The selection of a crane is made according to three main parameters:

load capacity;

Hook reach;

The height of the lift, and in some cases the depth of the lowering of the hook.

When choosing a crane for construction works use the working drawings of the object being erected, while taking into account the dimensions, shape and weight of the prefabricated elements to be installed. Then, taking into account the location of the crane, the largest required reach of the boom and the required maximum lifting height are determined.

Crane lifting capacity– cargo payload lifted by a crane and suspended by means of removable load-handling devices or directly to fixed load-handling devices. For some imported cranes, the mass of the lifted load also includes the mass of the hook clip, which must be taken into account when selecting a crane.

The required lifting capacity of the crane at the respective reach is determined by the weight the heaviest load with removable load-handling devices (grab, electromagnet, traverses, slings, etc.). The mass of the load also includes the mass of attachments mounted on the structure to be mounted before it is lifted, and structures for reinforcing the rigidity of the load.

Q is the lifting capacity of the crane;

P gr - the mass of the lifted load;

P gr.pr. - weight of the lifting device;

P n.m.e. – mass of mounted mounting devices;

P c.o. - the mass of structures for strengthening the rigidity of the lifted element and containers.

When choosing a crane for construction and installation work, it is necessary to ensure that the weight of the load being lifted, taking into account the lifting devices and containers, does not exceed the permissible (passport) lifting capacity of the crane. To do this, it is necessary to take into account the maximum weight of the mounted products and the need for them to be delivered by a crane for installation to the most remote design position, taking into account the permissible crane load capacity at a given boom reach.

When selecting cranes with a variable reach, it is necessary to pay attention to Special attention the fact that the lifting capacity of these cranes depends on the reach.

Necessary working sortie R p is determined by the horizontal distance from the axis of rotation of the rotary part of the crane to the vertical axis of the lifting body.

The calculation of the working reach of the crane is carried out according to the following options:

When tying tower cranes

R p - required working departure;

b is the distance from the building axis closest to the crane to the point farthest from the crane in the direction perpendicular to the axis of movement of the crane;

S is the distance from the axis of rotation of the crane to the nearest axis of the building;

a is the distance from the axis of the building to its outer edge (protruding part);

n is the approximation dimension;

R p - the largest radius of the turning part of the crane from the side opposite to the boom.

Figure 8.1 - Binding of the mounting mechanism. Attaching a jib crane to a building

Figure 8.1, 8.2 shows the binding of the mounting mechanism

Figure 8.2 - Binding of the mounting mechanism. Attaching a tower crane to a building

Distances a and b are determined from the working drawings of the building.

The approach dimension is taken as the distance between the protruding parts of a crane moving along ground rails (its rotary or other most protruding part) and the outer nearest contour of the building (including its protruding parts - canopies, cornices, pilasters, balconies, etc.), temporary construction devices located on the building or near the building (scaffolding, remote platforms, protective visors, etc.), as well as buildings, stacks of goods and other items, should be according to Art. 2.18.6 PB 10-382-00 from the level ground or working platforms at a height of up to 2000 mm - not less than 700 mm, and at a height of more than 2000 mm - not less than 400 mm. For cranes with a slewing tower and more than two sections in the tower, this distance is assumed to be at least 800 mm over the entire height due to the possible deviation of the tower from the vertical.

The distance between the turning part of self-propelled jib cranes, in any of their positions, and buildings, stacks of goods, scaffolding and other items (equipment) should be at least 1000 mm.

The largest radius of the turning part of the crane from the side opposite to the boom is taken according to the crane passport.

When installing the crane near unreinforced slopes of pits, trenches or other excavations

For tower cranes

S=r+C+0.5d+0.5K

r is the distance from the axis of the building to the base of the slope of the pit;

C is the distance from the base of the slope of the excavation (cutting) to the edge of the ballast prism;

d is the width of the base of the ballast prism

K is the track gauge of the crane. (Figure 8.3)

Figure 8.3 - Approximation dimensions

d=Sop.e.+2δ+3hb

S op.e. - the size of the support element across the rail, mm;

δ – lateral shoulder of the ballast layer (δ≥200 mm);

3h b - the size of two projections of the slopes of the ballast layer with a thickness h b, mm.

As supporting elements should be used:

With a load from the wheel on the rail up to 250 kN inclusive - half sleepers or reinforced concrete slabs;

When the load from the wheel on the rail is over 250 kN - reinforced concrete beams.

General views and dimensions of the supporting elements are given in D.3 of Appendix D to SP 12-103-2002 “Ground rail crane tracks. Design, construction and operation”.

The slopes of the sides of the ballast layer must be made with a slope of 1: 1.5, therefore, the size of the two projections of the slopes of the ballast layer with a thickness h b is 3h b.

The thickness of the ballast layer is determined by the project based on calculations and depends on the load on the crane wheel, the type of soil base, the ballast material and the design of the under-rail support elements.

Approximate ballast thickness is given in table 8.1

Table 8.1 - Approximate ballast thickness

Estimated ballast thickness h b crushed stone under reinforced concrete beams sandy under reinforced concrete beams crushed stone under wooden half sleepers with a subgrade made of clay, loamy or sandy loam soil and rails of types with subgrade of sandy soil and rails of types with a subgrade made of clay, loamy or sandy loam soil and rails of types with subgrade of sandy soil and rails of types P50 R65 P50 R65 P50 R65 P50 R65 P50 R65 P50 R65 up to 200 200 to 225 " 225 " 250 " 250 " 275 " 275 " 300 - - - - " 300 " 325 - - - - Notes 1. When the load on the wheel is more than 275 kN, it is recommended to use reinforced concrete supporting rail elements. 2. The distance between the axes of half sleepers should be taken as 500 mm with tolerances of ±50 mm. 3. Crushed stone from natural stone of a fraction of 25-60 mm, gravel and a gravel-sand mixture of a fraction of 3-60 mm (gravel) and 0.63-3 mm (sand) should be used as crushed stone ballast, by weight not more than 20%. 4. For the manufacture of crane rails, new or old rails of I and II serviceability groups should be used.

For jib cranes

r is the distance from the axis of the building to the base of the slope of the excavation (excavation);

C - distance from the base of the slope of the excavation (excavation) to the nearest support of the hoisting machine, determined according to table 8.2;

Table 8.2 - Minimum distances horizontally from the base of the excavation slope to the nearest supports of the machine (SNiP 12-03-2001 p.7.2.4) (C)

To determine the characteristics of the soil when installing a hoisting machine near a pit (excavation), it is necessary to be guided by an engineering and geological conclusion about the soils, while in the presence of heterogeneous soils in the slope, the determination of the approximation of the hoisting machine is carried out using one type of soil with the worst indicators (for the weakest soil) (Figure 8.4, 8.5).

Figure 8.4 - Installation of a rail crane at the slope of the pit

Figure 8.5 - Installation of jib cranes at the slopes of the excavations

when installing a crane near buildings with basements or other underground hollow structures

When installing lifting machines for buildings (structures) with basements or other underground hollow structures, design institutes (project authors) must calculate the bearing capacity of the walls of these structures for crane loads.

It is allowed not to perform verification calculations confirming the stability of basement walls, foundations and other structures if the distance from the nearest support of the hoisting machine or the lower edge of the rail track ballast prism to the outer edge of the basement wall meets the requirements of Table. 8.3 and figure 8.6. Wherein:

For tower cranes

For jib cranes

r is the distance from the axis of the building to the outer edge of the basement wall closest to the tap;

C is the distance from the outer edge of the basement wall closest to the crane to the nearest support of the lifting machine;

d is the width of the base of the ballast prism;

K - track gauge of the crane;

L op - the size of the track or base of the crawler crane, and for lifting machines with outriggers - the size of the support contour.

Figure 8.6 - Installation of lifting machines near buildings with a basement, without calculating the extrusion of walls from crane loads

The approach to the building (structure) of the attached crane is determined by the minimum overhang, which ensures the installation of the structural elements of the buildings closest to the crane tower, taking into account the dimensions of the crane foundation and the conditions for attaching the crane to the building.

where Rmin is the minimum overhang of the crane hook

Distances a and b are determined according to the working drawings of the building in the part of the building where the crane is supposed to be installed.

The minimum crane hook overhang is taken according to the crane passport.

The construction of the foundation of the attached crane in each case is determined by the calculation performed by a specialized organization.

Attachment structures of the attachment crane to the building structures are developed by a specialized organization and coordinated with the author of the building project.

Required lifting height h p is determined from the mark of the installation of lifting machines (cranes) vertically and consists of the following indicators:

the height of the building (structure) h s from the zero mark of the building, taking into account the marks of the installation (parking) of cranes to the upper mark of the building (structure) (upper mounting horizon);

a margin of height equal to 2.3 m from the conditions of safe work at the top of the building, where people can be;

the maximum height of the transported load h gr (in the position in which it is moved), taking into account the mounting devices or reinforcement structures fixed on the load,

length (height) of the lifting device h gr.pr. in working position as shown in figures 8.7. 8.8

where n is the difference between the marks of the parking of cranes and the zero mark of the building (structure).

Figure 8.7 - Binding of the mounting mechanism

Required lowering depth h op is determined from the vertical installation mark of the crane as the difference between the height of the building (structure) - when installing the crane on the structures of the structure being erected, or the depth of the pit and the sum minimum heights load and lifting device, as shown in Figure 4, with an increase in h op by 0.15-0.3 m to loosen the tension of the slings during unslinging.

Figure 8.8 - Binding of the mounting mechanism

P gr - mass of the lifted (lowered) load;

h gr - cargo height;

h gr.pr. - length (height) of the load-handling device;

h h - the height of the building;

h op - height (depth) of lifting (lowering);

Ur.s.k. - crane parking level;

Ur.z. - ground level;

Ur.d.k. - the level of the bottom of the pit;

Ur.p. - level of overlap (roof).

(when the crane is on the ground)

(when the crane is parked on the roof)

When choosing a crane with a lifting boom, it is necessary that a distance of at least 0.5 m be maintained from the boom dimension to the protruding parts of the building, and at least 2 m vertically to the overlap (cover) of the building and other areas where people can be, as shown in figures 1 and 2. If the crane boom has a safety rope, the indicated distances are taken from the rope according to figure 8.9.

Required working flight;

Weight of the lifted load;

The largest radius of the rotary part of the crane;

Building size;

Lift height mark;

Figure 8.9 - Vertical attachment of jib cranes with a safety rope

For the installation of structures or products that require smooth and precise installation, cranes with smooth landing speeds are selected. The compliance of the crane with the lifting height of the hook is determined based on the need to supply products and materials to the maximum height, taking into account their dimensions and the length of the slings.

Cross-tie of crane runways of tower cranes.

After selecting the crane, its final cross-linking is carried out, specifying the design of the crane runways.

Longitudinal binding of crane runways of tower cranes

To determine the extreme stops of the crane, serifs are sequentially made on the axis of movement of the crane in the following order:

from the extreme corners of the outer dimension of the building from the side opposite the tower crane - with a compass solution corresponding to the maximum working reach of the crane boom (Figure 8.10);

from the middle of the inner contour of the building - with a compass solution corresponding to the minimum reach of the crane boom;

from the center of gravity of the heaviest elements - with a compass solution corresponding to a certain boom reach according to the load characteristics of the crane.

Extreme notches determine the position of the center of the crane in extreme position and show the location of the heaviest elements.

According to the found extreme parking lots of the crane, the length of the crane tracks is determined:

or approximately

L p.p. – length of crane tracks, m;

1 kr - the distance between the extreme parking of the crane, determined according to the drawing, m;

H kr - crane base, determined from reference books, m;

1 torm - the value of the braking distance of the crane, taken at least 1.5 m;

1 blunt - the distance from the end of the rail to dead ends, equal to 0.5 m.

a - determination of extreme stops from the condition of the maximum working outreach of the boom;

b - determination of extreme stops from the condition of the minimum outreach of the boom;

c - determination of extreme stops from the condition of the required boom departure;

g - determination of the extreme parking of the crane;

e - determination of the minimum length of crane runways;

Figure 8.10 - Determination of extreme crane stands

The determined length of the crane runways is adjusted upwards, taking into account the multiplicity of the length of the half link, i.e. 6.25 m. The minimum allowable length of the runways according to the rules of Rostekhnadzor is two links (25 m). Thus, the accepted path length must satisfy the following condition:

6.25 - length of one half-link of crane runways, m;

n stars - the number of half links.

If it is necessary to install a crane on one link, i.e., on a pin, the link must be laid on a rigid base, excluding subsidence of the crane runways. Such a basis can serve as prefabricated foundation blocks or special prefabricated structures.

Binding of railings for crane runways

Crane runway railings are tied based on the need to maintain a safe distance between the crane structures and the railing.

The distance from the axis of the rail closest to the railing to the railing is determined by the formula

- crane gauge, m (accepted according to reference books);

- take equal to 0.7 m;

- the radius of the turntable (or other protruding part of the crane), is taken according to the passport data of the crane or reference books.

For tower cranes without a slewing part, it is maintained from the crane base. In the final form, with the designation of the necessary details and dimensions, the binding of the paths is drawn up in accordance with Fig. 8.11

The extreme parking of the tower crane must be tied to the axes of the building and marked on the SGP and the terrain with landmarks that are clearly visible to the crane operator and slingers.

­

e - binding of crane runways;

1 - extreme parking of the crane; 2 - binding of the extreme parking lot to the axis of the building; 3 - control load; 4 - the end of the rail; 5 - place of installation of a dead end; 6 - crane base

Figure 8.11 - Path binding

The crane operator must have an overview of the entire working area. The tower crane operating area should cover the height, width and length of the building under construction, as well as the area for storing the mounted elements and the road along which the goods are transported.

When tying tower cranes, one should take into account the need for their installation and dismantling, while paying special attention to the position of the boom and the counterweight located at the top in relation to the building (structure) being erected. During the erection and dismantling of these cranes, the boom and the counterweight located at the top must be above the free area, i.e. should not fall on buildings under construction or existing and other obstacles.

Installation and dismantling of cranes is carried out in accordance with the instructions for their installation and operation.

calculate the area of ​​the crane;

identify working conditions and, if necessary, impose restrictions on the crane coverage area

The choice of the right truck crane for the installation of structures, at the stage of drawing up a construction organization project, largely determines the further sequential chain of work.

If it is known that the existing dimensions of the structure do not allow the use of lifting mechanisms that are available or that can be rented in the region at a reasonable price, then the technology for performing work changes.

In any case, a person who is engaged in solving a similar problem - meaning the choice of a lifting mechanism - should have the necessary information at hand:

Cargo characteristics of cranes;
- dimensions of the building - length, height, width;
- the possibility of dividing the building into separate blocks.

Based on the available information, a decision is made on the use of the type of lifting mechanism - this can be:

Gantry or gantry cranes;
- tower cranes;
- self-propelled cranes on wheeled or caterpillar tracks;
- automobile cranes.

In addition to the type of crane, the possibility of using cranes with various types booms (meaning self-propelled and truck cranes) - such as:

Simple lattice boom;
- a simple lattice arrow with inserts;
- a simple lattice boom with a "jib";
- telescopic arrows.

Often, when it becomes necessary to perform installation in buildings with significant dimensions in terms of and not great height - truck cranes and self-propelled cranes are used - installation is carried out from inside the building - “on oneself”. Those. a self-propelled crane is located inside the building - it mounts structures around itself and gradually, at the exit outside the building, closes the gripper by mounting floor slabs and wall fencing - thereby closing the installation opening.

For long and tall buildings, it is more convenient to use a tower crane.

For underground structures of small width, gantry or portal cranes are better suited.

Today, with the advent of a large number high-performance truck cranes, high load capacity and long outreach - the choice of this type of cranes has become more relevant due to their lower cost. The types of tasks that are successfully solved with the help of truck cranes are really multifaceted: truck cranes are used for construction and installation, loading and unloading, etc. That's why, right choice work is a top priority.

So we decide, in our choice of a mobile crane (including an automobile one):

Crane lifting capacity - determined by the weight and dimensions of the heaviest building structure - with a minimum and maximum reach of the boom;
Crane boom length - boom reach - boom type - whether the truck crane can lift the load;
Are they safe design characteristics truck crane - to ensure necessary conditions security;
The basic dimensions of the crane - will the machine itself and its working bodies be able to move freely within the working area and, most importantly, safely;

Well, to complete the picture, it is necessary to have a plan and sections of the building, as well as a plan of the construction site as part of the working draft.

According to their characteristics, truck cranes can have different dimensions, load capacity (6 - 160 tons) and boom length.

The boom is the most important part of the truck crane. The length, reach of the boom, the design capabilities of the truck crane determine the possibility of working at different heights, with different designs. The reach of the boom is calculated as the distance from the axis of the turntable to the center of the hook mouth. That is, it is the projection of the length of the crane boom on the horizontal axis. This can be a distance of 4 to 48 meters. The design of the boom consists of several sections, which allows you to work on different heights. Today, telescopic booms based on three sections are in demand - they are quite compact, but at the same time they provide lifting of cargo to a great height. "Gusek" is currently used quite rarely.

So, first of all, we determine the places of possible parking of the truck crane - we put the parking points on the plan (drawing) of the construction site, near the place of the proposed installation;
We draw concentric circles from the center of the turntable on the same site plan - smaller (this is the minimum reach of the boom) and large (this is the maximum reach of the boom) and look at what we have in the "danger zone". The "danger zone" is the area between the larger and smaller circles;
We draw attention to the presence in the danger zone of parts of buildings and structures, power lines, open ditches and pits;
We take into account the possibility of supplying technological transport to the installation area - panel carriers, etc.

Picture 1.

We take graphical information on the load characteristic of the crane and a section of the building. On the section of the building, we mark the point of possible parking of the crane and the height of the turntable. From the obtained point on the scale with a ruler, we set aside the maximum length of the boom, which will provide the load capacity we need. The load capacity of a 75 ton truck crane with a maximum reach of the boom can be only 0.5 tons. Do not forget to take into account the safe length of the slings (no more than 90 degrees between the slings) and the safe distance from the boom to the protruding building structures of at least 1 m.

Figure 2.

If we get the required parameters, that is, we can mount the desired structure in right place- then we stop there. If the experiment fails, we change parking places. If this does not help, then we change the tap. Miracles do not happen - the problem clearly has a solution.

As a selection option (if you have a load characteristic on a scale) - cut out (on the same scale) - a square of paper according to the size of the section of the building and start moving it along the load characteristic diagram, achieving optimal compliance.

Calculation of the lifting capacity of the crane

Initial data for calculating the crane:

Lifting height, m ​​- 5

Load lifting speed, m/s - 0.2

Departure of an arrow, m - 3,5

Mode of operation, PV% - 25 (average)

The drive mechanism for lifting and lifting the boom is hydraulic.

Fig.1

We determine the lifting capacity of the crane based on the stability equation.

hence the maximum allowable weight load will be:

Where, Ku - coefficient of cargo stability, Ku = 1.4;

Mvost - a restoring moment;

Mopr - overturning moment;

Gt is the weight of the tractor, from the technical specification Gt = 14300 kg;

Gg - cargo weight;

a - distance from the center of gravity of the tractor to the tipping point;

b is the distance from the tipping point to the center of gravity of the load.

Calculation of the lifting mechanism, boom

1) we determine the multiplicity of the chain hoist, depending on the load capacity Q, according to the table (given below). (a=2)

2) We select the hook and the design of the hook suspension according to the atlas (hook No. 11)

3) I determine the efficiency of the chain hoist (h):

Where s is the efficiency of the pulley block

Efficiency of the bypass block

4) I determine the force in the rope:

I choose a rope type LK-R 6CH19 O.S. diameter 13

Where: d to - rope diameter (d to = 13 mm)

I accept D bl = 240 mm. D b - I preliminarily take more D bl. D b = 252 mm. For the convenience of placing the gear half-coupling inside the drum.

Hydraulic motor 210.12

R dvig = 8 kW

n = 2400 min -1

I dvig \u003d 0.08 kgm 2

Shaft diameter = 20 mm.

U p \u003d 80 (TsZU - 160)

We accept the value of D b = 255 mm rounding the calculated diameter to the nearest of the series of numbers R a 40 according to GOST 6636 - 69, while the actual lifting speed will increase slightly.

The discrepancy with a given speed is about 0.14%, which is acceptable.

Fig.2

Rk \u003d 0.54 * dk \u003d 0.54 * 13 \u003d 7.02? 7 mm

Determine the wall thickness:

Z slave - number of working turns:

where t is the cutting step

Permissible compressive stresses for cast iron СЧ15 = 88MPa

<3 составляет не более 10%, величину которого можно не учитывать, в нашем примере lб/Dб = 350/255 = 1,06 < 3 в этом случае напряжения изгиба будут равны:

With D k \u003d 14.2 mm => thread of the studs \u003d M16 d 1 \u003d 14.2 mm stud material St3, [d] \u003d 85

18) Brake selection.

T t? T st * K t,

T t \u003d 19.55 * 1.75 \u003d 34.21 Nm

I choose a band brake with a hydraulic drive, with a nominal T t \u003d 100 N * m

Brake pulley diameter = 200 mm.

T p \u003d T st * K 1 * K 2 \u003d 26.8 * 1.3 * 1.2 \u003d 41.8 N * m

I choose an elastic sleeve-pin coupling with a brake pulley w = 200 mm.

T out \u003d T st * U M * s M \u003d 26.8 * 80 * 0.88 \u003d 1885 N * m

Selected reducer Ts3U - 160

U ed = 80; T out = 2kNm; F k \u003d 11.2 kN

21) Check start time.

The acceleration value at start-up corresponds to the recommendation for lifting mechanisms during loading and unloading operations [J] is allowed up to 0.6 m/s 2 . The slowness is due to the peculiarities of the hydraulic drive.

The braking torque is determined by the selected engine T brake = 80 N * m.

Deceleration acceleration:

The amount of deceleration during braking corresponds to the recommendations for lifting mechanisms during unloading and loading operations ([i] = 0.6 m/s 2) .

Calculation of the boom lifting mechanism

4) I determine the force in the rope:

5) Choice of rope. The rope, according to the rules of ROSGORTEKHNADZOR, is selected according to the breaking force specified in the standard or in the factory certificate:

Where: K - safety factor, selected according to the table (for an average operating mode - 5.5)

I choose a rope type LK-R 6CH19 O.S. 5.6 mm in diameter.

6) I determine the diameter of the blocks from the condition of the durability of the ropes according to the ratio:

Where: d to - rope diameter (d to = 5.6 mm)

e is the permissible ratio of the drum diameter to the rope diameter.

We accept according to the standards of ROSGORTEKHNADZOR for cranes general purpose and average operating mode e = 18.

I accept D bl = 110 mm. D b - I preliminarily take more D bl. D b = 120 mm. For the convenience of placing the gear half-coupling inside the drum.

7) I determine the power required to select the engine, taking into account the drive mechanism:

8) I choose the hydraulic motor by the value of P st from the atlas:

Hydraulic motor 210 - 12

R dvig = 8 kW

n = 2400 min -1

T start \u003d 36.2 Nm (breakaway), maximum 46 N * m.

I dvig \u003d 0.08 kgm 2

Shaft diameter = 20 mm.

9) I determine the rated torque on the motor shaft:

10) I determine the static moment on the motor shaft:

11) I determine the frequency of rotation of the drum:

12) I determine the gear ratio of the mechanism:

13) I choose the gear ratio of a standard 3-speed spur gearbox from the atlas:

U p \u003d 80 (TsZU - 160)

14) I specify the frequency of rotation of the drum:

15) I am specifying the diameter of the drum, in order to maintain the set speed of lifting the load, it is necessary to increase the diameter, since its rotational speed has decreased to 30 when choosing the value of the first number of the standard gearbox.

We accept the value of D b = 127 mm rounding the calculated diameter to the nearest of the series of numbers R a 40 according to GOST 6636 - 69, while the actual lifting speed will increase slightly.

The discrepancy with a given speed is about 0.25%, which is acceptable.

16) I determine the dimensions of the drum:

Fig.2

I determine the pitch for cutting the grooves for the rope:

Rk \u003d 0.54 * dk \u003d 0.54 * 5.6 \u003d 3.02? 3 mm

Determine the wall thickness:

I determine the diameter along the bottom of the cutting groove:

I determine the number of turns of cutting:

Where: Z kr \u003d 3, the number of turns of fastening

Z zap = 1.5 number of spare turns

Z slave - number of working turns:

17) Calculation of the drum strength.

where t is the cutting step

Permissible compressive stresses for cast iron СЧ15 = 88MPa

2) bending stresses d and torsion f for short drums lb/Db<3 составляет не более 10%, величину которого можно не учитывать, в нашем примере lб/Dб = 109,4/127 = 0,86 < 3 в этом случае напряжения изгиба будут равны:

We determine the equivalent stresses:

18) Calculation of fastening the rope to the drum.

I determine the force of the rope branch to the fastening pad:

where e = 2.71; f = 0.15; b = 3*n

where: K T - 1.5 friction factor

Z m - 2 number of studs or bolts

The size of the lining is selected based on the diameter of the rope

With D k \u003d 6.9 mm => thread of the studs \u003d M8 d 1 \u003d 6.9 mm stud material St3, [d] \u003d 85

18) Brake selection.

I determine the static moment during braking:

The brake is selected taking into account the margin for braking torque i.e.

T t? T st * K t,

where: K t is the braking torque safety factor.

T t \u003d 2.01 * 1.75 \u003d 4.03 Nm

I choose a band brake with a hydraulic drive, with a nominal T t \u003d 20 N * m

Brake pulley diameter = 100 mm.

19) Choice of coupling. The choice of coupling should be made according to the calculated moment:

T p \u003d T st * K 1 * K 2 \u003d 2.01 * 1.3 * 1.2 \u003d 3.53 N * m

I choose an elastic pin-sleeve coupling with a brake pulley w = 100 mm.

20) Gear selection. It is produced according to the gear ratio U M = 80, the torque on the output shaft T out and the cantilever load F to on the output shaft.

T out \u003d T st * U M * s M \u003d 2.01 * 80 * 0.88 \u003d 191.2 N * m

Selected reducer Ts3U - 160

U ed = 80; T out \u003d 2 kN * m; F k \u003d 11.2 kN

21) Check start time.

T brake = ±T st. brake. +T in1.t +T in2.t

The sign (+) should be taken when lowering the load, because. in this case, the deceleration time will be longer.

The moment of resistance of the inertia forces of the rotating parts of the drive at start:

The moment of resistance from the forces of inertia of the drum:

The amount of acceleration at start-up is in accordance with the recommendation for hoists during loading and unloading operations. [J] to 0.6.

21. Checking the deceleration time:

T brake \u003d ± T st.t. +T in1t +T in2t

Where: T torm - the average braking torque of the engine; the plus sign should be taken when lowering the load, since in this case the braking time will be longer;

T st.t - static moment of resistance during braking;

T in1t - the moment of resistance from the forces of inertia of the rotating parts of the drive during braking;

T in2t - the moment of resistance from the forces of inertia of the translationally moving masses during braking.

The braking torque is determined by the selected engine T brake = 25 N * m.

I determine the moments of resistance during braking:

Deceleration acceleration:

The amount of deceleration during braking corresponds to the recommendations for lifting mechanisms during unloading and loading operations ([i] = 0.6 m/s 2).

Section 4. Calculation of a metal structure

tractor pipelayer crane boom

The calculation of the metal structure includes:

1) calculation of the strength of the metal structure of the boom

2) calculation of the strength of the axis of the block

3) calculation of the strength of the axis of the boom support

The load acting on the axis of the cable guide block is Q = 2930 kg = 29300 N. The block is mounted on the axis on 2 radial bearings. Since the axis of the guide block is stationary and is under the action of a constant load, the static bending strength is calculated. The calculated axis can be considered as a two - support beam, freely located on the supports, with two concentrated forces P acting on it from the side of the bearings. The distance (a) from the axle support to the action of the load is assumed to be 0.015 m.

Rice. 3

The plot of bending moments is a trapezoid, and the value of the bending moment will be equal to:

T IZG \u003d P * a \u003d (Q / 2) * a \u003d 2.93 * 9810 * 0.015 / 2 \u003d 215.5 N

The required axle diameter is determined from the following formula:

From a series of numbers, I accept the standard value of the diameter of the block axis d=30 mm.

We calculate the strength of the arrow axis.

where S cm is the crushing area, S cm = rdD,

where D is the thickness of the eye, m.

S cm \u003d p * 0.04 * 0.005 \u003d 0.00126 m 2,

Fcm \u003d G str * cos (90-b) + G gr * cos (90-b) + F pcs * cosg + F to * cosv,

where: b - boom angle,

c - the angle of inclination of the cable of the mechanism for lifting the load,

r - the angle of inclination of the cable of the boom lifting mechanism.

F cm \u003d 7 * 200 * cos (90-b) + G gr * cos (90-b) + F pcs * cosg + Fk * cosv \u003d 37641.5 N,

From here we take the diameter of the arrow axis 40 mm.

At the same time, we calculate the stress of the arrow in compression:

Taking l for 140, taking the termination factor for 1, we determine that the cross-sectional area is equal to:

S \u003d 140 * c / F szh \u003d 140 * 0.45 / 37641.5 \u003d 16.73 cm 2,

We also find the required radius of gyration:

r \u003d lstr / 140 \u003d 0.05 m \u003d 5 cm.

We accept the channel 20-P according to the prototype: r = 8.08 cm, S = 87.98 cm 2, W = 152 cm 3.

Calculate the compressive stress:

We are looking for a bending force acting perpendicular to the inclination of the arrow.

M izg \u003d l str * \u003d 11951.9 N * m

The moment of resistance will be

W \u003d 2W \u003d 2 * 152 \u003d 304 cm 3.

y izg \u003d 11951.9 / 304 \u003d 39.32 MPa,

which is less than acceptable.

Calculate the equivalent voltage:

which is also less than acceptable.

The main technical parameters of the self-propelled jib crane:

H tr- the required height of the boom, m;

L tr- required boom reach, m;

Q tr - required hook capacity, t;

I page- required boom length, m.

For determining technical parameters crane, it is necessary to select slinging devices for mounting prefabricated elements. The data are entered in the table "Slinging fixtures for the installation of prefabricated elements" in the form.

Scheme of building installation (for roof slab) with a self-propelled jib crane:

Required lifting height of the boom - H tr is determined by the formula:

N tr \u003d h 0 + h s + h e + h c + h p, m,

where h 0- excess of the support of the mounted element above the level of the crane parking lot, m;

h- headroom (not less than 0.5 m according to SNiP 12.03.2001), m;

h e- height of the element in the mounted position, m;

h s- sling height, m;

h p- height of the cargo chain hoist (1.5m), m.

H tr \u003d m

Required range - L tr is determined by the formula:

L tr \u003d (H tr - h w) x (c + d + b / 2) / (h p + h c) + a, m,

where H tr- the required height of the boom;

h w

with- half of the section of the boom at the level of the top of the mounted element (0.25m), m;

d- safe approach of the boom to the mounted element (0.5-1m), m;

b/2- half the width of the mounted element, m;

h p- height of the cargo chain hoist (1.5m), m;

h s- sling height, m;

a

…………… m

Required load capacity of the mounting hook Q tr- is determined by the formula:

Q tr \u003d Q e + Q s, t,

where Q e– weight of the mounted element, t;

Q with- weight of the slinging device, t.

Q tr determined from the installation condition of the heaviest element.

Q tr = …………. + ……………. = ……………. tn

Required arrow length - I page is determined by the formula:

I str \u003d (H tr -h w) 2 + (L tr -a) 2, m,

where H tr- required boom lifting height, m;

L tr- required boom reach, m;

h w- the height of the hinge of the heel of the arrow (take into account 1.25-1.5m), m;

a- distance from the center of gravity of the crane to the heel of the boom hinge (1.5 m).

I str = =…………… m

Choosing a Truck Crane ……………….. load capacity ……t

The main lattice boom of the crane has a length of ………….m

Specifications with boom length …………….m:

Load capacity on outriggers at boom outreach, t

The largest - ……………..

The smallest is ………………….

Departure of an arrow, m

The largest is …………….

The smallest is ……………….

Hook lifting height at boom outreach,

The largest - ………………..

The smallest - …………………

Occupational safety at urban construction and economy when using cranes and hoists.
Educational-methodical, practical and reference manual.
Authors: Roitman V.M., Umnyakova N.P., Chernysheva O.I.
Moscow 2005

Introduction.
1. OCCUPATIONAL HAZARDS WHEN USING CRANES AND LIFTS.
1.1. The concept of industrial hazard.
1.2. Dangerous zones at the construction site.
1.3. Examples of characteristic accidents and accidents associated with the use of cranes and hoists.
1.4. The main causes of accidents and accidents when using cranes and hoists.
2. GENERAL ISSUES OF LABOR SAFETY WHEN USING CRANES AND LIFTS.
2.1. General condition for ensuring labor safety.
2.2. Regulatory bases for ensuring labor safety when using cranes and hoists.
2.3. The main tasks of ensuring labor safety when using cranes and hoists.
3. ENSURING WORK SAFETY WHEN USING CRANES AND LIFTS.
3.1. Selection of cranes and their safe binding.
3.1.1. Crane selection.
3.1.2. Cross-linking of cranes.
3.1.3. Longitudinal binding of tower cranes.
3.2. Determination of the boundaries of hazardous areas of operation of cranes and hoists.
3.3. Ensuring labor safety in hazardous areas of cranes and hoists.
3.3.1. Instruments and safety devices installed on cranes.
3.3.2. Ensuring safety when installing cranes.
3.3.3. Protective grounding of crane tracks.
3.3.4. Ensuring safety in the joint operation of cranes.
3.3.5. Ensuring safety when using lifts.
3.4. Measures to limit the dangerous zone of the crane.
3.4.1. General provisions.
3.4.2. Forced restriction of the crane operation area.
3.4.3. Special Events to limit the hazardous area of ​​the crane.
3.5. Ensuring labor safety when installing cranes near power lines.
3.6. Ensuring labor safety when installing cranes near recesses.
3.7. Ensuring safety in the storage of materials, structures, products and equipment.
3.8. Ensuring safety during loading and unloading operations.
4. SOLUTIONS TO ENSURE LABOR SAFETY IN ORGANIZATIONAL AND TECHNOLOGICAL DOCUMENTATION (PPR, POS, etc.) WHEN USING CRANES AND LIFTS.
4.1 General provisions.
4.2. Stroygenplan.
4.3. Technological schemes.

3.1. Selection of cranes and their safe binding.
3.1.1. Crane selection.

The choice of a crane for the construction of an object is carried out according to three main parameters: lifting capacity, boom reach and load lifting height.
The required lifting capacity of the crane for the construction of a particular facility and the corresponding boom reach is determined by the mass of the heaviest load. The following are taken into account in the mass of the load: the mass of removable load-handling devices (traverse, slings, electromagnets, etc.), the mass of attachments mounted on the mounted structure before it is lifted and structures increase the rigidity of the load during installation.
The actual lifting capacity of the crane Qf must be greater than or equal to the allowable Qdop and is determined from the expression:

Q f \u003d P gr + P zah.pr + P nav.pr + P us.pr ≥ Q add (3.1)

P gr- the mass of the lifted load;
P input- weight of the lifting device;
P nav.– mass of mounted mounting devices;
P us.pr- the mass of the reinforcement of the element being lifted during the installation process.

The reach of the boom and the required lifting height of the load is set depending on the mass of the heaviest and most remote structure, taking into account the width and height of the building.
The required lifting height H gr is determined from the crane installation mark by adding the following indicators vertically (Fig. 3.1.):

• the distance between the crane parking mark and the zero mark of the building (±h st.cr);
• the height of the job from the zero mark to the upper mounting horizon h zd ;
• a margin of height equal to 2.3 m, from the conditions of safe work on the upper mounting horizon (h without = 2.3 m);
• the maximum height of the transported cargo, taking into account the devices attached to it - h gr;
• height of the lifting device h zah.pr ;

H gr = (h zd ± h st.cr ) + h without + h gr + h zah.pr , (m) (3.2)
In addition, to ensure the safety of work in these conditions, it is necessary that the distance from the counterweight console or from the counterweight located under the tower crane console to the platforms where people can be is at least 2 m.
When choosing a crane with a lifting boom, it is necessary that a distance of at least 0.5 m be observed from the boom dimension to the protruding parts of buildings, and at least 2 m vertically to the covering (overlapping) of the building and other sites where people can be (Fig. 3.2). If the crane boom has a safety rope, the indicated distances are taken from the rope.

Fig.3.2. Ensuring labor safety when using cranes with a lifting boom for the installation of elements of upper facilities under construction (reconstruction).