased engagement between said distal end of said blade portion and said distal end of said latch portion.

6. A snap hook according to claim 5, in which said base portion and said latch portion form a substantially V-shaped hook at the junction thereof.

7. A snap hook according to claim 5 or claim 6, in which said re-entrant portion has a generally tubular shape and is split along its length at said mouth.

8. A snap hook according to any one of claims 5 to 7, in which said mouth is defined by and lies between a pair of opposed lips.

9. A snap hook according to any one of claims 5 to 8, in which said re-entrant portion and said aperture provided thereby are substantially wider than and project laterally to both sides of said base portion and said latch portion.

10. A snap hook according to any one of claims 5 to 9, in which said re-entrant portion is strengthened by a reinforcing rib.

11. A snap hook according to any one of claims 5 to 10, in which said distal end of said blade portion, said distal end of said latch portion and said base portion are substantially parallel when viewed in transverse cross-section.

12. A snap hook according to any one of claims 5 to 11, in which said distal end of said blade portion includes a first plurality of projecting surfaces and said distal end of said latch portion includes a second plurality of projecting surfaces, said first plurality of projecting surfaces extending outwardly from said distal end of said blade portion and interfitting with said second plurality of projecting surfaces when said snap hook is in said locked condition, whereby lateral or transverse movement of said distal end of said blade portion with respect to said distal end of said latch portion is substantially limited.

13. A snap hook according to any one of claims 5 to 12, in which said blade portion converges in width along its length towards said distal end thereof.

14. A snap hook according to any one of claims 5 to 13, in which said base portion, said blade portion, said re-entrant portion and said latch portion are integrally formed of a plastics material.

1 5. A snap hook substantially as hereinbefore described with reference to Figures 1 to 6, or Figures 7 to 10, or Figures 1 to 6 or Figures 7 to 10 as modified by Figures 11 and 12 or Figures 13 and 14, of the accompanying drawings.

1 6. A snap hook and a retainer in combination therewith, said snap hook being formed in accordance with any one of claims 5 to 15, and said retainer including a substantially cylindrical portion confined in said aperture provided by said re-entrant portion of said snap hook and a further portion for securing a strap thereto.

1 7. A snap hook and a retainer according to claim 16, in which said retainer has a generally rectangular shape.

1 8. A snap hook and a retainer according to claim 1 6 or claim 17, in which each end of said substantially cylindrical portion of said retainer is bounded by a stop extending outwardly of said substantially cylindrical portion whereby longitudinal movement of said substantially cylindrical portion of said retainer with respect to said aperture provided by said re-entrant portion of said snap hook is substantially limited.

1 9. A snap hook and a retainer according to any one of claims 16 to 18, in which said retainer is integrally formed of a plastics material.

20. A snap hook and a retainer according to any one of claims 16 to 19, in which there is a plurality of different sizes of said retainers corresponding to a plurality of different widths of strap with a selected one of said retainers being secured to said snap hook.

21. A snap hook and a retainer according to claim 20, in which each of said plurality of different sizes of said retainers is of a different colour.

22. A snap hook and a retainer in combination therewith substantially as hereinbefore described with reference to Figures 1 to 6, or Figures 7 to 10, or Figures 1 to 6 or Figures 7 to 10 as modified by Figures 11 and 12 or Figures 13 and 14, of the accompanying drawings for said snap hook, in combination with Figures 1 5 to 17, or Figure 1 8, of the accompanying drawings for said retainer.

23. A snap hook and a ring in combination therewith, said snap hook being formed in accordance with any one of claims 5 to 15, and said ring including a first portion through which said latch portion of said snap hook has been inserted and a further portion for securing a strap thereto.

24. A snap hook and a ring according to claim 23, in which said ring has a generally triangular shape.

25. A snap hook and a ring according to claim 24, in which said generally triangular shape is that of an isosceles triangle.

26. A snap hook and a ring according to claim 24, in which said generally triangular shape is that of an equilateral triangle.

27. A snap hook and a ring according to claim 23, in which said ring has a generally rectangular shape defining a slot through which a strap may be inserted as well as a separate hole through which said latch portion of said snap hook has been inserted.

28. A snap hook and a ring according to any one of claims 23 to 27, in which said ring is integrally formed of a plastics material.

29. A snap hook and a ring according to any one of claims 23 to 28, in which there is a plurality of different sizes of said rings corresponding to a plurality of different widths of strap with a selected one of said rings being secured to said snap hook.

30. A snap hook and a ring according to claim 29, in which each of said plurality of different sizes of said rings is of a different colour.

31. A snap hook and a ring in combination therewith substantially as hereinbefore described with reference to Figures 1 to 6, or Figures 7 to 10, or Figures 1 to 6 or Figures 7 to 10 as modified by Figures 11 and 12 or Figures 13 and 14, of the accompanying drawings for said snap hook, in combination with Figures 1 9 and 20, or Figure 21, or Figure 22, of the accompanying drawings for said ring.

32. A combination according to any one of claims 1 6 to 22 itself in combination with a combination according to any one of claims 23 to 31 wherein said snap hook is common to both combinations to form a snap hook system.

33. A snap hook system according to claim 32, in which said retainer is secured to a strap, and said ring is secured to a strap.