CA2181858A1 - Method and apparatus for prevention of falls from extension ladders - Google Patents
Method and apparatus for prevention of falls from extension laddersInfo
- Publication number
- CA2181858A1 CA2181858A1 CA 2181858 CA2181858A CA2181858A1 CA 2181858 A1 CA2181858 A1 CA 2181858A1 CA 2181858 CA2181858 CA 2181858 CA 2181858 A CA2181858 A CA 2181858A CA 2181858 A1 CA2181858 A1 CA 2181858A1
- Authority
- CA
- Canada
- Prior art keywords
- cable
- ladder
- attached
- drum
- extension
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
- E06C—LADDERS
- E06C7/00—Component parts, supporting parts, or accessories
- E06C7/18—Devices for preventing persons from falling
- E06C7/186—Rail or rope for guiding a safety attachment, e.g. a fall arrest system
Abstract
This invention provides a method and apparatus for ensuring the saftey of a worker climbing an extension ladder. It has a safety cable which extends the full length of an extension ladder, regardless of the degree of extension of the ladder and the cable is fully retractible into a housing unit which both stores the cable such that the cable cannot be fouled, and provides a brake to prevent rapid movement of the cable such as might occur in the event of a fall of a worker. The invention makes it possible for a worker to climb and descend a ladder safely whether or not both hands are on the ladder and has particular application in the fire fighting field.
Description
~t ~18~8 METHOD AND APPARATUS FOR PREVENTION OF FALLS FROM
EXTENSION LADDERS
Field of Invention This invention relates to fall arrest safety systems for use by persons working 5 at height on ladders, namely extension ladders.
Background of the Invention There are many fall arrest safety systems which help ensure the safety of workers who are required to carry out specific tasks at significant heights. Safety systems which can be used in situations where individuals are lowered from 10 heights, such as in the window cleaning art, are well known (see for example Canadian Patent Application No. 2,074,078). There are also safety devices which are used on fixed ladders for climbing to significant heights such as in the case of water towers and many of these i"co"uo~dLe a fixed cable over which a clamping device is slidably attached. Such clamps have been described in United States Patent Nos. 3,348,632 and 4,059,871. Variations on this approach relate to solid rails which are attached to a secured ladder and i"w, ,uu, dLt: a safety fastener which attaches to the rail (see United States Patent No. 3,348,632) where the safety fastener clamps onto the rail in the event of a fall. This is also the effect of the clamping devices just " ,ellLiuned. In respect of these variations, the worker wears 20 a belt or harness (for example see the belt in U.S. Patent No. 5,316,102) which is reversibly secured to the clamping device. Indeed, the concept of using a sliding o ~18~8~8 clamping device in P.~o. .i,,l i. "~ with a cable connected between two fixed points is wellknownandfurtherexamplesmaybefoundinU.S.PatentNos.5,316,102and 4,071,926; United States Patent No. Re-issue 30,072 Such cable and slidable clamp safety systems have also been employed to 5 avoid injury from falls ~ssoci~L~d with entering or leaving manholes on the ladders used in such manholes. Such a device is described in United States Patent No.
3,598,200. This invention is a self-storing safety appliance consisting of a rigid sleeve attached to the rungs of the manhole ladder and has a slidable rod with a cable attached so that the rod may be extended out of the hole to provide a vertical 10 railing and safety line for workmen entering or leaving the manhole. In the collapsed position the safety cable which is hung from the upper end of the rod is simply lowered into the manhole when not in use.
From the perspective of providing a safety device where the worker is not confined to a specific location, devices which are attached at the height where the 15 worker is located and which deliver cabling are well known. These devices are typically mounted to a structure on which a worker is pe, ru" "i"g a task such as a bridge or a building with the end of the cable or rope being attached to the worker's belt or body harness. Alternatively, such devices can be mounted directly onto the worker's harness with the other end of the cable being mounted to the structure 20 upon which the worker is working. These devices provide a brake which engages when the cable is rapidly payed out such as when a worker falls. Examples of such 0 ~8185~
devices are illustrated in United States Patent Nos. 5,186,289 and 5,343,976 and in Canadian Patent No. 2,075,978.
In other situations an individual is often required to ascend to significant heights using an ~d~l ~ddL le ladder. When the individual is on the ladder, aside 5 from ensuring that the footing and the upper portion of the ladder are secured, there is means by which one can ensure the safety of the climber. An example is the situation where fire fighters in the course of battling a hre are required to climb extension ladders on the top ol a fire truck to signihcant heights unaided by any support or safety device. The application of existing fall and arrest safety systems 10 to such settings proves ~,, ubl~llldlic in that the ladder is extendable whereas most of the prior art relates to fxed climbing ladders. The extension aspect of the ladder makes use of fixed lengths of cable attached to the ladder i~ lduLicdl from two perspectives. First, the cable must be efficiently and neatly stored thereby making the approach to extension as suggested in U.S. No. 3,598,20û illl~JId-,Licdl. In this 15 setting, retraction of the extension ladder to its starting position would result in a length of cable not contained or wrapped or coiled in any way unless this was done manually and tied to the ladder. This free length of cable could easily be tripped over or be caught in part of the ladder as it is being retracted or otherwise become fouled. Further, such systems cu~ Jld~ there being suffhcient cable to extend 20 from the base of the ladder to the top when fully extended. Should an extension ladder not be at full length the cable would be slack and, dt:l.enli"g on the amount of slack cable, i.e., the degree of ladder extension, a worker on such an non-fully o ~:1818~extended ladder, in a fall could potentially sway quite a distance ofl the vertical line of the ladder, and thereby threai:en the security of the ladder potentially causing it to be pulled down on top of the falling worker. Consequently, there is a need for workers who are working on extension ladder systems to have a sufliciently safe means of climbing these ladders without fear of falling from a height.
Summary of Invention The deficit which exists in the fall arrest safety device f eld in ~iunnel.liun with extension ladders is overcome by the present invention. This invention provides a means for having a safety cable extend the full length of an extension ladder,regardless of the degree of extension of the ladder. Further, the cable is fullyretractible into a housing unit which both stores the cable such that the cable cannot be fouled, and provides a brake to prevent any rapid movement of the cable.
Rapid movements are those which would occur in the event of a fall of a worker.
Consequently, the invention also prevents the worker from moving a significant distance from the vertical plane of the ladder. The within invention makes it possible for a worker to climb and descend a ladder safely whether or not both hands are on the ladder. This is particularly advantageous in the fire fighting field where fire fighters are, on occasion, required to carry victims down a fire truck ladder from a burning building.
Thus, it is an object of this invention to provide in respect of extension ladders, a retractible life line safety device that cannot be fouled upon retraction of o ~18i8~
an extension ladder, as well as a safety harness to secure a climber to the safety line and thereby an extension ladder.
In one aspect, the invention provides a safety apparatus to prevent falls from an extension ladder, which apparatus comprises a retractible cable device which S is detachably secured at the base of the ladder, or on the lower rung, or other part of the ladder. However, it can optionally be secured at the top of the ladder, or top nung or other top portion of the ladder, or at some point lower than the top, or higher than the bottom, respectively. In other words, the positions of the housing and the free end of the cable end are reversible, the important point being that the cable be 10 able to extend a length great enough to provide the worker with a secure line on the ladder. The cable device is comprised of a housing which contains a rotatable drum upon which the cable is wound and unwound; a cable which is fixed at one end to the rotatable cable drum while the other end, or in other words the free end, is attached to the end of the ladder which is to be elevated. The rotatable drum is 15 biased such that the cable will retract upon return of the extension ladder to a starting position. Although a coiling drum is suggested here, it is understood that any other means of coiling, or gathering the cable as the extension ladder is retracted is within the scope of this invention.
This retractible cable device contains a braking ",el,l Idllialll to arrest the 20 rotation of the cable drum upon the event of a rapid movement such as a fall by a worker on the ladder.
_ 2~8~8 The apparatus further comprises a safety belt, or harness, or other such safety strapping, secured about a worker, attached either reversibly, or pe, 1 l Idn6l Itly to a cable gripping clamp which itself may either be reversibly attached, or permanently attached to the cable. Although only one person is normally on a 5 ladder at a time, in circumstances where it is ~ ,, idL~, such as in the fire fighting field, more than one such belt and gripping clamp a" ~nge" ,~"L may be used on the same cable on the same ladder. Indeed, more than one ,~t,d~ Lle cable device and cable may be used per ladder, depending upon the circumstances, and all such variations are within the scope of the present invention.
In a particular ~" ,L,odi" ~t:"L of the invention, the apparatus is attached to the extension ladder of an extension ladder fire truck where the retractible cable device is secured at the base of the ladder and the slidable gripping clamp is pre-attached to the cable. In addition the free end of the cable from the device is in an extended position, i.e., it extends the length of the u"exLt:nded ladder, where the free end of 15 the cable is attached to the top rung of the top portion of the ladder.
In a further ~Illbocli~ "e"L a brake is provided such that the cable is not free to play out from the retractible cable device. The brake is applied when the extension ladder has been extended to a desired length.
In a further embodiment, the free end of the cable of the ,~L,d~ ble cable 20 device is attached to a rod which is fixed to the upper portion of the ladder. It will be un~ Luod that any other type of dLLd-,l 111 ,el ~L to the upper portion, or top rung -~ ~ 8 of the ladder to which the apparatus has been applied is within the scope of this invention.
In yet a further ~" ,L,odi" le"~, the free end of the cable of the, t:l~d-,Ld~le cable device is attached to a polyester-based shock absorber which in turn is attached S to the rod located at the top of the ladder. However, it is u, Idt:l ~Lood that any type of shock absorber may be used and is within the scope of the present invention.
In yet a further embodiment, the slidable clamp is comprised of a lever and a spring clip which when released engages an upper lock and the lever engages a second lower lock simultaneously, thereby gripping and securing the clamp on the 10 cable. It will be understood that any slidable clamping device which will grip and secure its position, and thereby, the worker's position, is within the scope of this invention.
The invention also provides a method of preventing falls from retractible extension ladders by attaching a safety belt to a person who will climb the ladder 15 and further attaching this belt by a coupling ",e,.h~"is", such as a climbing carabiner to a slidable gripping clamp which is in turn attached to a cable. The cable is extended between the upper end, or top rung of the extension ladder and a retractible cable device which is secured at the base of the ladder. The cable device of this method is comprised of a housing, a rotatable cable drum which is 20 biased to rewind upon turning in a given direction, a cable which is attached to the drum and also to the end of the ladder which is to be elevated. The cable is retractibly drawn from the cabl3 device as the ladder is extended. The device of O ~:1818~8 this method also contains a brake which arrests the rotation of the drum upon rapid movement of the cable such as in the event oF a fall.
A further e",l,odi",e"l oF this invention is this method of preventing falls where the extension ladder is the ladder on a fire truck.
In a further ~Illbodi,,,~,,L this invention pertains to the use of an apparatus which is comprised of a retractible cable device secured at the base of a ladderwhere the cable device comprises a housing a rotatable cable drum which is biased to rewind upon turning in a given direction a cable which has a first endfixed to the rotatable cable drum and second end which is attached to the end of the ladder which is to be elevated such that the cable can be retractibly drawn from the cable device as the ladder is extended and it further consists of a brake (the retractible cable device brake) which arrests the rotation of the cable and thereby movement of the cable in the event of a fall from the ladder in addition to a safety belt secured on the person using this apparatus which in turn is attached to a grasping clamp which is slidably attached to the cable.
In a further e",bodi"~e"l a brake (cable brake) is provided apart from the retractible cable device brake and said brake is set when the ladder has been extended to a desired length. Said clamp assits in m dil lldil lil 19 cable position and taughtness or tension of the cable. In a further t~lllbodilllc:lll this cable brake is attached to the ladder with teflon bolts so that the brake will break away from the ladder if the ladder is extended under force while the brake is set.
~ ~8L8~38 In a further e,nbodi",e"l this invention is for use in preventing falls from retractible extension ladders which is the ladder on a fire truck.
Various e",bodi",e"l~ of the invention selected by way of example will now be described with reference to the auculllp~illying drawings.
s Desc~ lion of the Drawings Figure 1 depicts a side view of the apparatus of the invention.
Figure 2 depicts a front view of the apparatus of Figure 1.
Figure 3 illustrates the apparatus of Figure 1 attached to an extension ladder.
Figure 4 illustrates a slidable grasping clamp of the apparatus as shown in Figure 1.
Figure 5 illustrates a side view of a cable rod and shock absorber of the apparatus shown attached to the upper portion of an extension ladder shown in Figure 2.
Figure 6 illustrates a front view of a cable rod and shock absorber of the apparatus ~shown attached to the upper portion of an extension ladder as shown in Figure 2.
Figure 7 illustrates a cable brake of the invention in place on a ladder as shown in Figure 3.
0 218:~58 Figure 8 illustrates greater detail on a perspective view of the cable brake of Figure 7.
Des~ ,lion of Invention In the various drawings ~:u" ~s~,ol1.li, ,9 parts in different figures are denoted by the same reference and numerals.
Referring first to Figure 1, all of the parts of a specific blllbo~ "~l ,l of the apparatus of the invention are illustrated. COI "" ,en-.i"g with the dLLdL.I 111 It~l IL at the upper portion of the ladder, a metal rod 2 is attached by means of stainless steel U-bolts 4 to the upper portion of the extension ladder, in particular the top and second from the top rungs ol the ladder. These U-bolts are preferably 5/8"
stainless steel in CO~ Jo~ iUn, however, any means by which this rod, or a similar rod can be attached to the extension ladder is a~ .le. In an alternative ~1 1 Ibo-li, 1 1~1 ll the rod may be dispensed with, and the safety cable may be attached directly to the upper rung of the ladder, however, the rod is preferred so as toillllll-~:" - the upper end of the safety cable.
Attached at the upper end of the rod 2 is a first carabiner 6 which is in turn connected to a polyester-based shock absorber 8. In a preferred e" ,L,o.li" ,e"L, this shock absorber is a Miller Soft StopTM No 880 type of shock absorber. This shockabsorber, is in turn, connected to the travelling, or free end of the safety cable 10 by means of a further carabiner 6. The ~,d~dbil1er~ 6 are preferably UIM certified aluminum carabiners, however, any other type of strength tested connector may be ~1 2~ 8~ 858 used. The travelling end of the cable has affixed to it a carabiner and hook apparatus 12. The safety cabls is in a preferred embodiment a stainless steel cable consisting of 7/32" 5 000 Ib. test aircraft type cable. The retractible cable device 14 may be any device which provides the features described for this invention. Such devices have been described in Canadian Letters Patent 2 075 978or U.S. Patent No. 5 186 289. In a prefenred er"l-odi,l,t:"l the Miller Safety Fall Arrestor/ Retractor is used. The safety device is attached to the base of the ladder by means of a bracket 16 with securing bolts 18. Referring to Figure 1, the retractible cable device 14 is securely mounted to the ladder 19 by means of a further bracket 20 and bolt means 22. The cable clamp 26 is illustrated in greater detail in Figure 4. Referring now to Figure 4 this cable clamp or slideable grasping clamp is, o" ,~,, ised of an upper lock 28 a safety pin 30 a lever 32 and a second lock 34 housed inside a stainless steel trolley 36. In a preferred t:",L,o.li",~"L a Trylon-type safety cable sleeve is used. The ability of this cable clamp to slide over the safety cable can be adjusted by means of adjustment screws 38 and the safetybelt 44 worn by the user is attached by means of a clasp hook assembly 42 to theopening 40 of the lever 32.
Referring again to Figure 1, the slideable grasping clamp assembly 42 is attached to the lever as just I l lel l~i.n~ed which is in turn attached to the safety belt or harness 44.
_ o ~8~85g Referring to Figure 5 which is a close-up view of the upper portion of the apparatus attached to the upper rung of an extension ladder it may be seen that the extension ladder 18 at the top rung 46 has attached the support bar 2. The carabiners 6 are attached to the upper and lower ends of the polyester- based S shock absorber 8 which serves to cushion the fall of a worker. These same features are shown from the front in Figure 6.
Figure 7 illustrates the cable brake and in the e",obodi",e"l illustrated it consists of the clamping lower portion 34 and 36 of a slidable grasping clamp illustrated in Figure 4. It is welded to an L bracket 48 or means such that the 10 bracket can break away from the ladder in the event an attempt to extend the ladder is made while the brake is set. This may occur in an d,O~ of the present invention to a firetruck ladder which is mechanically extended. A suitable clip and chain 50 arrangement holds the clamping lever 32 in the unlocked and locked positions. A guide 56 may also be il 1-,01 IJOIdled as a part of the apparatus of this IS invention to ensure proper po~ilioni"g of the cable 10.
While the invention has been particularly shown and described with referencetopreferred~",bodi",~"l~ itwillbeu"~ ,loodbythoseskilledintheart that various other changes in form and detail may be made without departing from the spirit and scope of the invention.
EXTENSION LADDERS
Field of Invention This invention relates to fall arrest safety systems for use by persons working 5 at height on ladders, namely extension ladders.
Background of the Invention There are many fall arrest safety systems which help ensure the safety of workers who are required to carry out specific tasks at significant heights. Safety systems which can be used in situations where individuals are lowered from 10 heights, such as in the window cleaning art, are well known (see for example Canadian Patent Application No. 2,074,078). There are also safety devices which are used on fixed ladders for climbing to significant heights such as in the case of water towers and many of these i"co"uo~dLe a fixed cable over which a clamping device is slidably attached. Such clamps have been described in United States Patent Nos. 3,348,632 and 4,059,871. Variations on this approach relate to solid rails which are attached to a secured ladder and i"w, ,uu, dLt: a safety fastener which attaches to the rail (see United States Patent No. 3,348,632) where the safety fastener clamps onto the rail in the event of a fall. This is also the effect of the clamping devices just " ,ellLiuned. In respect of these variations, the worker wears 20 a belt or harness (for example see the belt in U.S. Patent No. 5,316,102) which is reversibly secured to the clamping device. Indeed, the concept of using a sliding o ~18~8~8 clamping device in P.~o. .i,,l i. "~ with a cable connected between two fixed points is wellknownandfurtherexamplesmaybefoundinU.S.PatentNos.5,316,102and 4,071,926; United States Patent No. Re-issue 30,072 Such cable and slidable clamp safety systems have also been employed to 5 avoid injury from falls ~ssoci~L~d with entering or leaving manholes on the ladders used in such manholes. Such a device is described in United States Patent No.
3,598,200. This invention is a self-storing safety appliance consisting of a rigid sleeve attached to the rungs of the manhole ladder and has a slidable rod with a cable attached so that the rod may be extended out of the hole to provide a vertical 10 railing and safety line for workmen entering or leaving the manhole. In the collapsed position the safety cable which is hung from the upper end of the rod is simply lowered into the manhole when not in use.
From the perspective of providing a safety device where the worker is not confined to a specific location, devices which are attached at the height where the 15 worker is located and which deliver cabling are well known. These devices are typically mounted to a structure on which a worker is pe, ru" "i"g a task such as a bridge or a building with the end of the cable or rope being attached to the worker's belt or body harness. Alternatively, such devices can be mounted directly onto the worker's harness with the other end of the cable being mounted to the structure 20 upon which the worker is working. These devices provide a brake which engages when the cable is rapidly payed out such as when a worker falls. Examples of such 0 ~8185~
devices are illustrated in United States Patent Nos. 5,186,289 and 5,343,976 and in Canadian Patent No. 2,075,978.
In other situations an individual is often required to ascend to significant heights using an ~d~l ~ddL le ladder. When the individual is on the ladder, aside 5 from ensuring that the footing and the upper portion of the ladder are secured, there is means by which one can ensure the safety of the climber. An example is the situation where fire fighters in the course of battling a hre are required to climb extension ladders on the top ol a fire truck to signihcant heights unaided by any support or safety device. The application of existing fall and arrest safety systems 10 to such settings proves ~,, ubl~llldlic in that the ladder is extendable whereas most of the prior art relates to fxed climbing ladders. The extension aspect of the ladder makes use of fixed lengths of cable attached to the ladder i~ lduLicdl from two perspectives. First, the cable must be efficiently and neatly stored thereby making the approach to extension as suggested in U.S. No. 3,598,20û illl~JId-,Licdl. In this 15 setting, retraction of the extension ladder to its starting position would result in a length of cable not contained or wrapped or coiled in any way unless this was done manually and tied to the ladder. This free length of cable could easily be tripped over or be caught in part of the ladder as it is being retracted or otherwise become fouled. Further, such systems cu~ Jld~ there being suffhcient cable to extend 20 from the base of the ladder to the top when fully extended. Should an extension ladder not be at full length the cable would be slack and, dt:l.enli"g on the amount of slack cable, i.e., the degree of ladder extension, a worker on such an non-fully o ~:1818~extended ladder, in a fall could potentially sway quite a distance ofl the vertical line of the ladder, and thereby threai:en the security of the ladder potentially causing it to be pulled down on top of the falling worker. Consequently, there is a need for workers who are working on extension ladder systems to have a sufliciently safe means of climbing these ladders without fear of falling from a height.
Summary of Invention The deficit which exists in the fall arrest safety device f eld in ~iunnel.liun with extension ladders is overcome by the present invention. This invention provides a means for having a safety cable extend the full length of an extension ladder,regardless of the degree of extension of the ladder. Further, the cable is fullyretractible into a housing unit which both stores the cable such that the cable cannot be fouled, and provides a brake to prevent any rapid movement of the cable.
Rapid movements are those which would occur in the event of a fall of a worker.
Consequently, the invention also prevents the worker from moving a significant distance from the vertical plane of the ladder. The within invention makes it possible for a worker to climb and descend a ladder safely whether or not both hands are on the ladder. This is particularly advantageous in the fire fighting field where fire fighters are, on occasion, required to carry victims down a fire truck ladder from a burning building.
Thus, it is an object of this invention to provide in respect of extension ladders, a retractible life line safety device that cannot be fouled upon retraction of o ~18i8~
an extension ladder, as well as a safety harness to secure a climber to the safety line and thereby an extension ladder.
In one aspect, the invention provides a safety apparatus to prevent falls from an extension ladder, which apparatus comprises a retractible cable device which S is detachably secured at the base of the ladder, or on the lower rung, or other part of the ladder. However, it can optionally be secured at the top of the ladder, or top nung or other top portion of the ladder, or at some point lower than the top, or higher than the bottom, respectively. In other words, the positions of the housing and the free end of the cable end are reversible, the important point being that the cable be 10 able to extend a length great enough to provide the worker with a secure line on the ladder. The cable device is comprised of a housing which contains a rotatable drum upon which the cable is wound and unwound; a cable which is fixed at one end to the rotatable cable drum while the other end, or in other words the free end, is attached to the end of the ladder which is to be elevated. The rotatable drum is 15 biased such that the cable will retract upon return of the extension ladder to a starting position. Although a coiling drum is suggested here, it is understood that any other means of coiling, or gathering the cable as the extension ladder is retracted is within the scope of this invention.
This retractible cable device contains a braking ",el,l Idllialll to arrest the 20 rotation of the cable drum upon the event of a rapid movement such as a fall by a worker on the ladder.
_ 2~8~8 The apparatus further comprises a safety belt, or harness, or other such safety strapping, secured about a worker, attached either reversibly, or pe, 1 l Idn6l Itly to a cable gripping clamp which itself may either be reversibly attached, or permanently attached to the cable. Although only one person is normally on a 5 ladder at a time, in circumstances where it is ~ ,, idL~, such as in the fire fighting field, more than one such belt and gripping clamp a" ~nge" ,~"L may be used on the same cable on the same ladder. Indeed, more than one ,~t,d~ Lle cable device and cable may be used per ladder, depending upon the circumstances, and all such variations are within the scope of the present invention.
In a particular ~" ,L,odi" ~t:"L of the invention, the apparatus is attached to the extension ladder of an extension ladder fire truck where the retractible cable device is secured at the base of the ladder and the slidable gripping clamp is pre-attached to the cable. In addition the free end of the cable from the device is in an extended position, i.e., it extends the length of the u"exLt:nded ladder, where the free end of 15 the cable is attached to the top rung of the top portion of the ladder.
In a further ~Illbocli~ "e"L a brake is provided such that the cable is not free to play out from the retractible cable device. The brake is applied when the extension ladder has been extended to a desired length.
In a further embodiment, the free end of the cable of the ,~L,d~ ble cable 20 device is attached to a rod which is fixed to the upper portion of the ladder. It will be un~ Luod that any other type of dLLd-,l 111 ,el ~L to the upper portion, or top rung -~ ~ 8 of the ladder to which the apparatus has been applied is within the scope of this invention.
In yet a further ~" ,L,odi" le"~, the free end of the cable of the, t:l~d-,Ld~le cable device is attached to a polyester-based shock absorber which in turn is attached S to the rod located at the top of the ladder. However, it is u, Idt:l ~Lood that any type of shock absorber may be used and is within the scope of the present invention.
In yet a further embodiment, the slidable clamp is comprised of a lever and a spring clip which when released engages an upper lock and the lever engages a second lower lock simultaneously, thereby gripping and securing the clamp on the 10 cable. It will be understood that any slidable clamping device which will grip and secure its position, and thereby, the worker's position, is within the scope of this invention.
The invention also provides a method of preventing falls from retractible extension ladders by attaching a safety belt to a person who will climb the ladder 15 and further attaching this belt by a coupling ",e,.h~"is", such as a climbing carabiner to a slidable gripping clamp which is in turn attached to a cable. The cable is extended between the upper end, or top rung of the extension ladder and a retractible cable device which is secured at the base of the ladder. The cable device of this method is comprised of a housing, a rotatable cable drum which is 20 biased to rewind upon turning in a given direction, a cable which is attached to the drum and also to the end of the ladder which is to be elevated. The cable is retractibly drawn from the cabl3 device as the ladder is extended. The device of O ~:1818~8 this method also contains a brake which arrests the rotation of the drum upon rapid movement of the cable such as in the event oF a fall.
A further e",l,odi",e"l oF this invention is this method of preventing falls where the extension ladder is the ladder on a fire truck.
In a further ~Illbodi,,,~,,L this invention pertains to the use of an apparatus which is comprised of a retractible cable device secured at the base of a ladderwhere the cable device comprises a housing a rotatable cable drum which is biased to rewind upon turning in a given direction a cable which has a first endfixed to the rotatable cable drum and second end which is attached to the end of the ladder which is to be elevated such that the cable can be retractibly drawn from the cable device as the ladder is extended and it further consists of a brake (the retractible cable device brake) which arrests the rotation of the cable and thereby movement of the cable in the event of a fall from the ladder in addition to a safety belt secured on the person using this apparatus which in turn is attached to a grasping clamp which is slidably attached to the cable.
In a further e",bodi"~e"l a brake (cable brake) is provided apart from the retractible cable device brake and said brake is set when the ladder has been extended to a desired length. Said clamp assits in m dil lldil lil 19 cable position and taughtness or tension of the cable. In a further t~lllbodilllc:lll this cable brake is attached to the ladder with teflon bolts so that the brake will break away from the ladder if the ladder is extended under force while the brake is set.
~ ~8L8~38 In a further e,nbodi",e"l this invention is for use in preventing falls from retractible extension ladders which is the ladder on a fire truck.
Various e",bodi",e"l~ of the invention selected by way of example will now be described with reference to the auculllp~illying drawings.
s Desc~ lion of the Drawings Figure 1 depicts a side view of the apparatus of the invention.
Figure 2 depicts a front view of the apparatus of Figure 1.
Figure 3 illustrates the apparatus of Figure 1 attached to an extension ladder.
Figure 4 illustrates a slidable grasping clamp of the apparatus as shown in Figure 1.
Figure 5 illustrates a side view of a cable rod and shock absorber of the apparatus shown attached to the upper portion of an extension ladder shown in Figure 2.
Figure 6 illustrates a front view of a cable rod and shock absorber of the apparatus ~shown attached to the upper portion of an extension ladder as shown in Figure 2.
Figure 7 illustrates a cable brake of the invention in place on a ladder as shown in Figure 3.
0 218:~58 Figure 8 illustrates greater detail on a perspective view of the cable brake of Figure 7.
Des~ ,lion of Invention In the various drawings ~:u" ~s~,ol1.li, ,9 parts in different figures are denoted by the same reference and numerals.
Referring first to Figure 1, all of the parts of a specific blllbo~ "~l ,l of the apparatus of the invention are illustrated. COI "" ,en-.i"g with the dLLdL.I 111 It~l IL at the upper portion of the ladder, a metal rod 2 is attached by means of stainless steel U-bolts 4 to the upper portion of the extension ladder, in particular the top and second from the top rungs ol the ladder. These U-bolts are preferably 5/8"
stainless steel in CO~ Jo~ iUn, however, any means by which this rod, or a similar rod can be attached to the extension ladder is a~ .le. In an alternative ~1 1 Ibo-li, 1 1~1 ll the rod may be dispensed with, and the safety cable may be attached directly to the upper rung of the ladder, however, the rod is preferred so as toillllll-~:" - the upper end of the safety cable.
Attached at the upper end of the rod 2 is a first carabiner 6 which is in turn connected to a polyester-based shock absorber 8. In a preferred e" ,L,o.li" ,e"L, this shock absorber is a Miller Soft StopTM No 880 type of shock absorber. This shockabsorber, is in turn, connected to the travelling, or free end of the safety cable 10 by means of a further carabiner 6. The ~,d~dbil1er~ 6 are preferably UIM certified aluminum carabiners, however, any other type of strength tested connector may be ~1 2~ 8~ 858 used. The travelling end of the cable has affixed to it a carabiner and hook apparatus 12. The safety cabls is in a preferred embodiment a stainless steel cable consisting of 7/32" 5 000 Ib. test aircraft type cable. The retractible cable device 14 may be any device which provides the features described for this invention. Such devices have been described in Canadian Letters Patent 2 075 978or U.S. Patent No. 5 186 289. In a prefenred er"l-odi,l,t:"l the Miller Safety Fall Arrestor/ Retractor is used. The safety device is attached to the base of the ladder by means of a bracket 16 with securing bolts 18. Referring to Figure 1, the retractible cable device 14 is securely mounted to the ladder 19 by means of a further bracket 20 and bolt means 22. The cable clamp 26 is illustrated in greater detail in Figure 4. Referring now to Figure 4 this cable clamp or slideable grasping clamp is, o" ,~,, ised of an upper lock 28 a safety pin 30 a lever 32 and a second lock 34 housed inside a stainless steel trolley 36. In a preferred t:",L,o.li",~"L a Trylon-type safety cable sleeve is used. The ability of this cable clamp to slide over the safety cable can be adjusted by means of adjustment screws 38 and the safetybelt 44 worn by the user is attached by means of a clasp hook assembly 42 to theopening 40 of the lever 32.
Referring again to Figure 1, the slideable grasping clamp assembly 42 is attached to the lever as just I l lel l~i.n~ed which is in turn attached to the safety belt or harness 44.
_ o ~8~85g Referring to Figure 5 which is a close-up view of the upper portion of the apparatus attached to the upper rung of an extension ladder it may be seen that the extension ladder 18 at the top rung 46 has attached the support bar 2. The carabiners 6 are attached to the upper and lower ends of the polyester- based S shock absorber 8 which serves to cushion the fall of a worker. These same features are shown from the front in Figure 6.
Figure 7 illustrates the cable brake and in the e",obodi",e"l illustrated it consists of the clamping lower portion 34 and 36 of a slidable grasping clamp illustrated in Figure 4. It is welded to an L bracket 48 or means such that the 10 bracket can break away from the ladder in the event an attempt to extend the ladder is made while the brake is set. This may occur in an d,O~ of the present invention to a firetruck ladder which is mechanically extended. A suitable clip and chain 50 arrangement holds the clamping lever 32 in the unlocked and locked positions. A guide 56 may also be il 1-,01 IJOIdled as a part of the apparatus of this IS invention to ensure proper po~ilioni"g of the cable 10.
While the invention has been particularly shown and described with referencetopreferred~",bodi",~"l~ itwillbeu"~ ,loodbythoseskilledintheart that various other changes in form and detail may be made without departing from the spirit and scope of the invention.
Claims (13)
1. A safety apparatus to prevent falls from an extension ladder which comprises:
a. a retractable cable device secured at the base of said ladder, said cable device comprising:
i. a housing, ii. a rotatable cable drum which is biased to rewind upon turning in a given direction;
iii. a cable which has a first end fixed to said rotatable cable drum of said cable device and a second end attached to the end of said ladder which is to be elevated, such that the cable can be retractably drawn from said cable device as the ladder is extended, and iv. a brake which arrests the rotation of said drum and thereby movement of said cable in the event of a fall;
b. a safety belt secured on a person;
c. a gripping clamp attached to said belt, the gripping clamp portion slideably attached to said cable;
a. a retractable cable device secured at the base of said ladder, said cable device comprising:
i. a housing, ii. a rotatable cable drum which is biased to rewind upon turning in a given direction;
iii. a cable which has a first end fixed to said rotatable cable drum of said cable device and a second end attached to the end of said ladder which is to be elevated, such that the cable can be retractably drawn from said cable device as the ladder is extended, and iv. a brake which arrests the rotation of said drum and thereby movement of said cable in the event of a fall;
b. a safety belt secured on a person;
c. a gripping clamp attached to said belt, the gripping clamp portion slideably attached to said cable;
2. The apparatus as recited in claim 1 wherein the extension ladder is the ladder on a fire truck.
3. The apparatus as recited in claim 1 wherein the gripping clamp is comprised of a lever; a spring clip; an upper lock; and a second lock, where in use, downward pressure on said lever disengages said spring clip and simultaneously engages said upper lock and said second lock onto said cable.
4. The apparatus as recited in claim 1 wherein the attachment of the second end of said cable is to the first end of a polyester-based shock absorber, and the second end is attached to the upper end of said ladder.
5. The apparatus as recited in claim 4 wherein a metal bracket is attached to the top step of said ladder, and the second end of said shock absorber is attached to said bracket.
6. The apparatus as recited in claim 5 wherein said retractable cable device is removably attached to the base of said ladder and said metal bracket is removably attached to the top of said ladder.
7. The apparatus as recited in claim 1 wherein the retractable cable device has a cable drum from which a cable can be drawn as said ladder is extended; braking means for arresting rotation of the drum, said braking means including relatively rotatable brake components; means for imparting frictional resistance to relative rotation of said relatively rotatable brake components; and clutch means which functions automatically to cause relative rotation of the relatively rotatable brake components against said frictional resistance means on rapid acceleration of the cable drum such as occurs in the event of a fall; and said clutch means including coupling elements which are displaceably connected to the cable drum abutments with which said coupling elements move into engagement so as to bring about the relative rotation of the brake components.
8. The apparatus of claim 7 with a cable clamp to maintain cable positions.
9. The apparatus as recited in claim 2 wherein said gripping clamp is comprised of a lever, a spring clip, an upper lock, and a second lock, where in use, downward pressure on said lever disengages said spring clip and simultaneously engages said upper lock and said second lock onto said cable; and wherein the attachment of the second end of said cable is to the first end of a polyester-based shock absorber, and the second end is attached to a metal bracket which is removably attached to the top step of said ladder and said retractable cable device is removably attached to the base of said ladder.
10. A method for preventing falls from a retractable extension ladder which comprises:
a. attaching a safety belt to a person who will climb said ladder;
b. attaching said belt to a gripping clamp where said gripping clamp is slideably attached to a cable;
c. said cable extending between the upper end of said extension ladder and retractable cable device which is secured at the base of said ladder, said cable device comprising:
i. a housing, ii. a rotatable cable drum which is biased to rewind upon turning in a given direction;
iii. a cable which has a first end fixed to said rotatable cable drum of said cable device and a second end attached to the end of said ladder which is to be elevated, such that the cable can be retractably drawn from said cable device as the ladder is extended, and iv. a brake which arrests the rotation of said drum and thereby movement of said cable in the event of a fall.
a. attaching a safety belt to a person who will climb said ladder;
b. attaching said belt to a gripping clamp where said gripping clamp is slideably attached to a cable;
c. said cable extending between the upper end of said extension ladder and retractable cable device which is secured at the base of said ladder, said cable device comprising:
i. a housing, ii. a rotatable cable drum which is biased to rewind upon turning in a given direction;
iii. a cable which has a first end fixed to said rotatable cable drum of said cable device and a second end attached to the end of said ladder which is to be elevated, such that the cable can be retractably drawn from said cable device as the ladder is extended, and iv. a brake which arrests the rotation of said drum and thereby movement of said cable in the event of a fall.
11. The method as recited in claim 9 wherein the extension ladder is the ladder on a fire truck.
12. An apparatus which is comprised of:
a. a retractable cable device secured at the base of an extension ladder, said cable device comprising:
i. a housing, ii. a rotatable cable drum which is biased to rewind upon turning in a given direction;
iii. a cable which has a first end fixed to said rotatable cable drum of said cable device and a second end attached to the end of said ladder which is to be elevated, such that the cable can be retractably drawn from said cable device as the ladder is extended, and iv. a brake which arrests the rotation of said drum and thereby movement of said cable in the event of a fall;
b. a safety belt secured on a person;
c. a gripping clamp attached to said belt, the gripping clamp portion slideably attached to said cable;
d. a cable clamp to maintain cable position and tension;
for use in preventing falls from retractable extension ladders.
a. a retractable cable device secured at the base of an extension ladder, said cable device comprising:
i. a housing, ii. a rotatable cable drum which is biased to rewind upon turning in a given direction;
iii. a cable which has a first end fixed to said rotatable cable drum of said cable device and a second end attached to the end of said ladder which is to be elevated, such that the cable can be retractably drawn from said cable device as the ladder is extended, and iv. a brake which arrests the rotation of said drum and thereby movement of said cable in the event of a fall;
b. a safety belt secured on a person;
c. a gripping clamp attached to said belt, the gripping clamp portion slideably attached to said cable;
d. a cable clamp to maintain cable position and tension;
for use in preventing falls from retractable extension ladders.
13. The use as recited in claim 11 wherein the extension ladder is the ladder on a fire truck.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2181858 CA2181858A1 (en) | 1996-07-23 | 1996-07-23 | Method and apparatus for prevention of falls from extension ladders |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2181858 CA2181858A1 (en) | 1996-07-23 | 1996-07-23 | Method and apparatus for prevention of falls from extension ladders |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2181858A1 true CA2181858A1 (en) | 1998-01-24 |
Family
ID=4158651
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2181858 Abandoned CA2181858A1 (en) | 1996-07-23 | 1996-07-23 | Method and apparatus for prevention of falls from extension ladders |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2181858A1 (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2374986A1 (en) * | 2010-04-12 | 2011-10-12 | Iveco Magirus AG | Falling safety device for a telescopic ladder set |
| WO2013135929A1 (en) * | 2012-03-13 | 2013-09-19 | Escaleras Aguerri, S.L. | Vertical lifeline for working at heights |
| US8997928B1 (en) * | 2013-10-08 | 2015-04-07 | Morgan Todd Ellis | Fall restraint traveler device |
| US20180369622A1 (en) * | 2015-12-23 | 2018-12-27 | Xsplatforms B.V. | Fall arrestor to gradually absorb a pull on a safety cable coupled with the fall arrestor |
| WO2019071337A1 (en) * | 2017-10-13 | 2019-04-18 | Northern Strands Co. Ltd. | Fall arrest system |
| US10940338B1 (en) * | 2017-12-19 | 2021-03-09 | 3M Innovative Properties Company | Top bracket for fall protection safety system |
| CN113616103A (en) * | 2021-07-26 | 2021-11-09 | 安徽大汉机器人集团有限公司 | Safety device for accidental falling of window cleaning machine |
-
1996
- 1996-07-23 CA CA 2181858 patent/CA2181858A1/en not_active Abandoned
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2374986A1 (en) * | 2010-04-12 | 2011-10-12 | Iveco Magirus AG | Falling safety device for a telescopic ladder set |
| WO2013135929A1 (en) * | 2012-03-13 | 2013-09-19 | Escaleras Aguerri, S.L. | Vertical lifeline for working at heights |
| US8997928B1 (en) * | 2013-10-08 | 2015-04-07 | Morgan Todd Ellis | Fall restraint traveler device |
| US20150096834A1 (en) * | 2013-10-08 | 2015-04-09 | Morgan Todd Ellis | Fall restraint traveler device |
| US20180369622A1 (en) * | 2015-12-23 | 2018-12-27 | Xsplatforms B.V. | Fall arrestor to gradually absorb a pull on a safety cable coupled with the fall arrestor |
| US10806955B2 (en) * | 2015-12-23 | 2020-10-20 | Xsplatforms B.V. | Fall arrestor to gradually absorb a pull on a safety cable coupled with the fall arrestor |
| WO2019071337A1 (en) * | 2017-10-13 | 2019-04-18 | Northern Strands Co. Ltd. | Fall arrest system |
| US11655677B2 (en) | 2017-10-13 | 2023-05-23 | Northern Strands Co. Ltd. | Fall arrest system |
| US10940338B1 (en) * | 2017-12-19 | 2021-03-09 | 3M Innovative Properties Company | Top bracket for fall protection safety system |
| US11883692B2 (en) | 2017-12-19 | 2024-01-30 | 3M Innovative Properties Company | Top bracket for fall protection safety system |
| CN113616103A (en) * | 2021-07-26 | 2021-11-09 | 安徽大汉机器人集团有限公司 | Safety device for accidental falling of window cleaning machine |
| CN113616103B (en) * | 2021-07-26 | 2022-06-03 | 安徽大汉机器人集团有限公司 | Safety device for accidental falling of window cleaning machine |
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