Minimum distance between supports for crane rails. Types of rails for crane tracks

Railroad tracks are used to move tower crane and are part of its structure, consisting of the lower and upper buildings.

Rail tracks can be temporary or permanent structures. Temporary rail tracks are laid under tower cranes used in the construction, reconstruction or repair of buildings. Permanent rail tracks are designed for cranes used at manufacturing enterprises of construction and installation organizations, assembly or storage sites.

The following depend on the technical condition of the rail tracks: the safety of the crane, labor productivity and the pace of construction and installation work, the reliability and service life of the main components of the crane undercarriage, the provision of high-speed and braking modes of operation of the movement mechanism, the resistance to movement of the crane and the associated energy consumption.

Design rail tracks and their technical condition have a significant impact on the operation of the crane and on the organization of work at the construction site, landfill, warehouse, manufacturing plant.

The lower structure of the rail track consists of subgrade and devices for water drainage.

Ground cloth. The subgrade is a flat area, made mainly of soil. It should provide sufficient strength and stability (invariability of shape under the influence of loads, precipitation and other factors), have a relatively low cost of construction and operation, while maintaining the required quality of the base.

All earthworks are carried out before the construction of the subgrade at the construction site, and underground communications are laid in the area of ​​the rail track. Then the construction site is cleared of debris, unnecessary building materials, ice, snow and foreign objects, and then removed upper layer soils with vegetation cover (turf).

The dimensions of the subgrade depend on the brand and size of the crane - on the size of the track and the pressure on the running wheel (Fig. 1-3). Specifications for the most common tower cranes are given in Table 1.

Fig.1. Rail track subgrade profile at the building

a - with a track up to 5000 mm; b - with a gauge of more than 5000 mm; A - track gauge; B - distance from the protruding part of the building to the axis of the first rail; B - subgrade width

Fig.2. Profile of the subgrade of the rail track at the slope of the excavation

a - with a track up to 5000 mm; b - with a gauge of more than 5000 mm; h is the depth of the pit; l - distance from the edge of the bottom of the pit to the inner edge of the ballast prism; B - subgrade width

Fig.3. Rail track profile on wooden sleepers

a - with a track up to 5000 mm; b - with a track up to 5000 mm with a side railing of the ballast prism; c - with a gauge of more than 5000 mm; d - with a track up to 5000 mm when arranging a track at the edge of the pit; e - with a gauge of more than 5000 mm when arranging a track at the edge of the pit; 1 - building wall; 2-ditch; A - track track; B is the distance of the path from the protruding part of the building to the axis of the first rail; D - the width of the prism on top; l - distance from the edge of the bottom of the pit to the inner edge of the ballast prism; h is the depth of the pit; h- height of the ballast layer

Table 4

Wooden supporting elements, together with other parts of the upper structure of the track, absorb and soften the dynamic and vibration loads that occur in the nodes and mechanisms of the crane during its operation, preventing from increased wear and premature destruction.

Support elements are widely used in construction:

from separate (placer) wooden sleepers (half sleepers);

from inventory links assembled from separate wooden sleepers (designed by A.I. Alperovich);

from wood-metal frames of the former trust Mosstroymekhanizatsiya N 5 Glavmosstroy;

from reinforced concrete beams of trapezoidal section of the structures of the trusts Stroymekhanizatsiya Glavvolgovyatskstroy of the USSR Ministry of Construction (Gorky) and Stroymekhanizatsiya N 2 (Ufa), etc.

It is recommended to mainly use inventory links crane runways on wooden sleepers, wood-metal frames and on reinforced concrete beams, since these types of tracks have been tested by many years of practice and, in comparison with other designs, are the most reliable in operation. However, the recommended options cannot be considered optimal in terms of efficiency.

The desire to save expensive and scarce wooden beams and metal, as well as to increase the service life of supporting elements, has led various organizations and individual specialists to develop and implement reinforced concrete elements instead of wood and wood-metal ones.

A number of new types of crane runways have been developed on reinforced concrete (sleepers, blocks, bed beams, rigid and flexible frames, slabs) and wood-reinforced concrete (frames) supporting elements.

Rail fasteners. Rail fasteners include linings, linings, clamps, crutches, screws, bolts, nuts and washers.

As you know, the stability of the entire crane runway depends on the quality of the rail joint. The gaps in the joints of the rails cause increased dynamic loads of all crane nodes, increase the resistance to its movement and contribute to the rapid wear of the running wheels. Therefore, it is necessary to strive to reduce the number of joints and reduce the gaps between joined rails. On railway tracks, rail joints are suspended, i.e. between sleepers. Such a joint has greater elasticity and provides the best conditions for the interaction of the wheel with the rail, including reducing impact loads wheels on rails.

The practice of operating rail tracks for tower cranes has shown that the location of the joint above the supporting element (above the sleeper) ensures its more stable operation in accordance with SN 78-73. The loads on the wheels of cranes, and, consequently, on the joint, are several times higher than the loads from locomotives on the railway, while the speeds of movement at cranes do not exceed 32 m/min, therefore, analogies in the arrangement of joints at crane tracks and at the railway track cannot be drawn.

The rails are joined together, as a rule, by standard two-headed rail pads (Fig. 6). It is allowed to use apron linings for joining rails R38 and R43 (Fig. 7).

Fig.6. Double-headed pads

a - for rails R38, R43 and R50; b - for R65 rails

Fig.7. Apron pad for rails R38 and R43

To fasten rail joints with standard railway linings, bolts with a reduced hexagonal head and a guide subhead, hexagon nuts of normal accuracy and spring washers are used.

For fastening rail joints with aprons, travel bolts and nuts made of mild steel are used. Tower cranes of types KB and MSK have unified undercarriages equipped with rail anti-theft clamps of the vise type with jaws permanently brought under the rail head, which cannot work on crane tracks where the rails are joined by standard railway slips.

To connect the rails on the tracks for these cranes, special, non-standard butt slips-clamps such as NIIMosstroy, VNIIStroydormash (Fig. 8-12) or other structures manufactured by construction organizations, and not by manufacturers, are used.

Fig.8. Butt joint of R43 rail with anti-theft pads

a - with a welded anti-theft fork; b - with anti-theft plates; 1 - left and right lining; 2 - hairpin; 3 - anti-theft fork; 4 - rail; 5 - nut; 6 - connecting finger; 7-washer; 8- anti-theft plate

Rice. 9. Details of butt straps-clamps

Fig.10. Details of butt straps-clamps temporarily allowed for use

a - overlay; b - connecting finger; c - hairpin; g - anti-theft plate

Fig.11. butt clamp

1 - base; 2 - clamp; 3 - hairpin; 4 - nut; 5 - spring washer

Fig.12. Upgraded butt clamp

1 - clamp base; 2 - emphasis; 3 - clamp; 4 - washer; 5 - nut; 6 - hairpin

Since non-standard pads have their own dimensions for each type of rail, operating organizations with a diverse fleet of tower cranes have to manufacture several clamp options, different in width, height and groove depth. Such pads are complex and time-consuming to manufacture, expensive, and most importantly, they do not provide reliable operation of the rail joint, which sometimes leads to an accident due to a violation of the rail joint. In addition, the details of the joint are weakened in the overlays-clamps; the shift of the rails in relation to the supporting elements when the wheels run over the joint is carried out in the longitudinal plane, therefore, the gap between the rails increases (theft of the rail); the shift of the rail heads relative to each other is carried out in the vertical and horizontal planes; there are cases of destruction (pricking out) of the sole of the rail; the joint of the elements with the rail is fragile; the design of reinforced concrete supporting elements is complicated.

Temporary use of clamp pads on the tracks for tower cranes of the KB series is allowed until the vice grips on their undercarriages are replaced with more advanced ones that allow the use of standard railroad pads. For these purposes, it is recommended to replace the vice clamps with TsNIIOMTP semi-automatic rail structures (Appendix 1), which enable cranes of the KB and MSK types to work on tracks where the rails are joined by standard railroad overlays and at the same time are in constant engagement with the rail head.

Currently, some construction organizations use folding screw grips instead of anti-theft grips of the vise type, similar to grips on BKSM-type cranes installed at the ends of the undercarriage, and the rails are joined with standard railway linings. Other organizations use the vises open to fit through standard-type two-headed rail plates, or remove them without replacing them so that the rails can be joined with standard rail plates.

However, none of these types of grips has been widely used for the following reasons:

1. In case of local subsidence of the track, as in the case of dynamic overload of cranes of types KB and MSK, the crane undercarriages slightly break away from the rail (by the value of the flange of the running wheel) and the flange disengages from the rail head, at this moment the trolley may turn around in relation to vertical axis or one of the wind vanes (on cranes of types MSK-10-12 and MSK-7-25, where not all wind vanes are fixed by rods to the running frame). Such a turn leads to the derailment of the crane and, consequently, to its fall.

2. When removing the vice grips and the absence of any other grips, the crane is not protected from wind hijacking, which is a violation of the "Rules for the Construction and Safe Operation of Hoisting Cranes" of Gosgortekhnadzor.

3. Vise grips, working with a constant pickup under the rail head, protect the crane from tipping over during overloads and subsidence of the track, since at the moment of stability violation, the grip through the rail head connects the crane runway as additional ballast. When replacing vice grips with folding ones, this advantage is lost.

For a more uniform distribution of pressure from the rail to the supporting element (sleeper, bed, block, slab), flat metal pads should be installed under the rails. Linings also serve to protect the sleeper from premature wear and enhance the fastening of the rails to the supporting elements. It is allowed to install rails on sleepers without lining when arranging tracks for cranes in which the pressure on the running wheel does not exceed 150 kN.

The designs of fasteners used to connect rails to support elements are very diverse and depend on the type of support elements. The most widely used for fastening rails to wooden sleepers are track screws with clamps (Fig. 13, a and b) and railway crutches (Fig. 13, c). The same elements are often used to attach rails to reinforced concrete support elements with wooden dowels. Linings used for fastening rails with sleepers with track screws and crutches are shown in Fig.14. The technical characteristics of the pads are given in tables 6 and 7.

Fig.13. Fastening rails with sleepers.

a - travel screws on a solid lining; b - the same, on two separate linings, c - with crutches, 1 - rail, 2 - travel screw; 3 - clamp; 4 - lining; 5 - sleeper; 6 - crutch

Rice. 14. Linings for attaching the rail to the sleepers

a and b - travel screws; c- crutches

Table 6. Specifications of pads for fastening the rail to the sleepers with travel screws (GOST 809-71)

Table 7

It is allowed to produce a lining with additional holes for fastening two types of rails, as shown by the dotted line in Fig. 14, a and c.

These pads can be replaced with strip steel pads (Fig. 14, b). Such linings are installed two for each sleeper.

When using railway pads, it is recommended to pre-cut the sleepers to ensure the vertical position of the rail axis (Fig. 15). According to SN 78-73, it is allowed to use railway linings without sewing up the sleepers or preliminary removing the slope.

Fig.15. Installation of the railway lining

1 - railway lining; 2 - rail; 3 - half sleeper

The rails are attached to the supporting elements using various clamps, brackets, bolts, embedded parts, welding, spring or other special fasteners.

Clamps are shown in Fig. 16, and their technical characteristics are given in Table 8.

Fig. 16 Clamps for fastening the rail to the sleepers with screws

a - normal; b - lightweight

Table 8 Technical characteristics of clamps for fastening rails to sleepers with travel screws

Note. The numerator gives the dimensions of the clamping performed according to Fig. 16, a, in the denominator - according to Fig. 16, b

No less common are embedded bolts and other fastenings of rails with reinforced concrete, metal and mixed (wood-metal, wood-reinforced concrete) supporting elements.

When fastening the rails to the supporting elements with the help of embedded bolts and screws, the vibration of the linings is reduced to a minimum, reliable pressing of the linings to the rails is ensured, and it becomes possible to adjust the position of the rails in height up to 15 mm by laying a set of steel plates of variable thickness between the rail sole and the lining.

Ballast layer designed to ensure the stability of rails and supporting elements under the action of vertical and horizontal loads (including transverse), uniform distribution and elastic transfer of them through the supporting elements to the subgrade.

The following materials are used as a ballast layer in the construction of rail tracks - sand, crushed stone, metallurgical slag, sorted and quarry gravel. (Tables 9 and 10).

Table 9. Granulometric composition of ballast materials and impurity norms

Table 10. Physical and mechanical properties of ballast materials

Notes: 1. The mechanical strength test of ballast materials is carried out on one of the drums. 1. Frost resistance tests are carried out only in cases where water absorption exceeds the norm.

It is not allowed to use granular slag for the ballast layer that has not passed the test for lime and iron decay. The slag basicity modulus M must be less than one.

If a sand-gravel or sand-gravel mixture is used for the ballast layer in a ratio of 1:1, sand of a finer fraction than indicated in Table 9 can be used.

To determine the quality of the ballast material, it is necessary to conduct control tests of samples for particle size distribution and purity of the ballast (percentage of impurities and small particles). Depending on the material of the ballast, such tests must be carried out by the methods specified in the technical specifications.

With the correct interaction of the base of the rail track with the ballast layer, its density should be equal to the density of the main subgrade area. The ballast layer laid on the subgrade, made of soil with non-standardized density (rocky soil, etc.), is compacted to the standards given in Table 2. The density of the ballast layer is checked by the same methods and devices as the density of the earth foundation of the track.

To ensure a given density, ballast materials are laid in layers no more than 200 mm thick, which are evenly (as they are laid) compacted. In the summer, each layer of sand is additionally compacted with a sprayed water jet.

The ballast layer is usually laid so that a prism is formed in the cross section. The dimensions of the ballast prism depend on the design parameters (see Fig. 3) and on the technical characteristics of the crane given in tables 11 and 12.

Table 11

Note. When installing separate prisms, their width is taken equal to 1750 mm.

Table 12. The size of the ballast prism and the consumption rates of ballast materials for the installation of one track link on reinforced concrete beams and slabs

Notes: 1. When installing separate prisms, their width is assumed to be 1200 mm, the height of the ballast layer of sand, granulated slag, gravel and crushed stone is at least 100.

2. The ballast consumption is given taking into account the partial layout of the base.

To maintain the given shape and dimensions of the track, it is not allowed to lay a ballast prism on an unprepared subgrade. When installing a ballast prism, it is necessary to observe certain slopes of its sides: for sand and granulated slag 1:2-1:3; for crushed stone and gravel 1:1.5.

When constructing a track on bulk soil in cramped conditions and in areas with strong winds, the sides of the ballast prism are fenced (see Fig. 3, b).

The electronic text of the document has been prepared

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Crane rails

To Category:

Parts of lifting and transport machines

Crane rails

Installation of almost all tower cranes is carried out on a special assembly link of the rail track of standard length (12.5 d), which is laid first on the site.

The location of the mounting link on the site should provide the possibility of free access to it or entry to it Vehicle with crane mounting elements. If it is necessary to enter a link of a road train with a crane or its individual elements, it is recommended to pour a layer of gravel or crushed stone in front of the link.

Rice. 12. Inventory anchor for a rope loop holding the boom of the SBK-1 crane
a) single frame; b) double frame; 1 - frame; 2 - connecting strip; 3 - axis; 4 - roller; 5 - ballast

The base of the link must be strong, all sleepers must be well darned, the sleeper boxes must be completely covered with sand and rammed.

When arranging the rail tracks, it should be taken into account that the crane must be at least 0.7 m away from the wall of the building under construction, ensuring that there is a passage between the protruding parts of the crane and the wall. Based on this condition, for most cranes, the distance from the wall to the near rail is at least 1-1.2 m.

The total length of the path laid near the building or structure being erected must be a multiple of the length of the standard link (12.5 m).

If it is necessary to install an assembly link near the edges of trenches and pits, the distance from the edge to the near rail should be determined by calculating the stability of the slopes of the recesses or calculating the strength of their fastenings (for shear). With soils of categories III and IV, the distance from the near rail to the edge of the pit or to the trench with a natural slope must be at least 1.5 m.

1) Materials and products used for track construction

Ballast materials. The following can be used as ballast materials for the installation of a crane runway for tower cranes: medium-grained sand, crushed stone from natural stone and quarry gravel.

Quality control of ballast materials is assigned to organizations that build crane tracks and operate tower cranes.

The sand must meet the requirements of GOST 2781-50 "Medium-grained sand". Fine-grained sands are not allowed for use as ballast material. Normal size particles for medium-grained sand are particles with a size of at least 0.5 mm; the smallest percentage of such particles should be above 50.

Crushed stone from natural stone must comply with the requirements of GOST 7392-55 "Crushed stone from natural stone for the ballast layer of the railway track" and have a particle shape approaching the shape of a cube with sharp ribs; crushed stone must be clean, free from dirt and debris; dust particles should be no more than 1%.

Table 29

Gravel for the installation of crane runway ballast must meet the requirements of GOST 7394-55 "Quar gravel for the ballast layer of iron-
Standards for the granulometric composition of crushed stone of roadways. Impurities of dust-like particles with a size of less than 0.1 mm should be no more than 6%. including clay particles - no more than 1.5%.

Table 30
Norms for the granulometric composition of gravel

Sleepers. For the installation of a crane runway, wooden sleepers made of wood of the following species are used: pine, spruce, fir, larch, cedar, beech, oak and birch (GOST 78-58 "Wooden sleepers for railways broad gauge). The use of sleepers made of soft wood (alder, aspen, etc.) is not allowed.

Rice. 13. Elements for the installation of crane runways for construction cranes
a) cross-section of edged, unedged and bar sleepers; b) cross section of the rail; c) travel screw

According to the cross-sectional shape, wooden sleepers (Fig. 13, a) are divided into edged (type A), unedged (type B) and beams. Wooden beams must meet the requirements of GOST 8486-57 "Softwood lumber".

Table 31
Cross-sectional dimensions of wooden sleepers

The standard sleeper lengths are 1.35 and 2.7 m.

The choice of the type of sleepers, depending on the pressure on the crane running wheel, is made according to Table. 32.

Table 32
Dimensions of sleepers for crane tracks of tower cranes

Rails. For the crane runway of tower cranes, standard railway rails of types are used: R-33, R-38, R-43, R-50 and R-65 (Fig. 13.6) according to GOST, respectively: 6726-53 “Broad gauge railway rails, industrial”, 3542-47 “Broad gauge railway rails”, 7173-54, 7174-54 and 8161-56 “Railway rails”.

Normal rail length is 12.5m (per link).

Table 33
Rail characteristic

Rice. 14. Elements for the device crane. construction crane tracks
a) overlays for R-33 rails; R-38; R-43; R-50; b) overlay for R-65 rail; c) lining for wooden sleepers under crutches; d) lining for travel screws

Overlays. To fasten the rails, two-headed and apron linings are used (Fig. 14), corresponding to GOST: 7638-55 “Two-headed rail linings for R-33 type rails”; 4133-54 “Two-headed rail pads for broad gauge railways; 8193-56 "Double-headed pads for R-65 type rails for broad gauge railways".

The characteristics of the overlays (see Fig. 14, a and b) are given in Table. 34.

Table 34
Overlay characteristics

Crutches. For attaching rails to sleepers (except for inventory links), crutches with an oval head are used that meet the requirements of GOST 818-41 “Crutches for broad gauge railways”.

Each sleeper must be attached to the rail with three spikes. The crutches are divided along the length: into normal - 165 mm long and elongated (heavy) - 205, 230, 255 and 280 mm long; cross section of the crutch 16×16 mm. Elongated crutches are used to repair the runway in winter.

Between the weight of the crutch and its length there is the following relationship.

Screws. To fasten the sleepers to the rails of the inventory links, “track screws of types I and III (see Fig. 13, c) are used that meet the requirements of GOST 809-41 “Track screws”.

Produced screws differ from each other only in length and have the following dimensions (in mm):
The screws are screwed into the sleeper after pre-drilling holes in it with a diameter of 16 mm.

The weight of the screw ranges from 0.53 to 0.9 kg.

Linings. Flat pads are laid on the sleepers under the rail (see Fig. 14.0 and d). It is allowed to lay railway linings under the rails of crane runways, having previously processed them (remove the slope).

Characteristics of linings are given: under crutches in table. 35, for travel screws in table. 36.

Table 35 Characteristics of pads for crutches

Table 36 Characteristics of pads for travel screws

Bolts with nuts. Bolts are used with duck head and round head. The normal bolt diameter is 24.22 mm (or 7/s”). Length 145, 125 or 115 mm. For all types of bolts, an extended nut with a height of 25 mm is used. The weight of bolts with nuts is shown below.

Spring washers are used in two types: reinforced and conventional. The weight of one washer with an inner diameter of 24 mm for the R-50 rail is 0.078 kg, and with an inner diameter of 22 mm for the R-43 rail it is 0.05 kg.

2) Path device

Bottom base. The following requirements are imposed on the lower base of the rail track - the subgrade. Rain and flood water must be drained from the canvas and measures taken against erosion of the upper base. The direction of water drainage must be indicated on the diagrams of the rail track. The slope of the subgrade is allowed no more than 0.1. When constructing a track on bulk soil, it must be pre-compacted. When one thread of the path is located above the sinus, the latter is covered with layers of soil 15-20 cm thick, which should be tightly compacted and watered. The subgrade, made according to the schemes (see Fig. 180, 181, 239 and 240), must withstand a specific pressure of 2 kg / cm2. Ordinary soil is suitable for the construction of a subgrade: loam, sandy loam and a vegetative layer. When constructing a track on weak (marshy) soils, the dimensions of the ballast layer, the length and number of sleepers should be taken according to a special calculation of the track for strength.

When constructing a subgrade in winter, snow and ice must be removed from the site; for its alignment it is allowed to use only thawed soil or dry sand.

The upper base of the track and the scheme of its device. The upper base of the track includes: ballast layer, sleepers, rails with fasteners.

The thickness of the ballast layer is the distance between the lower base of the sleepers and the subgrade. The area between the sleepers is filled with ballast material to the full height of the sleeper.

The dimensions of the ballast layer are given in the schemes for the arrangement of the rail track (see (Fig. 180, 181, 239 and 240).

When arranging the path, you need to be guided by the following. Short sleepers should be attached to the rails strictly in the middle. Permissible deviation from the track gauge, made according to the schemes shown in fig. 180, a and b and fig. 181, 239 and 240, no more than +3 mm; according to the scheme shown in Fig. 108,s, no more than +S mm. Three ties or long sleepers (beams) are laid on one link (except for the path made according to the scheme shown in Fig. 180, e); end stops must be installed at a distance of 1.5 m from the edge of the rails.

Inventory links of the crane runway. The advantage of constructing a crane runway from inventory links is that the elements of the link can be pre-manufactured at the factory and then assembled at the facility.

The diagram (see Fig. 181) shows the arrangement of a link assembled on wooden sleepers (Mechanization Control Trust overhaul residential buildings of the Moscow City Executive Committee).

For the device of inventory links, railway half sleepers, track screws and linings made of sheet or strip steel with a thickness of 12-16 mm are used. For ordinary links, crutches are used instead of screws.

The unloading of the elements of the links from vehicles and the laying of the inventory links on the upper base of the track can be done using a truck or tower crane. After leveling the link, it is recommended to tighten all loose screws on short sleepers.

Tools used in the construction of the rail track. For the mechanization of the processes of the device of the rail track, the following are used: - for darning and ballasting the track - electric sleeper tampers of the Central Research Institute weighing 19 kg with a capacity of 18-20 sleepers per hour; - for drilling holes in the sleepers of inventory links - electric drills for wood, including high-frequency ones; - for driving travel screws - screw wrenches ShGK-1 and ShGK-2, with a capacity of 90-100 screws per hour. With this key, you can not only wrap screws, but also drill holes for them in sleepers;
for sawing sleepers - chain saws type EP-1 weighing 21 kg or circular electric saws.

In addition to electrified tools, they are also used hand hammer crutch, paw for pulling out crutches, travel wrench, socket wrench for screws, fly and socket tampers, pointed pick, pliers for dragging sleepers, pliers for carrying rails, shovel shovel, bayonet shovel, rammer, wooden darning, template for checking track gauge and travel jack.

The grounding of the rail track must be carried out in accordance with the “Instructions for grounding mobile construction mechanisms and electrified tools CH 38-58”, approved by the USSR State Construction Committee dated 25 / KhP 1958. For grounding the rail track, a grounding center is arranged from gas pipes with a diameter of 48 or 60 mm (l'/g or 2”) 2-3 m long (usually three pipes).

At the end of each pipe facing the ground, several holes are drilled with a diameter of 5-10 mm. Pipes are driven near the rail track into the soil to a depth exceeding the freezing depth by 1 zh; their upper ends: are welded together with strip steel with a section of 5X30 mm; the hearth is welded to the rails with the same strip. The rail joints are connected by welding with a strip or wire with a diameter of 8-10 mm. The threads of the rails of the first link near the hearth and then every two links are interconnected by welding with strip steel.

Rice. 15. Scheme of the device of the center of grounding
1 - overlay; 2 - steel wire 0 8-10mm; 3 - steel strip 5 × 30 mm; 4 - gas pipe 0 48-60 mm; 5 - holes 0 5-10 mm

After the arrangement of grounding points and welding of the rails together, the reliability of the grounding is checked: the total resistance of the soil to the spreading of the ground current should not exceed 4 ohms. With greater resistance, the conductivity of the soil is artificially increased by introducing sodium chloride or charcoal and acids. Table salt is introduced into the soil in the form of a solution through the openings of the pipes.

If there are stony soils under the vegetation layer, the grounding center can be arranged in the vegetation layer. To do this, 3-4 trough-shaped ditches (length 8-10 m, width 0.5-1 m) are torn off along the crane runway, which are filled sawdust moistened with saline solution. Instead of pipes, in this case, steel sheets welded together with strip steel and covered with sawdust and a layer of earth can be used.

The diagram of the device of the ground center is shown in fig. fifteen.

Inventory dead ends. Stops should be installed at the ends of the rail track - dead ends, designed to absorb the impact of a crane moving with a maximum load and speed reduced as a result of the limit switch.

For heavy cranes with a gauge of 6 to 8 g, it is recommended to use wedge dead ends, for light cranes - simplified dead ends on brackets. Diagrams of the device of dead ends are shown in fig. sixteen.

The complexity of the device, disassembly and manufacture of the track. The average indicators given below for the composition of the link of workers (Table 37) and the time standards for the installation of a rail track on a sandy base are determined based on the following scope of work.

Path device. These works include laying rail tracks with partial loosening and tipping of the soil, leveling and leveling the subgrade within the ballast prism, tilting the brought ballast up to 3 times, laying the ballast base, laying the superstructure of the track with a toe of materials (except rails) for a distance up to 25 m, sawing, cutting, laying out the sleepers and laying the rails, baiting them with crutches, straightening the laid track according to the level and template, filling the gap between the sleepers with ballast, continuous darning of the sleepers by hand, tamping them and straightening the track.

Rice. 16. End stops
a - wedge: 1 - tension bolt; 2 - wedge clamp; 3 - crossbar; 4 - channel No. 30; 5 - wooden buffer from a sleeper; c - bushing; 7 - bar; 8 - finger; nine - steel sheet; b - simplified: 1 - rail R-43; 2 - persistent scarf; 3 - I-beam No. 27, 4 - handle, 5 - steel sheet; 6 - bolt; 7 - buffer from sleepers; 8 - bracket 0 24 mm; nine - base plate thickness 14-16 mm

Table 37
The composition of the link of workers for the device of rail tracks

The work does not include continuous cutting and moving of the soil, its compaction to the design strength, backfilling and compacting of the sinuses. These works should be carried out, as a rule, with the use of construction machines and mechanisms (bulldozers, rollers, vibrators).

For the installation of one link of the rail track 12.5 m long, the time standards provide for the following labor costs:

Notes.
1. Time standards provide for the production of work in summer conditions.
2. When performing work in winter conditions norms should be multiplied by 1.3. 3. When constructing curved sections of the crane runway (without special bending of the rails), the norms should be multiplied by 1.2.
4. For crushed stone and gravel ballast, multiply the norms by 1.3.

Breaking down the path. The composition of the link of workers for dismantling the rail track, depending on the width of its track, is given in Table. 38.

For the dismantling of one link of the rail track 12.5 m long, the time norms provide for the following labor costs:

The production of inventory links is provided for in stationary conditions at a specially equipped site. The work is carried out by a team of workers consisting of 3 people (one of the 5th category and two of the 3rd category).

The norm of time for one link (two elements) is 20 man-hours. (when applying circular saw and key ShGK-2).

The device of a way with use of inventory links. The installation of the link on the site is carried out using a truck crane or other lifting mechanism. The composition of the link of workers is given in table. 39.

For the installation of one inventory link of the rail track 12.5 m long, the time standards provide for the following labor costs:

Note. When performing work in winter conditions, multiply the norms: for sandy base-on 2; for crushed stone and gravel base - by 3.
The norms of time for the installation of an inventory link do not include loading and unloading elements of links and long sleepers using a truck crane onto a car and accompanying the car along the way.

Table 38
The composition of the link of workers for the dismantling of rail tracks

Table 39
The composition of the link of workers for the installation of the inventory link

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