AU2004201125B2 - A Ladder Climbing Device and Safety System - Google Patents

Description

Regulation 3. AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT (ORIGINAL) Name of Applicant: Buller Ski Lifts Pty Ltd Actual Inventor: Ronald Robert BATEUP Address for Service: DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000. Invention Title: "A Ladder Climbing Device and Safety System" Details of Associated Provisional Application Nos: Australian Provisional Patent Application No. 2003901199 filed 17 March 2003 AND Australian Provisional Patent Application No. 2003906316 filed 17 November 2003 The following statement is a full description of this invention, including the best method of performing it known to us: Q:\OPER\PHH\1 2426140 COMFILING.DOC - 17/3/04 P0PER\PIIi] 24264amend doc-5A8/2009 -2 A LADDER CLIMBING DEVICE AND SAFETY SYSTEM The present invention relates to the safe climbing of ladders and is particularly concerned with a ladder climbing device and with a ladder safety system for controlling the user's 5 ascent or descent of the ladder. The climbing of ladders is recognized as a potentially dangerous activity and in at least some work situations there are regulations requiring a fall arrest system to be used to provide a safe working environment for the climber of the ladder. 10 Currently, the only system available for confidently and reliably climbing ladders in icy conditions is a double lanyard system. In this system, the two lanyards are connected to the climber, each lanyard having a hook at its free end that is engaged with a ladder rung. As the climber grips a rung of the ladder with one hand, the other hand is used to move 15 each hook separately, ensuring one hook is attached at all times. This means the user has to stop climbing as the safety system is adjusted, and it is therefore slow and clumsy. According to the present invention, there is provided a ladder climbing device having a hook for engaging a rung of a ladder, means for receiving a tether from a user, a handle 20 portion for the user to grip the device and manually move the device from one rung to another rung to control the user's ascent or descent of the ladder, a latch for the hook, the latch being biased into a condition in which it closes an open end of the hook to prevent removal of the hook from a rung and being manually actuatable through a latch actuating mechanism of the device to move the latch from the closed condition to an open condition, 25 and a latch locking mechanism for locking the latch in the closed condition. Also according to the present invention, there is provided a ladder safety system comprising two ladder climbing devices each having a hook for engaging a respective rung of a ladder and further comprising tethering means for connecting the ladder engaging 30 devices to a user's body, each of the ladder engaging devices having a handle portion for the user to grip the device and manually move the device from one rung to another rung to P:\OPER\PHI\2426140 specidoc-17/0304 -3 control the user's ascent or descent of the ladder, a latch for the hook, the latch being biased into a condition in which it closes the hook to prevent removal of the hook from a rung and being manually actuatable to move the latch from the closed condition to an open condition, and a latch locking mechanism for locking the latch in the closed condition. 5 By the invention, the ladder safety system is used effectively as an extension of the climber's hands to actually ascend or descend the ladder. Thus, the hook of each climbing device gripped by the climber is engaged over a rung of the ladder instead of the climber's hand gripping the rung. Should the climber slip or otherwise fall from the ladder, his fall 10 will be arrested by the tether connected to the at least one hook that was engaged with a rung at the time. Use of the system of the invention is advantageous over the aforementioned double lanyard system because less energy is expended. Thus, it is not necessary to stop regularly during the ascent or descent of the ladder to move the hooks. 15 The tethering means of the safety system may be permanently connected to the ladder climbing devices, but more conveniently it is selectively engageable and removable from the ladder climbing devices and the ladder climbing device may be supplied without the tethering means. Thus, the ladder climbing device may have connector, such as a ring, opening or loop, for receiving a tethering means connected or to be connected to the user. 20 The tethering means may be connected to the ladder climbing device at any convenient location. However, most conveniently the means for receiving the tether is provided adjacent the open end of the hook so that when a force is applied to it, such as the weight of the user, with the device engaged with a rung, the force from the tethering means tends 25 to urge the hook in a direction such that the rung moves relatively further towards a closed end of the hook. The tethering means may comprise a respective tether associated with each ladder engaging device or a continuous tether, extending between the two ladder climbing 30 devices. In the latter arrangement, a user connector may be provided on the continuous tether that is selectively adjustible along the tether. This will allow relative adjustment of P:\OPER\PHHfl2426140 spei.doc.17/03/04 -4 the length of the portion of the continuous tether extending to each ladder climbing device. Preferably, the tethering means includes a user harness. However, such a harness may be supplied separately to the ladder safety system. In a most preferred embodiment, the 5 harness is a full leg and shoulder harness. The hook may take any of a variety of suitable shapes, so long as it defines a structure that is at least capable of being open at an end, to receive a ladder rung, but is preferably substantially deeper than the cross section of the rungs of the ladder so as to ensure secure 10 engagement with a rung. In one embodiment, the hook may have an axis of at least the open end portion that extends generally parallel to the length of the forearm when the engagement device is gripped by the user. This may assist the ergonomic usage of the device. In this 15 embodiment, the axis of a closed end portion of the hook may be inclined relative to that of the open end so as to enhance the secure engagement of the hook with the rung. The closed end portion may be reinforced and/or carry a wear strip that could be replaceable, to alleviate weakening of the hook by multiple engagements with ladder 20 rungs. The hook may be formed of, for example, forged steel, but preferably it is cast or otherwise formed in aluminium or other lightweight, high strength materials, such as metallic alloys, as are used in climbing equipment. 25 Conveniently, at least a free end portion of the hook has a small cross-section, for example smaller than that of the handle portion, so that the hook can be received in a permanent opening or other connection point on the installation that has been climbed using the ladder. The cross-section of the hook may vary depending upon the material used, in order 30 to provide the required strength in various parts of the hook.

P:\OPER\PHI\2426140 spci.doc.17/03/04 -5 The handle portion may take any suitable shape given that the ladder engaging device is not intended to be released from the user's hand while the user is ascending or descending the ladder. Generally, the handle portion will extend from the hook, that is the handle portion will be connected to or integral with the hook but be otherwise structurally separate 5 from it. For example, the handle portion may extend laterally to the plane or cross-section of the hook, so as to effectively extend substantially parallel to the rungs of the ladder in use and thereby better replicate the rung. In one variation of this alternative, the ladder climbing device could include two hooks, both connected or connectable to the same tether, with the handle portion extending between the hooks. 10 In a preferred embodiment, the handle portion and hook extend in a common plane. In this preferred embodiment, the handle portion and the hook extend upwardly away from the open end of the hook, with the handle portion preferably being in the form of a pistol grip. The handle portion may extend substantially parallel to a free end portion of the hook, that 15 is within about 30 * of each other. The fingers of the user's hand are conveniently received in an opening between the handle portion and the hook that is enclosed in said plane, with the opening and handle portion being sufficiently large to comfortably accommodate a gloved hand. 20 The ladder climbing device includes a latch for selectively closing the hook. The latch is preferably at the open end of the hook and is conveniently actuated by a lever, button or other actuating device that is engaged by the hand gripping the handle portion of the climbing device. Thus, when the hand is gripping the handle portion, the latch may be held in an open condition, but as soon as the hand releases the handle portion the latch 25 moves into its closed condition. The latch is urged into its closed condition by, for example, a spring or other biasing means. In a preferred embodiment, the latch is pivotable relative to the hook, for example to engage a free end portion of the hook in the closed condition. Actuation of the latch may 30 be by the aforementioned lever pivoted, for example, on or adjacent the handle portion. A linkage may be provided between the actuation device and latch for effecting at least the P X0PER\W HC 242614t0 amnd doc-$/0Na/2J9 -6 opening motion of the latch with corresponding movement of the actuation device. In one embodiment, such a linkage may comprise a slider on one of the actuation device and latch and a slide track on the other of the actuation device and latch. In another embodiment, the latch actuation device acts directly on the latch. The latch actuation device and any 5 associated linkage forms the latch actuating mechanism. When using the ladder climbing device to ascend or descend a ladder, it is not essential that the latch closes the hook each time the hook is engaged with a rung, since this may require at least a degree of release of the handle portion. However, as noted above, the 10 latch should move automatically to its closed condition when the handle portion, or more particularly the latch actuation device, is released. The arrangement of the latch, latch actuating mechanism and latch locking mechanism may be such that the latch can always be moved from the closed condition to the open 15 condition by a force acting directly on the latch, such as a rung on the outside of the hook as the climbing device is moved to engage the rung. Alternatively, the arrangement may be such that the movement of the latch from the closed condition to the open condition can only occur when the locking mechanism is released, possibly with corresponding movement of the latch actuating mechanism. Alternatively again, such movement of the 20 latch by an external force may be prevented altogether so that the opening of the latch can only occur by actuation of the manual actuating mechanism. The latch may be locked in the closed condition by any suitable mechanism. Such locking may be automatic when the handle portion is released. The latch locking mechanism may 25 act directly on the latch, on the latch actuation device, or on a linkage therebetween, and may be released by manual actuation of an associated release device such as a lever or button. Alternatively, the latch locking mechanism could be released by, for example, initial movement of the latch actuation device. The latch locking mechanism is preferably biased into a condition in which the latch is locked when in the closed condition. 30 Preferably, the latch locking mechanism and the latch actuating mechanism are both P:\OPER\PHH\I2426140 speci.doc-17/03/04 -7 operated by the hand of the user gripping the handle portion to release and open the latch, respectively. Conveniently, in the aformentioned preferred embodiment, the latch actuation device is provided on the back side of the handle portion, that is the side of the handle portion remote from the hook, and the locking mechanism release device is 5 disposed on the front side of the handle portion. Three embodiments of a ladder safety system and ladder climbing device in accordance with the invention will now be described by way of example only with reference to the accompanying drawings, in which: 10 Figure 1 is a side elevational view of one embodiment of the ladder climbing device showing a latch in a closed condition and, in dotted lines, in an open condition; Figure 2 shows a ladder safety system incorporating two of the ladder climbing devices of 15 Figure 1 being used to ascend a ladder; Figure 3 is a view similar to Figure 1, but showing a second embodiment of the ladder climbing device; and 20 Figure 4 is a view similar to Figure 3, but reversed and showing a third embodiment of the ladder climbing device. Referring to Figure 1, the ladder climbing device 10 comprises a hook 12 that is intended to be gripped at a handle portion 14 at all times as the user ascends or descends a ladder. 25 The device includes a connector ring or loop 16 to which, in use, a tether fastened to the user is secured (as described with reference to Figure 2). Thus, if the user accidentally releases the device 10 while it is hooked over a rung of the ladder, the user will be suspended by the device and the tether. The device will be used in pairs in a ladder safety system, one in each hand and each tethered to the user, so that at least one of the devices is 30 engaged with a rung at all times as the ladder is ascended or descended. The devices 10 are effectively used as extensions of the hands, so that the hands are not used to grip the P:\OPER\PHH\I2426140 speci.doc-17/03/04 -8 rungs directly at all during the ascent and descent. The hook 12 is generally gaff-shaped with an open end portion 18 extending generally upwardly to a closed end 20 between a free end portion 21 and a proximal portion 28. The 5 axis 22 of the. closed end 20 of the hook is inclined upwardly relative to the axis 24 of the open end portion so that the hook opens generally downwardly and towards the user. A throat 26 between the open end 18 and the closed end 20 of the hook is narrowed somewhat. The arrangement generally enhances the active engagement of the hook with a rung and may help to retain the hook on the rung should the handle portion 14 be released. 10 The open end portion 18 of the hook extends between the proximal portion 28 and a distal end 30 of the free end portion 21. The connector ring 16 extends from and is integral with the proximal end portion 28 of the hook adjacent the open end portion 21. 15 The hook 12 is formed in aluminium or other suitable material that, in mountainous conditions, can retain its strength and ductility at low temperature. The hook is conveniently cast or otherwise formed of the material, and the proximal portion 28 is suitably shaped in a base 25 to support the handle portion 14 and a latch assembly 32. 20 The handle portion 14 comprises a moulded or shaped cast grip 34 that projects upwardly from the base 25 substantially parallel to the axis 22 of the hook, between a lug 36 of the base 25 and a buttressing tie 38. The tie extends from a leading edge portion 40 of the closed end 20 of the hook and essentially closes an opening between and in the plane of the hook and the handle portion. The tie may be welded to the leading edge portion, but is 25 preferably integrally cast or moulded with it. The resultant enclosed opening 35 between the handle portion 14, the hook 12 and the tie 38 is sufficiently large to comfortably accommodate and protect the fingers of a gloved hand. A strip 42 of hard material, such as steel, may be welded or otherwise secured over the 30 leading edge 40 of the closed end of the hook, and conveniently over the tie 38 as shown, to act as an edge for the climber to use to break ice on the ladder or on a chairlift tower.

P:\OPERPHA1\2426140 spei doc-17/03/04 -9 The latch assembly 32 comprises a latch 44 that is pivoted at one end to the proximal end portion 28 of the hook about a pin 46. In a closed condition of the latch assembly 32, shown in continuous lines in Figure 1, a free end portion 48 engages the distal end 30 of 5 the hook. The latch 44 is a U-shaped cross-section and is prevented by a tab 49 of the end portion 48 from pivoting anti-clockwise beyond the distal end 30, so that the device 10 cannot be removed from a rung when the latch is closed. The latch 44 is actuated by a lever 50 that is pivoted at 52 from the end of the buttressing 10 tie 38 at the end of the handle portion 14 remote from the proximal end portion 28 of the hook. The lever 50 can be conveniently gripped by the hand of the user gripping the handle portion 14 to move the lever from the released condition shown in continuous lines in Figure 1 into an actuated condition adjacent, and conveniently parallel, to the hand grip 34 to pivot the latch 44 into its open condition parallel with the proximal end portion 28 of 15 the hook. A mechanical linkage between the lever 50 and the latch 44 comprises a pin 54 carried by an end of the lever remote from the pivot point 52 and a cooperating slide track 56 in the latch. Thus, as the lever is moved to its actuated condition, the pin 54 is displaced along 20 the track 56, causing the latch 44 to be pivoted clockwise about the pivot point 46. At this end, the lever 50 is bifurcated to extend over the proximal end portion 28 of the hook and over the latch 44, with the pin 54 extending between the bifurcated ends. The latch assembly 32 has a locking device so that the latch 44 cannot be opened without 25 actuating the lever 50. As shown, the locking device comprises a recess 58 at one end of the slide track 56, which receives the pin 54 when the latch 44 is in its closed condition. Thus, initial movement of the lever 50 out of the released condition unlocks the latch, as the pin 54 moves out of the track recess 58. Further movement of the lever opens the latch. In some circumstances an additional or positive latch locking mechanism may be 30 desirable.

PAOPER\PHH\12426140 speci.doc-17/03/04 - 10 The latch assembly 32 is conveniently biased into the closed condition. As shown, this is by a coil spring 60 that extends within the body of the proximal end portion 28 from a finger 61 on the pivoted end of the latch to a pin 63 on the proximal end portion. The spring is tensioned between the two mounting points and the tension increases as the latch 5 is moved to its open condition. For security, a second coil spring 65 extends within the handle portion 14 between a pin 67 and a mounting finger 69 on the pivoted end of the lever 50. In Figure 2, the use of the ladder safety system is illustrated, with the user 62 having a 10 respective ladder climbing device 10 in each hand, and each of the devices 10 tethered to the user by a respective tether 64. As noted above, the devices are used by the hands gripping the handle portion 14 and the lever 50 of the respective device to hold the latch 44 open as shown. The devices are then moved alternately upwardly or downwardly from rung 66 to rung 66 as the user 62 ascends or descends the ladder 68. At all times as the 15 user actively ascends or descends the ladder, the user maintains a grip on both devices 10 and at least one of the devices is always engaged with a rung 66. Once the user has reached the desired height on the ladder or on the tower or other installation 70 that has been climbed using the ladder, one or both of the devices 10 may be left engaged with the ladder 68 or with another structural point of the installation 70 so as to provide security 20 while the user works on the installation. As soon as the user 62 releases each device 10, the latch 44 automatically closes and locks in order to enhance this security. As may be seen, the proximal portion 28 of the hook 12 extends generally parallel to the wrist and forearm of the user, and the open end 18 of the hook opens generally in that 25 direction also. Each tether 64 is shown in the form of a rope 72 extending between the connecting ring 16 of the respective device 10 and a common ring 74 on the user's harness 76. The tether is connected to the device 10 and ring 74 by a suitable knot, such as prussic knot. 30 Alternatively, the tether could be connected by a suitable connector such as a karabiner. Furthermore the rope tether may be replaced by a suitable strap or webbing.

P\OPER\PHH\12426140 speci.doc-17/03/04 -11 The safety harness 76 is shown as full leg and shoulder harness, such as a parachute harness with the common ring 74 secured to the front. 5 Referring to Figure 3, the ladder climbing device 110 comprises a hook 112 that is intended to be gripped at a handle portion 114 such that its use is similar to the device 10. The device 110 includes a connector ring 116 to which, in use, a tether fastened to the user is secured. 10 The hook 112 is generally gaff-shaped with an open end portion 118 extending generally upwardly to a closed end 120. The axis 122 of the closed end 120 of the hook is inclined slightly upwardly relative to the axis 124 of the open end portion so that the hook opens generally downwardly and towards the user. However, a distal end 130 of the hook 112 is somewhat shorter than the distal end 30 of the hook 12. A throat 126 between the open 15 end portion 118 and the closed end 120 of the hook is narrowed somewhat. The open end portion 118 of the hook extends between a proximal portion 128 and the distal end 130. The connector ring 116 extends from and is integral with the proximal end portion 128 of the hook. The distal end 130 is rounded. 20 The hook 112 is formed in aluminium or other suitable material that, in mountainous conditions, can retain its strength and ductility at low temperature. The hook is conveniently cast or otherwise formed of the material, and is suitably shaped in the proximal end portion to support the handle portion 114 and a latch assembly 132. A 25 replaceable wear strip 131 is secured by screw-threaded fasteners 133 to the inner face of the closed end 120 of the hook to alleviate wear of the primary material of the hook by regular engagement with ladder rungs. A variety of grades of stainless steel or other wear resistant material such as tungsten carbide may be useful for this purpose. 30 The handle portion 114 comprises a shaped cast grip 134 that projects upwardly from the proximal end portion 128 of the hook to a buttressing tie 138, generally parallel to the axis P:\OPER\PHH\12426140 speci.doc.17/03/04 - 12 122 of the closed end 120 of the hook. The integrated tie extends from a reinforcing web 136 at the closed end 120 of the hook and essentially encloses an opening between the hook and the handle portion. The resultant enclosed opening is sufficiently large to comfortably accommodate a gloved hand. The reinforcing web 136 extends from the tie 5 138, around a leading edge portion 140 of the hook to the distal end 130, on the outside of the hook 112. A replaceable strip 142 of hard material, such as steel, is secured by fasteners to the reinforcing web 136 at the leading edge 140 of the closed end of the hook to act as an edge 10 for the climber to use to break ice on the ladder or on a chairlift tower. The latch assembly 132 comprises a latch 144 that is pivoted at one end to the proximal end portion 128 of the hook about a pin 146. In the illustrated closed condition of the latch assembly 132, a free end portion 148 engages the distal end 130 of the hook. The latch 15 144 is prevented by the engagement of the end portion 148 with the hook from pivoting anti-clockwise beyond the distal end 130, so that the device 110 cannot be removed from a rung when the latch is closed. The latch 144 is actuated by an L-shaped lever 150 that is pivoted about a pin 152 from the 20 proximal end portion 128 of the hook and extends upwardly from the proximal end position, on the back side of the handle portion 114, remote from the hook. The lever 150 can be conveniently engaged by the base of the palm of the hand of the user gripping the handle portion 114 to move the lever from the released condition shown in continuous lines in Figure 6 into an actuated condition (shown in dashed lines) adjacent and parallel to 25 the hand grip 134 to pivot the latch 144 into its open condition parallel with the proximal end portion 128 of the hook. The latch 144 and lever 150 are secured by the pins 146 and 152, respectively, in a slot within the proximal end portion 128 of the hook and the handle portion 114. 30 Advantageously, the pins 146 and 152 are removable fasteners that allow the latch components to be removed for checking, servicing and cleaning.

P:\OPER\PHH\12426140 speci.doc.17/03/04 - 13 The lever 150 and the latch 144 have cooperating engaged toothed end portions 154 and 156, respectively, within the slot in the proximal end portion 128. As the lever 150 is moved to its actuated condition, the end portion 154 is rotated about the pin 152, causing 5 the end portion 156 of latch 144 to be pivoted clockwise about the pivot point 146 and the latch to be opened. The latch assembly 132 is biased into the closed condition. As shown, this is by a coil spring 160 that extends within the slot of the handle portion 114 from an opening 161 on 10 the end portion 154 of the lever to a pin 162 in the handle portion. The spring is tensioned between the two mounting points and the tension increases as the lever 150 is moved to its actuated condition. As will be appreciated, the latch 144 is incapable of moving between the open and closed conditions without the lever 150 also being moved. However, a sufficient force applied to the outside of the latch in its closed condition will open the 15 latch, with corresponding movement of the lever 150, provided a latch locking mechanism 158 is released. The latch locking mechanism 158 comprises a lever 164, a locking finger 166 and a biasing spring 168, all received within the slot at the upper end of the handle portion 114. 20 The inverted L-shaped lever 164 is pivoted within the slot about a removable pin 170, and the locking finger 166 depends from the lever 164 at a pivot point 172. The spring 168 acts between the lever 164 and a removable mounting pin 174 to bias the locking mechanism into its locking condition. 25 A bearer 176 is provided on the mounting pin 174, and the locking finger 166 is free to slide substantially vertically between this and a back wall 178 of the handle portion as the lever 164 is pivoted. In the locking condition, a distal end 180 of the locking finger engages the top of the leading face of the released latch lever 150 to prevent the latch lever from being pivoted about the pin 152. In this condition, a trigger portion 182 of the lever 30 164 projects forwardly of the hand grip 134 for selective engagement by the index finger of the user. When the trigger portion 182 is actuated to pivot the lever 164, the locking P:\OPER\PHH\l2426140 speci.doc-17/03/04 - 14 finger 166 is displaced upwardly out of contact with the leading face of the latch lever 150, so permitting the latch lever to be pivoted forwardly by the base of the palm of the user as the user's hand grips the handle portion 114 more tightly. 5 As with the latch 144 and latch lever 150, the locking mechanism 158 is able to be removed from the ladder engaging device 110 by releasing the screw-threaded fasteners forming the lever and mounting pins 170 and 174. Similarly, the latch lever spring 160 can be removed from the device 110 by releasing the pin fastener 162. 10 Referring to Figure 4, the ladder engaging device 210 comprises a hook 212 that is intended to be gripped at a handle portion 214 such that its use is similar to the device 10. The device 210 includes a connector ring 216 to which, in use, a tether fastened to the user is secured. 15 The hook 212 is generally gaff-shaped with an open end portion 218 extending generally upwardly to a closed end 220 between a free end portion 222 and a proximal portion 224. The hook thus opens generally downwardly. The free end portion 222 is somewhat shorter than the proximal portion 224, to facilitate entry into the open end portion 218 of a ladder rung, and terminates in a distal end 230. 20 The connector ring 216 is provided in and is integral with a base 255 of the handle portion 214 and of the proximal portion 224 of the hook. The distal end 230 is rounded, but the distal end 230 and at least the adjacent part of the free end portion 222 have a relatively small cross-section, for example smaller than that of the handle portion 214, to enable the 25 free end portion to be received in a structural opening (not shown) for securing the device 210 thereto. The hook 212 is formed in aluminium or other suitable material that, in mountainous conditions, can retain its strength and ductility at low temperature. The hook is 30 conveniently cast or otherwise formed of the material, and is suitably shaped in the base 225 to support the latch assembly 232 as well as the handle portion 214 and proximal hook POPER\PHTHI2426140 speci.doc-17/03/04 - 15 portion 224 that extend upwardly from it. A replaceable wear strip (not shown) may be secured to the inner face of the closed end 220 of the hook to alleviate wear of the primary material of the hook by regular engagement with ladder rungs. However, as shown, the proximal portion 224 and closed end 220 of the hook 212 have a relatively substantial 5 width to achieve the same advantage, whereas the free end portion 222 has a relatively narrow, blade-like cross section except at the rounded distal end 230. The handle portion 214 comprises a shaped grip 234 having U-shaped cross-section and rivetted at 226 to an integral handle member 228 that projects upwardly from the base 225, 10 in the plane of the hook. The handle number extends to a buttressing tie 238, substantially parallel to the free end portion on 222 of the hook. By "substantially parallel" is meant within about 300 of the axis of the free end portion 222. The buttressing tie merges with the proximal portion 224 and closed end 220 of the hook and essentially encloses an opening between the hook 212 and the handle portion 214. The resultant enclosed opening 15 235 is sufficiently large to comfortably accommodate a gloved hand while providing protection for the hand, at least in the plane of the device. An integral reinforcing web 236 extends outwardly from the tie 238, around the closed end 220 at a leading edge portion 240 of the hook on the exterior of the hook 212, and merges with the blade-like free end portion 222 to provide an ice-breaking edge 242 along the web 236 and free end portion 20 222. As with the device 110 shown in Figure 3 a replaceable strip (not shown) of hard material, such as steel, may be secured to the reinforcing web 236 at the leading edge portion 240 of the hook to enhance the use of the edge 242 by the climber for breaking ice on the ladder 25 or on a chairlift tower. The latch assembly 232 comprises a latch 244 that is pivoted at one end to the proximal portion 228 of the hook about a pin 246. In the illustrated closed condition of the latch assembly 232, a distal end portion 248 engages the free end portion 222 adjacent the distal 30 end 230 of the hook. The latch 244 has a U-shaped cross-section and is prevented by the engagement of the distal end portion 248 with the hook from pivoting clockwise (in the P:\OPER\PHH] 2426140 speidoc.17/03/04 - 16 drawing) beyond the distal end 230, so that the device 210 cannot be removed from a rung when the latch is closed. The latch 244 is actuated by a hinged lever assembly 250 that is pivoted about a pin 252 5 from an upper end of the integral handle member 228. The lever assembly 250 comprises a lever 254 that extends downwardly from the pin 252 on the back side of the handle portion 214, remote from the hook, and a link 256. The lever 254 has a U-shaped cross section and can be conveniently engaged by the base of the palm of the hand of the user gripping the handle portion 214 to move the lever from the released condition shown into 10 an actuated condition adjacent and parallel to the integral handle member 228 to pivot the latch 244 into its open condition parallel with the proximal end portion 228 of the hook. The U-shaped cross-section of the latch 244 permits it to overlie the proximal portion 228 of the hook in its open condition. 15 The link 256 comprises a pair of parallel link members (one only visible) that are hinged at one end to the distal end of the lever 254 by a pin 253 and extend on respective sides of the handle member 228 below the grip 234. The link 256 is pivotally engaged at its other end with the latch 244 by a pin 255. 20 As the lever 254 is moved to its actuated condition, the link 256 is displaced forwardly and downwardly, causing the latch 244 to be pivoted about the pivot pin 246 and the latch to be opened. The latch assembly 232 is biased into the closed condition. This is by a helical spring (not 25 shown) supported axially on the pin 252 and acting between the lever 254 and the handle member 228 to urge the lever outwardly, away from the handle member. The latch 244 is incapable of moving between the open and closed conditions without the lever assembly 250 also being moved. However, a sufficient force applied to the outside of the latch in its closed condition, such as by a rung, will open the latch, with corresponding movement of 30 the lever assembly 250, provided a latch locking mechanism 258 is released.

P:\OPER\PHH\12426140 speimdoc-7/03/04 - 17 The latch locking mechanism 258 comprises a lever 264 pivotally supported by a pin 266 from the handle member 228 beneath the U-shaped grip 234. The lever 264 is biased into the locking condition shown in Figure 4 by a coil spring 268 acting between a projecting finger 270 on the lever 264 and a mounting pin 272 on the handle member 228, also 5 substantially beneath the shaped grip 234. In its locking condition, the lever 264 projects from beneath the hand grip 234 into the opening 235 and an engagement portion 274 abuts a mounting lug 276 on the proximal portion 224 through which the latch mounting pin 246 extends. 10 Beneath the engagement portion 274, the lever 264 has a slot 278 that receives the pivot pin 255 connecting the link 256 to the latch 244 in the locking condition of the latch locking mechanism 258. In this condition, the slot 278 opens upwardly and forwardly towards the latch mounting pin 246. Since the pivot pin 255 connecting the link 256 to the 15 latch 244 must move downwardly and forwardly to open the latch 244 when the latch lever assembly 250 is actuated, this movement is prevented when the latch locking mechanism 258 is in its locking condition. The latch locking mechanism 258 is released by depressing the lever 264 against the bias 20 of the spring 268 so that it no longer projects from beneath the hand grip 234. This movement of the lever 264 displaces the slot 278 to a sufficient extent to release the pivot pin 255 from the slot, thereby permitting the pivot pin 255 to move downwardly and forwardly when the latch lever assembly 250 is actuated to open the latch or when the latch 244 is opened by a direct force applied to it. 25 The lever 264 of the latch locking mechanism 258 is depressed to release the latch locking mechanism by the fingers of the hand gripping the handle portion 214. Advantageously, the opening 235 is sized and shaped such that depression of the lever 264 is essentially inherent when the hand, particularly a gloved hand, grips the handle portion. As soon as 30 the hand is released from the handle portion 214, the latch locking mechanism 258 will automatically move to its latch locking condition under the bias of spring 268.

P:\OPER\PHH\12426140 spci.doc-17/03/04 - 18 Both of the ladder climbing devices 110 and 210 of Figures 3 and 4 are used in the same manner as described with reference to Figure 2 in respect of the device 10 of Figure 1. 5 Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications which fall within its spirit and scope. The invention also includes all the steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and 10 any and all combinations of any two or more of said steps or features. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps 15 but not the exclusion of any other integer or step or group of integers or steps. 20

Claims (20)

1. A ladder climbing device having a hook for engaging a rung of a ladder, means for receiving a tether from a user, a handle portion for the user to grip the device and manually 5 move the device from one rung to another rung to control the user's ascent or descent of the ladder, a latch for the hook, the latch being biased into a condition in which it closes an open end of the hook to prevent removal of the hook from a rung and being manually actuatable through a latch actuating mechanism of the device to move the latch from the closed condition to an open condition, and a latch locking mechanism for locking the latch 10 in the closed condition.

2. A ladder climbing device according to claim 1 in which the means for receiving the tether is provided adjacent the open end of the hook. 15

3. A ladder climbing device according to claim 1 or 2 wherein the hook and handle portion extend in a common plane.

4. A ladder climbing device according to claim 3 in which a free end portion of the hook extends substantially parallel to the handle portion. 20

5. A ladder climbing device according to claim 4 in which at least the free end portion of the hook has a smaller cross-section than the handle portion.

6. A ladder climbing device according to any one of claims 3 to 5 in which the handle 25 portion and the hook extend upwardly away from the open end of the hook

7. A ladder climbing device according to claim 6 in which a hand-receiving opening between the handle portion and the hook is enclosed in said plane. 30

8. A ladder climbing device according to any one of the preceding claims in which a closed end portion of the hook is reinforced and/or carries a replaceable wear piece for engagement with a ladder rung. PAOPERT\PHI\I2426140 amnrd doc-5/08/2009 - 20

9. A ladder climbing device according to any one of the preceding claims in which an edge for breaking ice is provided on at least the exterior of the hook. 5

10. A ladder climbing device according to claim 9 in which the edge is strengthened.

11. A ladder climbing device according to any one of the preceding claims in which the latch is pivoted to engage a free end portion of the hook in the closed condition. 10

12. A ladder climbing device according to any one of the preceding claims in which the latch locking mechanism and the latch actuating mechanism are both operated by the hand of the user gripping the handle portion to release and open the latch, respectively.

13. A ladder climbing device according to any one of the preceding claims in which, 15 with the latch locking mechanism operated to release the latch, the latch is movable from its closed position to its open condition by an external force acting directly on the latch.

14. A ladder climbing device according to any one of the preceding claims in which the latch locking mechanism acts on the latch actuating mechanism to prevent the latch 20 actuating mechanism being operated to open the latch.

15. A ladder climbing device according to any one of the preceding claims in which the latch locking mechanism is biased towards its position for locking the latch in the closed condition. 25

16. A ladder climbing device substantially as herein described with reference to the accompanying drawings.

17. A ladder safety system comprising two ladder climbing devices each having a hook 30 for engaging a respective rung of a ladder and further comprising tethering means for connecting the ladder climbing devices to a user's body, each of the ladder climbing PAOPER\PHH-\2426140 speci.doc-17/03/04 -21 devices having a handle portion for the user to grip the device and manually move the device from one rung to another rung to control the user's ascent or descent of the ladder, a latch for the hook, the latch being biased into a condition in which it closes an open-end of the hook to prevent removal of the hook from a rung and being manually actuatable to 5 move the latch from the closed condition to an open condition, and a latch locking mechanism for locking the latch in the closed condition.

18. A ladder safety system according to claim 17 in which each ladder climbing device is according to any one of claims 2 to 16. 10

19. A ladder safety system according to claim 17 or 18 in which the tethering means comprises a continuous tether between the two ladder climbing devices.

20. A ladder safety system according to claim 19 in which a user connector is provided 15 on the continuous tether, the user connector being selectively adjustable along the tether. Dated this 17 th day of March, 2004 Buller Ski Lifts Pty Ltd By Its Patent Attorneys 20 DAVIES COLLISON CAVE