DESIGN, DESIGN AND SAFE OPERATION
RAILWAYS OF TOWER CRANES

RD 22-28-35-99

1 AREA OF USE

1.1. This document applies to the rail tracks of tower cranes, timber loader cranes (hereinafter referred to as the crane) with a wheel-to-rail load of up to 325 kN and establishes requirements for the design, arrangement and safe operation of rail tracks.

1.2. The requirements of this document do not apply to the rail tracks of cranes used in specific operating conditions:

in areas of permafrost and with snow ballast prisms;

in areas with high seismicity;

in areas with karst phenomena;

on macroporous subsidence soils;

on weak or waterlogged soils and in wetlands;

on slopes with a transverse slope over 1:10;

directly on the structures of the objects under construction;

over engineering networks laid without taking into account the subsequent installation of rail tracks;

on curved sections;

in the areas of a single haul of a crane from one object to another;

for jib cranes on rails;

with a total load from the wheels on the supports (rails) of more than 1300 kN, that is, using two rails on one "thread".

1.3. The requirements of this document are subject to fulfillment by employees of design, construction and railroad operating organizations.

1.4. Organizations developing railroad projects must have a license from the Gosgortekhnadzor of Russia for the right to design lifting structures.

1.5. When developing special projects, the requirements of RD 22-28-35-99 and additional data arising from the specific operating conditions of cranes should be taken into account.

1.6. Trial operation of new designs of elements of the upper structure of the rail track is allowed only on the recommendations of the parent organization ().

2. TERMS, DEFINITIONS AND REGULATIONS
LINKS

2.1. IN This RD uses the following terms and definitions:

rail track - a structure that perceives and transmits crane loads to the base and ensures the safe operation of the crane throughout the entire path of its movement.

Rail track device - preparation, construction and arrangement of the rail track.

Track maintenance - Maintaining the track in working condition.

The lower structure of the rail track - subgrade, providing a given bearing capacity of the soil, and drainage.

Superstructure of the rail track - a set of track structural elements laid on the subgrade, perceiving and transmitting loads from the crane wheels to the subgrade.

Track equipment - devices that ensure the safe operation of the crane (dead ends, switching off rulers, fences, safety signs, etc.).

grounding - electrical connection of the rail track with a grounding device.

Grounding device - a set of grounding conductors and grounding conductors.

grounding conductor - a metal conductor (a group of conductors) in direct contact with the ground.

Ground conductor - a metal conductor connecting the grounded parts of the rail track with the ground electrode.

Drainage - building for water drainage.

Ballast prism - an element of the upper structure of the track, which serves to distribute loads from the crane wheels through the supporting elements to the subgrade.

Subgrade shoulder "a" - horizontal distance from the lower edge of the ballast prism to the edge of the subgrade.

Arm of the ballast prism - distance from the upper edge of the ballast prism to the end face of the supporting element (excluding backfilling).

Lateral arm of the ballast prism " d» - the shoulder of the ballast prism to the end of the half-sleeper or the longitudinal surface of the reinforced concrete beam.

End arm of the ballast prism " dT» - the shoulder of the ballast prism to the longitudinal surface of the last half-sleeper or the end of the reinforced concrete beam.

Support elements - elements (sleepers, half sleepers, beams, slabs) used to transfer the load from the rails to the ballast prism.

Rail "thread" - rails interconnected by bolted connections with pads, perceiving and transmitting loads to the ballast prism from the crane supports along the entire length of the track.

old-time rails - serviceable rails previously used on railways or other industrial facilities.

dead end stop - a device designed to dampen the residual speed of the crane and prevent it from leaving the end sections of the rail track in emergency situations when the movement limiter or the brakes of the crane movement mechanism fail.

Copier (switching bar) - a device that disables the mechanism of movement of the crane when it moves beyond the working length of the path.

Screed - a structural element of the track, installed between the rail "threads" and ensuring the stability of the track gauge.

Longitudinal slope - the difference in the marks of the rail heads, related to the length of 10 m.

Cross slope - the difference in the marks of the rails in the cross section of the track, referred to the track.

The length of the rail "thread" - the total length of the rails.

Working path length - the distance that the crane can move freely along the path during operation without running into the switching rulers.

2.2. This document uses references to normative documents given in.

3. STRUCTURE OF THE RAILWAY

Rice. 1. Path:

A- on wooden sleepers; b- on reinforced concrete beams;
1 - subgrade; 2 - drainage system; 3 - ballast prism;
4 - rail; 5 - half sleeper; 6 - reinforced concrete beam; 7 - coupler;
8 - switching line; 9 - copier; 10 - dead end stop
unstressed type; 11 - an emphasis dead-end shock type;
TO- track; A- width of subgrade;S- the size of the support
elements (across the path axis);
A- shoulder of subgrade;d- side arm of the ballast prism;
h 6- thickness of the ballast prism;h- backfill layer thickness
ballast;h to- depth of the pit;l- distance from edge
ballast prism to the edge of the bottom of the pit;d T - end shoulder
ballast prism;L- the length of the rail "thread" of the track;
L RFP- length of roadbed

The length of the track for the period of crane installation or operation of a fixed crane (without moving it along the track) should be equal to 1.5 times the crane base, but not less than 12.5 m.

3.1. Understructure of the track

The structure of the lower structure of the track includes a subgrade and a drainage system.

3.1.1. The length of the subgrade is taken from the condition of ensuring the working length of the crane path, taking into account the requirements of this document.

3.1.2. The width of the subgrade, mm, (see) is determined by the formula

A³ K+S+ 2(a + d) + 3h d,

Where TO- track, mm;

S- size of the support element across the track, mm;

A- shoulder of subgrade ( A ³ 400 mm);

d- side arm of the ballast prism (d³ 200 mm);

3 h d- the size of two projections of the slopes of the ballast prism with a thicknessh d, mm.

3.1.3. The length of the subgrade, mm, (see Fig. 1) is determined by the formula

L RFP ³ L + 2 d t + 3 h d,

Where L- length of the rail "thread", mm;

d T - end arm of the ballast prism, mm (d t ³ 1000).

3.1.4. The subgrade is allowed to be made completely from bulk soil (the soil must be homogeneous with basic or sandy) or partially from bulk and basic soil.

3.2.3. The thickness of the ballast is determined by calculation from the condition of the strength of the subgrade.

3.2.4. The slopes of the sides of the ballast prism must be made with a slope of 1:1.5.

3.2.5. The top of the ballast prism is made flush with the bottom surfaces of the supporting elements.

The top of the ballast prism after laying the supporting elements (half sleepers) and rails is additionally sprinkled with a layer of ballasthnot less than 50 mm (see).

Ballast specifications

Ballast Prism Material	Particle size	Fraction of particles, mm		Tolerances				Note
				Maximum particle size, mm
					less than normal size	over normal size	sand
Crushed natural stone	Large (normal)							Particles smaller than 0.15 mm should be no more than 2%
quarry gravel
Gravel sorted
	Large and medium							Particles smaller than 0.15 mm should be no more than 10% by weight, including clay no more than 3%
granulated slag								Particles smaller than 0.1 mm are allowed no more than 4% by weight
blast furnace slag							Size up to 3 mm 20-50

Crushed stone under reinforced concrete beams

Sandy under reinforced concrete beams

Crushed stone under wooden half sleepers

with the accepted types of rails and earthen subgrade

sandy

clayey, loamy or sandy

sandy

clayey, loamy or sandy

sandy

200 to 225

225 to 250

250 to 275

275 to 300

300 to 325

3.2.6. The choice of supporting elements is made on the basis of a strength calculation. When the load from the wheel on the rail is up to 275 kN, wooden or reinforced concrete half sleepers are used. With a higher load, it is recommended to use reinforced concrete beams of the BRP-62.8.3 () type, which allow tamping of ballast material under the beam, or slabs.

Rice. 2.Reinforced concrete beam type BRP-62.8.3

The use of other types of reinforced concrete beams, as well as slabs, is allowed upon agreement with the parent organization.

3.2.7. For the path, wooden half sleepers are used, made by sawing into two equal parts of wooden sleepers according to GOST 78.

Half sleepers are made of pine, spruce, fir, larch, cedar.

It is allowed to use half sleepers from logs with hewn surfaces or from wooden beams in accordance with GOST 8486 ().

Half sleepers must have a length of at least 1375 mm and dimensions in accordance with

Rice. 3.Cross section of wooden sleepers:
A- edged; b- unedged; V- timber

Rice. 5.Rail pads with fastening:
A- with the help of screws; b- using crutches

3.2.13. The dimensions of the linings must correspond to the data.

railway crutches according to GOST 5812.

Holes must be drilled for fastening in wooden half sleepers:

diameter 12 mm and depth 130 mm (for crutches);

diameter 18 mm and depth 155 mm (for screws).

Schemes for attaching a rail to a half sleeper are shown on.

Rice. 6.Fastening the rail to the sleeper:
A- screws; b- crutches;
1 - rail; 2 - lining; 3 - half sleeper; 4 - travel screw;
5 - clamp; 6 - crutch

3.2.16. Clamps can be made of normal or lightweight steel grade St3sp4 according to GOST 535 ().

Rice. 7.Clamp:
A- normal; b- lightweight

The dimensions of the clamps for rail types P43, P50 and P65 must comply with the data.

Clamps dimensions, mm

3.2.17. The rails of one "thread" of the track must be connected to each other using two double-headed overlays according to GOST 8193, GOST 19127 and GOST 19128, tightened with track bolts according to GOST 11530 using spring washers according to GOST 19115 and nuts according to GOST 11532 ().

Rice. 8.Double head pads:

A- six-hole; b- four-hole

The dimensions of the overlays must correspond to the data.

Rice. 9.Screed designs:
A- on tracks with wooden sleepers; b- on the way with
reinforced concrete beams; V- fastening of couplers;
1 - screed from the pipe; 2 - screed from the channel; 3 - screed from the corners;
4 - rail; 5 - half sleeper; 6 - reinforced concrete beam; 7 - pad;
8 - clamping bar; 9 - bolt; 10 - screw; 11 - spring washer;
12 - clamp

Tie down dimensions

Track, m	Nominal passage of the pipe, mm	Profile number			Dimensions, mm
		with half sleepers		with reinforced concrete beams		A1 for rail type			B
		channel	corner	channel

3.3. Track equipment

Travel equipment includes:

fencing;

safety signs;

dead ends;

switching rulers (copiers);

trays (floorings) for a cable.

3.3.1. fencing

Path fencing must be carried out in accordance with the requirements of GOST 23407.

It is allowed to use other types of fences if they are provided for by the track design.

3.3.2. Safety signs

Safety signs must be posted along the path in accordance with GOST 12.4.026.

The location of the safety signs must be indicated in the route design.

3.3.3. End stops

3.3.3.1. On each "thread" of the track, shockless or shock dead ends recommended for this size group of cranes should be installed.

3.3.3.2. The dead end stop must be installed on the rail at a distance of at least 500 mm from the center of the last half-sleeper () or from the extreme point of support of the rail on the reinforced concrete beam ().

3.3.3.3. Dead ends that have passed acceptance tests and are recommended by Gosgortekhnadzor of Russia are allowed for operation.

3.3.3.4. End stops must be painted in a bright distinctive color and clearly visible from the crane operator's cab.

3.3.3.5. Dead ends must have passports in the form adopted in RD 22-226.

3.3.4. Copiers (switching rulers)

3.3.4.1. On one of the "threads" of the path in front of the dead ends, copiers (turning off the rulers) should be placed.

3.3.4.2. Copiers (switching rulers) must be installed in such a way that the electric motor of the crane movement mechanism is turned off at a distanceS, not less than the full braking distance specified in the crane passport, to dead ends.

The position of the crane undercarriage for selecting the installation location of the copier (switching bar) in relation to the dead ends at the moment the electric motor is turned off is determined by:

Rice. 12.Path grounding schemes:
A- location of grounding points at the ends of the track;
b- location of grounding points along the track;
1 - ground conductor; 2 - path; 3 - tap; 4 - jumper;
5 - distribution point; 6 - four-wire cable;
7 - grounding point

3.4.3. With a dead-earthed neutral, in addition to the “thread” grounding circuit, the paths are additionally connected to a dead-earthed neutral through the neutral wire of the line supplying the crane.

3.4.4. With an isolated neutral, grounding is carried out by connecting the "threads" of the path with the ground loop of the supply substation or with the device of the ground center.

Rice. 13.Connection diagram of vertical grounding conductors:
1 - ground electrode; 2 - ground conductor

With a short service life of the crane at the facility (up to 3 months), it is allowed to install grounding conductors in the ground without pits. In this case, the length of the protruding part of the ground electrodes must be at least 100 mm.

3.4.8. The ground center must be connected to both "threads" with two conductors.

3.4.9. For grounding conductors and jumpers at the rail joints, round steel with a diameter of 6–9 mm or strip steel with a thickness of at least 4 mm and a cross-sectional area of ​​at least 48 mm 2 should be used.

The use of insulated wires for grounding conductors and jumpers is not allowed.

Welding of jumpers and grounding conductors to the rails should be carried out to a vertical wall along its neutral axis through an intermediate steel plate (). The dimensions of the intermediate plate must be 30´ 3 mm, and the length of the plate must provide a weld with a conductor of at least 30 mm in length.

Rice. 14.Welding of ground conductors and jumpers to rails:
1 - intermediate plate; 2 - jumper; 3 - overlay, 4 - rail;
5 - ground conductor

3.4.10. All connections to the grounding device should be made by overlap welding.

3.4.11. Protruding parts of grounding conductors, grounding conductors and jumpers should be painted black.

3.4.12. When putting the track into operation, it is necessary to check the resistance to current spreading of the grounding device. It should be for a crane powered by a switchgear with a solidly grounded neutral, no more than 10 Ohm, with an isolated neutral - no more than 4 Ohm. The results of measuring the resistance to current spreading of the grounding device must be recorded in the act of putting the track into operation.

If the resistance of the grounding device is more than the indicated values, it is necessary to arrange an additional grounding center or increase the number of grounding conductors.

3.4.13. The track does not require grounding when the crane is powered through a four-wire cable from a separate mobile power station located at a distance of no more than 50 m from the crane track and having its own grounding device. In this case, the neutral wire of the cable must be connected to the rails.

4. DEVICE OF THE RAILWAY

4.1. The device of the subgrade should be carried out after the completion of work related to the laying of underground utilities. It is recommended to use the machines, equipment, tools and fixtures listed in.

4.2. The track area before the start of the construction of the subgrade should be cleared of construction debris, foreign objects and vegetation, and in winter - from snow and ice.

4.3. The layout of the subgrade, as a rule, should begin with areas adjacent to the object under construction or the edge of the excavation.

For planning, excavators on pneumatic wheels with a bucket of 0.25 m 3, excavators-planners on pneumatic wheels with a bucket of 0.4 m 3 or bulldozers of thrust class 3 - 10 tons are used.

4.4. Bulk soil should be laid in layers with mandatory layer-by-layer compaction. The thickness of the compacted layers (from 100 to 300 mm) is indicated in the project, depending on the machines and equipment used for soil compaction.

4.4.1. Dusty and clayey soils should be compacted by rolling or tamping, except for the places where the subgrade adjoins the edge of the pit, where only tamping should be used. Sandy and poorly cohesive soils are compacted by rolling or vibration.

4.4.2. Compaction of the subgrade should be carried out at the optimum soil moisture given in.

4.4.4. The degree of soil compaction should be determined before laying the ballast prism by methods: cutting rings, penetration, radiometric or other.

When arranging a track with wooden half-sleepers, measurements of the degree of compaction are carried out at least every 12.5 m, when arranging a track with reinforced concrete beams - at least at one point under each beam.

4.4.5. Reconsolidation is carried out after the entire width of the subgrade is covered by the traces of previous passes. The previous track must be overlapped by the next by at least 100 mm.

4.4.6. When erecting a subgrade from bulk soil, in addition to the restrictions given in subparagraph, it is not allowed:

carry out backfilling of the subgrade during a snowfall;

compact the soil with watering in winter.

4.4.7. When erecting a subgrade in winter, the time of freezing of the soil at an air temperature of: - 5 ° C - 90 minutes should be taken into account; - 10 °С - 60 min. The intensity of work should exclude the formation of a frozen crust on the previously backfilled layer.

4.4.8. Backfilling and compaction of trenches, ditches and sinuses located on the subgrade of the track must be carried out in compliance with established norms and rules.

4.5. After the work on the subgrade is completed, an Inspection Report for hidden works must be drawn up. The form of the Act is given in.

4.6. The installation of ballast prisms is carried out after the completion of work on the preparation of the subgrade.

4.6.1. When installing ballast prisms (loading, unloading and distribution of material), it is necessary to exclude the possibility of contamination and clogging.

4.6.2. Ballast prisms should be arranged with uniform compaction over the entire area.

For the device of ballast prisms, self-propelled loaders with a carrying capacity of 2 tons, dump trucks, motor graders with a power of up to 80 kW or bulldozers of traction class 3 - 10 are used.T .

4.6.3. Works on the installation of sand ballast prisms in winter should be organized in such a way that the ballast is delivered, laid and compacted until it freezes.

The freezing time of sand ballast is assumed to be the same as that of a pound of subgrade.

4.6.4. Ballast consumptionV B, m 3 , per path device (see) with separate prisms is determined by the formula

V B= 1.2 ´ 2( nl + 2 d T + 1,5h 6)/h 6 (S + 2 d + 1,5h 6),

where 1.2 is a coefficient taking into account the additional consumption of ballast (including for adding material);

2 - the number of separate ballast prisms;

P- the number of links in the path of one "thread";

l- path link length;

1.5 - coefficient taking into account the slopes of the ballast prism.

4.8. Inventory sections of the track are assembled, as a rule, at mechanization bases, less often - directly at the construction site.

Before assembling inventory sections, rails, fasteners and support elements must be checked for compliance with their quality requirements of regulatory documents.

4.9. On the way, a section 12.5 m long with permissible transverse and longitudinal slopes of not more than 0.002 should be provided for the parking of the crane in non-working condition. Near the site you need to put up a sign with the inscription: "Crane parking place."

4.10. Half sleepers must be placed perpendicular to the axis of the rail with the latter fastened to the half sleepers with a full set of track screws or crutches. The ends of the half sleepers should be in a straight line.

4.10.1. Not allowed:

fasten rails to wooden half sleepers with screws without installing clamps;

burn holes in the rails using electric welding.

4.10.2. Rail joints must be bolted with the full number of bolts. The bolts must be lubricated and set with nuts alternately inside and outside the track gauge.

The gap in the rail joint should not exceed 6 mm at a temperature of 0° C and a link length of 12.5 m. When the temperature changes, the clearance tolerance changes by 1.5 mm for every 10 °C.

The displacement of the ends of the joined rails should not exceed 1 mm in plan and in height.

4.10.3. The track size should be checked on each rail link in its middle part and in the area of ​​bolted joints with a steel tape measure with a division value of 1 mm. Deviation of the gauge from the design value should not exceed ±10 mm.

4.10.4. The deviation of the rails from a straight line in terms of a track length of 10 m should not exceed 10 mm.

The straightness of the path is checked by a stretched string or by geodetic methods.

4.10.5. The longitudinal and transverse slopes of the track should be checked by leveling along the rail head with the installation of a rail on each section in the middle part and in the area of ​​bolted joints.

The longitudinal and transverse slopes of the track throughout the entire length should not exceed 0.004.

4.10.6. The edges of the ballast prisms should be aligned parallel to the "threads", ensuring the same slope and the required size of the arm of the ballast prisms throughout the path.

4.11. Dead ends must be installed in such a way that in an emergency the crane runs over two dead ends simultaneously.

5. COMMISSIONING THE RAILWAY INTO OPERATION

5.1. After completing all the work in accordance with Sec. 4, the track should be run in by a crane without a load at least 10 times and at least 5 times with a maximum working load, after which it is necessary to level the track along the rail heads and straighten the sagging areas by tamping ballast under the supporting elements.

List of used regulatory documents

List of machines, equipment, tools and fixtures for the installation and operation of rail tracks

Certificate of inspection of hidden works

Act of delivery and acceptance of the rail track of the tower crane into operation



Safety devices for travel mechanisms

Safety devices that ensure the safety of movement of the crane (cargo trolley) in working and non-working states are supporting parts, movement and skew limiters, anti-theft devices, buffers, anemometers.

Shields must be installed in front of the running wheels of cranes and their trolleys to prevent the possible ingress of foreign objects under the wheels. The largest gap between the guards and the rail must not exceed 10 mm.

To ensure the safety of the operation of cranes controlled from the cab and having a bridge (trolley) speed of 0.5 m/s or more, movement limiters are installed, which, if necessary, automatically turn off the movement mechanism.

Rice. 52. Restrictors of movement

Rice. 53. Installation of movement limiters on two cranes operating in the same span: 1 - limit switch, 2 - extension cord, 3 - bracket, 4 - crane metal structure

The operation of the trolley movement limiter is shown in fig. 52. When the trip bar hits the roller, the limit switch lever turns in the direction of its movement (position II), which causes its contacts to open. After the ruler leaves the roller (when the crane moves in the opposite direction), the lever springs back to its original position I, and the limiter is again ready for operation. Limiters of mutual movement of cranes operating on the same tracks also work.

As a rule, a mechanical type travel limiter consists of a lever limit switch with self-return to its original position and a trip bar. The limit switch of the crane movement mechanism is installed on the crane itself, and the disconnecting line is fixed on the crane track in front of the dead end stop. To limit the travel of the crane trolley when approaching another crane with a bracket attached to it. Disabling the movement mechanism of the last crane is carried out by the device shown in fig. 53.

Rice. 54. Elastic Buffer:
1 - elastic element, 2 - casing, 3 - fixing bolts

The cut-off bar must be installed in such a way that the mechanism is switched off at a distance from the dead-end stop equal to at least half of the braking distance of the machine. Mutual disconnection of the movement mechanisms of overhead (console) cranes approaching each other along one crane runway should be carried out at a distance of at least 0.5 m.

To mitigate the consequences of a possible impact on dead ends or cranes against each other when the crane (trolley) approaches the edge of the track, buffers are designed. Elastic elements - buffers are elastic, spring, spring-friction and hydraulic and are installed on the crane metal structure or trolley frame. The last two types of buffers are used on heavy-duty cranes at high travel speeds. The elastic buffer with a monolithic rubber element has a high elasticity (Fig. 54). Recently, polymeric material has been used as a working element in elastic buffers instead of rubber.

Rice. 55. Spring buffers:
a-for crane trolleys, b-for cranes; 1 - housing, 2 - spring, 3 - stop, 4 - additional concentrically mounted spring

Use as buffers of soft breeds of a tree is allowed. Springs for trolley buffers are made by coiling from round steel wire (Fig. 55, a). In crane buffers, composite (concentric) spring elastic elements are used, which, with the same dimensions, have a large energy intensity (Fig. 55, b).

Anti-theft devices should be understood as mechanisms designed to keep the crane from stealing when exposed to wind pressure, the value of which is regulated by the requirements of GOST 1451-77. These devices are equipped with all cranes having a reserve of holding force of the movement mechanism of less than 1.2 and operating in the open air.

According to the principle of operation, anti-theft devices are divided into locking (latches) connecting the crane with a fixed support using embedded fingers, hooks or retractable stops; stops (pressure type), the action of which is based on the creation of friction forces between the rail and the braked ktsana wheel; tong grips based on direct clamping by the working surfaces of the head of the crane rail. Tick ​​grips are the most widely used.

According to the type of drive, anti-theft tongs are divided into manual and machine grips, and according to the nature of the loading, they are divided into grips with constant and variable braking force and, accordingly, with flat or eccentric working surfaces. The closure of grips with a manual drive is carried out only by force, while the machine drive provides for both forced and automatic closure. Simple in design and reliable in operation, anti-theft tongs with flat working surfaces and constant braking force are shown in fig. 56. The gripper consists of two symmetrical levers (pincers) hinged on axles. The lower ends of the levers are provided with replaceable jaws interacting with the side faces of the rail head, and the upper ends are made in the form of double-sided beams connected with nuts. The latter have right and left internal threads and are connected to the lead screw, during the rotation of which the nuts move translationally along the screw axis in opposite directions, controlling the position of the levers.

There are other designs of anti-theft grips (eccentric, with a hydraulic pusher, etc.).

Rice. 56. Anti-theft grip:
1-crane rail, 2-shackle, 3-levers, 4-end beam, 5-nuts, 6-end switch, 7-right and left-hand screw, 8-chain, 9-sprocket

To prevent possible crane theft by wind, to alert the crane operator with a sound signal about wind speed or pressure dangerous for work, and to automatically turn on the drive of anti-theft devices on gantry cranes with a lifting capacity of more than 8 tons, it is recommended to install special devices - anemometers. The most widely used instrument for measuring wind strength is the signal anemometer of the M-95 type of the Riga Experimental Plant of Hydrometeorological Instruments. The device consists of a sensor (a three-bladed turntable combined with a tachogenerator) installed on the highest part of the crane that is not in the aerodynamic shadow (in a closed zone), and an indexing console (recording device) placed in the cab in the driver's field of vision.

At an acceptable wind speed, its absolute values ​​are recorded on the scale of the instrument. In case of reaching a speed close to the limit, signal lamps turn on on the control panel and the control relay is activated, the contacts of which turn on an audible warning signal and turn off all crane mechanisms. In this case, only the lowering of the load remains possible. In this situation, the crane operator is obliged to stop work, de-energize the crane and secure it with all available anti-theft devices to the rail track.

TO Category: - More about overhead cranes

How does an overhead crane work?

Overhead cranes (Fig. 2.5) are installed in factory floors and warehouses. Bridge 4 The crane moves along the elevated crane track 2, which is laid on columns, so the crane does not occupy the usable area of ​​the room. Overhead cranes for general purposes can have a lifting capacity of 5 to 50 tons and a span of up to 34.5 m.

Rice. 2.5. Overhead crane:

1 - cabin; 2 - crane track; 3 - cargo trolley; 4 - bridge

An overhead crane consists of two main parts: a bridge and a trolley moving along it. 3. The trolley has a lifting mechanism and a trolley movement mechanism. In addition to the main lifting mechanism, an auxiliary mechanism can be installed on the trolley, the carrying capacity of which is 3 to 5 times less than the carrying capacity of the main mechanism.

Crane mechanisms are electrically driven. They provide three working movements of the crane to move the load to any part of the workshop: lifting the load, moving the cargo trolley, moving the bridge.

Cathead is an overhead crane, in which the cargo trolley is an electric hoist. They produce beam cranes with a lifting capacity of up to 5 tons. Such cranes are controlled from the floor using a pendant control panel.

How is a gantry crane arranged?

The gantry crane bridge (Fig. 2.6) rests on the ground crane track 1 using supports 2 and undercarriages 7. Consoles 3 - these are the parts of the bridge protruding beyond the supports, the consoles increase the crane service area. The figure shows a gantry crane with a suspended cargo trolley 5, together with which the control cabin moves 6.

Rice. 2.6. Gantry Crane:

1 - crane way; 2 - support; 3 - console; 4 - bridge; 5 - cargo trolley; 6 - cabin; 7 - undercarriage

Gantry cranes are used for loading and unloading operations in open warehouses. General purpose gantry cranes can have a lifting capacity of up to 60t and a span of up to 34.5m.

How are tower cranes arranged?

Tower cranes (Fig. 2.7) differ in design, type of boom, installation method.

1. By design:

crane with a rotary tower (Fig. 2.7, a);

crane with a fixed tower (Fig. 2.7, b).

2. Arrow type:

crane with a lifting boom (Fig. 2.7, a);

beam boom crane (Fig. 2.7, b).

Rice. 2.7. Tower cranes:

a - a crane with a rotary tower and a lifting boom; b - a crane with a fixed tower and a beam boom; 1 - frame; 2 - turntable; 3 - platform; 4 - counterweight; 5 - tower; 6 - cabin; 7 - arrow; 8 - undercarriage; 9 - console; 10 - head; 11 - cargo trolley

3. According to the installation method:

stationary crane;

mobile crane (see Fig. 2.7, a, 6).

Tower cranes perform four working movements: lifting and lowering the load, changing the reach, turning the crane, moving the crane.

Turntable 3 turret cranes rests on the running frame 1 with slewing device 2. Tower 5 with boom 7, counterweight 4 and crane mechanisms. The rotary part of cranes with a fixed tower includes a head 10 with boom and console 9 counterweight. For cranes with a lifting boom, the reach is changed by turning (raising) the boom relative to the support hinge. For cranes with a girder boom, the outreach is changed due to the movement of the cargo trolley 11 on a fixed boom.

Mobile tower cranes move along the crane tracks with the help of undercarriages 8. Cranes with a lifting height of more than 70 m are made stationary (attached), they are installed on the foundation and fixed to the building under construction.

At present, tower cranes with a lifting capacity of 5 ... 12 tons are mainly used in construction. The lifting height of some mobile cranes can reach 90 m, and of attached 220 m.

How are jib cranes arranged?

All jib cranes (Fig. 2.8) have their own source of energy (power plant) - a diesel engine, so they can work where there is no electricity.

Rice. 2.8. Jib cranes:

a - truck crane; b - crawler crane; c - crane on a special chassis; g - pneumatic wheel crane; 1 - arrow; 2 - hydraulic cylinder; 3 - platform; 4 - turntable; 5 - running frame; 6 - outrigger; 7 - tower-boom equipment; 8 - goose; 9 - drawers

The boom 1 of such cranes is pivotally mounted on a turntable 3, which, with the help of a turntable 4 is placed on the undercarriage 5. The crane mechanisms are placed on the turntable: the mechanism for lifting the load, the mechanism for changing the departure, the rotation mechanism. Heavy duty cranes can be equipped with main and auxiliary lifting mechanisms.

Truck cranes (Fig. 2.8, a), cranes on a special chassis (Fig. 2.8, V), short-base cranes are the most mobile, they move along roads in the transport position, but they can only lift cargo on outriggers.

Tracked (Fig. 2.8, b) and pneumatic wheels (Fig. 2.8, G) cranes can move around the construction site with a load on the hook, while the load capacity of pneumatic wheel cranes is approximately 2 times less than on outriggers.

Jib cranes differ in the design of jib equipment and the type of mechanism drive.

1. According to the design of the boom equipment, cranes are distinguished:

with flexible suspension of boom equipment (see Fig. 2.8, b, d);

rigid suspension of boom equipment (see Fig. 2.8, a, c).

2. According to the type of mechanism drive, cranes are distinguished:

with electric drive mechanisms;

hydraulically driven mechanisms.

The jib of flex-suspension cranes is held and tilted by ropes. In this case, a lattice boom is used. To increase the service area, the boom is supplied with a jib 8 or tower-boom equipment is used 7.

The boom of rigid suspension cranes is held and tilted by hydraulic cylinders 2. In this case, a telescopic boom is used, consisting of a main section and two to four retractable sections. 9. Changing the reach of cranes with rigid suspension is carried out by changing the angle of the boom, as well as by extending the boom sections (telescope).

Crawler and pneumatic wheel cranes usually have an electric drive of mechanisms and flexible suspension of boom equipment. The hydraulic drive of mechanisms and the rigid suspension of boom equipment are used by truck cranes, short-base cranes and cranes on a special truck-type chassis.

What devices and safety devices ensure the safety of cranes?

load limiter;

limiters of working movements for automatic stop of lifting mechanisms of the load-handling body in its extreme upper and extreme lower positions, change of departure, movement of rail cranes and their cargo carts;

limiters of working movements for automatic shutdown of crane mechanisms at a safe distance from the wires of power lines (power lines). Mounted on jib cranes;

crane operation parameter recorder;

coordinate protection to prevent collision with obstacles in cramped working conditions. Mounted on jib and tower cranes;

sound signal;

load capacity indicator corresponding to the reach;

crane inclination indicator (inclinometer). Installed on jib cranes;

anemometer - a wind speed indicator that automatically turns on a sound signal when a wind speed is reached that is dangerous for the operation of the crane. Mounted on tower, gantry and gantry cranes;

anti-theft devices. Are established on the cranes moving on a crane way in the open air. As anti-theft devices, rail grips and wedge stops are used.

In what case does the load limiter turn off the crane mechanisms?

All cranes boom type equipped with a load limiter (load moment), which automatically turns off the mechanisms for lifting and changing the departure. Shutdown occurs when a load is lifted, the mass of which exceeds the carrying capacity for a given departure:

more than 15% - for portal cranes and tower cranes with a load moment up to 20 t m inclusive;

more than 10% - for jib cranes and tower cranes with a load moment of more than 20 t m.

Cranes bridge type equipped with a load limiter if it is possible to overload them according to the production technology. The load limiter of such cranes should not allow an overload of more than 25%.

After the load limiter has actuated, it is possible to lower the load and reduce the overhang.

How does the lift stopper work?

The limiter of the load lifting mechanism is designed to automatically stop the mechanism in the extreme upper position of the load gripping body.

Rice. 2.9. Crane safety devices:

a - limiter of the lifting mechanism; b - load capacity indicator; 1 - hook suspension; 2 - cargo; 3 - limit switch; 4 - arrow; 5 - scale; 6 - arrow

The limiter is a limit switch 3 (Fig. 2.9, A), the electrical contacts of which are closed under the weight of a small load 2. Moving up, hook suspension 1 lifts the load, opens the electrical contacts of the limit switch, as a result of which the engine of the lifting mechanism is turned off.

The lifting device must stop at a distance of at least 200 mm to the stop. After the automatic stop of the mechanism when working on the rise, it can be switched on for lowering.

How to determine the lifting capacity of a jib crane depending on the reach?

According to the production instructions, the slinger must be able to determine the load capacity of the jib crane from the index, depending on the reach and position of the outriggers.

On cranes with flexible suspension of boom equipment, the load capacity indicator (Fig. 2.9, b) installed at the bottom of the boom 4. Such a pointer has an arrow 6, which is always in a vertical position, regardless of the angle of the arrow. The arrow indicates the value of the load capacity on scale 5 corresponding to the given reach and the position of the outriggers.

Modern jib cranes with a rigid suspension of jib equipment have a load capacity indicator, which is located in the crane operator's cab. In this case, the slinger must clarify the lifting capacity of the crane at a given reach from the crane operator.

What are the load handling units?

Lifting bodies - These are devices designed to suspend or grab a load. The most common of these are hook, grab, electromagnet. Depending on the type of lifting body, cranes are distinguished:

hook;

clamshell;

magnetic.

No slingers are required to service grab and magnetic cranes.

How are the load hook and hook suspension arranged?

cargo hook (Fig. 2.10) is designed for hanging loads using removable load gripping devices, such as slings, which are placed in its mouth 1. Safety lock 2 keeps the slings from spontaneous falling out of the pharynx.

Hooks are made of mild steel (steel 20), which is ductile, not prone to brittle fracture under load. According to the manufacturing method, hooks are of the following types: forged, stamped, lamellar.

Cranes with a lifting capacity of more than 30 tons are equipped with a two-horned hook (Fig. 2.10, b) having two gaps to accommodate a larger number of slings.

Rice. 2.10. One-horned (o) and two-horned (b)cargo hooks:

1 - pharynx; 2 - lock; 3 - shank; h- working section height

Rice. 2.11. Hook suspension:

1 - rope; 2 - cheek; 3 - block; 4 - axis; 5 - nut; 6 - bearing; 7 - traverse; 8 - hook

hook suspension shown in fig. 2.11. It connects hook 8 with cargo ropes 1 crane. The suspension consists of two cheeks 2 connected by bolts. The axle is located at the top of the suspension 4 rope blocks 3, in the lower part - traverse 7, on which the hook is installed.

The crane hook is mounted on a thrust bearing 6, which allows it to rotate and eliminates the twisting of the cargo ropes when moving the load. The hook fastening nut 5 must be reinforced with a locking bar to prevent spontaneous screwing.

Crane operation is not allowed with the following hook failures:

cracks and tears on the surface of the hook;

the hook does not rotate;

the safety lock is missing or defective;

the hook is unbent;

jaw wear is more than 10% of the original height h (see Fig. 2.10) of the working section of the hook.

How are lifting electromagnets arranged?

Lifting electromagnets are designed to move rolled ferrous metals, pig iron, shavings, scrap metal and other goods with magnetic properties.

Lifting electromagnet (Fig. 2.12) is suspended using chains 4 on the crane hook. In case 1 electromagnetic coils 2 are located, to which a direct electric current with a voltage of 220V is supplied through cable 3. The electric current creates a strong magnetic field that holds the load.

ATTENTION! As load-handling devices, electromagnets are not sufficiently reliable due to a possible power outage, therefore, when using them, additional safety measures are necessary.

What are the grabbers?

grapple - this is a double-jaw or multi-jaw bucket for moving bulk, large-sized cargo and round wood. Grabs differ in design and type of drive.

1. By design, the following types of grabs are distinguished:

double-jaw, designed for bulk cargo (Fig. 2.13);

multi-jaw, designed for large-sized cargo and scrap metal;

three- and four-fingered, designed for round wood.

2. According to the type of jaw locking mechanism drive:

rope (see Fig. 2.13);

motor.

Grabs with rope lock jaws are single-rope and double-rope. double rope grabs are installed on grab cranes, which are designed to handle large volumes of bulk cargo.

Rice. 2.12. Lifting electromagnet:

1 - body; 2 - coil; 3 - cable; 4 - chain

Rice. 2.13. Double jaw rope grab

single rope grabs are used in the case of moving small volumes of bulk cargo, for example, in construction. Such a grab is hung on a crane hook and is a removable load-handling device.

Each grapple must be provided with a plate indicating the manufacturer, number, volume, dead weight, type of material for which it is intended, and the maximum allowable weight of scooped material. If the plate is lost, it must be restored. The mass of the grab with the load must not exceed the lifting capacity of the crane at the working reach.

How is a rail crane track arranged?

For tower, gantry and other rail cranes, a rail track is laid (Fig. 2.14) on a prepared subgrade with drainage grooves 1. The crane track consists of a ballast layer (prism) 2, wooden or reinforced concrete sleepers 3 and rails 4. The rails are attached to wooden sleepers with crutches or travel screws, and to reinforced concrete sleepers - with bolts and nuts. At the joints, the rails are connected by overlays 7.

Dead ends 6 are installed at the ends of the track, preventing the crane from derailing. In front of the dead ends, switch-off lines 5 are fixed, designed to automatically stop the crane movement mechanism.

Rice. 2.14. Crane way:

1 - groove; 2 - ballast layer; 3 - sleeper; 4 - rail; 5 - switching ruler; 6 - dead end stop; 7 - overlay; 8 - jumper

Crane operation is not allowed with the following malfunctions of the crane tracks:

cracks and punctures of rails;

absence, destruction or incomplete set of fasteners;

fracture, transverse cracks, rot in wooden sleepers;

solid girdle cracks, exposure of reinforcement in reinforced concrete sleepers;

absence or malfunction of dead-end stops;

faulty grounding of the crane track.

What is protective earth? How does it protect a person?

Protective earth is the intentional connection of an electrical installation housing to a grounding device. Grounding is necessary to protect the operating personnel, since in the event of a violation of the insulation of parts of the electrical installation that are energized, the body of the electrical installation is also energized.

In three-wire electrical networks (Fig. 2.15, A) electrical installation housing 1 connected with ground wire 2 with grounding device. Electrical resistance of the human body R 4 not less than 1000 Ohm. Electrical resistance to earth R 3 should be no more than 4 ohms. In this case, a person who touches the body of the electrical installation under voltage will be connected in parallel to the low electrical resistance of the protective earth. The current strength is inversely proportional to the resistance, so a current will flow through the body that is not dangerous to human life and health.

Rice. 2.15. Schemes of a protective earthing device in a three-wire (a) and four-wire(b)electrical networks:

1 - electrical installation; 2, 3 - conductors; 4 - neutral wire

When the electrical installation is connected to a four-wire network (Fig. 2.15, b) with grounded neutral wire 4 the body of the electrical installation is connected to this wire with a conductor 3. This method of protective grounding is called zeroing. In this case, the breakdown on the body turns into a short circuit, in which the fuse is activated, the damaged circuit opens, preventing a person from being injured.

How is a crane earthed?

At rail cranes, the crane runway is grounded. All rails are connected with steel jumpers 3, 4 (Fig. 2.16) by welding. Crane way is connected to grounding conductors 6 at least two grounding conductors 5. Grounding conductors are steel pipes or corners driven into the ground. When connected to a four-wire network, the crane track is also connected with a steel conductor 7 to the switch body 1, energizing the crane.

Electric jib cranes must be grounded when connected to an external electrical network. To do this, the neutral wire of the supply cable is connected to the crane body.

ATTENTION! In the event of a malfunction or lack of grounding, the slinger, touching any part of the crane, may be under the influence of an electric current.

Rice. 2.16. Protective grounding of the crane:

1 - knife switch; 2 - cable; 3,4 - jumpers; 5.7 - conductors; 6 - grounding

Why does the slinger need to know the location of the switch that supplies voltage to the crane?

In the event of a fire on the crane, the slinger must turn off the power supply. It is also necessary to de-energize the electrical equipment when a person gets under the influence of electric current.

Knife switch (circuit breaker) 1 (see Fig. 2.16) is located at the point of connection of the crane to the electrical network.

18.01.2017 27.01.2018

Greetings to all lovers of the wonderful program Adobe Photoshop!

Often, when working in a program, it becomes necessary to measure the exact distance from an object to an object, draw a rectangle with sides of a certain size, place a photo at a given distance, etc. For such purposes, Photoshop has Ruler tool. Not to be confused with ruler tool, which is located in side toolbar!

How to turn rulers on and off in Photoshop

Turn on Ruler tool) in two ways: press the keyboard shortcut ctrl + R or go to the menu View-Rulers.

A new mini panel with a scale will appear on the left and at the top:

To hide the ruler scale, click again. ctrl + R.

How to change scale units

By default, the unit of measure will be centimeters. To change the scale units, right-click on ruler panels and select the desired unit of measure from the drop-down menu:

You can change the gradations of the scale by going to the menu Editing-Settings-Units and rulers (Edit-Preferences-Units & Rulers):

The following settings window will open:

The same window can be opened by double-clicking the ruler scale with the left mouse button:

How to add a guide

We have already learned how to add rulers, but how will they help us in placing objects or drawing a rectangle, you ask? In order not to get lost in a huge number of dashes on the ruler, Photoshop has provided another useful feature - Guides (Guide). Guides are of two types - Horizontal and Vertical.

There are several ways to add a guide. The simplest - with any active Photoshop tool, move the mouse to ruler scale, and drag the mouse button from top to bottom to add Horizontal rail, and from left to right to create vertical guide. Release the mouse button at the required mark. Here's what the guides look like on the canvas:

You can also add a guide through the menu View-New Guide (View-New guide):

The following window will appear in which you can select the location guide and enter the numerical values ​​of its position:

So we learned how to enable rulers in Photoshop. It wasn't difficult, was it?

Movement limiter. The travel limiter consists of a limit switch mounted on the crane undercarriage and a switch-off device in the form of a ruler or stop installed on the crane track. The operation of the limiters is shown in fig. 101. When the crane moves in the direction shown by the arrow, the limit switch lever is turned by the disconnecting device, as a result of which the switch contacts open the electrical circuit.

The design of the disconnecting device depends on the type of limit switch.

Rice. 101. Limiters of movement: a - with a shutdown ruler, 6 - with a shutdown stop; 1 - limit switch KU-701, 2 - ruler, 3 - limit switch ku-704, 4 - stop with limit switch KU-704,

Disconnect line 2 (Fig. 101, a) is used with the KU-701 limit switch, which has a return device, under the action of which the switch lever, being removed from the working position, returns to this position after the load is removed. The shut-off stop (Fig. 101, b) is used together with one that does not have a return device. The lever of this switch can be in three positions: working and two disabled. The lever rotates to the off position and returns to working when the crane moves back with the help of a stop.

The regulation of the limiters of movement consists in the installation of disconnecting rulers or stops.

Rice. 102. Turn limiters: a - with a drive limit switch, b - with a lever limit switch and a toggle plug; 1 - turntable, 2 - crown of the turntable, 3 - gear, 4 - limit switch VU-250, 5 - bracket, 6 - rotary part of the crane, 7 - limit switch KU-701, 8 - fork, 9, 11 - screw clamps, 10 - fixed part of the crane, 12 - limit switch lever

Turn limiter. In the turn limiter shown in Fig. 102, a, a VU-250 limit switch is used, the shaft of which, through a gearbox built into the switch (with gear 1-50), is connected with the gear rim 2 of the slewing ball circle using gear 3. The limit switch is mounted on a bracket to the 1" turntable. The rotation of the crane causes the shaft of the limit switch to rotate and the switch contacts to open when the shaft reaches a certain position. The limiter is adjusted by changing the position of the cams in the switch

VU-250. Such turn limiters are installed on most cranes of the KB series.

On a number of cranes, a rotation limiter is used (Fig. 102, b), which consists of a lever limit switch 7 mounted on the rotary part 6 of the crane, and a fork 8 pivotally mounted on the non-rotary 10 part of the crane. When the crane is turned to the right, the lever 12 of the limit switch runs into the inclined plane of the fork, turns and the contacts of the limit switch open. When turning to the left, the limit switch lever, after turning the valve 360 ​​°, enters the fork, turns it into the position indicated in fig. 102, b with a dotted line, and goes further until returning to its original position (through 360 °). With further rotation of the crane to the left, the lever runs into the inclined plane of the fork and the limit switch opens the electrical circuit.

The limiter provides the possibility of two turns of the crane from its original position. The limiter is adjusted by setting the level of the fork using screw clamps 9 and 11.

Limiters of a way of the cart and an angle of an inclination of an arrow. On cranes with a cargo trolley, the departure limiter is usually performed using the VU-250 limit switch, the shaft of which is connected by a chain drive to the gearbox shaft of the cargo trolley. On a number of cranes, the departure limiter is designed similarly to the crane travel limiter, with limit switches installed on the boom at the beginning and end of the trolley movement, and the shut-off stop is installed on the trolley itself.

On cranes with luffing jibs, the reach limit switch is connected to the boom in various ways and is activated when the boom reaches the maximum or minimum working reach.

Rice. 103. Structural diagram of the departure limiter-indicator: 1 - roller, 2, 4 - limit switches, 3 - cams, 5 - graduated scale, 6 - arrow, 7 - lever, 8 - thrust, 9 - drive, 10 - boom bracket

In some cases, the departure limiter is combined with the departure indicator (Fig. 103). The roller 1 of the limiter through the lever 7 and the rod 8 is connected to the boom bracket 10. In the extreme positions corresponding to the minimum and maximum reach, the cams 3 mounted on the roller turn off the limit switches 2 or 4. The arrow 6 connected to the roller indicates the reach on a graduated scale 5. Adjust limiter, changing the length of the rod 8 with the help of the spur 9.

Lift height limiter. These limiters are installed on the crane so that after the winch stops when lifting without a load, the gap between the hook suspension and the boom or trolley structure is at least 200 mm. The operation of the lift height limiter is usually based on the fact that the hook suspension rests against a load (or shackle) connected to the limit switch lever, either directly or using a rope and pull-back blocks.

Rice. 104. Lifting height limiter: a - for cranes with lifting booms, b - for cranes with cargo carts; 1 - limit switch, 2 - limiter rope, 3 - earring, 4 - load, 5 - guide bracket, 6 - cargo rope, 7, 13 - hook suspension. S - limit switch, 9 - blocks, 10 - limiter rope, 11 - cargo trolley, 12 - limiter load

The lifting height limiter, used on cranes with lifting booms (Fig. 104, a), consists of a limit switch 1 and a load 4 with two guide brackets 5, into which the branches of the cargo rope 6 are inserted. The load is connected to the lever through the earring 3 and the rope 2 limit switch. In the normal position of the load, the switch contacts are closed. When the hook suspension rests against the load and lifts it, the limit switch lever released from the load turns under the action of its own spring and opens the contacts.

In the crane height limiter with a cargo trolley (Fig. 104, b), the load 12 of the limiter is suspended on a rope or chain to the cargo trolley and connected with a rope 10 of small diameter with a limit switch 8. One end of the rope is mounted on the head section of the boom, and the other - on the switch lever. The rope is passed through a system of deflecting and guiding blocks 9 installed on the boom, trolley and load. Such a reeving system ensures the tension of the rope and, consequently, the working position of the limit switch lever during the movements of the cargo trolley. The limit switch 8 can be installed on the boom or in any other place of the crane metal structure.