Composite parts of a lifting crane. Overhead crane

Many years ago, the lifting equipment was one of the main achievements of the technique. But today, when advanced technologies and modern materials are actively introduced, it gradually becomes more and more traditional. Currently, there are a large number of companies that supply both different lifting equipment and a wide range of building and industrial equipment.

Lifting equipment: Terminology

Under the term "lift" today understands a special technique, which is capable of functioning continuously or periodically. Such equipment, such as load-lifting cranes, elevators, etc., has the main purpose - it is the movement of various cargoes with a carrying device moving along a high-strength vertical guide or railway tracks.

Lifting equipment today is represented by several varieties. The most common and most frequently used practically in all industrial areas are cargo lifts. In them, the device movement is attached to the envelope of the winches wound on the drum, or the rope pulley. Lifting taps operate mainly on electrical drives, as well as hydraulic.

Console cranes

Console lifts enjoy the greatest popularity and demand in the construction industry, which became possible due to the simplicity of their design and low cost. They are manufactured in the form of mast racks without fences, relative to which platforms are placed with a console method.

Safe operation of lifting cranes depends on the correctly selected view. It is worth noting that the cantilever equipment is divided into:

  • Column crane. It is a stationary column, on which the lifting of goods occurs, is widely used on machine-building production.
  • Wall-console crane. It differs from the first variant what consists of a wall farm, which moves the cart. Installation method - stationary. The main advantage is the ability to work in small rooms. As a rule, this type of crane is installed in order to reduce the load on the bridge lifts.

Crane bridge electric mine

There are also shaft cranes having, unlike the console, special device for the fencing of people in which lifting cabins or platforms are moved along the guide. Basically such a technique is used in the mining industry. Lifting cranes Bridge are designed to descend / lifting large-sized items. Thanks to a certain method of cargo delivery, this type of equipment can significantly reduce costs, especially in comparison with the inclined barrel and autos. Compliance with safety rules when working with such cranes allows you to reduce risk to a minimum. The main advantage of this type of equipment is fast and relatively safe transportation of heavy cargo.

Portal lifting cranes

This equipment moves in special ways, the number of which can vary from 1 to 3. The width of the knees - 6 m, 10.5 m, 15.3 m. The boom length can reach 100 meters. This type of cranes is widely used in the shipbuilding sphere, while both in marine and in river ports. Also, this equipment is used in floating docks and ship repair plants. Their specialization is quite narrow, used only to work in open areas.

Divided on subspecies:

  • mounted (KPM) - load capacity up to 300 tons;
  • overloading (gearbox) - designed for weight from 5 to 40 tons;
  • dock (efficiency) - used to work with cargoes whose weight does not exceed 30 tons.

The design of the equipment is a portal with a rotary arrow that moves along the crane paths. Special hooks and grabs are used to lift goods.

Operation of lifting cranes

Before you start working on lifting cranes, you need to explore the safety rules. All enterprises are instructed. Some items may vary depending on the type of equipment, however, the general essence of this documentation is the following paragraphs:

  • work with electrical equipment;
  • study and principle of work of the main components of the crane (trolley, gallery, etc.);
  • management method;
  • braking coefficient, etc.

Features of choice

In the process of choosing a freight lift for construction, a number of important factors must be taken into account. This is a way of fastening, loading capacity and many others. Additionally, various airproof devices and devices are also used. In addition, the frequency of lifting goods should be taken into account and calculate the approximate number of crane inclusions and turn off. Using the data obtained, you can choose a lift taking into account the weight of the transported cargo. It is important to know the rules of operation of lifting cranes and the features of their design. It will protect and significantly facilitate the process of moving heavy items.

Posted on November 26, 2012.

Types of cranes


Among the designs of lifting cranes are distinguished by the cranes of the boom type, bridge type, cranes with carrying ropes and taps-stackers.


1. The cranes of the arrow type are called lifting cranes with a loading body suspended to the arrow or cargo cart moving through the arrow.


These include:


a) boom cranes - crane cranes with an arrow fixed on the frame of the chassis or on the rotary platform placed directly on the chassis frame;

b) tower cranes - crop-type cranes with an arrow fixed in the upper part of the vertically located tower;

c) portal cranes - convoy cranes, swivel, on the portal;

d) semi-correct cranes - crane type cranes, swivel, half-pressure;

e) Mast cranes - crop-type cranes, swivel, with an arrow fixed by articulated on a vertical mast having lower and upper supports. At the same time, the guy cranes is fixed by cable deceit, and it is rigidly fixed with rigid-legged cranes;

e) Console cranes - boom cranes, which are suspended with a lifting organ suspended on a tap connected to a column or reference part of the console or on a trolley moving along the console. The group of cantilever cranes belongs to the column, a wall-mounted console crane, a mobile console crane and a bicycle crane.

2. Bridge-type cranes are called load-lifting cranes with a lifting body suspended to the cargo cart, to the rotary arrows on the cargo cart or hoist moving along the mobile bridge.


These include:


a) bridge cranes - bridge cranes with direct support of the bridge on the above-ground crane path;

b) gantry cranes - bridge cranes with supporting bridge on a crane path with two reference racks;

c) Semi-arched cranes - bridge-type cranes with a bridge based on the crane path on one side directly, and on the other - with the help of the support rack.

3. Cranes with supporting ropes are lifting cranes with a lifting organ suspended to a cargo trolley moving along the bearing ropes fixed on the supports. In cable cranes, carrying ropes are fixed in the upper part of the supports, and at mobility - at the ends of the bridge installed on the support racks.

4. Cranes-stackers are called lifting cranes equipped with a vertical column with a device moving along it for stacking of goods. The bridge crane-stacker column is suspended with a cargo trolley moving along the mobile bridge, and the stellage crane-stacker, the vertical column moves into the passage between the racks.

In addition to the classification of cranes in design, there are classifications for other features:

according to the design of the loading organ and the intended purpose - hook, grab, magnetic, magnetic grab, traverse, cranes with paws, multi-magnetic, multi-boiled, multi-pot, pin, copp, hardening, foundry, landing, cranks for stripping ingots, well, forging, container and etc.;

if possible, movement - stationary, downtime, self-lifting, rearranged, radial, mobile, self-propelled, trailed;

according to the design of the running device - rail, rail, walking, automobile, taps on the chassis type, tracked, tractor, pneumatic, floating;

according to the gear of the mechanisms - manual, mechanical, electrical, hydraulic, pneumatic, taps with a combined drive.


All about lifting cranes. General.


Lifting crane - a load-lifting cyclic action machine with a reciprocating movement of a lifting organ; It serves to lift and move goods. The cycle of P. to. Consists of capturing the cargo, the working turn to move the cargo and unloading, idling to return the empty loading device to the place of reception of the cargo. Movement P. K. can be both workers and installations for periodic change of the position of the crane, boom, etc. The main characteristic of P. K. - Load capacity, under which they understand the greatest mass of the loaded cargo, and in the case of replaceable shipping devices, their mass turns on in general load capacity.


Depending on the design and the adopted scheme of work P. k. There are rotary and non-reflective. Rotary cranes can be installed on the railway - rail and cathotic rails; on a straight move - pneumocoles, automobile and tracked P. k.; On the walls and roofs of buildings - wall-swivel and roofing; On pontoons and courts - floating and shipping. There are also rotary P. k., Moving along two located at different levels (below and at the top) rails, - so H. Cycling cranes. Railway, pneumocoles, automobile and tracked swivel P. k. Frequently combined with a common name - boom self-propelled cranes. The turning part of P. k. Rely on the column (crane on a fixed or on a rotating column) or on a rotary circle with wheels, rollers or balls (tap on the rotary circle). The rotary part may have the shape of a high tower - tower cranes, masts - mastovo-booms (rigor-legged and guy). It is possible to install it on the portal - portal cranes. Rotary P. K. can have a permanent or variable departure (the cargo distance from the axis of rotation of the crane), which changes through the swing of the dash (arrows) or movement on it of the cargo truck.


Non-reflective cranes include P. to. Of the span type (bridge cranes and overloaders), as well as wall-cantilever cranes. Bridge cranes have a cuckoo bridge moving along rails laid on the walls of buildings or on special overpass outside the building. A cargo trolley with a lifting winch moves along the bridge, in some structures, the cargo cart is supplied with a swivel arrow. Wall-cantilever cranes consist of a console wall farm and a cargo trolley moving along it with a lifting winch. Overheaders are similar to the device with bridge cranes, but their bridge has high supports (legs) moving through ground paths. With large spans, they are called bridge overloaders or transshipment bridges, and with small spans - gantry cranes. However, there is no clear division. Overhead bridges may have fixed or retractable consoles; Along the bridge moves a cargo truck or swivel crane. Console overloaders intended for loading (unloading) of ships, so on. Coastal cantilever overloaders, can also be installed on ships (ship overloads). A special type of overload is a cable crane, which cargo truck moves using a traction rope through the bearing rope, stretched between 2 catholic tower or stationary masts. A variety of cable cranes are bridge-cable cranes that carry the rope is attached to the ends of the bridge farm. Monorail roads whose trollers have lifting mechanisms are constructively close to the crane devices.


In modern construction conditions, helicopters are also used taps with devices for cargo capture. With their help lead work in hard-to-reach locations.


The areas of use of lifting cranes bridge cranes belong to typical equipment of production. Workshops, power plants, closed and open warehouses. Their load capacity reaches 500-600 tons, the spans (distances between the axes of the crane rails) - 50-60 m, the possible height of the lifting of the cargo is 40-50 m and in a special version up to 500 m; The speed of movement of the bridge (working motion) -30-160 m / min, a cargo truck - 10-60 m / min, lifting the cargo to 60 m / min.


On the bridge there can be 2 cargo carts on one or two (adjacent or two-row in height) paths. The bridge P. to. General purpose includes hooks, magnetic, grab and magnetic grab taps. Hook single-bore faces of the simplest type (see faucet-beam), support and suspended, have self-propelled electric hoists as a cargo trolley. The special group includes metallurgical bridges P. k. (Foundry, filling, wells, for "stripping" of ingots, etc.), which are equipped with special lifting devices and control mechanisms. One of the varieties of bridge P. to. - Crane stacker with a cargo truck having a rotary column, according to which a fork grip moves, carrying a load package on the pallet and allowing the laying and packet stacking.

Discuss on the forum


There are various types of cranes, respectively, they are arranged differently.

Portal cranes. It should be noted that such cranes also have different types and special designations are adopted for them:
KPM - Crane portal mounting,
CAT - Crane portal overload,
CPD - Crane portal dock.

The design of the portal cranes is a rotary boom system installed on the portal that moves along the subcrane paths. Semi-power to which portal crane is installed is designed to skip various types of transport. Portal cranes are used mainly in marine and river ports, on shipbuilding and ship repair plants and in floating docks, during the construction of hydraulic structures. Thus, unlike previous cranes, portal cranes suggest a narrow scope of use.
Lifting the load on portal cranes is carried out with the help of hooks and grabs, on the mounting with hooks.
The crane paths can be from one to three, respectively, the width of the knee of the subcrace path is 6, 10.5 and 15.3 m. The carrying capacity of the portal cranes is different for overload and mounting cranes. So, for overload cranes, the load capacity is 5-40t, for installation - up to 300t. Arrow departure reaches 40m.

Bridge cranes Widely used in construction and production workshops. So, bridge cranes are applied in industry, the construction industry, warehousing. Also, the bridge cranes with the grab is widely used in the metallurgical industry.
In essence, bridge cranes are a variety of lifting crane. Bridge crane is a design with a support or suspended bridge. The crane path is a supporting element for the bearing parts of the bridge crane. Rails for the bridge crane are stacked either on the walls of the building, or on the overpars outside the building. The railway beam or bridge moves along the rails. Thus, when using a bridge crane, the main platform does not engage. A cargo trolley with a winch that provides lifting loads, moves along the bridge. Bridge crane is equipped with a hook with a magnet or grab. Such an opportunity significantly expands the areas of using two-bang bridge cranes. Several bridge cranes are much easier and maneuvering two-ball. Additionally, you can hang a console cart on one-grazing bridge cranes.

One of the most common types of bridge crane is a crane-beam. Crane beam from end beams, span beams and lifting mechanism is consisting. End beams and span beam are mounted together, thereby ensuring the movement of the lifting mechanism. Due to the lifting mechanism, the cargo can move in a horizontal and vertical direction. At the same time, the lifting mechanism itself moves in a span beam. Crane beam is equipped either manual or electric talu (directly lifting mechanism). In no case cannot be used to move various poisoning and toxic substances for moving and to move people. Basically, the crane beam is used for loading and unloading and for installation at work or storage room.
Use the crane beam is best either under a canopy or indoors. Permissible temperature difference from -200C to + 400C. Crane beams can be manual or electrical (power comes from the electric motor connected to the network through a wire or cable) and support or suspended.
The reference crane beams move predominantly on guide paths. Such paths are either a square or rail installed on metal or concrete supports.
The crane beam reference includes the following components:

  • pleaten beam
  • end beams (have driving wheels)
  • trucks
  • lift mechanism

The lifting mechanism in the manual crane is arranged with a chain tale. Accordingly, the electrotals are used for a crane-beam with an electrical drive. You can control the crane-beam with an electrically driven or from the control panel or from the floor.
Suspended crane beams move along the suspended paths, which are located in the building itself, or outside the building, in the overpass.
Suspended crane-beams consist of:

  • span beam;
  • end beam tough
  • end beam movable
  • hanging carriages moving along a crane 2-way guide (beams suspended)
  • lift mechanism
  • push-button console for controlling electric valve-beam

If there is such a need, the span beam is enhanced with the help of a vertical shrothel design.
Crane beams There are two-ranking and single-break apartments. Their use in production depends on the maintenance area.
Having the same load capacity, the crane beam suspended is much easier than reference. Another plus suspended crane-beams is a large area of \u200b\u200bservice than the supporting. With the help of suspended crane-beams, it is possible to serve the area at the walls.

Console cranes.

Gantry cranes. Another type of cranes is gantry cranes. The carrier structures of gantry cranes are based on the crane path due to the supporting beams. Gantry cranes are widely used in various industries. In particular, without them can not do when servicing warehouses, piece goods, containers and forest cargo, for the installation of national industrial and civil facilities, to maintain hydroelectric power plants and sectional installation in shipbuilding. Install gantry cranes in open areas.

Crane Stacker The appearance resembles a crane beam, however, the design of the crane-stacker has several differences. The main thing is in the design of the crane-beam, the Tal is used, and for a crane-stacker - fork pile. Actually, approximately such a structure has a loader, but its maneuverable qualities and permeability, the loader is far from the crane-stacker. Crane stacker can travel even in a narrow passage and, accordingly, perform the work that is not available to the loader.

Self-propelled track cranes. There is a separate type of cranes, which moves on a tracked chassis - self-propelled tracked crane. Of course, to deliver such a crane is a rather time-consuming task, but the caterpillar crane justifies costs. With it, it is possible to achieve a greater lifting height and the caterpillar crane has a lot of lifting capacity. To reduce the cost of transporting the caterpillar crane from place to place, the principle of aggregate construction is widely used. Such an opportunity allows not only to facilitate the dismantling, but also the carriage of goods. Crawler cranes are working, both from a diesel-electric unit and an electrical network. The construction of tracked cranes includes a large number of different equipment, which increases the performance and power of these cranes. The tracked faucet consists of: chassis and swivel, winch, mechanism of rotation, generator and diesel-electric station, mounting rack, cabin, cargo suspension and hook coil, etc. Transportation of the caterpillar crane occurs with special vehicles.

Console cranes. The next variety of cranes is a console crane. Console cranes are two varieties: a wall-console crane and a column crane.
1. The wall-console crane consists of a wall farm, which is moving a wall trolley with a winch that provides loading. Wall-cantilever cranes are used mainly in the workshops, in order to reduce work with bridge cranes. Wall-cantilever cranes are installed stationary: the column is set, and the console is based on it. The possibility of using console cranes largely depends on the specifics of production and premises, but still predominantly cantilever cranes are used in small rooms.
2. When using a column crane, instead of a wall farm, a stationary column is used. Column cranes are used to maintain various aggregates, therefore apply them on machine-building factories.

Cranes on the rail move. On the construction (cargo port, etc.), special rails are installed, for which the crane is moving. The most common cranes on the rail move - with an arrow of 15 m (the bundle complements the cargo hook for single loads), sometimes there may be an insertion arrows on 5m, also complement the design of the granting, winches and other details. Various types of cranes on the rail turn are produced: with a turn of the tower and without, stationary, fixed and freely standing on the support frame.

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With lifting cranes, cyclic machines are called for lifting and moving in the space of cargo held by the lifting organ. Cranes are used in the shops, construction, transport and in other areas of the national economy. Lifting cranes consist of carrying structures (bridges, towers, farms, masts, arrows), power plant, lifting mechanism (winch, electrotals), supporting elements (cable and chain polystes), load-bright fixtures, as well as movement and control mechanisms.

According to the construction of the cranes, divided into bridges, gantry, tower, portal, boom, cable. Consider the cranes most often used in construction.

7.2 Bridge cranes

Bridge crane (Figure 7.1) has a bridge that relies directly on the above-ground crane path. The faucet consists of a bridge span structure or beam 1 equipped with end beams with chassis carts 4 moving along rails. Rails are usually laid on the crane beams, which are placed on the console protrusions of the walls in closed rooms or on columns. The cargo lifting mechanism is mounted on a cargo truck 3 moving along the span structure. Such cranes with a carrying capacity of 5 ... 450 T are used as the main lifting and transport equipment in mechanical, assembly, foundry and other workshops of industrial enterprises and enterprises of the construction industry, as well as in warehouses of finished products.

7.3 Cranes

Kozlova Crane (Figure 7.2) has a bridge that relies on the crane path with two reference racks. Crane consists of a span structure 1 and two legs 2 with drier carts 3 . By a transit structure moves a cargo truck 4 With a lifting device. The mechanisms of lifting the cargo and the movement of the trolley are mounted both directly on the trolley and on the end of the span structure. When using consoles 5 Extending the span structure, the space serviced by the crane increases.

Overhead crane

1 - span structure (bridge); 2 - the mechanism of movement of the crane; 3 - cargo truck with cargo lifting mechanisms and cargo movement; 4 - Tootped Wheels Bridge

Figure 7.1.

Gantry crane


a - circuit stocks of cargo rope; B - Scheme supply rope cargo carriage

Figure 7.2.

To increase the stiffness of the entire structure, at least one of the legs of the crane is performed as a farm. Gantry cranes are usually installed on open warehouse and mounting sites, less often use as a means of intra-water transport. Common cranes are 4 ... 40 m (sometimes up to 170 m); load capacity 3 ... 50 tons (sometimes up to 800 tons); Cargo lifting height reaches 30 m.

7.4 Tower cranes

Tower cranes are cranes of an arrow type with an arrow attached to the top of the vertically located tower. Cranes have a tower, a swivel boom and a lifting winch. Inpatient and mobile tower cranes distinguish. Stationary support frame is attached to a monolithic or predatory reference basis. The tower of mobile cranes is based on the driving wheeled or tracked trolleys, which move along the railway or directly on the soil. The carrying capacity of the mobile tower cranes reaches 100 ... 120 tons, and stationary - 400 tons. Lifting height to 150 m, departure a hook up to 50 m. The main parameter of tower cranes is a cargo moment, determined by the work of the load for the hook.

According to the method of changing the hook, the hook is distinguished by tower cranes with a cargo cart, carrying a hook and moving along horizontal arrows, and cranes with a lifting boom, changing departure by inclusting the boom to an angle allowed by the crane design.

By the location of the rotary device, the tower cranes with the lower turn is distinguished, i.e. with a tower rotating with the arrow (Figure 7.3, but), and with the upper twist - with a rotary boom and a non-turning tower (Figure 7.3, b.). Crane tower are tubular or spatial structures of various sections.

Tower cranes


a - with a tubular rotary tower and a changing departure of the arrows; b - with a lattice tower, a rotary head and a movable cargo carriage on the arrow; 1 - arrow; 2 - cabin; 3 - Tower; 4 - Board winch; 5 - cargo winch; 6 - turning mechanism; 7 - swivel frame; 8 - Rotary circle; 9 - chassis; 10 - running trolley; 11 - headband; 12 - counterweight; 13 - ballast; 14 - Cargo Trolley

Figure 7.3.

The booster boosters are performed by spatial from the corner profile or small diameter pipes. Also are used from the pipes of large diameter and the box of the box. A counterweight is used to equilibrate the mass of the boom and the mass of cargo in tower cranes.

The rise and lowering of the goods in tower cranes is carried out with the help of electroreverter winches. Most cranes have single-speed winches. But there are crane winches having two, three, four speeds and more. The presence of several speeds increases the capacity of the crane, and expands its scope.

7.5 Gift Self-Proper Cranes

Boom self-propelled cranes (Figure 7.4) have a console arrow installed on a full-rod frame. Depending on the undercoming device, car cranes and cranes on a special chassis are distinguished. Cranes on a special chassis are divided into caterpillar and pneumocoles. Car taps are mounted on special chassis of automotive type and on the chassis of serially produced cars. Thanks to the versatility and high maneuverability, the boom self-propelled cranes were widespread on construction and warehouse work.

Board self-propelled cranes


a - on a caterpillar; b - on a pneumocole move, 1 - driving equipment, 2 - counterweights; 3 - swivel platform, 4 - power plant; 5 - arrow; 6 - Gusek; 7 and 8 - hooks of the auxiliary and main mechanism of lifting goods; Q - weight of cargo; L is the length of the arrows; L - departure hook; H is the height of the lifting of cargo; K - King; In - base

Figure 7.4.

Depending on the work performed, the arrangements of arrows can be straightforward, curved with a headband, telescopic, with a houson, fixed on the rotary platform or on the tower with tower-booster work equipment. The telescopic boom allows steadlessly changing the departure of the goods and with greater accuracy to serve goods into hard-to-reach places. Towder-boom equipment significantly expands the scope of arrovar cranes and in some cases allows you to successfully replace the tower rail cranes. The arrow of the cranes with the help of additional sections can be elongated or equipped with a houson that allows you to apply the second hook. Cranes equipped with two hooks have two lifting machines: one (main) is used to lift large cargo at low speed; The second (auxiliary) with a small multiplicity polyaste is to raise small cargo at greater speed. All mechanisms of arrovar cranes besides the movement mechanism are placed on a rotary platform.

7.6 Cable Cranes

Cable cranes (Figure 7.5) are cranes with supporting ropes, fixed at the upper ends of the mast support racks. These cranes are used in the construction of bridges and for servicing construction on a strongly rough terrain (river, mountains). The most widely used stationary cable cranes with two fixed supports (tubular or lattice masts) and tensioned between them the bearing rope, which moves the cargo cart with a polyaste and hook. Depending on the purpose, other cable cranes are used: swinging, mobile and radial. In swinging cable cranes, as a result of tension, both masts can be tilted at an angle of up to 8 °, which allows you to create an area of \u200b\u200bmaintenance in the form of a rectangle. Mobile cable cranes both masts are made in the form of towers installed on the running rail trolleys, which move along the parallel crane paths. In radial cable cranes, one tower is fixed, and the other moves along the rounded rail path. The crane can serve the sector site.

The load capacity of cable cranes does not exceed 25 tons (usually 5 ... 10 tons). The span of the cable crane (the distance between the supports) reaches 400 m. The speed of lifting the cargo 0.5 ... 1.5 m / s, the speed of movement of the cargo truck 2 ... 4 m / s.

Cable crane


a - crane scheme; B and D - schemes of stocks of cargo and traction ropes; in - cargo truck; G - the tension scheme of the carrier rope; 1 - masts; 2 - the mechanism of tension of the carrier rope; 3 - guys; 4 - cargo rope; 5 - traction rope; 6 - Tension Polyastes of Vant; 7 - carrying rope

Figure 7.5.

7.7 Mast cranes

Mast cranes are stationary lifting cranes with an independent location of metal structures and mechanisms. The metal structure of such cranes is a combination of mast, hinged with an arrow (Figure 7.6). Cranes are separated on the grief and guy. The mast is still motionless. It can be attached to the wall of the structure or supported by the pink. The boom hinge is designed so that it can be rotated in the vertical plane and around the vertical axis. Mast of the guy crane has hinge supports: the bottom ball and the upper cylindrical (in the form of "spider"), said guys. Load capacity of mast cranes 1 ... 200 t and more. These cranes are used mainly at concentrated installation.

Mast cranes


a - grave; b - vest; 1 - Troop; 2 - arrow lift polyspers; 3 - arrow; 4 - mast; 5 - swivel frame; 6 - winches; 7 - mast headpoint (spider); 8 - Vantha

Figure 7.6.

7.8 Defining basic parameters

Cranes performance is also determined by the capacity of cyclic effects: calculating-structural (kg / h):

;

technical (kg / h):

;

operational (kg / shift):

;

where Q. - load capacity of the crane, kg; T C. - cycle time, C; To I. - coefficient of use of load capacity; p - the number of cycles of 1 h; Q CP. - the average weight of the lifting goods, kg; T. - shift duration, h; To B. - The coefficient of use of the machine in time.

Cycle time:

where is the total time of machine operations (working crane), C; t z - time suspension and removal of goods, C; t U. - the time of the loading of the cargo when installing it in the specified location, C; t B. - time for each auxiliary machine operation, C; m. - number of machine operations (lifting, descent, rotation with cargo and reverse rotation, movement, etc.).

Total time of machine operations:

,

where s. - The path of movement of the crane or change the departure of the hook, m; J. 1 , J. 2 - movement speeds and lifting, m / s; N. - lifting height (lowering) of cargo, m; b. - angle of rotation of the arrow, hail; p - the speed of rotation of the boom, rpm; To C. - coefficient of combining operations.

Tower and boom cranes work with a load made outside the supporting base of the machine, and therefore must have sufficient resistance when exposed to cargo, inertia and wind loads. The stability of these cranes is ensured by their own mass and increases the use of counterweights and remote supports. The sum of the moments of the forces holding a tipper must be exceeded with some reserve to exceed the sum of the moments of the forces seeking to overturn the crane. The rules of the Gosgortkhnadzor provide for the need to ensure the reserve of stability characterized by the sustainability coefficient.

There are two types of crane stability (Figure 7.7): truck - with a possible tipping of the crane towards the lifted goods and its own - with the possible tipping of the crane backward, in the direction opposite to arrows (in the absence of cargo). Cargo stability ratio:

;

where M K.G. - the moment holding the crane from tipping towards the cargo; - the sum of all overturning moments from additional loads (wind, inertial, etc.); Q. - cargo weight; ( but – b.) - shoulder tipping torque.

Coefficient of own sustainability:

;

where M K.S. - the moment holding the crane from tipping towards the counterweight; M B. - Tilting moment from wind load.

If, when calculating the stability, the effect of slope, inertial forces and wind load are not taken into account, then the coefficient of cargo stability k. ³ 1.4. Truck stability of the crane is checked both for maximum and minimal departures and, accordingly, for the minimum and maximum cargo.

Schemes for determining the stability of the boom crane


a - cargo; b - own; G - crane weight; Q - weight of cargo; q - dynamic pressure; a - the distance from the axis of rotation of the crane to the center of gravity of the goods; b - the distance from the axis of rotation to the rib of tipping; C is the distance from the axis of rotation to the center of gravity of the crane; H is the distance from the headguard of the arrows to the center of gravity of the cargo; h is the distance from the arrow's ledge to the support plane; H. 1 - distance from the reference plane to the center of gravity of the crane; R is the distance from the reference plane to the center of the dynamic pressure application; A - Crane Tilt Angle (Support Surface)

Figure 7.7.

Due to the fact that when changing the arrows, the center of gravity of the system moves, the crane load capacity regulated by the stability coefficient changes. The crane loading capacity also depends on the length and departure of the boom and the use of remote supports that increase the reference contour.

In accordance with the requirements of the Gosgortkhnadzor and in order to comply with the conditions of safety during the operation of the lifting machines, all cranes are allowed only after their examination and tests.

What lifting machines serves the slings?

For lifting machines (Fig.2.1), which serve the soloers include lifting cranes, pipe-layer cranes, taps-manipulators.

Crane arm - this is a lifting machine consisting of a shut-off setting 3 mounted on a vehicle 4 or foundation.

What are the types of lifting cranes?

Bridge cranes - these are cranes that have a loading organ 5 (see Fig. 2.1) suspended to a cargo truck 7 moving along the bridge 6. These include bridge and gantry cranes.

Cable taps - these are cranes that have a loading organ suspended to a cargo trolley moving through the bearing ropes 8. This type includes cable and cable-bridge cranes. Cable crane carrying ropes are fixed in the upper part of the support mast 9.

Crime type cranes - these are cranes that have a loading organ suspended to the arrow or a cargo trolley moving along arrows.

Fig.2.1 Lifting machines: 1 - caterpillar tractor; 2 - arrow; 3 - shut-screen installation; 4 - vehicle; 5 - cargo traffic; 6 - bridge; 7 - cargo truck; 8 - carrying rope; 9 - mast; 10 - portal; 11 - Tower; 12 - Railway Platform

The rift type includes portal, tower, rail and boom cranes.

Portal crane - This is a swivel crane located on the portal 10, intended for skipping railway or road transport.

Tower crane - This is a crane swivel, with an arrow 2 fixed in the upper part of the vertically located tower 11.

Railway crane - This is a crane mounted on the platform 12, moving along the railway track.

Boom - This is a swivel crane, in which the boom is fixed on the rotary platform placed directly on the movement. Boer cranes vary by type of chassis:

  • · Automotive crane mounted on a car chassis;
  • · Pneumocole vents, mounted on a pneumocole chassis;
  • · Short-base crane mounted on a short-base chassis;
  • · Crane on a special chassis installed on a special chassis of a car type;
  • · Crane crawler installed on a tracked running device.

What are the main parameters characterize the crane?

Load capacity Q (Fig.2.2) - the maximum weight of the goods, on the rise and movement of which the crane is calculated in the specified operating conditions. The amount of lifting capacity includes a mass of removable lifting devices and containers used to move the cargo.

Departure L -the distance horizontally from the axis of rotation of the convoy crane to the axis of the shipping organ.

Cargo moment M -production of lifting capacity and its corresponding departure M.= Ql (T * M).

Span S -the horizontal distance between the axles of the crane path rails for bridge cranes. Departure and span are parameters characterizing the value of the zone serviced by the crane.

Lift height N -the distance from the level of the Crane parking to the airproof organ located in the upper position.

Depth of lowering h -the distance vertically from the level of the parking of the crane to the airproof organ located in the lower operating position.

Pitch - the distance horizontally between the axles of the rails or wheels of the chassis of the convoy crane.

Base IN -the distance between the axes of the supports (running trolleys) of the crane, measured along the path.

The slings must know the technical characteristics of the cranes serviced by them. The technical characteristics of the crane are the numerical values \u200b\u200bof its parameters.


Fig.2.2

Q - loading capacity; L - departure; S - span; H - lifting height; h - depth of lowering; In - base

How does the crane crane depends on the cargo?

The carrying capacity of the boom cranes depends on the departure back proportionally. The maximum load capacity of the faucet has a smallest fly, and with an increase in the departure of its carrying capacity


Fig.2.3

The dependence of the crane of the crane from the departure shows it cargo characteristic. Consider the cargo characteristic of the DEC-251 caterpillar (Fig. 2.3), which has a maximum load capacity of 25 tons on an outlet 5 m. With an increase in the departure, the crane loading capacity decreases, so with the highest for this boom equipment, 14 m - the crane can raise only 4 t.

What tipping forces act on the crane and affect its stability?

The following forces are valid for the crane:

  • · The mass of cargo Q (Fig.2.4);
  • · The power of inertia R in, which occurs when changing the speed of lifting and lowering the cargo.

The bias of the working platform also reduces the stability of the crane. Tipping forces are created tipping moment regarding the ribs of overturning (RO). Tipping torque created by cargo is equal to the product of the mass of cargo Q on the shoulder b:

M ORD \u003d. QB.

Obviously, with an increase in departure increases shoulder b,consequently, overturning moment increases.


Fig.2.4.

1 - remote support; 2 - counterweight; G - the mass of the crane; F In - power of inertia; Q - weight of cargo; a, b - shoulders of strength; RO Rib Tipping

What holds the crane from tipping?

The boom crane is a free-standing machine that is kept from tipping its own mass. G (see Fig.2.4). Mass of the crane creates regenerating moment equal to the product of the mass of the tap G on the shoulder but:

M Restore \u003d GA

The stability of the crane is increased by increasing the mass of the tap of the counterweight 2, which is mounted in the back of the turntable platform.

In the second way to increase the stability of the boom crane is the installation of remote supports 1. The crane puts remote supports, as a person to increase stability wider puts his legs, while the shoulder increases, respectively, the shoulder b decreases .

What are the reasons for taps lose stability and overturn?

Possible causes of tipping cranes:

  • · The crane load is exceeded on this departure;
  • · Violated rules for the installation of boom crane (remote supports are not installed, installation on freshly saturated soil, etc.);
  • · Faulty rail crane path;
  • · The faucet works at wind speed, which exceeds the passport specified in his passport;
  • · Tower or other rail crane is not installed on anti-theft devices at the end of work.

All cranes are calculated with a stability margin, so tipping the crane is always the result of a gross violation of the safety rules.

ATTENTION! Tipping the crane may occur due to the wine-changer in the event of a lines of cargo exceeding the crane loading capacity on this departure.