How to make a hand winch from scrap material. What is a chain hoist, why and where is it used? Double chain hoist

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 differ from conventional hoists in the larger size of the blocks and the thickness of the rope.

The cable that connects two blocks to work together is called a tackle hoist. The end with which the lopar is tightly sealed into 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 and steel cables, as well as rigging chains, are used for hoists.

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. To lift a load with 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 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 the 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. The lifting mechanism of the hoist is an electric motor connected to a drum that replaces the upper block of the 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. Manual winches are manufactured with a lifting 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 screw jacks ranges from 5 to 120 kg.

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

Blocks and pulleys- simple mechanisms used to lift loads either with little effort or with effort in a position convenient for the user.

Blocks and pulleys consist of two parts: a wheel with a circumferential groove (pulley) and a rope or cable. A block, as a rule, is a device consisting of one pulley in a frame with a suspension and one cable. A pulley block is a combination of pulleys and cables. The principle of its operation is similar to the operation of a lever - the gain in force affects the increase in distance with theoretical equality of the work performed.

These mechanisms can be used independently of other lifting units, such as winches, hoists, cranes, and also as their parts.

The pictures show the operating principle block and pulley:

In Fig. 1a, a load weighing W1 is lifted using a single block with a force P1 equal to the weight. In Fig. 1b, the load W2 is lifted with the simplest multiple pulley system, consisting of two blocks, with a force P2 equal to only half the weight of W2. The impact of this weight is divided equally between the branches of the cable on which pulley B2 is suspended from pulley A2 by hook C2. Consequently, in order to lift the load W2, it is sufficient to apply a force P2 equal to half the weight of W2 to the branch of the cable 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 pulley 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 block B3. Note that the multiple of the gain in strength when lifting weights is always equal to the number of cables on which the movable block B3 hangs.

Rice. 2

In the past as a cable for blocks and pulleys flexible and durable hemp rope was used. It was woven with a braid of three strands, each of which consisted of many small strands. Pulley hoists with such ropes were used wherever it was necessary to lift loads: on sea vessels, in agriculture, on construction sites. The most complex of them (Fig. 2) were often used on sailing ships. There they were needed to work with sails, spar parts and other movable equipment.

Over time, hemp edges were replaced by steel cables and cables made of synthetic and mineral fibers. They are more durable and wear-resistant. Pulley hoists with steel cables and multi-groove pulleys are integral parts of the lifting mechanisms of all modern lifting equipment. Pulleys blocks usually rotate on roller bearings and all their moving surfaces are forcibly lubricated.

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 a simple rule: how many ropes come from the load, this 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 versions of this cargo device are connected into one system; 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 as numbers from 0 to 1, and if we use a rope with a large diameter or too stiff, 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 strength gain of a simple type of lifting mechanism, it is necessary to calculate the load on each branch of the rope and add them up. To calculate the gain in strength of 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 general purpose clamp. 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.

Homemade chain hoist

The chain hoist is known to be a very useful thing. The principle of operation was studied at school. System of movable and non-movable blocks. We lose in distance, we win in strength. I decided to buy one for my farm. I bought 200 kg, Chinese, with nylon rope. It turned out not quite what I expected - the ropes are tangled, 200 kg is not enough. I decided to do it myself. First I started looking on the Internet to see what other people were doing. But as it turned out, finding a normal example is not easy - the search mainly pointed to shitty sites that steal text and pictures from each other.
I decided to look into some of the intricacies of the design. What I have in mind is sold for around 60,000 thousand rubles. A little expensive for me. I decided to make a chain hoist with my own hands.
Here are the subtleties you need to consider when making a chain hoist yourself:
First the diagram:

Now let's move on to the design of the pulley block.
I planned to make a chain hoist from two blocks of three rollers each, approximately 6 tons.
Let's start with the load capacity, which depends on the thickness of the cable - here the load capacity simply depends on the thickness of the cable. Approximately and very roughly, the carrying capacity can be divided into a coefficient, a multiplier of the pulley system I planned, which can be seen in the above diagram. Let's say the required chain hoist is needed for 6 tons, then 6000 kg. divide by 6 and we get exactly a ton for the cable. A 10 mm cable is suitable for a ton.
In stores, all winches and pulleys using steel cable are made completely incorrectly. The diameter of the roller should be selected taking into account the diameter of the steel cable and should be equal to at least 16 cable diameters, and preferably 24 diameters. This is not observed in store crafts. The diameter of the roller pulley is catastrophically small, the diameter of the cable absolutely does not correspond to the permissible loads. The roller, at best, has a single-row radial bearing or no bearing at all, which is also not very good. The groove on the pulley is most often too large. The material is generally made from the cheapest steel and does not have any safety margin. Cheek parts made of thin sheet steel. It’s getting ridiculous: a manual winch with a declared load capacity of 1.5 tons and a cable with a diameter of 3 mm is being sold.
But on the Internet you can easily find a table of the load-carrying capacity of steel cables

Rope diameter

1 kN is approximately equal to 100 kg.
The groove on the pulley or roller should be the same size as the cable and be slightly larger than the diameter of the cable. Roughly speaking, the size of the groove should be such that the cable does not flatten and at the same time fits freely in the groove.
Taking the crane pulley as a prototype, I calculated everything, drew it and came up with the following design. Each pulley is on two bearings for the corresponding load, the axle is made of durable steel. There is also a subtlety - the pins for laying the cable do not give the cable excess freedom. The number of block parts is surprisingly large for a simple pulley. Well, I think everything else will be clear from the photographs.

The chain hoist turned out to be heavy but very convenient to use.
The weight of one block is 15 kg. Cable with a diameter of 10 mm and a length of 30 m.

Lifting a heavy load even to a small height without the use of special tools is not always possible. We're not just talking about cranes, truck cranes and forklifts - there are other devices to solve this problem.

One of the mechanisms for lifting loads is a chain hoist.

Polyspast is a block system with chain or rope transmission. Its task is to simplify and speed up the lifting of any heavy load using human power. Such schemes (or their close analogues) were used even before our era - during the construction of the Egyptian pyramids and the Great Wall of China.

Stationary lifts are used in warehouses and production facilities where it is necessary to lift various weights. Portable block systems are used in construction, logistics, and rescue work.

Design and principle of operation

The chain hoist allows you to lift weights using less human effort. The principle is similar to the action of a lever to lift a load, but instead of a lever, a cable is used.

Structurally, the simplest chain hoist consists of 1 block and a rope. The roller is fixed above the load (on the ceiling, beam, or a movable special support). One end of the rope with a hook goes down to the load. The person holds the second end of the rope in his hands and pulls on it, lifting the weight.

The following factors influence the gain in strength:

Number of rollers.
Rope length.

1 block increases the force by about 2 times (approximately - because some losses will be written off due to friction). That is, if a person without a lift can lift 30 kg to a height of 1 meter, then with a chain hoist it will be 60 kg. If there are more rollers, then more weight can be lifted.

As for the length of the rope: the longer it is, the more weight a person can lift, but also the more time it will have to be spent on it.

Types of pulleys

Pulley hoists are divided according to several criteria:

By appointment. There are power schemes, and there are speed schemes. Power lifts allow you to lift more weight, but more slowly. High-speed ones allow you to lift weights faster, but will “handle” less weight.
By the number of blocks. The simplest option is 1 video. But there can be 2, or 3, or 4, or more. The more there are, the more weight you can lift.
According to the complexity of the scheme. There are simple schemes (when the rollers are connected in series by 1 rope) and complex ones (when 2 or more separate pulleys are used). Complex systems are more productive, producing more results with fewer blocks. For example, if you combine 2 chain hoists (from 1 and from 2 blocks), you will get a 6-fold gain in strength. Whereas a simple scheme will give a 6-fold win only when using 6 rollers.

What affects the efficiency of a lift?

The multiplicity mentioned above (gain in strength) is very approximate, rounded up. In practice it is less.

The effectiveness of the lift (what exact gain in strength it will give) is influenced by the following factors:

number of blocks;
cable material;
bearing type;
quality of lubrication of all axes;
rope diameter and length;
the angle between the rope and the middle plane of the roller.

How is the rope attached to the mechanism?

You can attach the lifting mechanism to the cable in the following ways:

Knots connected from cords. Number of revolutions - 3-5.
General purpose clamp.

What is a refill, how is it made and what is it like?

Refilling is a change in the position of blocks and the distance between them. It is carried out to change the speed or height of lifting weights.

There are different types of refill schemes:

Single: the hook is hung by 1 rope, which is then passed sequentially through each fixed block and wound onto a drum.
Double. For beam cranes, 1 end of the rope is attached to the boom root, and the second end is passed through the bypass drum, all the blocks, and then attached to the winch. For cranes, the rope is attached to the winch and the stationary blocks are located on the boom head.
Quadruple. A combination of the schemes listed above is used for each hook suspension unit.
Variable. The movable rollers are complemented by 1 or 2 movable cages.

How to make a chain hoist with your own hands?

Let's consider a scheme for creating a double chain hoist.

You will need:

2 bushings.
2 videos.
2 clips.
Bearings.
Hook (to hook the load).
Rope.

Step by step design:

Bushings, rollers and bearings are connected and inserted into the cage. The result is 2 rotating blocks.
The cable is passed through the block.
The clip with the missing rope is attached to the support under which the load will be located.
The second end of the rope is passed through the second block.
A hook is attached to the second clip.
The end of the rope that remains hanging is fixed (you will need to pull on it to lift the load).

After this, all that remains is to secure the load (pick it up with a hook), and you can begin lifting.