GB2503674A - Step bolt nut and step bolt assembly - Google Patents

Step bolt nut and step bolt assembly Download PDF

Info

Publication number
GB2503674A
GB2503674A GB1211777.6A GB201211777A GB2503674A GB 2503674 A GB2503674 A GB 2503674A GB 201211777 A GB201211777 A GB 201211777A GB 2503674 A GB2503674 A GB 2503674A
Authority
GB
United Kingdom
Prior art keywords
section
nut
step bolt
threaded
bolt
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.)
Granted
Application number
GB1211777.6A
Other versions
GB201211777D0 (en
GB2503674B (en
Inventor
Dorin Git
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.)
Balfour Beatty PLC
Original Assignee
Balfour Beatty PLC
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 Balfour Beatty PLC filed Critical Balfour Beatty PLC
Priority to GB1211777.6A priority Critical patent/GB2503674B/en
Publication of GB201211777D0 publication Critical patent/GB201211777D0/en
Publication of GB2503674A publication Critical patent/GB2503674A/en
Application granted granted Critical
Publication of GB2503674B publication Critical patent/GB2503674B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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
    • E06C7/08—Special construction of longitudinal members, or rungs or other treads
    • E06C7/082—Connections between rungs or treads and longitudinal members
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G3/00—Scaffolds essentially supported by building constructions, e.g. adjustable in height
    • E04G3/24—Scaffolds essentially supported by building constructions, e.g. adjustable in height specially adapted for particular parts of buildings or for buildings of particular shape, e.g. chimney stacks or pylons
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04H—BUILDINGS OR LIKE STRUCTURES FOR PARTICULAR PURPOSES; SWIMMING OR SPLASH BATHS OR POOLS; MASTS; FENCING; TENTS OR CANOPIES, IN GENERAL
    • E04H12/00—Towers; Masts or poles; Chimney stacks; Water-towers; Methods of erecting such structures
    • E04H12/22—Sockets or holders for poles or posts
    • E—FIXED CONSTRUCTIONS
    • E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
    • E06C—LADDERS
    • E06C7/00—Component parts, supporting parts, or accessories
    • E06C7/08—Special construction of longitudinal members, or rungs or other treads
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B35/00—Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws
    • F16B35/04—Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws with specially-shaped head or shaft in order to fix the bolt on or in an object
    • F16B35/041—Specially-shaped shafts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B37/00—Nuts or like thread-engaging members
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
    • A62B35/00—Safety belts or body harnesses; Similar equipment for limiting displacement of the human body, especially in case of sudden changes of motion
    • A62B35/0043—Lifelines, lanyards, and anchors therefore
    • A62B35/0068—Anchors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
    • F16B33/00—Features common to bolt and nut
    • F16B33/02—Shape of thread; Special thread-forms

Landscapes

  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Suspension Of Electric Lines Or Cables (AREA)
  • Mutual Connection Of Rods And Tubes (AREA)
  • Bolts, Nuts, And Washers (AREA)
  • Connection Of Plates (AREA)

Abstract

A step bolt nut and step bolt assembly are disclosed. The step bolt nut comprises a threaded portion 14a and a sleeve portion 14b; preferably the sleeve portion is unthreaded. It is suitable for use with a step bolt, the step bolt having a threaded portion 12 and an unthreaded support portion 10. The step bolt nut is screwed to the end of the step bolt, such that the threaded section 14a of the step bolt nut engages with a threaded portion 12 of the step bolt. The sleeve portion 14b of the step bolt nut extends over the unthreaded support section 10 of the bolt. This moves the point at which a bending moment is applied to a location along the support portion 10 and away from the threaded part 12 of the step bolt. Preferably, the step bolt assembly comprises a second nut 16 which mounts over the threaded section 12 of the bolt.

Description

I
STEP BOLT AND NUT FOR A STEP BOLT
This invention relates generally to step bolts.
Step bolts are used as a means of climbing electricity transmission towers or the like. Such bolts normally comprise a threaded portion that may be passed through a hole in the steel section structure of the transmission tower. The bolt has a first nut threaded fully to the end of the threaded portion. The bolt is secured by means of a second nut introduced onto the free end of the threaded portion after it has passed through a hole in the steel section. In this way, the steel section is clamped between a pair of nuts at the end of the threaded section. A further locking nut is also typically used.
Once the step bolt has been firmly secured to the transmission tower it forms a generally horizontally projecting rod that can be utilised as a step for a person climbing the transmission tower. Thus, once a number of these step bolts have been attached to the transmission tower at various heights they can be utilised as steps to climb the tower to a desired height.
More recently, interest has focused on the health and safety aspects for persons engaged in climbing the transmission towers, using the step bolts. One improvement has been to use the step bolt as an anchor to tie to whilst climbing.
The step bolt thus becomes part of fall arrest system designed to prevent a person climbing the tower from falling off.
A problem with this type of step bolt is that it is prone to bending, particularly if it has to support a falling climber. Bending is also a problem if the step bolts are made longer (and therefore provide a safer foot support) because of the increased bending moment. This is a particular problem because the bending moment is applied at the point along the step bolt at the end of the threaded section rather than on the stronger support part of the bolt.
An obvious way to resolve this problem is to use larger bolts. However, the transmission towers have existing bolt openings, for example of 16mm diameter, so it is desirable to maintain the same diameter.
Another obvious approach is to use a higher grade steel. However, these materials can be brittle at lower temperatures, so that other problems are introduced.
GB 2 342 681 recognises the problem of bending at the end of the threaded section, and discloses a step bolt with an integral flange to replace the first nut.
This results in a more expensive step bolt design.
According to the invention there is provided a nut for use as pad of a step bolt, as defined in claim 1.
The invention provides a step bolt nut for receiving a step bolt having a first, unthreaded, section and a second, threaded, section, the nut comprising a threaded portion for engaging with the second section and a sleeve portion extending from the threaded portion, for fitting around a part of the first section, at the junction between the first and second sections.
This nut has a collar which extends along the unthreaded pad of the step bolt. This means that a bending moment applied to the step bolt acts at a location along the unthreaded shaft, rather than at the junction between the threaded and unthreaded sections. The shaft is thus less prone to bending.
The sleeve portion is preferably unthreaded, since it is for extending over an unthreaded pad of the step bolt.
The invention also provides a step bolt assembly comprising the nut of the invention and a step bolt having the first section and the second section. The nut is screwed to the end of the second section such that the threaded portion engages with the end of the second section and the sleeve portion extends over the first section. A second nut is then used for mounting over the second section, thereby to clamp a supporting structure between the nuts.
The first section is designed to support the weight of a person. The diameter of the first section can be approximately 16mm to fit to existing transmission towers.
An example of the invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 shows a known step bolt assembly; Figure 2 is used to explain the problem of bending; Figure 3 shows a step bolt assembly of the invention; Figure 4 shows a first example of the nut of the invention in more detail; and Figure 5 shows a second example of the nut of the invention in more detail.
The invention provides a step bolt nut and step bolt assembly, in which a nut which is screwed to the end of a threaded section of the bolt has a sleeve which extends over the unthreaded support part of the step bolt. This moves the point at which a bending moment is applied to a location along the stronger support part and away from the weaker threaded part of the step bolt.
Figure 1 shows a known step bolt assembly.
The step bolt has a first unthreaded support section 10 and a second threaded section 12. A first nut 14 is screwed to the end of the threaded section 12, and the threaded end of the bolt is passed through a hole in the structure to which the step bolt will be fastened, such as a transmission tower. A second nut 16 is screwed over the threaded section to clamp the structure between the nuts 14,16.
Washers are also shown in Figure 1. A further locking nut may be used.
Figure 2 is used to explain the problem of bending.
The thread of the second section 12 extends right through both nuts 14,16 (as shown in Figure 2 as hidden detail). Thus, a bending moment as represented by arrow 20 is applied at the transition between the threaded and unthreaded parts of the step bolt. As a result of the reduced cross sectional area in the threaded section, this is a weaker part of the step bolt, and it is prone to bending.
Figure 3 shows a step bolt assembly of the invention.
Only the nut 14 is changed. It comprises a threaded portion 14a for engaging with the second section 12 and a sleeve portion 14b extending from the threaded portion 14a, for fitting around a part of the first section 10, at the junction between the first and second sections 10,12.
This means that a bending moment is applied at a location along the support part 10, which has greater resistance to bending.
Figure 4 shows the nut of the invention in more detail.
The threaded part 14a can be seen more clearly, and only extends partly through the nut.
The step bolt and nuts are formed of steel. The invention enables steels to be used that withstand low temperatures well (such as fine grade steels). Low Carbon, Manganese Boron Steel can for example be used for the step bolt. This is a fine grain steel with a closely controlled range of chemical analysis suitable for heat treatment. The steel has high levels of ductility together with very good low temperature properties.
The length of the threaded portion of the shaft is for example in the range 50mm to 100mm to allow the step bolt to be passed through two layers of steel section/s or two structural members (not shown) utilised in electrical transmission towers and for the bolt to be secured to the tower by the use of a nut 6, a washer 7 and a further locking nut (not shown).
The support part of the step bolt can for example have a length in the range 150mm to 300mm.
The diameter of the support part can be just below 16mm to pass through 16mm holes, which are standard in transmission towers. However, other dimensions are of course possible.
The unthreaded section only needs to be long enough to move the bending moment to the unthreaded support part of the bold. The threaded section 14a can be around 1cm long (e.g. 10mm to 15mm) and the unthreaded section 14b can be around 2cm long (e.g. 10mm to 25mm).
Figure 5 shows one example of nut in more detail. Figure 5 shows a side view (top image), a cross sectional side view (middle image) and a top view (bottom image).
The internally threaded part 1 4a has a circular outer face, and the unthreaded part 1 4b is provided with the hexagonal outer face. This makes it easier to tighten after mounting, because the hexagonal part is slightly spaced from the support structure. Of course, both sections could have the hexagonal outer face (as in the example of Figures 1 to 4) or only the unthreaded section. The total length of the nut is for example less than or equal to 1.25 times the circular diameter. In one example, the circular diameter is 30mm and the total length is 30mm, comprising a 12mm long section 14a and an 18mm long section 14b. The threaded part can be an M16 thread, so that the inner diameter of the unthreaded part is 16mm (or slightly more). The hexagonal outer nut part can be 24mm.
In summary, the nut of the invention can be considered to be a double gauge nut having two sections for use on a standard step bolt. The first section is a plain bored section and the second section is threaded. The threaded side of the step bolt is provided in the sleeve side of the nut and exits the nut through the threaded side of the nut. The nut is threaded fully to the end of the threaded portion of the step bolt and the sleeved section is thus engaged over the shank of the step bolt.
The bolt is secured by means of a second nut introduced onto the free end of the threaded portion after it has passed through a hole in the steel section. In this way, the steel section is clamped between the double gauge nut and a normal nut at the end of the threaded section. A further locking nut is also typically used.
The invention can be used not only for transmission towers but also for other climbing applications.
The step bolt has been shown as a straight rod. However, it may incorporate features to facilitate tying ropes to the bolt, such as pig tails as disclosed in GB 2 342 681.
is Various modifications will be apparent to those skilled in the art.

Claims (6)

  1. CLAIMS1. A step bolt nut for receiving a step bolt having a first, unthreaded, section and a second, threaded, section, the nut comprising a threaded portion for engaging with the second section and a sleeve portion extending from the threaded portion, for fitting around a part of the first section, at the junction between the first and second sections.
  2. 2. A nut as claimed in claim 1, wherein the sleeve portion is unthreaded.
  3. 3. A step bolt assembly comprising the nut of any preceding claim and a step bolt having the section and the second section, wherein the nut is screwed to the end of the second section such that the threaded portion engages with the end of the second section and the sleeve portion extends over the first section.
  4. 4. An assembly as claimed in claim 3, further comprising a second nut for mounting over the second section, thereby to clamp a supporting structure between the nuts.
  5. 5. An assembly as claimed in claim 4, wherein the first section is designed to support the weight of a person.
  6. 6. An assembly as claimed in claim 4 or 5, wherein the diameter of the first section is approximately 16mm.
GB1211777.6A 2012-07-03 2012-07-03 Step bolt and nut for a step bolt Expired - Fee Related GB2503674B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1211777.6A GB2503674B (en) 2012-07-03 2012-07-03 Step bolt and nut for a step bolt

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1211777.6A GB2503674B (en) 2012-07-03 2012-07-03 Step bolt and nut for a step bolt

Publications (3)

Publication Number Publication Date
GB201211777D0 GB201211777D0 (en) 2012-08-15
GB2503674A true GB2503674A (en) 2014-01-08
GB2503674B GB2503674B (en) 2018-02-07

Family

ID=46721800

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1211777.6A Expired - Fee Related GB2503674B (en) 2012-07-03 2012-07-03 Step bolt and nut for a step bolt

Country Status (1)

Country Link
GB (1) GB2503674B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111335719B (en) * 2020-02-18 2021-05-07 浙江德宝通讯科技股份有限公司 Communication beautifies tower

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4254542A (en) * 1979-04-11 1981-03-10 Craig Gerald V Construction nut and bolt assembly and method of erecting structural steel
JP2006063605A (en) * 2004-08-26 2006-03-09 Chugoku Electric Power Co Inc:The Step bolt for ascending and descending steel tower
JP2012095394A (en) * 2010-10-25 2012-05-17 Chugoku Electric Power Co Inc:The Tower-climbing scaffold device
CN202251338U (en) * 2011-08-18 2012-05-30 黄剑辉 Stepped nut

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4254542A (en) * 1979-04-11 1981-03-10 Craig Gerald V Construction nut and bolt assembly and method of erecting structural steel
JP2006063605A (en) * 2004-08-26 2006-03-09 Chugoku Electric Power Co Inc:The Step bolt for ascending and descending steel tower
JP2012095394A (en) * 2010-10-25 2012-05-17 Chugoku Electric Power Co Inc:The Tower-climbing scaffold device
CN202251338U (en) * 2011-08-18 2012-05-30 黄剑辉 Stepped nut

Also Published As

Publication number Publication date
GB201211777D0 (en) 2012-08-15
GB2503674B (en) 2018-02-07

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20230703