Blocks are used to change the direction of traction when lifting and moving small weights or when tightening gear, as well as for founding hoists. The block consists of a wooden, metal or molded plastic housing, inside of which one or more metal pulleys are loosely mounted on an axis called a dowel. The blocks come in one-, two-, three- and multi-pulley types. The block body has partitions that separate one pulley from the other. The outer surfaces of the outermost partitions are called cheeks.

Rice. 1. Gorden.

The simplest design is a single-pulley block. A cable passed through such a block, fixed motionless, is called a gorden (Fig. 1). The arbor allows you to change the direction of thrust when lifting and moving a load, but does not provide a gain in strength, so it is used for lifting small weights. Single-pulley blocks with halyards passed through them are used to hoist flags and pennants, signal lights and signs.

Wooden and plastic blocks are used only when working with vegetable and synthetic cables. Most marine equipment uses metal blocks.

Rice. 2. Metal blocks.

Double-pulley metal block (Fig. 2, A) consists of a body 3, two steel or cast iron pulleys 4, bushings 5 with lubrication groove or with bearing, dowel 6, shackles 7 , mounting bolts 1 and pendants 2.

To equip the block, the cable must be passed between the cheeks of the block and placed in the pulley bale. Equipment simple block inconvenient, since you have to thread the cable from the end. Therefore, on ships they use single-pulley blocks with a folding cheek - rosin blocks (Fig. 2, b). The folding jaw allows you to insert the middle of the cable into such a block.

To prevent excessive bending of the cable passing through the pulley of the block, the dimensions of the block must correspond to the thickness of the cable. Pulley diameter metal block should be at least 10 - 15 diameters of a steel cable, and a wooden one - 2 times the circumference of a vegetable or synthetic cable.

The blocks must be periodically disassembled, cleaned of dirt and rust, and lubricated rubbing parts. If cracks or significant wear of the dowel or pulley are detected, the block should be replaced. Units that are not in use must be thoroughly lubricated and stored in a dry place in a suspended state.

Hoists are devices that allow you not only to change the direction of traction, but also to gain strength when lifting and moving heavy objects, when tightening gear and in other cases. According to their design, hoists are divided into ordinary and mechanical.

Ordinary hoists consist of two blocks, through the pulleys of which a cable called a rope is passed. One end of the shovel, attached to the block, is called the main end, the other, coming out of the block, to which an external traction force is applied, is called the running end. One block of hoists, fixed, is secured in place through a suspension. The other block is called movable, since during operation it rises along with the load or moves in the direction of tightening the gear. According to the number of pulleys in both blocks, hoists are divided into two-, three-, four- and multi-pulley.

Rice. 3. Ordinary two-pulley hoists.

The simplest are double-pulley hoists, based on a lopar between two single-pulley blocks. Such hoists can be based in two ways: the running end of the lopar comes off the stationary one (Fig. 3, A) or from a mobile one (Fig. 3, b) block. Let's consider the gain in force when lifting a load with a mass T will be in both cases.

In the first case, the mass of the load is distributed over two branches of the lopar coming out of the lower, movable block, and in the second - over all three branches. Therefore, to hold a load weighing T in the first and second cases, efforts must be made to the running ends of the lopars F 1 And F2, equal to 1/2 respectively T and 1/3 T. This means that the gain in strength is equal to the number of loaded branches of the Lapp or the total number of pulleys in both blocks in the first case and the total number of pulleys plus one in the second. Thus, indicating the total number of pulleys in both blocks P, we obtain formulas expressing the dependence of the force applied to the running end of the lopar to hold the load suspended, and the total number of pulleys in both blocks:

F 1 =m/n; F 2 =m / (n+1)

To lift the load to the running end of the lopar, additional effort is required to overcome the friction forces arising in the hoists. It is practically believed that the effort to overcome frictional forces in each pulley of hoists based on vegetable or flexible steel cable is 10 and 5% of the mass of the lifted load, respectively.

Rice. 4. Ordinary multi-pulley hoists.

Ordinary hoists are used on ships various designs and load capacity. To tighten the gear, three-pulley grip hoists are used (Fig. 4, A). Along with them, hoists are used, based between two blocks with the same number of pulleys - gintsy (Fig. 4, b). The armament of heavy booms includes multi-pulley hoists having blocks with pulleys on ball bearings - gini (Fig. 4, V).

The methods for founding hoists depend on the number of pulleys in the blocks (Fig. 5). They are always founded with the root end of the lapar clockwise for right-hand descent cables and counterclockwise for left-hand descent cables. The hoists are based on the deck, placing one block opposite the other at some distance with the pendants outward. For the base of double-pulley hoists (Fig. 5, A) behind fixed block take the one that has a device for attaching the root end of the lapar. The root end is passed through the pulley of the stationary block, then through the pulley of the movable one and attached to the stationary block.

Rice. 5. Methods for founding hoists.

When founding three-pulley hoists (Fig. 5, b) a two-pulley block is taken to be a fixed block, and a single-pulley block is taken to be a movable block. The root end is passed through the lower (closest to the deck) pulley of the two-pulley block, through the single-pulley pulley, then through the upper pulley of the two-pulley and attached to the single-pulley block.

When founding four-pulley hoists (Fig. 5, V), consisting of two two-pulley blocks, the root end is passed sequentially, first through the lower pulleys of the fixed and movable blocks, then through the upper pulleys of these blocks, after which the root end is brought to the fixed block and secured to it.

The base between two three-pulley blocks of six-pulley guineas (Fig. 5, G) is carried out with the root end of the lopar according to the scheme: the middle pulley of the fixed block - the lower pulley of the movable - the lower pulley of the fixed - the middle pulley of the movable - the upper pulley of the fixed - the upper pulley of the movable - to the attachment point on the fixed block. This wiring diagram for the root end of the paddle prevents the blocks from skewing while lifting the load.

In all cases, after passing the root end of the lapar through all the pulleys of both blocks, it is sealed with a fire and a thimble, with which it is attached to the butt on the corresponding block.

Mechanical hoists allow you to obtain multiple gains in strength, the ability to smoothly lift the load and keep it automatically locked in any position.

Rice. 6. Mechanical differential hoists.

Mechanical differential hoists are widely used on ships (Fig. 8). The suspension of such hoists contains a fixed block cage, which consists of two rigidly connected pulleys of different diameters with a diameter ratio of 7:8 or 11:12. The suspension with the block is attached to a fixed support or to the traverse of a trolley moving along a suspended rail. The lower (movable) single-pulley block is also placed in a cage that has a hook for hanging the load. The closed operating chain sequentially covers the small pulley of the fixed block, the pulley of the movable and the large pulley of the fixed block. Lifting of the load is ensured by turning the large pulley of the stationary block by applying a traction force to the branch of the working chain running from this pulley.

When lifting heavy loads with differential hoists, a 16-fold (with a ratio of the diameters of the fixed block pulleys of 7:8) and 24-fold (with a ratio of these diameters of 11:12) theoretical (without taking into account friction) gain in strength is obtained.

Ordinary hoists that are not in use are stored in a dry, ventilated area in a suspended state. All rubbing parts of the blocks are well lubricated. After finishing work with portable hoists, they are carefully folded, preventing the hoist from becoming tangled. When working with ordinary hoists, try to avoid sudden jerks, which can lead to breakage of the paddle or damage to the blocks. If, upon inspection of the blocks, significant wear of the dowels, hooks, brackets or butts is discovered, such blocks are replaced and the hoists are re-founded.

Mechanical hoists are kept clean, rubbing parts are regularly lubricated, and their serviceability is monitored.

Gorden - a single-pulley block with a cable passed through it; to gain strength in rigging, they use a grab-tali and a gini (Fig. 137).

Rice. 137. The simplest mechanisms for lifting loads:
a - gorden, b - hvat-tali, c - gini

A hoist is a chain hoist, i.e. a system of single-pulley blocks (two or more) with one cable, designed to work together. Most often, hoists are used in the form of two blocks with one to three pulleys in each. The most widely used are grab hoists that have one movable block and the other (upper) block in the form of double hoists.

Hoists are called gins that have two blocks with three or more pulleys in each. Multi-pulley blocks (more than three) are rarely used; they have a special design and are used only in special devices. Ginis are the largest hoists, used for lifting heavy weights; they are different from regular hoists large sizes blocks and the thickness of the rope-rope.

The cable that connects two blocks to work together is called a tackle hoist. The end with which the lopar is tightly embedded in the butt of the upper or lower block is called the main lopar, and the end coming out of the upper block, which is pulled when lifting the load or etched when lowering it, is called the running lopar; the remaining branches of the hoist cable are called lopar branches, the number of which is equal to the number of pulleys of both blocks.

Hoists come with two single-pulley blocks, one single-pulley and one double-pulley; with two two-pulley blocks, with one two-pulley and one three-pulley and, finally, with two three-pulley blocks (gini). Consequently, the branches of the Lapp can be from three to seven.

Plant ropes are used for hoists and steel cables, as well as rigging chains.

Mechanical hoists are hoists that are called differential hoists. There are also differential hoist systems with screw drive and gear drive hoists.

To lift loads to a small height, manual hoists are used; According to the load capacity, hoists are produced from 1-10 tons; they are made geared with gear and worm drives.

Manual hoists with a worm drive consist of a hook on which they are suspended from structures, an upper steel fixed block, on the rim of which teeth are cut to engage the elements of the chain drive; this drive unit is connected to the worm. A welded calibrated chain, made as a closed endless chain, is thrown over a drive block that rotates when the chain is handled by hand. As the drive unit with the worm rotates, the worm gear connected to the sprocket also rotates. If you manually move the rotation chain of the drive block, the worm will rotate and transmit rotation to the upper block along with the load chain located on the sprocket slots. The load chain passes through the lower block (small diameter) of the hoists and the upper sprocket. When the worm gear and sprocket rotate, the load chain shortens in length and lifts the load. For lifting loads manual hoists It is necessary to apply a traction force of 33-68 kgf to the chain (depending on the load being lifted).

Lifting a load using mechanical hoists with a gear drive occurs in the same way as lifting a load using hoists with a worm drive. However, in the first case, the load is lifted in a parallel plane in which the drive unit rotates, and in the case of a worm gear, in a mutually perpendicular planes. To reduce the lifting effort, two gear transmissions are made (Fig. 138).

Rice. 138. Differential (mechanical) hoists

Manual mechanical hoists have a limited range of action; they can only lift the load at the point where it is secured.

To expand the range of action of hoists, they are suspended from a trolley, which moves along tracks made of I-beams, suspended from the floors of the workshop.

A more advanced lifting device is a hoist - an electric hoist with a trolley moving on a monorail. Lifting mechanism The hoist has an electric motor connected to a drum that replaces the upper block of hoists. The lifting and movement of the hoist is controlled via a remote control with buttons on a flexible wire. Telphers can also be moved over considerable distances using a trolley - a current-carrying wire located on the side of the monorails or above them.

In shipbuilding and ship repair, capstans and winches are also used. They are manual and electric.

A hand winch has a strong and massive base, a frame, a main drum (with a horizontal axis), shafts with gears for changing speeds, a brake and handles for applying muscle force. Hand winches manufactured with a load capacity of 0.5; 1.0; 3.0; 5 tons. When working with such winches, rosin blocks and hoists are used. Rosin blocks are used to divert the cable going to the drum, and hoists are used to obtain a greater gain in strength.

The capstan, unlike the winch, has a vertical axis of rotation. Spiers and winches usually operate at low speeds with high traction forces. When lifting light loads, use one branch of the cable (pendant), and when lifting heavy loads, use hoists.

Electric capstans (Fig. 139) and winches operate on shore from a power plant or plant substation, and on a ship from a generator. The shaft with the drum on them is driven into rotation by an electric motor. To control them, controllers and starting rheostats are used. By turning the starting rheostat lever in one direction or another, the mechanisms are given the desired speed.

Rice. 139. Spiers and winches:
a - diagram of the operation of the capstan, b - diagram of the operation of the winch, c - manual rigging winch; 1 - drum, 2 - handle, 3 - adjustable handle shaft, 4, 5 - spur gear, the drive wheel of which can be engaged and disengaged, 6, 7 - drum gear, 8 - locking mechanism for stopping the shaft, 9 - ratchet brake , 10 - sheet steel panels, 11 - spacer bolts

Before lifting loads, it is necessary to check the correct rotation of the winch (or capstan) and determine its suitability for the job. Particular attention should be paid to the serviceability of the stopper. If the stopper and brake are faulty, the winch cannot operate.

Jacks are used to lift heavy machines and units to a small height and move them over short distances, as well as perform various rigging works. Their advantages: low weight, high load capacity, simplicity of design, ease of braking and ease of handling.

Jacks are: screw, hydraulic, air and rack-and-pinion; their common disadvantage is the relatively low efficiency. The lifting capacity of jacks reaches 20-25 tons. The average lifting height of loads is 400 mm, the weight of rack and pinion screw jacks ranges from 5 to 120 kg.

Rope products and rigging chains are widely used in the operation of mechanisms.

A pulley block is a system of movable and fixed blocks connected by a flexible connection (ropes, chains) used to increase the force or speed of lifting loads. A chain hoist is used in cases where it is necessary to lift or move a heavy load with minimal effort, provide tension, etc. The simplest pulley system consists of just one block and a rope, and at the same time it allows you to halve the traction force required to lift a load.

Usually in lifting mechanisms power pulleys are used to reduce the tension of the rope, the moment from the weight of the load on the drum and the gear ratio of the mechanism (hoist, winch). High-speed pulleys that allow you to gain a gain in the speed of movement of the load at low speeds of the drive element. They are used much less frequently and are used in hydraulic or pneumatic lifts, loaders, and mechanisms for extending telescopic booms of cranes.

The main characteristic of the pulley is the multiplicity. This is the ratio of the number of branches of the flexible body on which the load is suspended to the number of branches wound on the drum (for power pulleys), or the ratio of the speed of the leading end of the flexible body to the driven end (for high-speed pulleys). Relatively speaking, the multiplicity is a theoretically calculated coefficient of gain in strength or speed when using a chain hoist. Changing the multiplicity of the pulley system occurs by introducing or removing additional blocks from the system, while the end of the rope with an even multiplicity is attached to a fixed structural element, and with an odd multiplicity - on the hook clip.

Depending on the number of rope branches attached to the drum of the lifting mechanism, single (simple) and double chain hoists can be distinguished. IN single pulley hoists, when winding or unwinding a flexible element due to its movement along the axis of the drum, an undesirable change in the load on the drum supports is created. Also, if there are no free blocks in the system (the rope from the hook suspension block directly passes to the drum), the load moves not only in the vertical, but also in the horizontal plane.

To ensure strictly vertical lifting of the load, double pulleys (consisting of two single ones) are used; in this case, both ends of the rope are fixed to the drum. To ensure the normal position of the hook suspension in case of uneven stretching of the flexible element of both pulleys, a balancer or equalizing blocks are used. Such pulleys are used mainly in overhead and gantry cranes, as well as in heavy tower cranes, so that two standard cargo winches can be used instead of one large, high-power one, and also to obtain two or three speeds for lifting loads.

IN power pulleys when increasing the multiplicity, it is possible to use ropes of reduced diameter, and as a result, reduce the diameter of the drum and blocks, reduce the weight and dimensions of the system as a whole. Increasing the multiplicity allows you to reduce the gear ratio, but at the same time requires a larger rope length and rope capacity of the drum.

High-speed pulleys differ from power ones in that they work force, usually developed by a hydraulic or pneumatic cylinder, is applied to a movable cage and the load is suspended from the free end of the rope or chain. The gain in speed when using such a pulley is obtained as a result of increasing the height of the load.

When using pulleys, it should be taken into account that the elements used in the system are not absolutely flexible bodies, but have a certain rigidity, so the oncoming branch does not immediately fall into the stream of the block, and the running branch does not straighten out immediately. This is most noticeable when using steel ropes.

A person is not very strong for lifting large loads, but he has come up with many mechanisms that simplify this process, and in this article we will discuss pulleys: the purpose and design of such systems, and we will also try to make the simplest version of such a device with our own hands.

A cargo pulley is a system consisting of ropes and blocks, thanks to which you can gain effective strength while losing in length. The principle is quite simple. In length we lose exactly as many times as we win in strength. Thanks to this golden rule of mechanics, large masses can be built without much effort. Which, in principle, is not so critical. Let's give an example. Now you have won 8 times in strength, and you will have to stretch a rope 8 meters long to lift the object to a height of 1 meter.

The use of such devices will cost you less than renting a crane, and besides, you can control the gain in strength yourself. The pulley has two different sides: one of them is fixed, which is attached to the support, and the other is movable, which clings to the load itself. The gain in strength occurs thanks to the movable blocks, which are mounted on the movable side of the pulley. The fixed part serves only to change the trajectory of the rope itself.

Types of pulleys are distinguished by complexity, parity and multiplicity. In terms of complexity, there are simple and complex mechanisms, and the multiplicity means a multiplication of force, that is, if the multiplicity is 4, then theoretically you gain 4 times in strength. Also rarely, but still used, a high-speed pulley block is used; this type gives a gain in the speed of moving loads at a very low speed of the drive elements.

Let's first consider a simple assembly pulley. It can be obtained by adding blocks to a support and a load. To get an odd mechanism, you need to secure the end of the rope to a moving point of the load, and to get an even one, we fasten the rope to a support. When adding a block, we get +2 to strength, and a moving point gives +1, respectively. For example, to get a pulley for a winch with a multiplicity of 2, you need to secure the end of the rope to a support and use one block that is attached to the load. And we will have an even type of device.

The operating principle of a chain hoist with a multiplicity of 3 looks different. Here the end of the rope is attached to the load, and two rollers are used, one of which we attach to the support, and the other to the load. This type of mechanism gives a gain in strength of 3 times, this is an odd option. To understand what the gain in strength will be, you can use simple rule: how many ropes come from the load, such is our gain in strength. Typically, pulleys with a hook are used, on which, in fact, the load is attached; it is a mistake to think that it is just a block and a rope.

Now we will find out how a complex type chain hoist works. This name refers to a mechanism where several simple options of this cargo device, they pull each other. The gain in strength of such constructions is calculated by multiplying their multiplicities. For example, we pull one mechanism with a multiplicity of 4, and another with a multiplicity of 2, then the theoretical gain in force will be equal to 8. All of the above calculations take place only for ideal systems that have no friction force, but in practice things are different .

In each of the blocks there is a small loss in power due to friction, since it is still spent on overcoming the friction force. In order to reduce friction, it is necessary to remember: the larger the bend radius of the rope, the less frictional force will be. It is best to use rollers with a larger radius where possible. When using carabiners, you should make a block of identical options, but rollers are much more effective than carabiners, since the loss on them is 5-30%, but on carabiners it is up to 50%. It is also useful to know that the most effective block must be located closer to the load to obtain maximum effect.

How do we calculate the real gain in strength? To do this, we need to know the efficiency of the units used. Efficiency is expressed by numbers from 0 to 1, and if we use a rope large diameter or too hard, then the efficiency of the blocks will be significantly lower than indicated by the manufacturer. This means that it is necessary to take this into account and adjust the efficiency of the blocks. To calculate the actual gain in strength simple type lifting mechanism, it is necessary to calculate the load on each branch of the rope and fold them. To calculate the gain in strength complex types it is necessary to multiply the real forces of the simple ones of which it consists.

You should also not forget about the friction of the rope, since its branches can twist among themselves, and the rollers under heavy loads can converge and pinch the rope. To prevent this from happening, the blocks should be spaced relative to each other, for example, you can use a circuit board between them. You should also purchase only static ropes that do not stretch, since dynamic ones give a serious loss in strength. To assemble the mechanism, either a separate or a cargo rope can be used, attached to the load independently of the lifting device.

The advantage of using a separate rope is that you can quickly assemble or prepare a lifting structure in advance. You can also use its entire length, this also makes it easier to pass knots. One of the disadvantages is that there is no possibility of automatic fixation of the lifted load. The advantages of a cargo rope are that automatic fixation of the lifted object is possible, and there is no need for a separate rope. The important thing about the disadvantages is that it is difficult to pass through the knots during operation, and you also have to spend a cargo rope on the mechanism itself.

Let's talk about the reverse motion, which is inevitable, since it can occur when the rope is caught, or at the moment of removing the load, or when stopping to rest. To prevent backlash from occurring, it is necessary to use blocks that allow the rope to pass in only one direction. At the same time, we organize the structure so that the blocking roller is attached first from the object being lifted. Thanks to this, we not only avoid backtracking, but also allow us to secure the load while unloading or simply rearranging the blocks.

If you are using a separate rope, the locking roller is attached last from the load being lifted, and the locking roller should be highly effective.

Now a little about attaching the lifting mechanism to the cargo rope. It’s rare that we have the right length of rope at hand to secure the moving part of the block. Here are several types of mechanism mounting. The first method is using grasping knots, which are knitted from cords with a diameter of 7-8 mm, in 3-5 turns. This method, as practice has shown, is the most effective, since a gripping knot made of 8 mm cord on a rope with a diameter of 11 mm begins to slide only under a load of 10-13 kN. At the same time, at first it does not deform the rope, but after some time, it melts the braid and sticks to it, beginning to play the role of a fuse.

Another way is to use a clamp general purpose. Time has shown that it can be used on icy and wet ropes. It begins to crawl only with a load of 6-7 kN and slightly injures the rope. Another method is to use a personal clamp, but it is not recommended, since it begins to creep with a force of 4 kN and at the same time tears the braid, or can even bite the rope. These are all industrial designs and their application, but we will try to create a homemade chain hoist.

Weight lifting mechanism

First letter "b"

Second letter "l"

Third letter "o"

The last letter of the letter is "k"

Answer for the clue "Mechanism for lifting weights", 4 letters:
block

Alternative crossword questions for the word block

Union of states public organizations or groups for joint action

Volleyball defense

Volleyball defense or Russian poet

French writer (1884-1947, "Sibilla", "Spain! Spain!", "Toulon")

Defense technique in sports

Famous Russian poet Alexander

Technique in martial arts

Definition of the word block in dictionaries

Explanatory dictionary of the Russian language. D.N. Ushakov The meaning of the word in the dictionary Explanatory Dictionary of the Russian Language. D.N. Ushakov
block, m. (English block) (fur.). Simple machine for lifting weights using a rope (chain, belt) thrown over a wheel fixed at a height with a groove around its circumference. Pick up something. block.

Explanatory Dictionary of the Living Great Russian Language, Dal Vladimir The meaning of the word in the dictionary Explanatory Dictionary of the Living Great Russian Language, Dal Vladimir
m. Morsk. gate, veksha, vekoshka; block with opening and roller; two wooden cheeks, between which a circle, roller, ayushka (pulley) with a groove (kip) along the edge is inserted on the axis (dowel), for pulling tackle and ropes through it. In our everyday life it is also called a roller block...

Wikipedia Meaning of the word in the Wikipedia dictionary
Block is a surname of Jewish-German origin. Known carriers: Blok - Russian noble family. Block, Abraham van den (1572-1628) - Renaissance architect and sculptor of the Free City of Danzig. Block, Adrien (c. 1567-1627) - Dutch merchant,...

Examples of the use of the word block in literature.

When he realized that all the water from pure condensate tanks and from chemical water treatment was switched to emergency block, he immediately reported to Fomin in the bunker that he would shut down the reactor.

He was running around block, mainly along the deaerator shelf, in order to cut off the left two deaerator tanks, from which water flowed to the destroyed emergency feed pump.

Zemskov, who had just conscientiously bypassed the emergency block and heavily irradiated.

Suspension possible blocks with 80 mm rockets, machine guns or grenade launchers, as well as 2 or 4 aerial bombs with a total weight of 500 kg.

Berezhkov came to the idea that a modern aircraft engine requires block cylinders, such a design was seen in his imagination, he even expressed it in sketches, and now, looking at this motor that arrived from America, disassembled in the ADVI assembly hall, Berezhkov again felt as if someone from a foreign country had snatched and carried out his plan.