Diagram, components and operation of a hook suspension. Hook hangers: classification and features

Hook hangers, overhead crane pulleys

The hook suspension includes blocks, which, together with the upper blocks on the trolley frame and the rope that goes around the blocks, form a chain hoist. On overhead cranes, to ensure that when lifting and lowering a load, only its vertical movement, creating a uniform load on the drum supports and favorable conditions for loading the bridge span, double pulleys are used, i.e., those in which two branches of the rope are simultaneously wound onto the drum. To automatically equalize forces in symmetrically located branches of the rope and eliminate suspension misalignment, an equalizing block or balancer is inserted into the chain hoist, and if the multiplicity of the chain hoist is even, they are mounted on the trolley frame, and if it is odd, on the suspension. Due to the symmetry of the double pulley, the rope branches supplied to the equalizing block or balancer remain motionless when the suspension is lifted, so the block (or balancer) only rotates on its axis at a small angle. The use of a balancer allows, instead of one whole rope, to include two pieces of it in the pulley, equal to half the total length of the rope.

Hook hangers

Single-horned forged (or stamped) hooks, double-horned forged or plate hooks, which comply with GOST 6627-74 “Single-horned hooks,” are used as lifting elements in general-purpose cranes. Blanks. Types. Design and dimensions", GOST 6628-73 "Double hooks. Blanks. Types. Design and dimensions" and GOST 6619-75 "Plate hooks, single and double-horned". Single hooks have two designs: 1 - without tide; 2 - with a boss for installing a safety lock and are made short (type A) and extended (type B). Double-horned forged hooks of the same type. Hooks are calculated according to the methodology outlined in the work.

The design of the pendants can be normal or shortened. In a normal suspension, all blocks are installed on the same axis, and the hook is mounted on a traverse. The shortened suspension provides for the installation of blocks on the consoles of the hook traverse, which in these suspensions simultaneously performs the functions of the axis of the blocks. All other things being equal, the length of the shortened suspension is less than the length of the normal suspension, and its use increases the lifting height of the load.

In Fig. 6.4 shows: a - shortened suspension with a lifting capacity of 50 tons (suspension weight 980 kg); b - normal suspension with a load capacity of 20 tons (weight 280 kg); c - shortened suspension with a lifting capacity of 250 tons (weight 11,000 kg). The suspension contains a traverse with a thrust bearing, on which the forged single- or double-horned hook rests directly, and the plate hook rests through the fork. The nut screwed onto the shank of the hook or fork interacts with the bearing. The plate hook with the fork is hingedly connected by an axis. In the shortened suspension, blocks are cantilevered on bearings at the ends of the traverse. In a normal suspension, the blocks are mounted on an axle, which is connected to the traverse by cheeks. The design of the casing must prevent the possibility of the rope coming out of the block thread in case of accidental loosening of the rope and its pinching between the outer surface of the block and the inner surface of the casing.

To ensure the tension of the ropes without a load, the mass of the hook suspension, depending on the multiplicity of the pulley, must be at least 2-5% of its load capacity.

A special suspension with variable multiplicity of the pulley, which allows you to adjust the speed of lifting the load depending on its mass, is shown in Fig. 6.5. It makes it possible to have two lifting capacities: 10 tons when connecting the upper and lower parts and 5 tons when separating them. The lower part is a slightly modified normal suspension with two blocks.

Rice. 6.5. Hook suspension for two lifting capacities

The blocks (Fig. 6.5, a) are installed on the axis consoles in the middle part of which there is a vertically located protrusion.
Inside the protrusion there is a through hole with a rectangular groove.

The upper part of the traverse consists of a welded beam, two blocks mounted on the axle shafts, and a pin lock designed to automatically connect the upper part of the suspension with the lower part (Fig. 6.5, b) or with the trolley frame beam, which also has a hole with a rectangular groove.

The pin mounted on rolling bearings has a T-shaped lower end, and a rectangular bar, rigidly secured with a nut, is located perpendicular to the head of the pin end. When the parts of the suspension are brought close to each other, this end of the pin is located inside the hole, in the lower part of the suspension, and when the upper part rests against the frame beam, the upper end of the pin, together with the horizontal bar, is located inside the hole in the beam.

Rice. 6.6. Hook hangers with swivel devices

Grooves in the lower part of the suspension and. The beam frames are mutually perpendicular, and by turning the pin, the upper part of the suspension can be separated from the lower part and connected to the trolley frame, and vice versa. The pin is rotated using a bushing placed on the middle part of the pin and equipped with fingers. These fingers interact with the grooves located on the pin. At the bottom, the grooves are screw-shaped, and then straight, parallel to the axis of the pin. Thanks to this, the pin is rotated by the fingers of the bushing at a certain angle and is held when the lower part rises by inertia above a given position.

Rice. 6.7, General view (a) and diagram (b) of the device for preventing rope twisting

To connect the upper part of the suspension to the cart frame, both parts of the suspension are raised until it rests on the frame beam. After this, the lower part, rising, enters the guides and, sliding along them, lifts the bushing. In this case, the pins fit into the grooves of the sleeve. In turn, rising, the sleeve rotates the pin, and therefore the bar. Thanks to this, the upper part is connected to the trolley frame and disconnected from the lower one. When lowering the lower part of the suspension, the bushing lowers to the lower position under its own weight.

To connect the upper part of the suspension with the lower, the latter rises up again, and the operations are performed in the same sequence, only when the pin is turned, the parts of the suspension are connected and its upper part is disconnected from the trolley frame.

A stop is installed on the lower part of the suspension, which actuates the limit switch of the electrical circuit of the lifting mechanism.

If it is necessary to rotate the lifted load in a horizontal plane, the suspensions are equipped with additional drive devices. In Fig. 6.6, a shows a suspension with a hydraulically driven turning device. A pumping station is mounted on a bracket, which is fixed in the upper part of the cheeks, containing an electric motor, a hydraulic pump, a tank for working fluid, a hydraulic cylinder and hydraulic distributors. The hydraulic cylinder rod is connected to a nut by a bracket. When the working fluid is supplied to the hydraulic cylinder, the nut, moving forward in the guides, turns the screw, which is an elongated hook shank. The rotating suspension device shown in Fig. 6.6, b, is driven by a vertically mounted electric motor. The latter, through a gearbox with a gear ratio of ~340, turns the hook, on the shank of which a gear is attached. With a suspension load capacity of 5 tons and a hook rotation speed of 2 rpm, the electric motor power is 0.4 kW.

To prevent twisting of the pulley ropes caused by the reactive moment of rotation of a long load, stabilizing devices are used. Such a device, which is hung on a suspension hook (Painer, Germany), is shown in Fig. 6.7.

Rice. 6.8. Safety locks

A rod with a loop for attaching a load and a rotor is installed in the bracket on a thrust bearing. The latter, together with the stator, forms an electric motor, the housing of which rests on a rod through rolling bearings. A flywheel is attached to the body. Current is supplied to the motor through a ring current collector. When the engine is turned on, the stator rotates relative to the rotor, and the rotor with a lower angular speed rotates in the opposite direction.

The inertia of the flywheel increases the reaction torque. The devices have a lifting capacity from 4 to 32 tons. The power of their electric motors (from 0.8 to 25 kW) depends on the turning time (6-40 s when turning the load at an angle of 90°), the moment of inertia of the load and the operating mode of the device.

To keep the sling from falling out of the hook when it is loosened, various types of locks with spring (Fig. 6.8, a) and weight (Fig. 6.8, b, c) closures are used.

The durability of ropes interacting with blocks largely depends on the material of the block strand. Endurance tests of ropes with a tensile strength of wires of 180 kgf/cm2 on blocks of modified cast iron, which had a hardness of HRC 50-55 in the contact zone and a thickness of the strengthened layer of 2-7 mm with a hardness of the unstrengthened metal IV 160, established that the durability of the ropes is reduced by 3-6%. At the same time, there is virtually no wear and tear on the stream. It is more correct from the point of view of increasing the durability of the ropes to reduce the stress in the area of ​​contact of the wires with the surface of the strand by making the latter from a material less hard than the rope. Thus, when lining the strand with an elastic polymer material - nylon, the elastic modulus of which is 200-250 times less than the elastic modulus of the metal, conditions are created for increasing the contact area of ​​the rope with the block and, as a consequence, reducing wear and destruction of the wires. As studies and many years of operation show, this makes it possible to increase the durability of ropes by 2-2.5 times; The wear of the block lining is approximately 2 times less than the wear of the metal block (without lining).

According to the industry standard “Blocks lined for steel ropes. Design and Dimensions”, which applies to blocks operating at air temperatures from +40° to -25°C, provides for lining the block stream with separate liners, which are 10 pcs. installed in the annular profiled groove of the block. The liners are made by injection molding from nylon and are held in the groove of the block due to tension.

Since the speeds of movement of the individual branches of the pulley are different and the blocks have different angular speeds, they are installed without connecting to each other (Fig. 6.9). As a rule, they are mounted on fixed axles and rolling bearings.

Rice. 6.9. Installing blocks on axes

In the first case, the ropes do not have the ability to rotate relative to their longitudinal axes, which is necessary when the distance between the balancers and the hook suspension changes during lifting and lowering of the load. This leads to the rolling and sliding of the ropes along the stream of blocks, which to a certain extent increases the wear of the rope. When using swivels, inside which the ends of the ropes, fixed in conical clamps, are supported by thrust bearings, the operating conditions of the ropes are improved.

When securing the end of the rope with clamps, the distance between them and the length of the free end of the rope must be equal to at least six rope diameters.

The installation of blocks in hook hangers is shown in Fig. 6.4, and on the cart - in Fig. 6.10.

Ropes. Pulley hoists

Rice. 6.10. Installation of upper blocks on common (a) and separate (b) brackets

Rice. 6.11. Balancers

In LK type ropes, the contact of the wires in the strands occurs along a line, and in LK-RO ropes, wires of different diameters are located in different layers, and in LK-3 ropes, filling wires of smaller diameter are located between the layers. With linear contact, the tension between the wires is significantly less than with transverse contact in TLC ropes.

According to the type of lay, ropes are divided into ordinary (unwinding) and non-unwinding, in which, after removing the dressings, unwinding into separate strands, but no strands into wires. Non-untwisting ropes have greater durability and dynamic strength than ordinary ones, since when the wires are pre-bent during the manufacturing process, most of the initial stresses are removed. In addition, these ropes are less prone to forming knots and loops. Of the cross-lay and one-way lay ropes, the latter have a 1.25-1.5 times longer service life, which is explained by the longer (up to 2 times) length of contact of the wires with the drum, lower rigidity, and greater wear resistance. It is most correct to use ropes with a tensile strength of 160 to 200 kgf/mm2. At lower strength limits, the diameter of the rope, and therefore the drum and blocks, increases irrationally, and at higher strength limits, the rope has increased rigidity, which reduces its service life due to the fatigue strength of the wires.

The durability of ropes increases when working on blocks made of gray cast iron by 15-30% compared to working on steel blocks. The service life of ropes increases by 20-40% when they are periodically lubricated.

When operating the crane outdoors or in rooms with humid air, it is recommended to use ropes made of galvanized wire. The cost of such ropes is 125-150% higher than ropes made of ordinary light wire.

In double chain hoists with an even multiplicity, the equalizing block (or balancer) is located on the bogie frame (Fig. 6.12, a), and with an odd multiplicity - on a hook suspension (Fig. 6.12,6).

A change in the distance from the axis of the drum and the axes of the upper blocks to the axis of the blocks mounted on the suspension during lifting and lowering causes a change in the angles of deflection of the rope on the blocks and drum, which can lead to damage to the rope and its friction against the side surfaces of the block stream or drum groove. Therefore, and also in order to eliminate the possibility of damage to the flange of the block by the rope, the angle of deflection of the rope on the block y0 (Fig. 6.13, a) is limited in magnitude. The angle ag of the rope deflection from the axis of the groove on the drum towards the empty groove (Fig. 6.13.6) is limited so that the rope does not fall out of the groove, and the angle a2 of the rope deflection towards the groove in which the adjacent turn is located is also limited so that eliminate the possibility of the rope touching an adjacent turn.

Rice. 6.12. Schemes of chain hoists

Rice. 6.13. Rope deflection angles

In preliminary calculations, the values ​​of angles a, a and a2 are taken within the range of 4-6°.

When calculating a rope, its diameter dK is determined based on the mass of the load being lifted and the breaking force at the accepted value of the tensile strength of the wires.

TO category: - Overhead crane units

The tension of the sling branch increases with increasing angle of inclination of the branch to the vertical (figure) in accordance with the formula:

where: Q – mass of the lifted load; n – the number of sling branches on which the load hangs;

- angle of inclination of the sling branch to the vertical; S – tension of the sling branch.

Table 1 – Dependence of the coefficient
from the sling angle α to the vertical

When calculating general-purpose slings, the angle of inclination of the branch to the vertical is assumed to be 45 º, which corresponds to the angle between the sling branches of 90 º. When calculating slings with more than three branches carrying the design load, no more than three sling branches are taken into account.

1. For slings made from rope K, no less than 6

2. For slings made from chains, K is not less than 4

3. For slings made of textile tapes, K is not less than 8

Examination card No. 4

1.Safety precautions when operating cranes equipped with a grab or magnet

No people are allowed in the operating area of ​​magnetic and grab cranes. The slinger is allowed into the workplace only during a break in crane operation. When people appear in the dangerous zone of crane operation, the operator must stop work, ring the bell, and begin work only after people have been removed from the dangerous zone.

For safe operation, the responsible person must develop instructions for the safe transportation of goods by cranes.

The operating area of ​​a crane equipped with an electromagnet or a grab must be fenced, and it is strictly prohibited for people to be in it. The slinger can approach the electromagnet only when it is lowered to the ground and de-energized.

At the entrance and exit to the workshop there must be a luminous sign with the inscription “Danger, a magnet or grab is working”

If faucets work intensively with magnets, then there should be an additional magnet for replacement. The replacement is done like this:

a) the slinger gives the command to turn off the magnet and install it in the designated place;

b) the driver installs the magnet in the designated place stably;

c) the slinger, having convinced the driver that the magnet is turned off (the driver gives a response signal), pulls out the plug from the terminal box.

Before starting work, the cranes inspect the magnet and grab and do a test lift.

It is prohibited to transport loads not intended for them with a magnet or grab, hang slings on the teeth of the grab, lift people, load cars with a magnet...

2.Purpose and design of hook suspension

Hook hangers serve for the convenience of lifting and transporting loads and are connected by a rope to the drum of the load lifting mechanism. Hook hangers come in normal and shortened types. In the first, a hook with a short shank is used, which is suspended on a separate crossbeam at the bottom of the suspension. Secondly (shortened), a hook with a long shank is used, which is directly on the axis of the pulley blocks. Shortened suspensions allow, as a result of reducing the height of the suspension, to obtain a greater lifting height of the load.

The hook in the hook suspension is installed so that it can rotate freely and be installed during operation in accordance with the position of the load. The lower end of the hook nut rests on the upper race of the thrust ball bearing.

Blocks in hook hangers are mounted on fixed axles and rolling bearings. To prevent the possibility of the rope coming out of the block thread and pinching it when the rope is accidentally loosened on the blocks, casings (retaining body plates) are mounted.

All suspension elements are mounted in casings (cheeks).

If your goal is to deliver a load from one place to another using a crane, you must first grab it and secure it firmly. For such a task you will need a hook crane suspension. It will become an intermediate element between the machine and the cable.

Design features

Most suspensions have a standard design consisting of:

• “Cheeks” and traverses for connecting bypass block elements;
• Special tubes for direct fastening of the “cheeks”;
• Rotation axis of the “cheeks”;
• Pulleys attached to the cheek area;
• Traverse located in the base area;
• Hook attached to the traverse.

The free movement of the element occurs due to the rotation of the traverse in the “cheeks”.

Kinds

There are some criteria, based on them, hook crane elements are divided into types.

1) Number of axes: there are biaxial and single-axis. The first pendants have a pair of axes and “cheeks”. They are connected by bolts. The hook rests on the traverse, and through a ball bearing is located on the block elements. Rotation occurs. The movement is relative to the hanging element and the “cheeks”.

The bearing is in such a position that dirt cannot enter it. The biaxial suspension can rotate around a vertical plane. A special lock ensures security.

There are also types of suspensions that have three axles. This is the same system with a pair of axes, which has an additional cage with two “cheeks”. The “earring” and “finger” help with fastening in this situation.

Standard ones consist of several blocks and rotational bearings. The hook is held on by a nut. The “cheeks” are made of steel in the form of sheets; they hold the traverse. In situations where the suspension will handle more than several tons, the hook is connected to the crossmember by a ball bearing.

The shorter ones are pulley blocks located on the same plane as the traverse. Elements with a minimum length do not have “cheeks”, which makes it possible to use equipment in closed spaces where there are space restrictions.

They are also divided by carrying capacity: the range of tons is from one to several tens.

Features of work

The requirements for the elements in question are very serious, since suspensions are a key link in the work. If the quality is lower than expected, the cargo will be in danger. Only by paying attention to good fixation will you be able to perform high-quality movement.

Also in the work process, a rope made of steel plays an important role. Lifting occurs when it is wound onto a drum.

Each suspension is equipped with special blocks rotating on a shaft, a hook and a traverse. All this is a hook clip.

Speaking about the duration of operation of a particular device, it depends on the quality of use of the product. Often breakdowns occur in bypass parts. This occurs due to excess friction force.

Before purchasing a hook crane suspension, decide which one you need.

Hook suspension (hook suspension for crane)- a part of a lifting mechanism, which is a system of a hook and a hook, which are connected to a crossbeam and cast parts.

The main purpose is to connect the lifting rope to the load hook, i.e. for hanging a load on a crane load rope.

When designing, the mass of the hook suspension is selected so that it lowers under the weight of its own force, without load.

The hook suspension device is a composite part, therefore, for fault diagnosis and rejection, methods and standards developed for the elements that make it up are used. The main wear in the crane hook suspension is in the parts of hooks and blocks, each of which has its own rejection standards:

Correction of defects if crane hangers fail is not allowed; if they are detected, the hanger must be replaced.

Drawing 15.1. Typical single roller hook suspension

Drawing 15.2. Typical multi-roll hook suspension

Our standard range includes crane hook hangers in accordance with GOST 24.191.08-81 with a lifting capacity from 3 to 50 tons, including hook hangers for overhead cranes. Please check with our managers for the possibility of supplying standard sizes not shown on our website.

Table 15. Technical characteristics of crane cargo hangers

The price, if you decide to buy or order the position “crane hook suspension” from our company, we will optimize it as much as possible, taking into account the total amount of the order and the history of our cooperation.