CA1315752C - Fall-arrest safety device - Google Patents

Fall-arrest safety device

Info

Publication number
CA1315752C
CA1315752C CA000555049A CA555049A CA1315752C CA 1315752 C CA1315752 C CA 1315752C CA 000555049 A CA000555049 A CA 000555049A CA 555049 A CA555049 A CA 555049A CA 1315752 C CA1315752 C CA 1315752C
Authority
CA
Canada
Prior art keywords
guide
cable
stop
drum
tie member
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.)
Expired - Fee Related
Application number
CA000555049A
Other languages
French (fr)
Inventor
George P. Sharp
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sala Group Ltd
Original Assignee
Barrow Hepburn Equipment Ltd
Barrow Hepburn Sala Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Barrow Hepburn Equipment Ltd, Barrow Hepburn Sala Ltd filed Critical Barrow Hepburn Equipment Ltd
Application granted granted Critical
Publication of CA1315752C publication Critical patent/CA1315752C/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • AHUMAN NECESSITIES
    • A62LIFE-SAVING; FIRE-FIGHTING
    • A62BDEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
    • A62B35/00Safety belts or body harnesses; Similar equipment for limiting displacement of the human body, especially in case of sudden changes of motion
    • A62B35/0093Fall arrest reel devices

Landscapes

  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Emergency Lowering Means (AREA)

Abstract

ABSTRACT

Fall-Arrest Safety Device A fall-arrest safety apparatus comprising a cable (5) wound onto a drum (2) has a fixed cable guide (25) and a stop (26) which is secured to the cable (5) near its tail end. The guide prevents passage of the stop under pulling forces exerted on the cable in normal use and thereby ensures that a reserve length of cable remains on the drum. The stop is forced through the guide under the larger pulling force exerted if the worker attached to the cable falls when the stop is against or adjacent the guide.

(Fig. 1)

Description

- 1 3 ~ 2 ``

Fall-Arre6t Safety Device This invention relate6 to apparatu~ comprising a rotatably mounted drum or ~pool on which a rope, cable or other coilable tie member can be wound, and a braking mechanism which automatically stop~ or retard6 rotation of the drum or 6pool if its rotational speed or acceleration rise6 above a certain value.
Apparatus of this kind can be used, for example, for safety lowering or fall-arre6t purposes by attaching the drum or spool holder or casing to a fixture and a~taching the free end of a safety line, wound onto the drum or spool, to a person or object to be protected. A
particularly important u6e of such apparatus is for the protection of a per~on working at high levels above the ground, u6ing a 6afety line which is attached to a p~r~onal 6afety belt or harness. Apparatus for such purpo~e ~u~tomarily incorporates a drum which is self-winding by spring action so ~hat ~lack in the safety line is au~omatically taken up and cannot accumulate and thereby create a further 6afety hazard.
It is important for worker~ using such a fall-arrest apparatu6 to be warned again6t working with the cable near to the limit of its pay-out length, becau6e in the event of a fall the pay-out limit might be reached before the fall spead has been 6ubstantially decelerated by the brakee in Which ca6e the fall would ba abruptly arrested with con6equent high risk of serious personal in3ury.
It i6 known in the art to mark a tail end 6ection of the cable length 80 that that ~ec~ion i~ vi6ually identifiable as such as it emerge6 ~rom the drum or drum housing. Apparatu6 i6 commercially available in which a ,,~

.

- ~ 3 ~ 2 tail end cable section of about 1 metre in length is painted red.
The marking of the tail end section oE the cable is efEective Eor its purpose only lf a watch is kept for its appearance, either by the worker attached to the safety line or by another person posted as look-out. This precaution involves difficulty or inconvenience and it is in practice liable to be omitted.
The present invention provides more reliable means of warning.
According to the present invention there is provided apparatus comprising a rotatably mounted drum on which a rope, cable or other coilable tie member can be wound, and a braking mechanism which automatically stops or retards rotation oE the drum if its rota-tional speed or acceleration in the unwinding direction rises above a certain value, characterized in that a guide through which the tie member passes is mounted at a loca-tion ; in the vicinity of the drum; and a stop for abutting said guide is attached to the tie member near to its tail end and serves by abutting said guide to resist further pay-out of tie member from the drum under pulling force up to a certain magnitude; said guide or said stop being formed or mounted so as to yield and so allow further pay-out of the tie member under pulling forces exceeding such limit.
The magnitude of the resistance to pay out of the tie member beyond the limiting position determined by the stop is a factor to be selected with due regard to the intended use of the apparatus. The resistance should of course be high enough to :~31~7~2 200~0-3~2 prevent passage of the stop under normal working loacls on the cable.
In the case oE personnel fall arrest safety apparatus, the said resistance should be high enough -to resist any pull on the tie member (hereaf-ter called 2a ,, ,,~., . ~ , .;

1 3 ~ 2 , ~

"cable") which the worker i6 likely to exert during normal working in an attempt to move further away from the drum.
The resistance must thwart any 6uch attempt and therefore give the worker 6ensible warning that he i~ at the safety limit of the cable extension. At the same time ~he guide and/or the stop i6 required to yield in the event of a worker falling when the cable is at or approaching that limit. Therefore the yield resi6tance must be overcome by the smalle6t force which might be imposed in the event of a worker falling when the cable is a~ or approaching the said limit. In the case of appara~us intended to be used as personnel fall-arrest safety apparatu~, it is suitable for the yield resistance, expressed in term~ of the steady load which must be applied to the cable to overcome the resi6tance to further pay--out of the cable, to be between 50 lbs (or 22.7 Kg) and 150 lbs (or 68 Kg) and prefe..ably the said resistance is be~ween 80 lbs (or 36.3 Kg) and 140 lbs (or 63.6 Kg).
The yield resi6ta~ce can for example be the resistance of the guide or the stop to bodily displacement under pulling force on the cable. For example, the guide can be held in place by bolts or other fa6teni.ng means which yields by rupturing. Alternatively the material of which the guide or the stop is formed and/or i~s geometry can be such that it fractures or deforms to allow further pay-out of the cable when a predetermined pulling force is exceeded.
In preferred embodiment6 of the invention the 6top can be forced past the guide without breakage or bodily di~placement of the 6top or the guide or of ~lean6 holding the 6top or guide in place. There i6 therefors in such ca6e6 no ri6k of broken or di6placed pieces interfering with the continued operation of the apparatus.
In the mo6t preferred embodiment~ of the invsntion the yield occurs by ela6tic deformation of material. The yield resi6tance can readily be predetermined by the u6e ~ - ~3~ 5~2 4 20080-3~2 o such material and it can have a useful cushioning effect at the moment of an impact of -the stop against the cable guide.
In one very satisfactory way of carrying out the invention, the guide comprises elastically deformable material which defines a guide passage through which the tie member is Ereely movable but through which said stop can pass only under a force large enough to cause radial expansion of said passageway by said stop.
Preferably the stop is in the form of a ferrule through which the cable extends.
The -trailing end portion of the cable, which intervenes between the cable stop and the point at which the cable is attached to the drum, should be of sufficient length to ensure that a falling load can be smoothly decelerated by the drum braking system during the unwinding of that intervening cable portion, even if the cable stop encounters the guide right at the beginning of the fall.
The drum braking mechanism can comprise a centrifugal clutch via which friction braking forces are applied in the event that the unwinding speed of the drum exceeds a predetermined value.
The mechanism can be constructed so that co-operating friction braking components are forced together under a progressively increasing pressure responsive to the operation of the clutch, e.g. as described and illustrated in United l~ingdom Patent 1 552 667. Preferably however the braking mechanism comprises relatively displaceable friction braking components which are permanently held pressed together, at least one of such components ,~

3~7~2 -4a- 20080-342 being fixed and the other or another of them being displaceable relative to such fixed component(s) by force which is transmitted from the drum or spool via the centri-Eugal clutch.

~, :

-` ~L3~7~2 An embodiment of the invention, selected by way of example, i8 illu~trated in the accompanying drawings, in which:
Fig. 1 is a part sectional elevation of the apparatus; and Fig. 2 i6 a detail view 6howing the cable 6top and guide on a larger ~cale.
The apparatu~ i~ a so-called 6afety block. ~xcept for the cable ~top and guide feature of the present invention, the block i~ basically similar in construction and function to that described in the aforesaid European Patent Applica~ion 0 247 818. The block comprises a casing 1 within which a cable drum 2 is mounted for free rotation about a ~haf~ 3 the ends of which are supported by the casing. At the top of the casing there is a shackle by which the block can be suspended from a fi~ture.
A cable 5 is wound onto the drum 2 and leads out of the casing via a bottom aperture 11 60 ~hat the free end of the cable can be attached ~o a per~on or object to be protected.
By pulling on the cable 5, the drum can be rotated in the unwinding direction, against the action of a spiral spring 12 housed within the drum. So long as the unwinding speed remains below a certain level, the block offer~ virtually no re~istance to the unwinding of the cable other than that imposed by that spring. However if the unwinding speed increa~es to that level, due for example to a person attached to the cable 5 falling, the drum becomes arre6ted by a friction brake through the agency of a centrifu~al clutch mechani6m. This mechani~m comprise~ pawls 6uch as 19 which are pivotally connected to the drum. If the drum accelerates in the unwinding direction due to the fall of a workman attached to the cable, the pawls pivo~ under the centriEugal force, i 6 IL ~ 2 again~t the action of 6pring6 21 into positions in which free end~ of the pawl6 engage behind ratchet teeth of a friction braking ring 14 which i6 in friction-braking contact with a co-operating fixed component. The frictional resistance to rotation of the eing 14 i6 such that the pay-out speed of the cable is decelerated to zero at a safe rate.
Between the drum and the cable exit aperture 11 there is a fixed cable guide 25 through which the cable passes.
The guide define6 for the cable a pas~ageway 2~a which i~
7.0 mm in diameter. The cable diame~er is 5.0 mm. The guide is made of an elastomeric material: synthetic rubber, and is a one-piece moulding.
A steel ferrule 26 has been swaged onto the cable at a position along the cable which i~ about 1.0 m from the point at which the cable is attached to the drum. The fe~rule has an outer cylindrical surface 7.0 mm in diameter but its lower end is slightly enlarged so tha~
the ferrule will not pass through the passageway 25a in the guide 25 unless the passageway is expanded by elastic di~tention of ~he passagway wall. The resistance to this elastic deformation is such tha~ when the ferrule is in contact with the guide, with the lower end of ~he ferrule against the guide, and a progre~sively increasing axial force tending to increase the abutment pressure is applied to the part of the cable projecting from ~he guide, the ferrule becomes pulled through the passageway only when the loading force reache6 100 lbs (or 45.4 Kg).
Thi6 re~i6tance impo6ed by the guide en6ure~ that the cable will not be pulled beyond thi~ pay-out position by force6 exerted on the cable in consequence of normal movement6 of a worker attached to the cable. If the worker attempt~ to move further from the drum, he will ~en6e the re6i6tance and be alerted to the fact that he i~
at the limit of the regulation working range of the cable.
. .

!

~3~7~2 Should the worker fall when the cable i~ at or near such limit, the ferrule will be pulled ~hrough the guide by the applied load but the fall will be decelerated by the drum brake mechanism so that an abrupt destruction of kinetic energy l~kely to cause very serious and possibly fatal injury is avoided.
The trailing (upper) end of ~he ferrule may also be slightly enlarged so that once the ferrule has been pulled down past the guide the cable cannot very easily be rewound without attention being drawn to the fact that the cable has been pulled out beyond its intended working limit and that a check should therefore be made that the apparatus is in serviceable condition.
It will readily be perceived that as an alternative to the illustrated arrangement, the guide 25 can be a rigid component and the ferrule 26 can be of elastically deformable material (which can for example be moulded onto the cable) so that it can be forced ~hrough the guide by a cable loading above the predetermined limit.
As a further alternative, the ferrule 26 can be secured to the cable by pins which shear under a given cable loading exerted while the ferrule is abutting against the guide. In this case the guide can of course be of rigid material.

.. .. . ..... .. .. .. ... . .

Claims (6)

1. Apparatus comprising a rotatably mounted drum on which a rope, cable or other coilable tie member can be wound, and a braking mechanism which automatically stops or retards rotation of the drum if its rotational speed or acceleration in the unwinding direction rises above a certain value, characterised in that a guide through which the tie member passes is mounted at a location in the vicinity of the drum; and a stop for abutting said guide is attached to the tie member near to its tail end and serves by abutting said guide to resist further pay-out of tie member from the drum under pulling force up to a certain magnitude; said guide or said stop being formed or mounted so as to yield and so allow further pay-out of the tie member under pulling forces exceeding such limit.
2. Apparatus according to claim 1, wherein said guide or stop yield(s) by deformation thereof.
3. Apparatus according to claim 2, wherein said yield occurs by elastic deformation of material.
4. Apparatus according to claim 3, wherein said guide comprises elastically deformable material which defines a guide passage through which the tie member is freely movable but through which said stop can pass only under a force large enough to cause radial expansion of said passageway by said stop.
5. Apparatus according to claim 4, wherein the stop is in the form of a ferrule through which the cable extends.

8a
6. Apparatus according to any one of claims 1, 2, 3, 4, or 5, wherein a steady load of between 80 lbs. (or 36.3 Kg) and 140 lbs. (or 63.6 Kg) must be exerted on the tie member in order to overcome the said resistance to further pay-out of the tie member.
CA000555049A 1986-12-23 1987-12-22 Fall-arrest safety device Expired - Fee Related CA1315752C (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8630789 1986-12-23
GB868630789A GB8630789D0 (en) 1986-12-23 1986-12-23 Fall-arrest safety device

Publications (1)

Publication Number Publication Date
CA1315752C true CA1315752C (en) 1993-04-06

Family

ID=10609529

Family Applications (1)

Application Number Title Priority Date Filing Date
CA000555049A Expired - Fee Related CA1315752C (en) 1986-12-23 1987-12-22 Fall-arrest safety device

Country Status (3)

Country Link
EP (1) EP0272908A3 (en)
CA (1) CA1315752C (en)
GB (2) GB8630789D0 (en)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9001908D0 (en) * 1990-01-27 1990-03-28 Ferranti Meters Ltd Denis Safety device
GB9013045D0 (en) * 1990-06-12 1990-08-01 Nutter Nicholas C Theft detection device
FR2714612B1 (en) * 1994-01-05 1996-05-15 Marcel Jose Peltier Anti-fall safety device.
CN1050766C (en) * 1995-07-05 2000-03-29 马塞尔·J·佩尔蒂埃 Safety device for preventing elevator from falling down
FR2883758B1 (en) 2005-04-01 2007-06-15 Capital Safety Group Emea Sa ENERGY ABSORPTION DEVICE
FR2886165B1 (en) 2005-05-24 2007-07-13 Capital Safety Group Emea Sa METHOD FOR MOUNTING A SAFETY LINE CABLE ON A TENDER
FR2886166B1 (en) * 2005-05-24 2007-08-03 Capital Safety Group Emea Sa TENSIONER FOR SAFETY LINE WITH ENERGY ABSORPTION DEVICE
US8499890B2 (en) * 2007-07-18 2013-08-06 Rescue Reel, Llc Personal escape device
GB2467953B (en) * 2009-02-20 2013-07-17 Latchways Plc Fall arrest system safety device
FR2965183B1 (en) 2010-09-29 2013-08-16 Tractel Sas SAFETY LINE CABLE RETRACTOR FALL BRAKE AND CABLE RESERVE
US10792520B2 (en) 2014-09-12 2020-10-06 D B Industries, Llc Personal descent system
GB201518027D0 (en) * 2015-10-12 2015-11-25 Swisslogo Ag Self-braking pulley
GB2621122A (en) * 2022-08-01 2024-02-07 Latchways Plc Systems and methods for reserving a portion of a lifeline for fall arrest

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB694186A (en) * 1950-09-01 1953-07-15 Bowden Eng Ltd Method of securing an attachment piece to a wire cable
GB831195A (en) * 1956-05-04 1960-03-23 David Rushworth Improvements relating to self winding reels for use with safety lines
US3388716A (en) * 1965-11-16 1968-06-18 Wilsons Sons Inc William M Hose reel
GB1552667A (en) * 1977-10-07 1979-09-19 Barrow Hepburn Equip Ltd Self winding drum

Also Published As

Publication number Publication date
EP0272908A2 (en) 1988-06-29
GB2199552A (en) 1988-07-13
EP0272908A3 (en) 1989-03-22
GB8729910D0 (en) 1988-02-03
GB8630789D0 (en) 1987-02-04

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