Types of ropes. Characteristics and marking of steel cables

Cables are products twisted or woven from vegetable and synthetic fibers or twisted from steel wires. Depending on the material from which the cables are made, they are divided into vegetable, synthetic, steel and combined.

Plant cables are made from plants (fibers of leaves and stems).

From the fibers of plants from left to right, a thread is drained, called kabochki.

From several kaboloks, help winds up to the left strand.

The strands are twisted from left to right, we get three cable work of direct descent.

The reverse lay gives three cable work of the reverse descent.

Cable work ropes are made from cable work ropes by reverse laying them.

Hemp ropes are made from high quality hemp (treated with hemp fiber). Produced by the industry white and resin.

Hemp white ropes are light gray, and resin ropes are light brown.

Elasticity without breaking the roll is 8-10%.

Resinous ropes are practically used at low temperatures, they are less prone to decay, but their strength is 10% less than white ones, and their weight is 16-18% more.

Hemp ropes are used for rigging rigging, moorings, conductors, slings.

Wet hemp ropes are indicated by 8-12% and lose up to 20% in strength compared to dry ones.

Sisal ropes are made from the fibers of the leaves of a tropical plant - ACHAVA.

It is produced by the industry as non-resined three-row with a circumference size of 20 to 350 mm in three groups: Special, elevated and normal.

Two ropes are introduced into the ropes of the special group, and one colored cable is introduced into the ropes of the increased group. Sisal ropes are light yellow in color, they are approximately equal in strength to hemp white ropes, but they are somewhat lighter and less susceptible to decay. Extend without loss of strength by 15-20%.

small ropes made from the fibers of a wild-growing tropical banana - ABAKA.

They are golden brown in color and are the strongest and most resilient of all vegetable ropes. They do not sink in water, are little mobile to decay, lengthen without loss of strength by 20-25%.

Synthetic ropes are made from artificial fibers of chemicals that form plastics - nylon, nylon, polyethylene, polypropylene.

Nylon rope has a silky white color. With equal strength, they are 5 times lighter than hemp ones, and 2 times lighter than insoles.

Elongation without losing strength up to 40%.

Nylon ropes in appearance they resemble silk, it is well dyed, depending on the dyed, they have different shades. In terms of strength and elasticity, they are equivalent to kapron.

Polypropylene ropes they are equivalent in strength to lavsan, but much lighter than them, they do not sink and do not get wet in water.

Synthetic ropes have a number of significant operational disadvantages:

1) With prolonged exposure to sunlight, they lose strength up to 30%, and from a long stay in water - up to 15%.

2) Deteriorate in contact with olive, fuel oil, somra and minerals.

3) When working with high friction, it melts, strongly electrocutes and can cause sparking.

Synthetic ropes are most widely used as mooring lines, tugboats, signal halyards and cords.

Steel ropes are made from high quality steel wire coated with aluminum or galvanized.

By design, steel ropes are divided into:

Single lay(spiral) twisted from individual wires in several layers.

Double lay - consisting of strands, strands of cables.

Triple lay - Consisting of twisted double lay ropes (strandey)

Steel cables can have a right Z or left S lay direction.

The most widely used are six-strand double-lay steel cables with a limited core (vegetable fibers impregnated with anti-basket grease.

Steel cables are 6 times stronger than hemp and 2.5 times stronger than synthetic ones of the same thickness.

Vegetable and synthetic cables are measured by their circumference.

Steel cables are measured by their diameter.

Combined cables(Hercules) - steel four-six-strand ropes with a core restriction.

His strands are braided with nylon, sisal or hemp strands.

The strength of the rope is characterized by breaking load (the minimum weight of the load at which this rope breaks).

- the maximum weight of the load, at which three works a positive period without loss of strength.

Explosive reinforcements Rk=K*d - dm steel ropes

Rn=K*C - dm rast. And synthetic

Where K is the strength factor

d - rope diameter

C - rope circumference

Where n is the safety factor

When growing, the values ​​\u200b\u200bof the strength factor are taken:

1) For vegetable ropes n=6

when working with people n=12

2) For steel cables n=5.0

for working with people n=12.0

3) For synthetic n=6 - 9

Rigging chains are used from steel welded oval links without buttresses with a thickness of 6-16 mm.

They are used on ships for equipping side rails, steering rope chains, mechanical hoists, chain stoppers, etc. .

New rigging chain for some time due to lapping of elongation links by 3-4%.

A chain of links that has worn out by 10% compared to the original diameter is considered unusable.

The items of ship's rigging equipment in marine practice include: hooks, staples, lanyards, blocks, thimbles, butts, eyes, ducks, dowels.

gaki – new or stamped steel hooks used in lifting devices for fastening blocks of hoists, lifting loads.

By appointment, gaki are:

1) Simple

2) Rotated

4) Verb-gons

5) Penter-hook

6) Swivel

7) Cargo

If there are no markings on the hooks, then the allowable load per kg is calculated according to the formula

where d = hook back thickness

It is forbidden to use hooks with a crack, deformation, worked out by more than 10%.

Staples are used to connect segments of chains and cables, as well as to connect them to various devices and ship hulls.

By value there are: Anchor, connecting, cargo, rigging.

The allowable reinforcement for staples can be determined by the formula:

Lanyards are used for tightening and fastening cables, rigging, handrails, etc.

The allowable load in kg-forces is calculated by:

Butt - a metal half-ring on the corresponding half, welded to the deck or superstructure of the vessel.

Gears of the person standing are also attached to the butts, stoppers, toprens, etc.

The permissible load on the butt is calculated by the formula:

Rym – a steel round or oval ring threaded through a scented butt.

The permissible load on the eye is calculated according to the formula:

Where d is the thickness of the ring

Koushi – it is metal galvanized. Used for sealing the centers of steel and vegetable ropes.

Blocks - these are devices consisting of one or more pulleys rotating on an axis with grooves, the pulleys are mounted in one housing, having a suspension in the form of a hook, bracket or butt.

According to the number of pulleys, they are divided into one-, two-, three-, four-, etc.

According to the material of manufacture:

Metal, wood, plastic.

In order to avoid premature wear and damage, a minimum ratio of the pulley diameter D to the rope diameter d is set.

For metal blocks:

for wooden and plastic blocks with plant and nylon ropes:

For metal blocks with lifting chains.

Gorden is the simplest device used on ships for lifting cargo.

The horde consists of a cable threaded into a single-pulley block, which is fixed movably.

The end of a cable to which a hook or other device for lifting a load is attached is called root end.

The end of the cable to which the force is applied to lift the load is called running end.

Tali – lifting device, consisting of two blocks, fixed and movable, and the main cable in the pulleys.

The end of the rope attached to the block is called the root end.

The end of the cable going to the winch or fitted by hand is running.

The hoists give a gain in strength minus losses due to friction of the clips and cable bends due to the loss in the distance traveled.

Tali are simple and mechanical.

When lifting with the help of hoists, the mass of the load is distributed equally to all branches of the fall.

To lift the load to the running end, it is enough to apply a force that is n times less than the mass of the load being lifted, i.e.

where n is the number of loading branches of the fall.

Sometimes a tool is used, in which the running end of the fall comes off the movable block,

in this case, the running end must be taken into account on a par with other branches of the fall, so the gain will be equal to the total number of pulleys + one, i.e. …………….

Small hoist, based between blocks with the same member of the pulleys and the establishment of some kind of tackle to fit it, is called gintsy.

With more than three pulleys in each block, such hoists are called chines.

Gini are used for lifting heavy loads.

The base of the hoists i.e. winding the torso into a system of blocks is usually done when the blocks are laid out on the cheek, hooks or staples are placed outside.

Application on ships mechanical hoists are called differentiable.

Differentiable hoists are a device consisting of two sections of different diameters, rigidly connected to each other and placed in the holder of a fixed two-pulley block and one movable single-pulley block.

The endless working chain spans in succession the small pulley of the fixed block and the large pulley of the fixed block.

With the usual ratio of the diameters of the fixed block pulleys equal to 7:8, a 16-fold gain in strength is obtained.

If the ratio is 11:12, then the gain in strength is 24 times.

Steel rope - rope designs can contain one or many strands (table 5.1), (fig. 5.1). The strands consist of wires that are divided into equally normal section structure (all wires with the same section) and different diameters (combined section structure). The magnitude of the breaking force of the rope mainly depends on its diameter. With the same diameter, a rope with a large number of wires is more flexible.

Rice. 5.1 Double lay steel rope
1 - wire; 2 - strand; 3 - core

Table 5.1 Types of strands
(1 - wire, 2 - strand, 3 - core)

Name	Image
Closed construction with two layers of wedge wire, one layer of Z-wire and TK core

Ropes vary in design.

Single lay (spiral)- consisting of one, two or three layers of wire, twisted into concentric spirals (Fig. 5.2)

Rice. 5.2 Single lay (spiral)

Double lay - consisting of six or more strands twisted into one concentric layer (Fig. 5.3).

Fig.5.3 Double lay

Triple lay - consisting of strands twisted in a spiral into one concentric layer (Fig. 5.4).

Rice. 5.4 Triple lay

According to the type of wire contact between the layers, ropes are distinguished:

With point touch (TK type)- the strands of wires have different steps in the layers of the strand, and the wires intersect between the layers. Such an arrangement of elements increases their wear during shear during operation, creates significant contact stresses that contribute to the development of fatigue cracks in the wires, and reduces the fill factor of the rope section with metal.

With linear touch (LK type)- such strands are made in one technological step, while the constancy of the wire laying pitch in all layers of the strand is preserved. To obtain a linear touch, the diameters of the wire and strand are chosen depending on the design of the latter. So, in the upper layer of the rope strands of the LK-0 type, wires of the same diameter are used in layers, the strands of the LK-R type have wires of different diameters in the outer layer, and in the strands of the /7 / S-Z type, wires are used that fill the space between the wires of different diameters . There is a type of rope with a linear touch of the wire between the layers and having layers in the strand with wires of both different and identical diameters - LK-RO. In three-layer strands of linear contact, various combinations of the above types of strands take place. It should be noted that the performance of ropes with a linear touch of the wires in the strands, with the right choice of rope design, is much higher than the performance of ropes with a point touch of the wires.

With dot-line touch (TLK type)- strands of point-linear contact are obtained by replacing the central wire in the strands of linear contact with a seven-wire strand: in this case, a layer of wires of the same diameter with point contact is laid on a two-layer strand of the LK type. The designs of these strands make it possible to manufacture them on spinning machines with a relatively small number of spools. In addition, TLC strands, with an appropriate choice of lay parameters, have increased non-rotating properties;

According to the material of the core, the ropes are distinguished:

Organic core (OC). In most rope designs, lubricated organic cores of hemp, manila, sisal or cotton yarn are used as the core in the center of the rope, and sometimes in the center of the strands, to provide the required flexibility and resilience. It is also allowed to use cores made of asbestos cord and artificial materials (polyethylene, capron, nylon, etc.).

Metal core (MC). It is expedient to use a metal core in those cases when it is required to increase the structural strength of the rope during its multilayer winding on a drum, to reduce the structural elongation of the rope in tension, and also when the rope is operated at elevated temperatures. One of the most common designs of this type is a double lay rope of 6-7 wire strands arranged around a central seven-wire strand. The metal core can be made of ordinary rope or soft wire with a tensile strength of not more than 900 N/mm2.

According to the combination of lay directions of strands and rope:

Rope one-sided lay- with the same direction of laying wires in strands and strands in a rope (Fig. 5.5).

Rice. 5.5 Single lay rope

Rope cross lay- with the opposite direction of laying strands and rope (Fig. 5.6).

Externally, the cross lay rope is distinguished by the fact that the wires on its surface are parallel to the axis of the rope. The wires of a one-sided lay rope are located at an angle to its axis.

One-sided lay ropes are less rigid, but tend to untwist. In crane mechanisms, as well as for the manufacture of slings, ka

cross lay nats, which are stiffer, but not prone to unwinding under load. Non-twisting ropes, twisted from pre-deformed wires, the description of which will be given below.

According to the laying method, the ropes are divided into:

unwinding- the wires are not released from internal stresses arising in the process of laying wires into strands and strands into a rope. Strands, strands and wires in this case do not retain their position in the rope after removing the dressings from its ends;

Non-twisting (N)- when laying wires into a strand and strands into a rope, internal stresses are removed by straightening and preliminary deformation in such a way that after removing the dressings from the end of the rope, the strands and wires retain their predetermined position. Non-untwisting ropes have a number of advantages compared to untwisting ropes: somewhat greater flexibility and more uniform distribution of tensile forces on the strands and wires, increased resistance to fatigue stresses, and no tendency to break straightness during unfolding.

According to the degree of twisting, the ropes are divided into:

spinning;

Low-rotating (MK). These ropes should be distinguished from non-untwisting ones. In low-rotation ropes, due to the selection of lay directions for individual layers of wires (in spiral ropes) or strands (in multilayer double-lay ropes), the rotation of the rope around its axis is eliminated when the load is freely suspended. A low-rotation rope can be made both non-rotating and untwisting. A prerequisite for the manufacture of low-spinning ropes is the arrangement of strands in two or three concentric layers with the opposite direction of the lay of each concentric row of strands. In this case, the torques of all strands of the rope are balanced, which prevents the overall rotation of the rope around its axis.

Rice. 1: a - TK (6x19 + p.); b – LK-O (6x19 + 7x7); V – LK-R (6x19 + s.); G – LK-RO (6x36 + s.); d – LK-Z (6x25 + 7x7); e – TLC-O (6x37 + s.)

Depending on the material of the core, there are ropes with an organic core made of bast (hemp) or synthetic (nylon, kapron) fibers, and when working at elevated temperatures or chemically aggressive environments - from asbestos fibers and ropes with a metal core, which is also used as a double lay wire rope (Fig. 65, b, e). Ropes with a metal core is used for multi-layer winding on a drum, since this rope does not lose its shape under the action of a load from overlying turns, as well as with a sharply changing load and when operating at high temperatures, excluding the use of ropes with an organic core. The metal core rope, although it has a higher metal cross-sectional fill factor, due to the different working conditions of the core strands and the rope strands, practically does not become stronger. Ropes with an organic core are more flexible than ropes with a metal core, and better retain the lubricant, since the lubricant to the wires comes not only from the outside (during operation, the ropes are regularly lubricated), but also from the core impregnated with lubricant.

Classification of ropes by type of lay

According to the type of laying of wires in strands, they distinguish:

TK type ropes(Fig. 1, a) with point contact of individual wires between the layers of strands;

ropes type LK with a linear touch of the wires in the strand. Ropes type LK have several varieties:

• LK-O (Fig. 1, b), where the wires of individual layers of the strand have the same diameter;

  LK-R (Fig. 1, c), in which the wires in the upper layer of the strands have different diameters;

  LK-RO (Fig. 1, d) - in the strands there are layers made up of wires of the same diameter and wires of different diameters;

  LK-Z (Fig. 1, e) - filling wires of smaller diameter are placed between two layers of wires.

ropes type TLC-O and TLC-R with a combined point-line contact between the wires in the strand (Fig. 65, e).

Ropes type TK with a point touch of the wires are used only for non-stressful operating modes, when the duration of the service life is determined mainly not by the quality of the rope, but by the conditions of its use. Ropes with a linear touch have a better filling of the section, they are more flexible and wear resistant. Their service life is 30–100% higher than the service life of TK type ropes. Due to the better filling of the section, they have a slightly smaller diameter for the same breaking load.

Classification of ropes by lay type

By type of twist ropes subdivided into:

ordinary or untwisted ropes(in these ropes, the wires and strands tend to straighten up after removing the dressings of the ends);

untwisted ropes, twisted from pre-deformed wires and strands: their shape corresponds to the position in the rope. The wires of non-untwisting ropes in the unloaded state do not experience internal stresses. These ropes have a significantly longer service life. The tensile load in them is more evenly distributed between the strands and between the wires in the strands. They have greater resistance to variable bending. Broken wires in them retain their original position and do not come out of the rope - this facilitates its maintenance and reduces wear on the surface of the drum and block by broken wires.

non-spinning ropes- these are multilayer ropes that have the opposite direction of laying the strands in separate layers. However, individual layers easily move relative to each other when wrapping around the block, which sometimes leads to bulging of the strands and premature failure of the rope.

Fastening ropes to structures.

Blocks about chain hoists

tall lifting mechanisms, the main parts of which are a wheel with a circumferential groove (pulley) and a rope or cable; are used for lifting heavy loads with little effort (or with the application of effort in a comfortable position of the worker) both as working bodies of lifting machines (winches, hoists, cranes), and independently of them. Usually a block is a device consisting of one pulley in a frame with a suspension and one cable; chain hoist - a combination of pulleys and cables. The principles of operation of these mechanisms are illustrated in the figures. In Fig. 1a, a load with a weight W1 is lifted using a single block with a force P1 equal to the weight. In Fig.1,b, the load W2 is lifted by the simplest multiple chain hoist, consisting of two blocks, with a force P2 equal to only half the weight W2. The effect of this weight is divided equally between the rope strands on which pulley B2 is suspended from pulley A2 by means of hook C2. Therefore, in order to lift the load W2, it is sufficient to apply a force P2 equal to half the weight W2 to the cable branch passing through the groove of the pulley A2; thus, the simplest chain hoist gives a double gain in strength. Fig. 1, c explains the operation of a chain hoist with two pulleys, each of which has two grooves. Here, the force P3 required to lift the load W3 is only a quarter of its weight. This is achieved by distributing the entire weight of W3 between the four suspension cables of the B3 unit. Note that the multiplicity of the gain in strength when lifting weights is always equal to the number of cables on which the movable block B3 hangs. The chain hoist is similar to a lever in its principle of operation: the gain in strength is equal to the loss in distance with the theoretical equality of the work performed. In the past, a flexible and durable hemp rope was usually used as a cable for blocks and pulleys. It was woven with a braid of three strands (each strand, in turn, was woven from many small strands). Hemp rope pulleys were widely used on ships, agricultural farms, and generally where episodic or periodic application of force is required to lift a load. The most complex of these chain hoists (Fig. 2) were apparently used on sailing ships, where there was always an urgent need for them when working with sails, spars and other moving equipment. Later, for the frequent movement of large loads began to use steel cables, as well as cables made of synthetic or mineral fibers, as they are more wear-resistant. Chain hoists with steel cables and multi-groove pulleys are integral components of the main lifting mechanisms of all modern hoisting and transport machines and cranes. Block pulleys usually rotate on roller bearings, and all their moving surfaces are forcibly lubricated.

Rice. 1. OPERATING PRINCIPLE OF THE BLOCK AND POLYSPAST. a - a single block (with one cable stretched along the groove of a single pulley); b - a combination of two single blocks with a single cable covering both pulleys; c - a pair of two-groove blocks, through four paired grooves of which a single cable passes.

Rice. 2. Reeves with various combinations of blocks of three types: on the left - a pair of double blocks; in the center - a triple block with a double; on the right, a pair of triple blocks. In the triple pulley, the end of the rope to which the pulling force is applied passes through a central trough; at the same time, the lower - movable - block is fastened with a thimble so that its axis is perpendicular to the axis of the upper - fixed - block.

Classification of construction machines. General requirements for machines

According to the production (technological) basis, all construction machines and mechanisms can be divided into the following main groups: -

1) lifting;

2) transporting;

3) loading and unloading;

4) for preparatory and auxiliary work;

5) for earthworks;

6) drilling;

7) pile driving;

8) crushing and screening;

9) mixing;

« 10) machines for transporting concrete mixtures and mortars; "11) machines for placing and compacting concrete;

12) road; - 13) finishing; 14) mechanized tool.

Road and other construction machines that are not listed are not considered in the textbook, since their study in the course program "Construction machines and their operation" is not provided.

Each of these groups of machines, in turn, can be divided into several subgroups according to the method of performing work and the type of working body, for example, machines for earthworks can be divided into the following subgroups:

a) earth-moving vehicles: bulldozers, scrapers, motor graders, grader-elevators, etc.;

b) single-bucket and multi-bucket excavators; earth-moving and milling machines, planners with a telescopic boom, etc.;

c) equipment for the hydromechanical method of excavation of soils: hydraulic monitors, suction and dredging equipment, etc.

d) soil-compacting machines: rollers, vibro-compacting machines, rammers, etc.

The operating conditions of construction machines are characterized by a certain complexity. Construction machines must provide the necessary performance in the open, in any weather, at any time of the year; move on dirt roads and off-road, in cramped conditions of the construction site. Therefore, based on the specific operating conditions, a number of requirements are imposed on a particular machine, and the more fully the machine meets all the operating requirements, the more suitable it is for use in the construction industry.

Each machine must be reliable in operation, durable and adapted to changing working conditions; should be easy to operate, easy to maintain, repair, assemble, dismantle and transport, economical to operate, i.e. consume the minimum amount of electricity or fuel per unit of output. The machine must ensure the safety of work and the convenience of the operating personnel, achieved by the appropriate placement of instruments, controls, a good overview of the front of work, automatic cleaning of the cab sight glasses, a pneumatic or hydraulic control system that helps to reduce the effort on the control levers, isolation of the cab from the effects of noise, vibration and dust. The machine must have beautiful external forms, good finish and lasting color.

Machines operating at low or, conversely, elevated temperatures must be adapted to work under the specified conditions.

Often relocated non-self-propelled construction vehicles must have a minimum weight, ease of installation, dismantling and transportation.

For self-propelled machines, which often change their place of work, among the requirements that are required are maneuverability, machine cross-country ability and stability.

Maneuverability (mobility) of the machine is the ability to move and turn around in cramped conditions, as well as move around the construction site and outside it at a speed sufficient for production conditions.

The patency of a car is the ability to overcome "roughness of the terrain and shallow water obstacles, to pass through wet and loose soils, snow cover, etc. The patency is determined mainly by the specific pressure on the ground, the amount of ground clearance (clearance) - with longitudinal Ri and transverse Yag patency radius of wheeled vehicles (1), minimum turning radius.

The stability of a machine is the ability to resist the action of forces that tend to overturn it. The lower the center of gravity of the machine and the larger its support base, the more stable the machine.

Machine productivity is the amount of products (expressed in weight, volume, or pieces) produced per unit of time - an hour, a shift, a year. There are performance: theoretical (calculated, constructive), technical and operational.

The device of machines. Requirements for the working body and drive of the machine

transmissions

Transmission (power transmission) - in mechanical engineering, a set of assembly units and mechanisms connecting the engine (motor) to the driving wheels of the vehicle (car) or the working body of the machine, as well as systems that ensure the operation of the transmission. In the general case, the transmission is designed to transmit torque from the engine to the wheels (working body), change traction, speeds and direction of movement. The transmission is part of the power unit

The vehicle transmission includes:

Clutch;

Transmission;

Intermediate cardan shaft;

Transfer case;

cardan shafts to drive axles;

Main gear;

Differential;

• Joints of equal angular speeds;

  Power take-off.

The composition of the transmission of tracked vehicles (for example, a tank) generally includes:

Main clutch (clutch);

Input reducer ("guitar");

Transmission;

Rotation mechanism;

Onboard gearbox.

There are about four dozen varieties of steel rope on the modern market. All of them are made in strict accordance with GOSTs, but at the same time they can differ greatly from each other. To understand this, it is necessary to study the classification of ropes.

Selection Criteria for Steel Ropes

People who constantly work with metal cables and ropes have practically no problems with their choice. Trouble begins when a non-standard rope is required for the job. In this case, you need to use GOST, which describes the exact classification.

According to this GOST, all metal ropes can differ in such parameters as:

• construction type;
• wire cross-section type;
• type, method and direction of lay details;
• core material;
• degree of balance and torsion;
• maximum strength level;
• mechanical properties of the wire;
• appointment.

The main design feature of all steel ropes is the number of strands (pigtails) and the way they are twisted. According to this feature, the lay can be single, double or even triple. In the first case, the wire is twisted in a spiral shape in one or more layers. If the cable is still covered with shaped wire from above, then it is called closed.

Double-lay ropes consist of thin single strands, the number of which can be up to six. They are also used for the manufacture of triple lay ropes.

Classification of ropes by lay parameters

A twist is the process of twisting strands of a metal rope. The strands can touch each other pointwise, linearly or in a combined way. Strands of different layers may have the same or different diameters. If filling wires are laid between them, then the rope is marked as "LK-Z". In the event that wires of different diameters are laid between the strands, this is an LK-RO rope.

Sometimes during the production process, the wire and strands go through a preliminary deformation. This is done in order to obtain a non-twisting rope. If the strands fall apart immediately after removing the retaining ties, then you have an unwinding rope in front of you.

The lay direction of the metal rope can be right or left. This takes into account not only the position of the strands of the outer layer, but also their position in relation to the rope itself. On this basis, the twist can be:

• cross,
• unilateral,
• combined.

Types of ropes by core type

The core is located in the very center of the steel rope and is necessary to give it the necessary flexibility and strength. It is usually produced using metal or organic materials. Ropes with a metal core are used to solve problems such as:

• increase in structural strength,
• increase in wear-resistant properties when working at high temperatures,
• reduction of structural elongations under tension.

The organic core of metal ropes can be made from natural or synthetic materials. Usually these are cotton threads, polyethylene, nylon and more.

Types of ropes according to the degree of balance and twist

The balance of a metal rope is determined by whether straightening was used in the process of its production. It relieves stress on the strands when they are hung horizontally. It is thanks to this that the product retains its straightness.

If, being in a horizontal position, the rope at the end is twisted into a ring, it means that straightening was not carried out during its production.

To determine the degree of twist of the rope, you need to study the direction of all the strands of the lay. They can have the same direction in all layers (rotating) or the opposite direction in different layers (low-rotating).

Other characteristics of metal ropes

When buying metal cables, you need to pay attention to the quality of the wire, as well as the accuracy of manufacturing. Typically, they are produced using wire of normal, high or high quality. It can be coated with a galvanized or polymer layer, which protects it from medium, hard or especially hard aggressive environments.

It can be used to lift and transport goods only, or both goods and people. To determine its strength characteristics, you need to pay attention to the latest value in the marking. It can be in the range of 1370-1770 N/mm2. The higher the strength characteristics of a metal rope, the more load it can withstand.

Vegetable and synthetic cables come from the manufacturer in bays. Depending on the thickness of the cable, up to four or five separate pieces of cable can be laid in the bay. Cables thicker than 100 mm are laid in a bay in one piece. On the tags fixed on the coils, and in the certificates for the cable, there must be a stamp of the manufacturer. The cable taken on board the ship must be carefully inspected. During the inspection, the uniformity and density of the twist, the integrity of the strands are checked. Vegetable cables should not have traces and smell of mold and rot. It is necessary to check the thickness of the cable and its design and compare with the data indicated on the tag and in the certificate. The thickness is measured along the circumference in at least ten places along the entire length of the cable. In order to make sure that there are no internal defects, it is necessary to slightly unwind the strands in a small area and inspect them. Especially carefully should be inspected cables that have a long time of manufacture. To completely unravel the coil in order to inspect the cable or cut it into pieces of the required length, it is recommended to put it on a crosspiece suspended on a cable to the swivel, and unravel the cable from the outer end. In order to unravel the bay of the vegetable cable and unwind a small piece, the inner end of the cable should be brought out and the bay should be unraveled from the inside. A coil of synthetic rope is rolled out on the deck and unraveled from the outer end. The cable unraveled from the bay is stretched along the deck and cut into pieces of the desired length. To protect the cable from untwisting, on both sides of the cut points, stamps from a cable, shkimushgar or sailing thread are preliminarily applied to it. The free ends of the synthetic cable are melted with a blowtorch. The cable intended for mooring lines is closed at both ends with fires (gash) and wound on mooring sheets or laid in bays on lattice wooden stands - banquettes. It is necessary to lay the cables in the coils in a twist, that is, the direct descent cables - clockwise, and the reverse descent cables - counterclockwise. Vegetable cables stored on views or banquettes on deck should be covered with covers in wet weather, and ventilated in dry weather. Synthetic cables must be protected from sunlight.

Ropes not in use should be stored clean and dry in well ventilated areas. Synthetic ropes should be stored in rooms with an air temperature not exceeding 30°C and a relative humidity of not more than 70%. To reduce the hygroscopicity of plant cables, which increases due to the deposition of salts on them, the cables wetted in sea water should be washed with fresh water and then dried. Synthetic cables are not afraid of moisture, so drying them is not necessary. However, if the rope is to be stored on a sling, it should be dried in the shade to prevent rusting of the sling and rope. Steel cables are supplied to the vessel in small coils or in standard length pieces wound on reels. Each cable spool is supplied with a tag and a certificate, which indicates the main characteristics of the cable and its dimensions, as well as the date of manufacture and the name of the manufacturer. To completely unravel the cable from the reel, a crowbar is passed through the middle of it and fixed on vertical supports. To unravel a small coil of cable, it is rolled out on the deck, starting from the outer hoses. During an external inspection of the cable, it is necessary to compare its design data with those indicated on the tag and in the certificate, check the diameter of the cable with a caliper. The cable must not have dents, broken wires, cracks or other damage to the galvanizing. The strands of the cable should fit snugly against each other. Before cutting a steel cable, on both sides of the cut, marks made of soft wire or vegetable cable are applied to the cable to protect it from unwinding. Steel cables not in use should be stored in a dry place, lubricated and neatly coiled. Mooring cables on the views should be sheathed, and in dry weather - open for ventilation.

In all devices, only serviceable cables should be used. The vegetable cable must be replaced if there is a rupture of the cables, charm, significant abrasion or deformation. To avoid flattening and distortion of the structure, the cables must not be subjected to sharp bends under load. Therefore, all parts of the ship's devices through which the cables pass must be rounded. Plant cables shorten up to 10-12% when wet, and lengthen when dry. Therefore, in wet weather, heavily tensioned cables must be loosened to prevent them from breaking.

The outer fibers of vegetable and especially synthetic ropes are not sufficiently resistant to abrasion. Therefore, in places where they rub against metal surfaces, mats, canvas, etc. should be placed. Considering that synthetic cables are subject to melting during friction. Special requirements are imposed on the details of the equipment: on the surface of drums, bollards, bale planks, rollers there should be no ribs, protrusions and roughness in the form of sharp edges, burrs, shells, etc. When operating synthetic cables, sand and other solid particles should not be allowed to enter between the strands, as they cause the destruction of the cable. It is necessary to protect the cable from coal tar, drying oil, lubricants, varnishes and paints, as well as organic solvents. Synthetic ropes used on tankers, gas carriers or ships intended for the carriage of flammable and chemical cargoes in bulk must undergo a treatment to remove static electricity charges, which consists in soaking the rope in a 2% saline solution (20 kg of table salt per 1 m3 of water ) during the day. Ropes in operation should be doused on the deck with sea water at least once every 2 months. The steel cable should not have knots and pegs, broken and protruding wires. The pebbles should be spaced in advance, the broken wires should be cut short, and the cable should be caged in these places. If, according to the working conditions, the steel cable must be in sea water, then it is recommended to pre-lubricate it with a boiled hot mixture of equal parts of wood resin and lime, and after work, rinse with fresh water, dry and lubricate. When working with cables, precautions must be taken. It should be remembered that the steel cable does not have great elasticity under a load close to breaking force, it lengthens by only 1-2%. Therefore, it is almost impossible to predict the moment of its break, and this obliges people working with the cable to be extremely careful. When cutting steel cables with a chisel, goggles must be worn. Work with steel cables must be carried out in gloves. A great danger is working with synthetic cables due to their great elasticity. It must be borne in mind that the critical limit, after which there is a risk of rupture, is the elongation of polyamide cables by 40, polyester and polypropylene - by about 30%. When broken, the synthetic cable contracts with great force, its ends fly off rapidly in the direction of tension to the attachment point, which creates a danger to nearby people.