Used by professional riggers, the word lanyard may seem unfamiliar, but at the same time, everyone must have seen this item at least sometime. For the first time, such a fastener was used in the field of cargo shipping cargo securing specialists. This was the name of the device, which is still used today when tightening, choosing slack in rigging, building buildings, installing cables, poles and other supports, such as buttresses.
To understand what it is - a lanyard, get acquainted with its types, functions and concrete examples applications.
Turnbuckles of two types
Key details and design features
The turnbuckle, also known as a ratchet by experts, most often consists of two counter-threaded screws that are screwed into a ring with matching threaded holes.
Classic lanyard consists of details:
- strong cast coupling elliptical or elongated rectangular shape;
- two holes with the opposite direction of thread rotation, located in the center of the coupling fillets and strictly along the axis of the entire product;
- two screws with fasteners (rings/hooks/loops/forks) at the ends, made in the form of rods, providing the necessary tension (cables/ropes/chains) when they rotate in opposite directions.
Hook-ring lanyard
The ends of the screws are produced both with an eye (eye) and with a hook - fork. It is to them that the cable (chain) should be attached. Tension adjustment occurs when the ring rotates, when the screws should gradually move towards the center. Ratchets are used in situations such as pulling rope between poles where a high pulling force is needed.
Turnbuckles vary in weight, starting from a few grams, when a tension force of several kilograms is needed, for example, when installing curtain strings, reaching tens of tons when the devices are included in engineering projects for the construction of buildings and bridges.
Rope tension
GOSTs and other normative standardization documents
The regulations for the manufacture of cable tensioners in the post-Soviet space adopted the following regulations:
- GOST 9690-71;
- OST 5.2314-79.
Views and guests
International Standards production regulation, specifications turnbuckles are based on DIN 1478, DIN 1480.
Get all important information, just by carefully looking at the handle with the accepted marking, at the hooks indicating the caliber (diameter) of the cable / chain that is acceptable for use.
Typical Dimensions
Principle of operation and tension adjustment
The correct functioning of the tensioners ensures that the two screws rotate in opposite directions at the same time, which is available due to the application of opposite threads. This process ends when a sufficient tension force is reached in the cable / rope / chain, which allows you to secure at a certain moment a specific object - cargo, property, pole, mast, etc.
Riggers, builders, interior designers, antenna installers and even piano tuners, precisely because of their maximum skills in sensing the moment of sufficient fastening tension, can be considered professionals in their field.
Fastening structures
Simple tension adjustment makes it easy to loosen, and fastener installation technology provides a comfortable dismantling option, should the need arise. The simplicity of the designs of such fasteners can also be considered a valuable advantage, which always eliminates additional risks of its destruction during operation.
Masters have the possibility of preliminary preparation / assembly a large number elements for fasteners, if such preparatory work give additional benefits in the speed of their installation already directly on the object, it is also possible to use non-separable ratchets.
Cargo attachments reach a weight of 25 kg, withstanding a load guaranteed by certificates of up to 90 tons. This means that with the help of several fasteners it is possible to fix almost any object, correctly calculating the load.
Tension system device
Types of tensioners for cables and chains
All tensioners can be divided according to several important features, one of which is the material for their manufacture.
Principles of classification and types of devices
Due to the use of this fastener in conditions of constant adverse effects of atmospheric phenomena, lanyards are mainly used:
- from stainless steel alloys;
- made of galvanized metal.
For the manufacture of tensioners, only the highest quality steel is suitable, from which products are produced by forging, which are subjected to the passivation process in the next technological step.
Passivation is the application of a protective layer by exclusively hot galvanizing, which provides the necessary anti-corrosion properties to fasteners used for continuous long-term operation in humid environments without loss quality characteristics.
plug-plug type
In addition, it is important to break down the types of fasteners at the ends of the screws, among which the most commonly used products are marked:
- C+C (hook/hook);
- C+O (hook/ring);
- O+O (ring/ring).
Hook-ring type
Such fasteners can be open and closed. The second type is more common in more modern models used to fix fiber optic cables.
The choice of fasteners for specific tasks
Experts recommend using turnbuckles of a specific marking in the optimal configuration for each task. So, for example, “C + C” fasteners are most often used where it is necessary to lengthen the cable / chain, change their tension. Most often, these are masts and antennas.
The C+O system serves a similar purpose. And lanyards marked "O + O" will come in handy where ropes / chains / cables with hooks at the ends are used. Chain ratchets allow you to pull together loads that are quite distant from each other. The features of such fasteners are described in more detail in the next paragraph.
Application in cabling
Chain ratchet - design and application
The lanyard shown as an example in the photo is called a chain ratchet. It is highly durable and reliable.
Applications and main purpose
Such a tensioner is intended primarily for fastening systems on trawls, as well as for rigging when transporting goods in the logging industry. A chain lanyard is necessary for high-quality tension of chains used in tying bulky goods.
Chain tie in most rigging instructions recommended for use when transporting especially heavy loads (pipes of large diameters, logs), as well as special special equipment (turbine parts, large oversized machines, for example, equipment for running in wheel sets of railway trains, or for turning large parts) on trawls.
Such rigging devices are distinguished by their ergonomics - their device allows the operation of tension with one hand, so that the second one can calmly hold the chain during its execution.
Ratchet chain
Features of the design and operation of chain ratchet
Ratchet chains using a ratchet mechanism are more often made with hooks, but models with eyelets at the ends are also used. The standard version of the chain turnbuckle uses hooks that are suitable only for chains of a certain caliber (diameter).
The device was created under the parameters of exposure to an exclusively axial linear force, therefore it is categorically contraindicated side loads. They are never used to lift loads. The standard chain tie kit includes:
- chain with hooks at the ends (3-5 m);
- chain lanyard.
Screen fixing
Each ratchet, according to the results of laboratory tests, is necessarily certified, as it is a source of a potential threat to injury to workers, damage to property, and the creation of emergency situations. When choosing this type of attachment, always take into account the load power in relation to the gauge of the chain used!
Areas of application for tensioners
Where can you see working lanyards? The answer is simple - almost everywhere where you need to fix objects of various sizes with symmetrical tension from opposite sides. Devices are not suitable for lifting / transshipment of goods, but are used only for fixing during transportation by any vehicles, as well as on stationary objects - for guaranteed stability. It can be:
- TV / radio towers;
- lightning rods;
- satellite dishes;
- water towers;
- poles;
- fasteners for shelving in logistics centers;
- tower structures;
- auxiliary construction equipment;
- industrial/civil buildings/other structures;
- objects that require reconstruction or maintenance of a safe condition that protects against further damage;
- flagpoles;
- sports equipment;
- heavy fences;
- monuments;
- attractions, high-rise parks;
- temporary/transport facilities (tents, tents).
Antenna Mast Mount
The areas of application are constantly expanding. But just a century ago, turnbuckles were used exclusively by sailors! This is true both for everyday life and for industrial applications fasteners. You can see small items in the design window openings curtain rods/curtains/blinds. And you can't help but notice the giant lanyards in the structures of modern bridges and buildings with a special architecture that involves additional supports and fixation.
Rope tension instructions
Before pulling the cable between the posts, you should study all the rules for the safe use of turnbuckles - both for the installation process and for subsequent operation. To do this, you must first choose the right tensioner for the task. Use the table below to make the right choice.
Main stages and rules of work
Having chosen the necessary lanyard, you should act in compliance with the following technology:
- Wipe the tensioner with gasoline.
- Polish it with a felt wheel.
- Apply grease (graphite/molybdenum bisulfate).
- Run empty.
- Turn a couple of times during installation.
- When installing with sea water ingress, rinse with fresh water (to prevent parts from sticking together).
- Install the cable tensioner by turning the screws in opposite directions until the effective tension is reached, when the load or structure is effectively secured.
- If the cable is overstretched, loosen the tension by gently turning the screws in the opposite direction to the original.
- If necessary, replace bent parts.
- Make sure there is no load other than axial.
- Periodically check the quality of the cable tension, adjusting it if necessary by the same method that was used during the initial installation.
Rope tension
For such devices, the most important is the correct installation, which allows, during the further operation of the tensioners, to give them a minimum time for condition monitoring, scheduled maintenance, while maintaining the guaranteed quality characteristics specified in the certification documents. Following all the points of the above instructions, you can always qualitatively, reliably tighten the cable without outside help.
Having studied the information about lanyards, and having figured out what it is, what it is used for and how it is divided into types, you can independently choose a fastening device for specific purposes without risking the reliability of the structure being fixed.
Beginners who want to improve their professional level, as well as for those who use fasteners on their own in everyday life, it is useful to watch a video with details right technology installation for various types lanyards.
Video: What is a lanyard and how it works
We can safely say that almost everyone has seen this useful device like a cable tensioner. Many even know how to use this device. However, few people know that this device has a name - it is a lanyard. This word was coined by professional riggers. In our article we will talk about lanyards, their key features as well as tips for proper use.
Application of lanyards - where they are used
This type of tensioners has found wide application in the field of freight and shipping. To date, it is impossible to imagine any heavy or oversized cargo that would be fastened without the help of lanyards. Due to the special design, the device has the ability to cope with very heavy loads, the mass of which reaches several tens of tons. Initially, craftsmen used a mechanism to connect metal and wooden structures of different types and types.
The lanyard is a device that is ideal for securing loads during rigging, as well as transporting goods. For example, the mechanism will be indispensable in cases where it is required to install bulky antennas or metal structures.
Modern lanyards are made from high quality stainless steel. Due to this, the mechanisms are resistant to the destructive effects of corrosion. For amplification performance characteristics, as well as to increase the level of reliability, strength and durability of the device, they are often coated with various coatings. Galvanized lanyards are very popular, the cost of which is slightly higher than the average price for similar devices.
At the same time, the cost is fully justified. The bottom line is that metal cable tensioners are usually used to secure loads from the outside, under open sky. Therefore, they are subject to environment. If you purchase a tool coated with zinc, then about the problems associated with deformation or destruction due to the action precipitation, you can forget forever.
When buying cable tensioners, first of all, attention should be paid to the thickness and length of the ropes and cables that require a turnbuckle to work with. Despite the fact that they are able to withstand the colossal loads created by multi-ton objects, the parameters of the lanyards themselves are compact. So, the sizes are in the range from several to tens of centimeters. By choosing the right mounting tensioner for cables, you can count on the successful fixing of the necessary objects.
Lanyard from the inside - how it works
Outwardly, the lanyard resembles a conventional clutch, which consists of several screws. The peculiarity lies in the fact that the threads with the opposite course are applied on the screws. Another important element of any lanyard is the metal base on which the screws are screwed. Usually the base is different. cylindrical shape. However, bases are not always used. More simple and primitive models are equipped with special rings. Naturally, the metal base provides greater strength and reliability of the device. In any case, the operation of the mechanism is carried out by tightening the screws closer to the center. The result is maximum tension in cables, ropes, belts or ropes, depending on what exactly is being pulled together by a turnbuckle.
Cargo transportation and rigging is far from the only scope of tensioners. For example, turnbuckles can be used in everyday life, in particular, for piano tuning (stringing the strings to achieve a better sound), as well as, if necessary, tightening curtain fasteners.
In most cases, cable devices are made open, that is, the screws for adjusting the tension force are in sight. The body can be made by casting, welding or forging. The next stage of the technological process is the milling of two holes, through which you can change the force and length. Regardless of the method of production of each specific part that is part of the tensioner, the device itself is made by turning.
The design of any lanyard is represented by the following main components:
- metal body
- Two screws with opposite threads
- The head of a screw, which is made in the form of a ring, hook or fork.
It should be noted that there are also models with closed type screws that are required to ensure additional protection transported goods, since it will take more time to loosen the screws. In addition, closed turnbuckles are in demand when working with heavy huge objects in difficult weather conditions.
Lanyards for ropes - their main types
When buying a lanyard for stretching cables, you must decide on its marking, as well as the features of each particular model. There are several types of devices for fastening goods:
- 1. O + O - rings are located on each head of the screw
- 2. C + O - there is a ring and a hook on the heads
- 3. С+С - the lanyard is presented in a configuration with two hooks
- 4. B + B - there are plugs on the screws
These are the most popular models that are currently on the market. To increase or loosen the tension, it is necessary to rotate the screws, as a result of which they will move either from the center or towards the central part of the device. In the first case, the tension force will decrease, while the movement of the screws towards the center indicates an increase in the cable tension force. There are reinforced models called cargo turnbuckles. A feature of such devices is strong and durable steel that can withstand huge loads. Thus, cargo mechanisms weighing about 25 kilograms ensure the fastening of objects with a total mass of up to 90 tons.
To increase the tension, you need to turn the screws
We also note that hook-hook turnbuckles have found application in cases where the load is attached to durable products like antennas, masts, as well as cables or ropes. If you purchased a ring-to-ring type device, then a hook-shaped object is required to secure such a lanyard. Otherwise, the O-shaped tensioner cannot be fixed. The moving elements of such mechanisms have a special thread that is necessary to adjust and change the length of the cable. In modern devices, additional devices appear, the task of which is to change the level of tension smoothness. The scope of such devices is the pulling of fiber-optic cables under small loads.
When working with lanyards of the above varieties, one should take into account the fact that their use is strictly prohibited for fixing load-bearing structures. In this case, the "fork-fork" option on the screw heads can help. A very popular and demanded version of the tensioners. Using such a device, riggers get the opportunity to quickly adjust the length of the cable and the level of its tension. However, this tool is not suitable for lifting objects. Its main purpose is to belay, stretch, and also tune the suspension.
In some situations, chain turnbuckles are used, which boast a significantly longer length. Thanks to this feature, the tool can be used to grab two or even more objects in order to pull them together, setting a certain level of tension.
Proper operation of lanyards - what is the secret of successful work
It is necessary to subject the lanyard for the cable only to such loads for which it is designed. In the event of any deformation individual elements due to increased loads, it is necessary to immediately respond to what is happening: reduce the level of cable tension and replace components that have failed. Moreover, such actions must be carried out with the utmost care and attention in order to tight rope did not destroy the mechanism and did not harm you.
Radial or lateral loads significantly reduce the life of the devices, since turnbuckles are not intended for testing such loads. In this regard, constant monitoring of the tool before work, during and always after is required. Any, even the smallest and seemingly insignificant deformations at first glance, are unacceptable. Choosing correct device to work with loads of appropriate dimensions and weight, you will minimize the likelihood of failure of the device.
- Lubrication
- Felt polishing
- Flushing with gasoline
- Tool run dry
One of the most common problems with tensioners is a tightly stuck turnbuckle, the screws of which can be incredibly difficult to unscrew even for physically developed men. To avoid such problems, it is necessary to use special lubricants, including those with an additive of molybdenum bisulfate or graphite, and also periodically rinse the device in clean fresh water.
As you can see, the lanyard is an excellent tool for performing complex work associated with the transportation of heavy loads, as well as their securing. BUT proper care ensures long and trouble-free operation of the mechanism.
pendant carrier cable and its stretching is done in two steps. At first, the cable is pulled along the length of the wiring and fixed at one end to the end anchor structure, the tension bolt of which is previously loosened. The 2nd free end of the cable is measured according to the actual length of the eyeliner, taking into account the length of the cable needed to seal loops, install tensioners and compensate for sag, and attach it to a pre-loosened special tensioner, if necessary. Then a preparatory tension of the carrier cable is created together with a tension device, which, at the same time, is put on the 2nd end anchor hook. The tension of the carrier cable, depending on its length, is carried out at small gaps manually, and at huge gaps - using blocks, chain hoists or winches.
As already mentioned, the cable tension should be created until the calculated sag is obtained, but with a force not exceeding the tension force allowed for a given carrier cable. Control over the correct tension of the carrier cable is carried out by a dynamometer, switched on alternately with the chain hoist cable or block, with which the cable is tensioned, or by measuring the sag. The final tension and adjustment of the carrier cable is created by tightening the previously loosened tensioners. Works on suspension and stretching of bearing cables are recommended to be carried out at an ambient temperature of at least -20°C.
To unload the carrier cable and its end fasteners and reduce the sag in cable wiring, various unloading devices are used in the form of additional vertical, longitudinal and transverse auxiliary wire suspensions and braces.
To make the cable wiring more immobile and to prevent lateral swings, side braces are installed.
Vertical wire hangers are installed approximately every 3-12 m, placing them at the locations of branches from wires and cables, installation and suspension of branch boxes, branches and lighting fixtures.
Vertical wire pendants are made of metal wire with a diameter of 2 - 6 mm for power lines as more heavy in weight and a diameter of 2-3 mm for lighter lighting wiring.
Longitudinal lateral and transverse guys are made of metal wire with a diameter of 2 - 6 mm.
For string electrical wiring, in contrast to cable wires, the supporting string in a taut state is attached tightly to ceilings, trusses, supports, walls and protruding parts of walls, columns and others. building grounds different methods.
Figure 12.7 - End fastening structures of cable wiring and methods for their installation:
c - tension bolt with a hook, b - cable tension anchor, "- anchors for the end fastening of wire strings, fixed with studs, pins, dowels, and electric welding, g - cable anchors for the end fastening of prefabricated steel cables, e - structures for fastening the cable and wire to metal trusses from profile steel and T-beams, e - design for fastening parallel load-bearing cables
As load-bearing elements, braces suspensions are used: steel rope (cable with a diameter of 1.95 - 6.5 mm, galvanized steel wire with a diameter of 2.5 - 6 mm, hot-rolled round wire (rolled wire) with a diameter of 5 - 8 mm, bare galvanized steel wire with a diameter of 6, 8 and 7.5 mm, twisted from ordinary steel or copper-plated steel wires, a rope that simultaneously serves as a carrier cable and a neutral wire.
In the process of procurement work, suspensions, branch clamps for aluminum and copper wires and boxes for wires brand ANRG, make the necessary connections and descents to connect the wiring to the supply line.
Figure 12.8 - Products and parts for the installation of cable wiring:
a - a box for a branch from the main lines, 6 - a cross-shaped and tee clamp, c - a flat clamp, d - a suspension with plastic clips, d - steel suspensions, e - a strip with a buckle and a strip-buckle for bundling wires and cables; 1 - strap for fastening the branch box, 2 - box body, 3 - clamp, 4 - dies, 5 - suspension brackets, 6 - eyelet for fixing the lamp
For branches from trunk lines made with three- and four-core wires of the APT brand, a branch box is used (Figure 12.8, a), which can be of three types: 0.2 - for lighting networks with a core cross section of main wires 4-10 mm2 and -2.5 mm2; C2 - for lighting and power networks with a cross section of main and branch wires of 4-10 mm2; SZ - for power networks with a cross section of main wires of 16-35 mm2 and branch wires of 4-10 mm2.
Branches from the main aluminum and copper wires are performed using cross-shaped and tee clamps (Figure 12.8, b). For branches of wires with a cross section of 6, 10 and 16 mm2 from wires of trunk lines with a cross section of 35 and 50 mm2, plate clamps are used (Figure 12.8, c).
For suspension to a cable with a diameter of 4-7 mm four insulated wires with a cross section of up to 6 mm2 and fixtures, a U930-U934 plastic suspension is used (Figure 12.8, d), and for a cable on a cable with a diameter of up to 10 mm - steel suspension U954-U956 (Figure 12.8, e).
Banding of wires and cables is performed with a steel strip with a buckle or a strip-buckle (Figure 12.8, e).
3 Methods for attaching cables
At the second stage of installation, prepared sections and assemblies are assembled cable wiring into a common whip and hang them on tensioners and supporting structures installed at the first stage of installation.
The prepared cable wiring delivered to the installation site is unwound and straightened, while checking its condition and completeness. If the wiring is added in the form of separate sections and nodes, they are assembled into cable whips, and then the finished wiring is hung in place. Assembly and suspension of cable wiring are shown schematically in Figure 3.
To assemble and suspend cable wiring, one end of the carrier cable (right in Figure 3) is terminated with a loop 1 and thrown onto the temporary right anchor hook 2, installed at a height of 1.5 m. The second temporary anchor hook 2, located on the opposite wall of the room, is thrown a loop of one end of the chain hoist 8, and a wedge clamp 5 is attached to the free end of the chain hoist, which captures the cable at a certain distance from the end loop of the carrier cable. In this case, the free (left in Figure 3) end of the cable and the tensioning sleeve 9 mounted on it will be in a suspended position. The carrier cable suspended between temporary anchors, together with the electrical wiring elements fixed on it, is pulled with a chain hoist until the required sag is formed. The tension of the carrier cable is controlled by a dynamometer located between the chain hoist and the wedge clamp.
Figure 3 - Scheme of assembly and suspension of cable wiring at the installation site: 1 and 1 "- end loops on the carrier cable, 2 and 2" - temporary and permanent anchors, 3 - inventory stands, 4 - lash of cable wiring, 5 - wedge clamp, 6 - auxiliary cable section, 7 - free end of the carrier cable, 8 - chain hoist, 9 - tension clutch, 10 - dynamometer, 11 - vertical wire hangers
Efforts at a tension of a cable of wires ATRG should not exceed: 100 kgfs for cable wires with a section of veins 4-10 mm2; 500 kgf - for wires with a conductor cross section of 16-35 mm2.
At the end of the tension of the cable wiring, the free end of the carrier cable with the tensioning device is put on the left anchor hook 2, the chain hoist 8 is loosened and removed from the hook. Next, inventory stands 3 are installed under the cable, supporting the electrical wiring at a height convenient for work.
At the final stage of installation, the luminaire housings are suspended and fixed on a cable, but without glass parts (reflectors, glass caps, etc.), the height of the wiring suspension between the anchors is adjusted (by changing the length of the suspensions 11), and a number of other installation operations are also performed.
The mounted electrical wiring whip is lifted, connected to anchor fasteners and a tension device, tensioned using tension devices, the vertical wire suspensions are finally adjusted and fastened, lamps are installed in the lamps and reflectors and caps are fixed in the lamp housings, the correct relative position of all electrical wiring parts is checked.
In accordance with the requirements of the PUE, the elements of cable wiring (carrying cable, lamp housings, cable sheaths, etc.) must be grounded. To ground the cable wiring, its fastening structures and the supporting cable are connected to the ground busbars using flexible jumpers made of a steel cable with a diameter of at least 5 mm or stranded copper wire with a cross section of at least 2.5 mm2.
In the case of using a carrier cable as a neutral or ground wire, the cross section of the jumper must correspond to the calculated cross section of the neutral or ground wire.
Grounding is done like this. Cut off a piece of cable or flexible copper wire of the required length and required section for use as a ground jumper. A steel sleeve or flag is welded to one end of the jumper, which, in turn, is welded to the ground bus. The opposite free end of the jumper is attached to the carrier cable using a bolt clamp.
The metal support and cable structures grounded by securely attaching them to the carrier cable.
Cable wiring, made with ATRG wires, is grounded by connecting the section of the bearing millet freed from insulation with the body of the junction box, inside which there is a special device.
In lighting installations with a dead-earthed neutral, the neutral wire and luminaire housings are also connected to the anchor device of Special boxes or to the neutral wire in ordinary boxes. In this case, the electrical wiring, together with the supporting cable, is grounded through the neutral wire of the lighting network.
Metal housings of luminaires in cable wiring with open laying of wires are grounded using separate grounding insulated copper conductors with a cross section of at least 1.5 mm2. The ends of the grounding conductors are attached to the housings of the fixtures under the grounding screws, and to the neutral wire or to the carrier cable (if used as a neutral wire) - by soldering or mechanical compression.
In cable wiring with open laying of protected wires and cables, grounding of fixtures is performed using an additional core, which is part of the cable and wire design. In these cases, the grounding conductor is connected not to the neutral wire in the branch box, but to the luminaire body - inside or outside it, depending on the design of the luminaires.
After the installation of cable wiring:
- measure the insulation resistance of the cores of wires and cables of cable wiring with a 1000 V megger with the fuses removed and the lamps in the lighting circuits unscrewed, but with the switches, plug sockets and group shields connected; insulation resistance must be at least 0.5 MΩ;
- determine the correctness of the performed phasing of cable wiring and branches from it; the phases must match;
- check the condition of the insulation conductive cores wires and cables in relation to the carrier cable, as well as the continuity of the grounding circuit: cable - junction box - ground wire.
If the test results are satisfactory cable wiring handed over for use.
Cable wiring installation
Installation of electrical wiring is carried out in two stages.
At the first stage in the workshop, electrical wiring elements are prepared, anchor, tension structures and supporting devices are completed.
They measure the cable of the required length and “charge” one of its ends into the lanyard ring, at the second end they make a loop under the hook or close it on the lanyard if tension couplings are used on both sides. The cables are connected to the end fasteners by arranging a loop at the end of the cable, performed different ways, for example, using the so-called thimble and bolt clamps.
Picture. Execution of the cable end loop: a - cable termination scheme; b - thimble; c - bolt clamp-clip.
The sequence of operations for performing a loop is as follows.
The cable is bent around the thimble and a clip-clip is attached to the end of the cable (stage 1). The second clamp is attached as close as possible to the thimble (step 2). Install the remaining clamps between the first two (stage 3) while tightening the nuts of the clamps with force, but do not fully tighten. [The total number of clamps in the loop is determined by the calculated pulling force of the cable, which in turn depends on the length of the span of the cable wiring, the mass and number of electrical products attached to the carrier cable.] If a “weakness” of the cable has formed between the clamps, then it is eliminated by pulling the thimble end of the cable, and then finally tighten the nuts of the clamps.
Picture. Bolt clamp K676 for carrying out the end loop of the carrying cable
Below are a few videos that show the principle of making an end loop on a carrier cable using various clamps.
Picture. Making a loop on the carrier cable using a compression sleeve
The sequence of operations in this case is as follows. The cable is threaded into the sleeve with a loop so that its end comes out of the sleeve by 1-2 cm. Next, the sleeve is crimped using special tool- a press (manual, electric, hydraulic), having previously selected a matrix for it (the size of the matrix depends on the type of sleeve used for crimping). Crimping starts from the middle of the sleeve, then crimping is performed from the edges of the sleeve. After crimping, its quality is checked using special templates.
It is possible to carry out the end loop of the carrier cable without the use of special devices (clamps, sleeves, etc.) and tools. In this case, the end of the cable is woven in a special way into the main part of the carrier cable. It should be noted that the execution of the loop in this way requires much more time.
In the case of using steel wire or wire rod as a cable, the loops at the ends are made without the use of clamps, by simply twisting the wire in a spiral over a length of 60-80 mm.
In addition, it is also possible to terminate the carrying cable without organizing a loop, using special tips mounted on the cable by crimping. An overview of these mounting products, as well as an example of a carrier cable termination, is shown in the video below.
After completing the termination of the carrier cable, they are installed on the cable wiring and the branch, junction and input boxes are fixed. Attach pre-measured wires and cables to the carrier cable, the distance between the cable attachment points to the carrier cable should not exceed 50-60 cm.
At the second stage carry out installation of cable wiring to building structures at the installation site. Luminaires are attached to the wiring, as a rule, at the second stage of installation, when the cable wiring is unwound on the floor, temporarily suspended at a height of 1.2-1.6 m for straightening wires, suspension and connection of luminaires (if they were not mounted on a cable line in workshops). Then the wiring is raised to the design height.
Perform the installation of end fastening structures to the building elements of buildings and structures.
The most reliable fastenings of anchor structures to building surfaces are fastenings in brick and concrete walls and ceilings using through bolts and through-through anchors or fastening anchors using through studs with the installation of enlarged square washers on the reverse side of the fastening. In anchors with such fasteners, the pull-out forces correspond to the actual strength of the material from which the anchor is made, depending on the steel grade and the cross section of the threaded part of the fastening rods.
Picture. Scheme for the implementation of end fastening using a through anchor bolt
Anchor structures are also fastened to walls and ceilings with the help of embedded studs or expansion dowels. Such fasteners are less reliable, since they largely depend on the quality of workmanship and the accuracy of the prepared holes in terms of size and the reliability of anchoring in them. Therefore, these anchoring methods are used for less critical intermediate fasteners load-bearing cables and braces.
Picture. Scheme for the implementation of the end fastening with the help of: a - slip-in studs; b - expansion dowels.
Anchor structures are fastened to metal trusses and building structures using crimped steel fasteners or similar parts, as well as using bolted joints or by welding the anchor along its perimeter by electric welding.
Picture. Scheme for the implementation of the end fastening to the metal elements of building structures using: a - crimp steel fasteners; b - welding.
To wooden bases the tension cable is fixed with metal screws with a hook.
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In every separate case the choice of the design of the anchor and the method of fastening it is carried out depending on the specific local conditions, the material from which the parts of the anchor structures are made, and the compliance of the design with the design pull-out force created by the cable wiring.
Picture. Cable wiring installation
The suspension of the carrier cable and its tension is performed as follows. First, the cable is pulled along the length of the wiring and fixed at one end to the end anchor structure. Tensioners(lanyard, anchor bolts) must be loosened beforehand (so that after that there is a move to adjust the degree of tension of the cable). Then produce a preliminary tension of the carrier cable. Depending on the length of the span, pre-stretching is carried out: for small spans - manually, and for large spans - using blocks, chain hoists or winches. The cable is tensioned until the calculated sag is obtained, but with a force not exceeding the allowable for this carrier cable. The control of the tension force of the carrier cable is carried out by a dynamometer connected in series with the chain hoist or pulley cable. The final tension and adjustment of the carrier cable is carried out by tightening the previously loosened tensioning devices: lanyard (tension sleeve), anchor bolts.
The cable sag in the spans should be within 1/40-1/60 of the span length. Splicing of cables in the span between the end fixtures is not allowed. To prevent swinging of lighting wiring on steel rope extensions must be installed.
After tensioning the carrier cable, it is grounded.
To connect the ends of a cable or rope, as well as to form loops at the ends, are used various varieties steel, copper or aluminum clamps. Relating to rigging fasteners, cable clamps are used in the elevator industry, during various installation work, as well as in everyday life.
Types of clamps
To ensure durability and reliability, all structural elements clamps are made of stainless steel, and for light operating loads - also made of copper, brass or aluminum.
The most popular are:
Features of using different types of cable clamps
The main technical parameters of the products in question are the maximum diameter of the cable and the guaranteed clamping force. The dimensions of the clamp are also important, since it is recommended, regardless of type, to use several clamps in series (at least three), especially if the weight of the load does not guarantee its safe movement or lifting.
Clamps according to DIN 741 are used for ropes with a diameter of 5 ... 62 mm, in the presence of a spring washer in accordance with GOST 6402-70 and a nut in accordance with GOST 5915-70. The design of such a clamp provides for the possibility of installing a locking bar, which provides a more reliable clamping of the cable to the bracket. The clamping block must be made by stamping from steel grade not lower than St.3kp in accordance with GOST 380-94 (only for small clamping forces cast pads made of steel 25L are allowed according to GOST 977-75). It is not allowed to use cable clamps, the parts of which do not have a protective anti-corrosion coating from zinc.
In the fasteners of flat clamps, threads must be used in accordance with GOST 24705-81. The lining material is St.3 steel, the plates should be used for fastening cables with a diameter of 4.6 ... 30 mm.
In the case of successive use of several clamps, the distance between them should not be less than six cable diameters.
In Duplex double clamps, the shear force is taken up exclusively by bolted connection, so the choice of fastener diameter is determined by the diameter of the cable. The following ratios are recommended:
- For a cable with a diameter of 2 mm and 3 mm - M4 fasteners;
- For a cable with a diameter of 4 mm and 5 mm - fasteners M5;
- For a cable with a diameter of 6 mm - fasteners M6;
- For a cable with a diameter of 8 mm - fasteners M8;
- For a cable with a diameter of 10 ... 12 mm - M10 fasteners.
Wedge clamps are not recommended for lifting loads. Because the operational loads on fasteners are reduced, since the axes of action of forces during the operation of such a clamp coincide, and, therefore, shear stresses do not occur. The operating parameters of the wedge-type clamps are regulated by DIN 15315. For screw clamping of the cable or rope to the supporting surface of the wedge, high-strength fasteners are used (strength class at least 5.6), with a protective anti-friction coating. Periodically, the connection needs to be tightened.
The barrel clamp is often made of aluminum and is not designed for large diameters cable: the rational range of diameters is 2 ... 8 mm. The absence of protruding elements and the compactness of such a clamp allows it to be used in confined spaces.
Is it possible to make a cable clamp with your own hands?
The price of clamps, depending on their size and permissible load capacity, is, rub / piece:
- For Simplex clamps - 4 ... 14;
- For Duplex clamps – 7…24;
- For clamps according to DIN 741 - 4…160;
- For wedge clamps – 200…250;
- For barrel clamps - 3 ... 40 (aluminum), and 60 ... 160 (stainless steel).
In everyday life (for example, for motorists), there is often a need to manufacture cable clamp with your own hands. To form a reliable loop, it is advisable to use an ordinary aluminum (not duralumin!) tube, inside which a cable of the desired diameter should freely enter. The tube is bent in an arc, after which a cable is inserted there at a distance of 120 ... 150 mm, its ends are covered with brackets, and connected with a bolt.
When building up parts of the cable, the diameter of the pipe is chosen so that both cables freely enter there, and from different ends. All other actions are performed in a similar way. It should be noted that load bearing capacity such a cable clamp will be determined by the bending strength of the pipe material, therefore the permissible force of a home-made clamp device will be noticeably lower than that made by a specialized company.
