Improved ladder securement device

Abstract

A ladder securement device 1 is disclosed for securing a ladder 2 to a vehicle for transportation. The device comprises an anchor 10, defining an engagement portion such as a hook (11, figure 6) engag

Description

Field of the invention The invention relates to an improved ladder securement device for securing a ladder to vehicle mounting elements, such as roof bars. Background to the invention A ladder is often transported on a vehicle, such as a van, by lying it flat along a pair of roof bars. A securing means is then utilised to fix the ladder in place on the roof bars, by clamping or locking the ladder to the roof bars. A variety of different solutions exist to serve this purpose. One type of existing securement device utilises a bridge, an anchor and a clamp. The anchor has a hook integral with a rod. The hook connects to the underside of the bar, with the rod upstanding to connect with the bridge and clamp. The bridge has a through hole to receive the rod, and spans across the top of the rails of the ladder. The clamp is connected to the rod and, during manual securement, is pushed down against the bridge, at the same time as pulling up on the hook of the anchor, thus sandwiching the ladder between the roof bar and the bridge. This arrangement allows quick fitting and release of the ladder. However, the reliability with which the ladder is held depends on the force of the clamp. During transit, and over time, the ladder can work itself loose, with the clamp slipping along the rod. This arrangement also makes the ladder prone to theft, with the force of the clamp being relatively easily overcome. It is against this background that the present invention has been devised. Summary of the invention According to a first aspect of the present invention there is provided a ladder securement device, preferably for securing a ladder to a vehicle for transportation. Preferably, the device comprises at least one of: an anchor, ideally defining an engagement portion (such as a hook) engageable with a vehicle mounting element (such as a roof bar); and a retainer ideally cooperable with the anchor to releasably retain a ladder to the vehicle mounting element. Preferably, the anchor further defines a threaded rod. Preferably, the retainer comprises a coupling assembly. Preferably, the coupling assembly comprises a nut portion defining a threaded bore for complementary threaded engagement with the threaded rod of the anchor. The coupling assembly may comprise at least one handle. The at least one handle may extend radially outwards from the nut portion, ideally to facilitate manual tightening of the coupling assembly via its rotation relative to the anchor. Preferably, the coupling assembly may comprise a contact surface facing towards the ladder in use, and arranged to move towards the ladder, along an axis of the threaded bore, during tightening of the coupling assembly via its rotation relative to the anchor. Preferably, the nut portion of the coupling assembly further defines a slip bore. Preferably, the slip bore defines an axis substantially intersecting but inclined relative to the axis of the threaded bore. Preferably, the slip bore has a diameter greater that of the threaded rod of the anchor. Preferably, the nut portion can be tilted between: a quick-release configuration in which the threaded rod of the anchor is aligned with the slip bore, ideally releasing the coupling assembly to be freely slidable axially along the threaded rod of the anchor; and an engaged configuration in which the threaded rod of the anchor is aligned and engaged with the threaded bore, constraining movement of the coupling assembly relative to the anchor ideally to a screwing motion. Preferably, the retainer comprises a bridge for spanning across the ladder. Preferably, the bridge defines at least one of: a ladder-facing surface for contacting with the ladder in use; and a through-hole arranged to slidingly receive the threaded rod of the anchor. Preferably, the through-hole extends along a through-hole axis that is substantially perpendicular to the ladder-facing surface. Preferably, the bridge further comprising a top surface shaped in complement with the contact surface of the coupling assembly to urge the through-hole of the bridge and the threaded bore of the coupling assembly to become substantially coaxial with one another as the coupling assembly tightens against the bridge. Preferably, the top surface of the bridge and the contact surface of the coupling assembly are shaped, when in abutment with one another, to slide against one another, and rotate relative to one another about the axis of the through-hole. Preferably, the ladder-facing surface of the bridge defines at least one lip, the at least one lip being located towards the edge of the bridge, and protruding away from the surface so as to limit lateral slippage of a ladder beyond the ladder-facing surface. Preferably, the device comprises a lock assembly arranged to be switchable by a user between a locked and unlocked configuration, wherein when the nut portion is in the engaged configuration, and the lock assembly is in the locked configuration, the lock assembly restrains movement of the coupling assembly relative to the anchor. Preferably, the lock assembly acts between the bridge and the coupling assembly, locking them to one another when the lock assembly is in the locked configuration. Preferably, the lock assembly comprises a lock plate, configured to slide between the bridge and the coupling assembly, coupling them to one another when the lock assembly is in the locked configuration. Preferably, the lock plate is arranged to slide into a keep defined by coupling assembly when the lock assembly is in the locked configuration. It will be understood that features and advantages of various aspects of the invention may be combined or substituted where context allows. For example, the features of the device of the first aspect of the invention may be provided as part of a method according to a second aspect of the present invention. Furthermore, individual features in isolation, such as the coupling assembly, bridge and anchor of the device of the first aspect of the invention may themselves constitute further aspects of the present invention. Brief description of the drawings In order for the invention to be more readily understood, embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic overhead perspective view of a ladder securement device according to an embodiment of the present invention, the device being shown securing a ladder to a roof bar of a vehicle; Figure 2 is an overhead perspective view of a coupling assembly of the device of Figure 1 in isolation; Figure 3 is an overhead perspective view of a nut portion of the coupling assembly of Figure 2 in isolation; Figure 4 is a cross sectional view of the nut portion of Figure 3; Figure 5 is an overhead perspective view of a bridge of the device of Figure 1 in isolation; Figure 6 is an overhead perspective view of an anchor of the device of Figure 1 in isolation; Figure 7 is an underside perspective view of the coupling assembly of Figure 2; Figure 8 is a perspective view of a cylinder lock of the bridge of Figure 5; Figure 9 is a perspective view of a lock plate of the bridge of Figure 5; Figure 10 is an enlarged partial cross-sectional view of the device of Figure 1 in a locked configuration; Figure 11 is a cross sectional view of the device, ladder and roof bar of Figure 1, the device being in the same locked configuration as Figure 10; Figure 12 is an enlarged partial cross-sectional view of the device of Figure 1 in an unlocked configuration in which the coupling assembly is engaged with a threaded rod of the anchor; Figure 13 is a cross sectional view of the device, ladder and roof bar of Figure 1, the device being in the same unlocked configuration as Figure 12; Figure 14 is an enlarged partial cross-sectional view of the device of Figure 1 in a quickrelease configuration in which the coupling assembly is disengaged from the threaded rod of the anchor; and Figure 15 is a cross sectional view of the device, ladder and roof bar of Figure 1, the device being in the same quick-release configuration as Figure 14. Specific description Figure 1 is a schematic overhead perspective view of a ladder securement device 1 according to an embodiment of the present invention. The device 1 is shown in Figure 1 securing a ladder 2 to a vehicle mounting element in the form of a roof bar 3. In practice, the ladder 2 extends to and is secured relative to another roof bar, but for clarity this is not shown. The ladder securement device 1 comprises an anchor 10, and a retainer composed of a coupling assembly 20 and a bridge 40. Figure 2 is an overhead perspective view of the coupling assembly 20 which comprises a pair of arms 21, 22, a cylindrical hub 23, and a nut portion 30. The hub 23 defines a nut recess within which the complementarily shaped nut portion 30 is received. The arms 21, 22 are integrally formed with the hub 23, and extend away from it at diametrically opposed positions. Each arm 21, 22 is kinked to define a root portion that is proximal to the hub 23 and extending radially away from it, and an end portion that is distal from the hub 23 that is inclined upwards at an acute angle relative to the root portion. The raised end portions of the arms 21, 22 form handles that ease manual twisting for tightening and loosening of the coupling assembly 20 as will be described below. Figure 3 is an overhead perspective view of the nut portion 30 in isolation. The nut portion 30 comprises an enlarged midsection with a pair of flat sides 31, 32 that locate within the complementarily-shaped recess within the hub 23 preventing relative rotation, in use, of the nut portion 30 and the hub 23. An upper shoulder 33 of the midsection limits insertion of the nut portion 30 within the hub 23 during fabrication, allowing an upper cylindrical section 34 of the nut portion 30 to sit within a hole in the upper central part of the hub 23, as visible in Figure 2. Likewise, a lower shoulder 36 marks a step transition between the midsection and a lower cylindrical section 37 of the nut portion 30. Figure 4 is a cross sectional view of the nut portion of Figure 3 taken along section line IV-IV of Figure 3. The nut portion 30 defines a threaded bore extending axially along axis T between the upper and lower cylindrical sections 34, 37. The nut portion 30 also defines a smooth slip bore that also extends between the upper and lower cylindrical sections 34, 37 along axis S, and partially overlaps with the threaded bore. The axis S of the slip bore is inclined relative to that of the axis T of the threaded bore, with the axes S, T intersecting midway through the centre of the nut portion. Thus, the internal shape of the nut portion 30 comprises both threaded regions 35 and smooth regions 38. Figure 5 is an overhead perspective view of the bridge 40 in isolation. The bridge 41 defines a central through-hole 41 leading from an upper wall defining an upper top surface 42 to a lower wall defining a lower ladder-facing surface 43. Broadly, the top and lower walls extend longitudinally along horizonal parallel planes, with the axis B of the through-hole of the bridge 40 extending perpendicularly to these planes. Central spines 44 interconnect the upper and lower walls, the spines 44 extending at intervals along a vertical plane that extends longitudinally, bisecting the upper and lower walls, and the axis B of the central through-hole 41. The lower surface 43 of the bridge 40 is textured with lateral non-slip ribs 45. Additionally, the lower surface 43 of the bridge 40 defines a lip 46 at each side edge of the bridge, each lip protruding downwardly, away from the lower surface 43. An annular seat 47 forms a depression in the upper wall in the region surrounding the central through-hole 41. A plate slot 48 cuts into the upper wall, the plate slot 48 leading into an interior lock chamber of the bridge 40, the lock chamber defining a lateral bushing 49 opening to the front of the bridge 40. Figure 6 is an overhead perspective view of the anchor 10. The anchor 10 defines an engagement portion in the form of a hook 11, and a threaded rod 12. The rod 12 and hook 11 are integral with one another, typically formed from a hardwearing metal such as steel. Figure 7 is an underside perspective view of the coupling assembly 20. The coupling assembly further comprises an annular baseplate 24 having an internal diameter snugly accommodating the diameter of the lower cylindrical section 37 of the nut portion 30. During fabrication of the coupling assembly 20 the nut portion 30 is inserted into the hub 23 from underneath, and then the baseplate 24 is fixed in place via bolts underneath the nut portion 30, with the lower cylindrical section 37 of the nut portion 30 being held level with the lower surface of the baseplate 24. Bolt holes 25 allow insertion of the bolts into threaded bolt recesses 28 within the hub. The baseplate 24 protrudes from the underside of the coupling assembly 20 to the same extent as the annular seat 47 forms a depression in the upper wall of the bridge 40. An underside of each root portion of the arms 21, 22 defines a recessed keep 26. An underside of the end portion of the arms are also recessed to reduce material usage, but with lateral and longitudinal arm spines 27 providing strength to the arms of the coupling assembly 20. Figure 8 is a perspective view of a cylinder lock 50, and Figure 9 is a perspective view of a lock plate 60 of the bridge of Figure 5. The lock 50 fits within the lateral bushing 49 and is arranged to receive a key via key slot 51 to allow authorised rotational operation of the lock 50. A tail portion 52 of the lock 50 mates with a complementary aperture 61 defined with the lock plate 60 to allow the lock plate 60 to pivot together with the rotational operation of the lock 50. The lock plate 50 is arranged to pivot within the interior lock chamber of the bridge 40, sliding through the plate slot 48. Securement and release of a ladder 2 to a roof bar 3, using the ladder securement device 1 of the present embodiment will now be described primarily with reference to Figures 10 to 15. Figures 10 and 11 are cross sectional views of the device 1 in a locked configuration, securing the ladder 2 to the roof bar 3. Figure 10 shows an enlarged view of the central section of Figure 11 marked with a dashed box. Figures 12 and 13 are cross sectional views of the device 1 in an unlocked configuration, but with the coupling assembly being engaged with the threaded rod 12 of the anchor 10. Figure 12 shows an enlarged view of the central section of Figure 13 marked with a dashed box. Figures 14 and 15 are cross sectional views of the device 1 in an unlocked and quickrelease configuration, with the coupling assembly being disengaged from the threaded rod 12 of the anchor 10. Figure 14 shows an enlarged view of the central section of Figure 15 marked with a dashed box. Starting with Figures 14 and 15, a securement process is described. The ladder 2 is rested on the roof bar 3, and the hook 11 of the anchor 10 is engaged with the roof bar 3 by hooking underneath it. The threaded rod 12 extends upwards and the bridge 40 is fitted in place by sliding the rod 12 via the through-hole 41 of the bridge 40. The lower surface 43 of the bridge 40 rests across the rails of the ladder 2. The coupling assembly 20 can then be quickly fitted to the threaded rod 12 by tilting it so that the axis of the slip bore S of the nut portion 30 is aligned with the axis A of the threaded rod 12 of the anchor 10. The slip bore S has a diameter greater that of the threaded rod 12 of the anchor 10, and so the coupling assembly 20 is freely slidable in the axial direction along the rod 12 until an arm 21, 22 of the coupling assembly 20 contacts with the bridge 40. The coupling assembly 20 can then be tilted relative to the threaded rod 12 of the anchor 10 as shown in Figures 12 and 13. This causes the threaded rod 12 of the anchor 10 to become aligned and engaged with the threaded bore of the nut portion 30, with the axis T of the threaded bore becoming aligned with the axis A of the threaded rod 12 of the anchor 10. This constrains movement of the coupling assembly 20 relative to the anchor 10 to a screwing motion. Using the arm handles 21, 22 the coupling assembly 20 can be rotated manually relative to the threaded rod 12 screwing it in toward the bridge 40. Eventually, the coupling assembly 20 comes into full abutment with the bridge 40, with the baseplate 24 registering with the annular seat 47, as shown in Figure 10 and 11. More generally, the top surface of the bridge 40 is shaped in complement with the underside contact surface of the coupling assembly 20 so as to urge the through-hole 41 of the bridge and the threaded bore of the coupling assembly 20 to become substantially coaxial with one another as the coupling assembly 20 tightens against the bridge 40. The coupling assembly 20 can be tightened to an extent that urges the hook 11 upwards and sandwiches the ladder 2 between the roof bar 3 and the bridge 40. Due to the contact between the coupling assembly 20 and the bridge 40, the coupling assembly 20 cannot be tilted to the quick-release angle, thus securing the ladder. Furthermore, the lips 46 limit how far the device 1 can be laterally displaced relative to the ladder 2. The coupling assembly 20 is rotated to an extent that aligns one of the recessed keeps with the plate slot 48, thus allowing the cylinder lock 50 to be operated to raise the lock plate 60 into the keep 26, thus preventing unauthorised removal of the ladder securement device 1. Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the scope of the appended claims.

Claims

1. A ladder securement device for securing a ladder to a vehicle for transportation, the device comprising:an anchor, defining an engagement portion engageable with a vehicle mounting element, the anchor further defining a threaded rod;a retainer cooperable with the anchor to releasably retain a ladder to the vehicle mounting element;wherein the retainer comprises:a coupling assembly comprising: a nut portion defining a threaded bore for complementary threaded engagement with the threaded rod of the anchor; at least one handle extending radially outwards from the nut portion to facilitate manual tightening of the coupling assembly via its rotation relative to the anchor; and a contact surface facing towards the ladder in use, and arranged to move towards the ladder, along an axis of the threaded bore, during tightening of the coupling assembly via its rotation relative to the anchor;wherein the nut portion of the coupling assembly further defines a slip bore, the slip bore defining an axis substantially intersecting but inclined relative to the axis of the threaded bore, the slip bore having a diameter greater that of the threaded rod of the anchor, thereby allowing the nut portion to be tilted between:a quick-release configuration in which the threaded rod of the anchor is aligned with the slip bore, releasing the coupling assembly to be freely slidable axially along the threaded rod of the anchor; andan engaged configuration in which the threaded rod of the anchor is aligned and engaged with the threaded bore, constraining movement of the coupling assembly relative to the anchor to a screwing motion.

2. The device of claim 1, wherein the retainer further comprises a bridge for spanning across the ladder, the bridge defining: a ladder-facing surface for contacting with the ladder in use; and a through-hole arranged to slidingly receive the threaded rod of the anchor, the through-hole extending along a through-hole axis that is substantially perpendicular to the ladder-facing surface.

3. The device of claim 2, wherein bridge further comprises a top surface shaped in complement with the contact surface of the coupling assembly to urge the through-hole of the bridge and the threaded bore of the coupling assembly to becomesubstantially coaxial with one another as the coupling assembly tightens against the bridge.

4. The device of claim 3, wherein the top surface of the bridge and the contact surface of the coupling assembly are shaped, when in abutment with one another, to slide against one another, and rotate relative to one another about the axis of the through-hole.

5. The device of any one of claims 2 to 4, wherein the ladder-facing surface of the bridge defines at least one lip, the at least one lip being located towards the edge of the bridge, and protruding away from the surface so as to limit slippage of a ladder beyond the ladder-facing surface.

6. The device of any preceding claim, wherein the device comprises a lock assembly arranged to be switchable by a user between a locked and unlocked configuration, wherein: when the nut portion is in the engaged configuration, and the lock assembly is in the locked configuration, the lock assembly restrains movement of the coupling assembly relative to the anchor.

7. The device of claim 6, when dependent on any one of claims 2-5, wherein the lock assembly acts between the bridge and the coupling assembly, locking them to one another when the lock assembly is in the locked configuration.

8. The device of claim 7, wherein the lock assembly comprises a lock plate, configured to slide between the bridge and the coupling assembly, coupling them to one another when the lock assembly is in the locked configuration.

9. The device of claim 8, wherein the lock plate is arranged to slide into a keep defined by coupling assembly when the lock assembly is in the locked configuration.11

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