rail gauge- these are two rail threads installed at a certain distance from one another and attached to sleepers, beams or slabs. The device and maintenance of the rail track depend on the design features of the running gear of the rolling stock.
These include the presence of flanges (ridges) on the wheels that hold the wheels on the rails and direct the movement of locomotives and wagons. The wheels are tightly pressed onto the axle and together with it form a wheel pair. The axes of the wheelsets, united by a common rigid frame, always remain mutually parallel.
The rolling surface of the wheels is not cylindrical, but conical in shape with a slope in its middle part of 1:20.
The distance between the inner edges of the wheels is called the nozzle T = 1440 mm with a maximum tolerance of ± 3 mm.
The distance between the extreme axles fixed in the frame of one bogie is called a rigid base.
The distance between the extreme axles of a wagon or locomotive is called the full wheelbase of a given unit.
So, the full wheelbase of the VL-8 electric locomotive is 24.2 m, the rigid base is 3.2 m.
The distance between the working faces of the wheel flanges is called the width of the wheelset.
The thickness of the flanges of the wheelsets must be no more than 33 mm and no less than 25 mm. In order for a wheelset with the widest nozzle and unworn wheel flanges to fit inside the track, its width must be 1440 + 3 + 2 × 33 = 1509 mm, but the wheelset will be clamped (wedged) between the rails.
Track width is the distance between the inner edges of the rail heads, measured 13 mm below the tread. The gauge on straight sections of the track and in curves with a radius of 350 m or more should be 1520 mm. On existing lines, up to their transition to a 1520 mm gauge, on straight sections and in curves with a radius of more than 650 m, a gauge of 1524 mm is allowed. In curves with a smaller radius, the track width is increased according to the Rules technical operation(PTE).
Gauge tolerances are set for broadening plus 8 mm, for narrowing the gauge minus 4 mm, and in sections where speeds of 50 km / h or less are set, tolerances of +10 for broadening, -4 for narrowing are allowed (PTE TsRB-756.2000). Within tolerances, the track width should change smoothly.
Rail underlay. In straight sections of the track, the rails are not installed vertically, but with an inclination into the track, i.e. with a slope to transfer pressure from the bevel wheels along the axis of the rail. The conicity of the wheels is due to the fact that the rolling stock with such wheelsets has a much greater resistance to horizontal forces directed across the track than cylindrical wheels, the "wobble" of the rolling stock and the sensitivity to track failures are reduced.
Variable conicity of the rolling surface of the wheels from 1:20 to 1:7 (Fig. 4.35) is given in order to avoid the appearance of grooved wear of the wheels and for a smooth transition from one track to another through the turnout. Rail threads must be in the same level. Permissible deviations from the norm depend on the speed of trains.
Fig. 4.35. The most of the time is to be the same as a matter of 2 - layer, extruded
expanded polystyrene 40 mm thick
On long straights it is allowed to keep one rail thread permanently 6 mm higher than the other. With this position of the rail threads, the wheels will be slightly pressed against the lowered straightening thread and move more smoothly. On double-track sections, the straightening thread is the inter-track thread, and on single-track sections, as a rule, it is the right one along the course of kilometers.
The work of the track in curved sections is more difficult than in straight sections., because when rolling stock moves along curves, additional lateral forces appear, for example, centrifugal force. The features of the track gauge in curves include: increasing the gauge in curves of small radii, raising the outer rail thread above the inner one, connecting straight sections with circular curves by means of transition curves, laying shortened rails on the inner thread of the curve. On double-track lines in curves, the distance between the axes of the tracks increases. Gauge widening on curved sections of our roads is done at radii of less than 350 m.
The need for broadening It is caused by the fact that the wheel pairs included in a common rigid frame, while maintaining the parallelism of their axes, make it difficult for the bogies of the rolling stock to pass along curves. In the absence of broadening, the necessary gap between the wheel flanges and the rail disappears, and an unacceptable jammed passage of the rolling stock occurs. In this case, there is a great resistance to the movement of the train, as well as additional wear of the rails and wheels, and traffic safety is not ensured.
The smaller the curve radius and the larger the rigid base, the wider the track should be.
Elevation of the outer rail. When the crew moves along the curve, a centrifugal force is generated that is directed outward of the curve. This force creates an additional impact of the wheel on the outer rail thread, greatly wearing out the rails of this thread. If both rail threads are set at the same level in the curve, then the resultant of the centrifugal force and the weight force will deviate towards the outer rail, overloading it and, accordingly, unloading the inner rail. In order to reduce the lateral pressure on the rails of the outer thread, reduce their overload, achieve uniform wear of the rails of both threads and relieve passengers of discomfort, they arrange an elevation of the outer rail h (Fig. 4.36).
Fig. 4.36. Scheme of acting forces in the device of the elevation of the external rail in the curves
In this case, the vehicle leans towards the center of the curve, part of the weight force H will be directed inside the curve, i.e. in the direction opposite to the centrifugal force. Therefore, tilting the carriage by means of the outer rail elevation device balances the centrifugal force. This equalizes the impact on both rails.
With curve radii of 4000 m or less, an elevation of the outer rail thread is made, which can be from 10 to 150 mm. This elevation depends on the speeds of the trains, their gross mass and the daily number of trains on the curve under consideration and the radius of the curve. Retraction of the elevation of the outer rail, i.e. a gradual decrease in the increased outer thread to zero is done smoothly. Deviation of the calculated elevation in terms of level is allowed depending on the speed of trains.
Transition curves. To smoothly fit the rolling stock into the curves, a transition curve is arranged between the straight section and the circular curve, the radius of which gradually decreases from an infinitely large value at the point where it adjoins the straight section to a radius R at the point where the circular curve begins. The need to insert spiral curves is caused by the following. If a train from a straight section of the track enters a circular curve, where the radius of curvature immediately changes from ¥ to R, then the centrifugal force instantly acts on it. At high speeds, the rolling stock and the track will experience strong lateral pressure and wear out quickly. When arranging transition curves, the radius slowly decreases, respectively, and the centrifugal force slowly increases - a sharp lateral pressure on the train and the track will not occur. On the railways ax RF transition curves are built along a radioidal spiral, i.e. apply a curve with a variable radius of curvature. They are accepted in standard lengths from 20 to 200 m.
Within the transition curves, the elevation of the outer rail and the widening of the gauge, arranged in circular curves, are smoothly diverted, and the widening of the intertrack is also made.
There are special tables for breaking down the transitional and following circular curves, that is, for marking their position on the ground.
Laying shortened rails in curves. The inner rail thread in the curve is shorter than the outer one. If all the rails of the same length are laid along the inner thread of the curve as along the outer thread, then the joints along the inner thread will run forward relative to the joints on the outer thread and they will not be located along the square, as is customary on our network. To eliminate a large run of joints in a curve, rails of a shortened length are laid along the inner thread. Three types of rail shortening are used: 40, 80 and 120 mm for 12.5 m rails and 80 and 160 mm for 25 m rails. Large shortenings are used on steep curves. The laying of shortened rails is alternated with rails of normal length so that the run or underrun of the joints does not exceed half of the standard shortening, i.e. respectively 20; 40; 60 and 80 mm. During the operation of the track, the run or underrun of the joints is allowed in curves - 8cm plus half of the standard shortening of the rail in this curve.
In curved sections of the track, the rolling stock deviates from the vertical axis of the track (see Fig. 5.1). The steeper (smaller) the radius of the curve, the greater the elevation of the outer rail above the inner h, and, consequently, the greater the deflection angle s from the path axis. In this regard, in order to ensure traffic safety on curved sections of the track, the dimensions of the clearance of the approach of buildings increase. Values for increasing overall distances D depend on the radius of the curve, the location of the device in relation to the curve on the inside or outside, the distance from the path axis and is determined according to table 5.1.Rice. 5.1 The position of the crew in the curve with the elevation of the outer rail:
I- centrifugal force;
a- distance from the center of gravity of the vehicle to the level of the rail head;
G- crew weight;
h- elevation of the outer rail;
s- the angle of inclination of the calculated plane to the horizon.
The norms for increasing the horizontal dimensions of the overall dimensions of the approximation of buildings are given:
From the outside of the curve - at any elevation of the outer rail;
On the inner side of the curve - with the calculated elevations of the outer rail, varying from D=60 mm up to D=100 mm for curve radii of 4000 - 1800 m, as well as 160 mm for curve radii of 1500 m or less.
Table 5.1
Norms of increase in horizontal dimensions (D) of the clearance of the approach of buildings (mm)
| Device location | Curve radius, m | |||||||||||||
| On the outside of the curve | ||||||||||||||
| On the inner side of the curve when the device is located on a straight section of the track at a distance from the axis of the track: | ||||||||||||||
| 2450 mm | ||||||||||||||
| 2750 – 3100 mm | ||||||||||||||
| 5700 mm |
The nominal size of the gauge between the inner edges of the rail heads on straight sections of the track and on curves with a radius of 350 m or more is 1520 mm. The gauge on steeper (smaller) curves should be:
With a radius of 349 m to 300 m 1530 mm;
With a radius of 299 m and less than 1535 mm.
An example of constructing an outline of an approximation dimension
Buildings and inscribing the dimensions of the rolling stock into it with the placement of engineering structures and devices
The task provides for the study, drawing and comparison of the sizes and outlines of various dimensions, as well as the conditions for the mutual placement of railway devices. Drawing dimensions and devices is recommended to be performed in in electronic format or on A4 drawing paper on a scale of M 1:50.
When performing a task, you must consider:
1) Where and under what conditions (at the station, on the stage, on a straight or curved section of the track) is it required to draw the clearance of the buildings approaching;
2) The task begins with the drawing of lines denoting the UGR and the axes of the railway track. It is advisable to draw the dimensions of the approach of buildings, rolling stock and loading separately. Dimensions are affixed in accordance with the existing requirements of GOSTs in places convenient for reading;
3) If the task provides for the placement of devices on a curved section of the track, then the actual dimensions of the overall dimensions are calculated and put down after their corresponding increase by the value D depending on the radius of the curve and the location of the devices.
For example:
1. It is required to place a high passenger platform on the outside of a curved track section. The radius of the curve is R=3000 m. On a straight section of the track, the distance from the axis of the track to the inner edge of the high passenger platform is 1920 mm. According to table 5.1, the increase in overall distance D=10 mm. Thus, the minimum allowable distance from the axis of the track to the inner edge of the high passenger platform on the outside of the curved section of the track is 1930 mm.
2. The rolling stock is on a curved section of the track at R=200 m. In accordance with the PTE clause 3.9, we widen the rail gauge to 1535 mm.
Examples of building combined dimensions C and T at the station and the stage on a straight section of the track with the placement of mast dwarf lights are shown in Figure 6.1.
Rice. 6.1 Combined arrangement of C and T dimensions at the station and the haul
Bibliography
1. Instructions for the use of building approximation dimensions GOST 9238-83 No. TsP/4425. Moscow: Transport, 1988 - 143 p.
2. Instructions for the use of rolling stock gauges GOST 9238-83 No. TsV/4422. M: Transport, 1988 - 133 p.
3. Railways. General course: Textbook for universities / Ed. M.M. Uzdina. 5th ed. revised and additional - St. Petersburg: Information centre"Choice", 2002.-368 p.
4. Xu Yu.A., Telyatinskaya M.Yu., Ulyanenkova N.V. Structures and devices of railways. Tutorial. M.: MIIT, 2003 - 19 s, 3rd ed. revised and additional, 2008 - 78 p.
5. GOST 9238-73. Approach dimensions of buildings and rolling stock of 1520 (1524) mm gauge railways (for lines with a train speed not exceeding 160 km/h). Instead of GOST 9238-59. Introduction 1973-39 p.
St.plan 2010, pos.257
Vakulenko Sergey Petrovich
Somov Alexey Nikolaevich,
Baranova Marina Viktorovna
General course of transport
(Dimensions on transport: railway transport)
Tutorial
Signed for printing Format Circulation 100 copies.
Conditions.print.l. - Order -
127994 Moscow, A - 55 st. Obraztsova, 9 building 9
Printing house of MIIT
* OSJD members are transport ministries and central government bodies 27 countries in charge of railway transport: the Republic of Azerbaijan, the Republic of Albania, the Republic of Belarus, the Republic of Bulgaria, the Republic of Hungary, the Socialist Republic of Vietnam, Georgia, the Islamic Republic of Iran, the Republic of Kazakhstan, the People's Republic of China, the Democratic People's Republic of Korea, the Republic of Cuba, the Kyrgyz Republic, Republic of Latvia, Republic of Lithuania, Republic of Moldova, Mongolia, Republic of Poland, Russian Federation, Romania, Slovak Republic, Republic of Tajikistan, Republic of Turkmenistan, Republic of Uzbekistan, Ukraine, Czech Republic and Estonian Republic. In addition, German (DB AG), French (SNCF), Greek (TsKh), Finnish (VR), Yugoslav (South) railways and Gyor-Sopron-Ebenfurt Railway JSC (DySHEV JSC) participate as observers in OSJD. ).
0Rail fasteners. Anti-theft
Rail track - two continuous rail threads located at a certain distance from each other. This is ensured by attaching the rails to the sleepers and the individual rail links to each other.
Rail fastenings are divided into intermediate and butt.
Intermediate fastenings must ensure a reliable and sufficiently elastic connection of the rails with the sleepers, maintain a constant track gauge and the necessary rail underslope, and prevent longitudinal displacement and overturning of the rails.
Intermediate fasteners are divided into three main types: inseparable, mixed and separate.
Inseparable fastening (crutches) - the rail and the linings on which it rests are attached to the sleepers with the same crutches (three), in accordance with Figure 1a
Figure 1 Intermediate spike fastenings for wooden sleepers: a - inseparable; b - mixed; 1 - rail; 2 - crutch; 3 - lining; 4 - sleeper.
Mixed fastening (DO) - (crutch) linings are attached to the sleepers with additional crutches (five), Figure 1 b.
Its advantage is the simplicity of design, low weight, ease of filling, resewing and disassembly of the track.
The disadvantage is that it does not guarantee the constancy of the gauge, contributes to the wear of the sleepers, and poorly resists theft of the track.
In the DO fastening, the main crutches keep the rail from lateral shift and tipping over, and the sheathing crutches reduce the shift of the lining under the action of horizontal forces and the vibration of the linings. The wedge-shaped lining is provided by the rails' sloping.
Separate fastenings (terminal) KD - the rail is attached to the linings with rigid or elastic terminals and terminal bolts, the linings to the sleepers - with bolts or screws in accordance with Figure 2.
Figure 2 Intermediate separate fastening for wooden sleepers: 1 - gasket; 2 - lining; 3 - screw; 4 - terminal; 5 - two-turn washer; 6 - nut; 7 - terminal bolt.
In these fastenings, the linings are permanently attached to the sleepers with screws, and the rail is constantly pressed with clamps to the linings.
The advantage of these fasteners is the absence of large vibration of the pads, resistance to rail theft and the ability to change rails without removing the screws.
For a track with reinforced concrete sleepers, terminal fasteners of types KB, KB65 with a bar terminal, ZhBR-65, BPU are used, in accordance with Figure 3
Figure 3 Fastening KB-65 with a bar terminal: 1 - terminal; 2 - washer; 3, 8 - gaskets; 4 - lining; 5 - two-turn washer; 6 - insulating sleeve; 7 - bracket for insulating sleeve
In large quantities, KB fastening is used, in which a flat gasket is attached to the sleeper with mortgage bolts.
The rail links are connected to each other by means of butt fasteners.
Butt fasteners firmly connect the rails into a continuous thread. The connection points are called rail joints. The ends of the rails are covered with overlays, which are bolted through the holes. Spring or Belleville washers are placed under the nuts of the bolts, in accordance with Figure 4
Figure 4 rail joint: 1 - crutch; 2 - lining; 3 - bolt; 4 - overlay; 5 - rail; 6 - washer; 7 - nut.
Butt plates are designed to connect rails and absorb bending and transverse forces at the junction. Double-headed pads are made of high-strength steel and subjected to hardening. Recently, they are switching to the use of six-hole overlays.
According to the location relative to the sleepers, joints are distinguished on weight, on sleepers and on double sleepers. Hanging joints (Figure 4) are accepted as standard, providing greater elasticity and convenience of tamping ballast for butt sleepers. The ends of the rails are connected in the middle between two butt sleepers, and the joints of both rail strands are located one against the other - along a square.
A gap is left between the ends of the rails at the joints, since the length of the rails changes with a change in temperature. In order to avoid strong impacts of rolling stock wheels, the gap should not exceed 21 mm. Each temperature of the rails corresponds to a certain butt gap.
lz \u003d γ (tmax - t),
where γ is the coefficient of linear expansion of steel lp is the length of the rails in m.
tmax, t - respectively, the highest temperature in the area and the temperature at the time of laying the rail.
On lines with auto-blocking, insulating joints are arranged at the boundaries of block sections to electricity could not pass from one of the connected rails to the other. There are two types of insulating joints: with metal enclosing pads and glue-bolted, in accordance with Figure 5
Figure 5 Cross section of the insulating joint: a - with enclosing metal plates; b - glue-bolt; 1-rail; 2 - overlay; 3 - side gasket; 4 - plank made of fiber or polyethylene for bolts; 5 - locking bar; 6 - bushing; 7 - bottom insulating gasket; 8 - lining; 9 - butt bolt; 10 - nut; 11 - washer; 12 - insulation made of fiberglass impregnated with epoxy glue; 13 - insulation on the bolt.
In the first case, insulation is provided by laying gaskets and bushings made of fiber, textolite, or polyethylene. In the butt gap, gaskets made of textolite or tricol, having the shape of a rail, are also placed.
In the second case, glue-bolt joints are used, in which metal butt plates, insulating fiberglass spacers and bolts with insulating bushings are glued with epoxy glue to the ends of the rails into a monolithic structure.
On lines with electric traction and auto-blocking, special butt connectors are installed for the unhindered passage of current through the joint.
Under the action of forces that are created when trains move under the rails (wave-like bending of the rails under the train, friction between the wheels and rails, wheel collisions, train braking), the rails can move longitudinally along the sleepers or together with the sleepers along the ballast, called the track angle.
On double-track sections, theft occurs in the direction of travel, and on single-track sections, theft is two-way.
The best way to prevent track theft is to use crushed stone ballast and separate intermediate fasteners, which provide sufficient resistance to the longitudinal movement of the rails and do not require additional means of fastening.
For inseparable and mixed fastenings, spring anti-thefts are used - these are spring clips fixed on the rail sole and resting against the sleeper, in accordance with Figure 6
Figure 6 Spring anti-theft
From 18 to 44 pairs are put on a link 25 m long, depending on the load density, type of ballast and train traffic conditions.
Seamless path
The jointless path is more progressive in comparison with the link path. The absence of joints in the rail lashes reduces the dynamic impact on the track, reduces the wear of the wheels of the rolling stock, improves the smoothness of the movement of trains, prolongs the service life of the track superstructure, reduces track maintenance costs, etc.
Reducing the number of joints due to welding of individual links in a whip gives savings of up to 1.8 tons per 1 km.
A feature of a seamless track is that well-fixed rail lashes cannot change their length when the temperature rises or falls, except for small movements of the end parts. Longitudinal tensile and compressive forces up to 2.5 MPa arise in the rails, which in hot weather can lead to the track being thrown to the side, and in severe frost - to a break in the whip with the formation of a dangerous gap. Therefore, the jointless track is laid on reinforced concrete sleepers with separate fastening and crushed stone ballast. The ballast prism is carefully compacted.
The lashes are welded from heat-hardened R65 or R75 rails without bolt holes. The rails are welded by electrocontact method on stationary or mobile contact welding machines. The length of the rail lashes depends on the location of insulating joints, large metal bridges, crossings, turnouts, etc. And as a rule it is 950 m.
On artificial structures with a bridge deck on ballast, a seamless track is laid without restrictions; on metal places with bridge beams - according to the project. The ends of the lashes should be outside the cabinet wall of the abutment at a distance of 50-100m. When the temperature fluctuates, it is possible to change the length of the end sections of the lashes. In order to make this change in length possible, leveling rails are laid between adjacent lashes, forming a leveling project (two or three pairs of rails 12.5 m long). At the end of the block section with automatic blocking in the area of the leveling rails, an insulating joint is placed according to the scheme, in accordance with Figure 7
Figure 7 Scourge of a seamless track: 1 - insulating joint; 2 - whip; 3 - leveling rails.
The laying of leveling rails also ensures, if necessary, the discharge of thermal stresses in the lashes during repair and other work. To do this, weaken the fastening of the wattle with the sleepers, after removing the leveling rails. As a result, the whip is shortened or lengthened. After that, the whip is fixed and leveling rails of the desired length are laid. The longer the lashes, the more obvious the advantages of a seamless path. On a number of roads, there is experience in laying lashes the length of a block section and even a whole haul. Abroad, there are lashes 30-40 km long, when the haul tracks, turnouts and station tracks are welded into a single whole.
The device of the rail track on straight sections
The arrangement of the rail gauge is associated with the design and dimensions of the wheelsets of the rolling stock.
The wheelset consists of a steel axle, on which the wheels are tightly mounted, having guide ridges (flanges) to prevent derailment, in accordance with Figure 8
Figure 8 Wheelset on a rail track
The tread surface of the wheels in the middle part has a 1/20 taper, which provides more uniform wear, greater resistance to horizontal forces directed across the track, less sensitivity to its malfunctions and prevents the appearance of a groove on the tread surface, which makes it difficult for wheelsets to pass through turnouts.
The rails are also installed with a 1/20 inward inclination on straight sections due to the wedge lining with wooden scales, and with reinforced concrete - with a corresponding slope of the surface of the sleepers.
The distance between the inner edges of the rail heads is called the track gauge. This width consists of the distance between the wheels (1440 ± 3mm), two thicknesses of the ridges (from 25 to 33mm) and the gaps between the wheels and the rails.
The track gauge in straight and curved sections of the track with a radius of 349 m or more is 1520 mm with tolerances of 6 mm in the direction of broadening and 4 mm in the direction of narrowing.
In accordance with the PTE, the top of the rail heads of both threads in straight sections must be at the same level.
It is allowed on straight sections of the track to contain one rail thread per 6 mm. higher than the other in accordance with the norms established by the relevant instruction of the Ministry of Railways of Russia.
The joints on both rail threads are placed strictly one against the other along the square.
To prevent the wheelset from turning around a vertical axis, the wheelsets of wagons and locomotives are connected by a rigid frame (two or more each).
The distance between the extreme axles connected by the frame is called a rigid base, and between the extreme axles of a wagon or locomotive - a full wheelbase, respectively, with Figure 9
Figure 9 Rigid and full wheelbases:
a - electric locomotive VL 80; b - one section of the diesel locomotive TE3; in - in a steam locomotive of the FD series; g - four-axle gondola car.
The rigid connection of the wheel pairs provides a stable position on the rails, but makes it difficult to pass in small radius curves (jamming).
To facilitate fitting into curves, the rolling stock is produced on separate bogies with small rigid bases.
Track construction on bridges and in tunnels
On metal bridges, the rail track is made without ballast on wooden or reinforced concrete beams or slabs.
The bars are bolted to the longitudinal beams. To hold the rolling stock in case of derailment, guard bars or corners are placed outside the track, and counter rails or corners inside, in accordance with Figure 10, 11.
Figure 10 Bridge deck on wooden cross-beams with separate terminal-screw fastening of the rails: I - the protective corner is attached with a pawl bolt; II - the protective corner is attached with screws; minimum gaps are given in brackets, mm.
Figure 11 Ballastless bridge deck on reinforced concrete slabs: 1 - counter-angle; 2 - rail; 3 - reinforced concrete slab; 4 - high-strength plate fixing pin; 5 - cement-sand filling (mounting wooden gasket is monolithic); 6 - reinforcing mesh.
On stone, concrete and reinforced concrete places and overpasses, the track has a conventional design, and is laid on crushed stone ballast and ordinary sleepers.
Track arrangement in curved track sections
The railway track in curved sections works more difficult than on straight lines, since additional centrifugal forces appear during the movement of the rolling stock. The features of the arrangement of such a track include: the elevation of the outer rail above the inner one, the presence of transition curves, the broadening of the gauge at small radii, the laying of shortened rails on the inner rail thread, the reinforcement of the track, the increase in the distance between the axes of the tracks on two and multi-track lines.
Elevation of the outer rail
The elevation of the outer rail is provided for with a curve radius of 4000 m or less, so that the load on each rail thread is approximately the same. Such an elevation can be from 10 to 150 mm.
Figure 12 Scheme of forces acting on the rolling stock in a curve when the outer rail is raised.
When the outer rail is raised by the value h, a component of the weight force H appears, directed inside the curve, in accordance with Figure 12
For the same pressure on the rail threads, it is necessary that H balance I, then the resultant N will be perpendicular inclined plane way.
Given that the angle a is small and at the maximum allowable elevation of the outer rail of 150 mm cosa=0.996, we can assume that H=I.
g=9.81 m/s 2 and expressing the speed V in km/h and the radius R in m we get the elevation in mm.
Since in real conditions trains of different masses Qi and with different speeds Vi pass along the curves, for uniform rail wear, the mean square speed is substituted into the above formula.
At h=12.5 V 2 /R, in trains traveling at a speed higher than Vavg, passengers and goods will be subject to an outstanding acceleration equal to the difference between the centrifugal acceleration V 2 /R and the acceleration gh/Si directed towards the center of the curve
Permissible outstanding acceleration on the roads of Russia is allowed 0.7 m / s 2 and only in exceptional cases 0.9 m / s 2.
When trains move at a speed less than Vav, the load on the inner rail will be greater than the outer one.
The device of transition curves is necessary for smooth inscribing of rolling stock into curves between a straight section and a circular curve, the radius of which gradually decreases from yes to the radius R of the curve (from 20 to 200 m). If a train from a straight section of the track enters a circular curve, where the radius of curvature immediately changes from yes to R, then the centrifugal force instantly acts on it. At high speeds, the rolling stock and the track will experience strong lateral pressure and wear out quickly.
The plan transition curve in Figure 13 is a variable radius curve decreasing from infinite to
R - the radius of a circular curve with a decrease in curvature in proportion to the change in length. A curve with this property is a radioidal spiral whose control is expressed as a series.
where c is the transition curve parameter (c=lR)
Due to the fact that the length of the transition curve l is small compared to C, it is practically sufficient to confine ourselves to the first two numbers-a member of the series of the above formula.
In the profile, the transition curve under normal conditions is an inclined line with a uniform slope i=h/l.
The widening of the gauge is necessary to ensure that the rolling stock fits into the curves.
Within a rigid base, the wheelsets are always parallel to each other, and in the bogie only one wheelset can be located along the radius, while the rest will be at an angle. In order to avoid jamming of wheel sets, it is necessary to widen the track, Figure 13
Figure 13 Scheme of free fit into the curve of a two-axle bogie
For a two-axle bogie to fit freely into a curve, the required track width
Sc =qmax+fn +4
where fn is the arrow of the curve bending along the outer thread with a chord of 2λ qmax is the maximum distance between the outer faces of the wheel flanges
4 - wheel narrowing tolerance, mm.
The following norms for track width in curves are established: at R≥350m - 1520mm at R=349: 300m - 1530mm at R≤299m - 1535mm
The laying of shortened rails in the inner thread is necessary to prevent the expansion of the joints. The inner rail thread in the curve is shorter than the outer one. Therefore, to eliminate the forward running of joints at each curve radius, it is necessary to have its own value of rail shortening. Apply standard shortening of rail links by 40, 80, 120 mm - for rails 12.5 m by 80, 160 - for rails 25 m.
Total number of short rails n required to lay in a curve
where ε is the total shortening
k - standard shortening of one rail
The laying of shortened rails in the inner thread is alternated with the laying of rails with a normal one so that the run of the joints does not exceed half the shortening, i.e. 20, 40, 60 and 80 mm.
During the operation of the track, the run or underrun of the joints is allowed in curves - 8cm plus half of the standard shortening of the rail in this curve.
Strengthening of the path in curves is carried out at R≤1200m to ensure the necessary equal strength with adjacent straight lines. To do this, increase the number of sleepers per kilometer, widen the ballast prism from the outside of the curve, put asymmetric pads with a large shoulder to the outside, select the most solid rails.
In circular curves on two and multi-track lines, the distance between the axes of the tracks increases in accordance with the requirements of the clearance, which is achieved within the transition curve of the internal track by changing its parameter C.
Used literature: Voronkov A.I.
General course of railways. Lecture texts:
Textbook - Orenburg: Sam GU PS, 2009.
Crew fitting schemes in curves. The movement of the crew cart at a constant speed along a circular curve causes its rotation (rotation) relative to the center of this curve, i.e. such a movement can be considered as consisting of translational, performed in the direction of the longitudinal axis of the rigid base of the vehicle, and its rotation relative to a certain point 0, called the center (pole) of rotation, which is taken as the point at the intersection of the longitudinal axis of the rigid base of the cart with a radius perpendicular to it ( or radius-perpendicular).
Depending on the ratio of the dimensions of the rail track and the wheelset, the forces applied to the vehicle, the radius of the curve and the speed of movement, there may be different schemes for fitting (setting) the vehicle in the curves. We can distinguish between jammed and non-jammed. Non-jammed fitting, in turn, is divided into forced and free.
Jammed Circuit takes place at the minimum theoretically possible track width for a given vehicle, when, with the selected axle runs, the vehicle cannot move in the transverse direction in the rail track (Fig. 7.8, a). For two-axle and three-axle bogies, with a wedged fitting, forces arise between the wheel and the rail for the outer axles of the bogie along the outer rail threads. The third force arises along the inner thread for the rear axle of the bogie with a two-axle design and for the middle axle with a three-axle one. With a wedged fitting due to such an installation of the wheels along the outer thread, the pole of rotation 0 is in the middle of the rigid base 1 of the reinforced concrete.
A non-jammed fitting scheme occurs when the rigid base of the vehicle has the ability to move in the transverse direction due to free gaps or run-up of wheel sets. Turn center O while shifted to the rear axle.
When transverse forces occur in the first axis along the outer thread and in the back axis along the inner thread, a forced entry is observed (Fig. 7.8, b); if the last force is zero, then such an inscription is called free (Fig. 7.8, in).
Rice. 7.8. Schemes for fitting rigid bases of crews into curves: a- jammed; b- forced; in- free ("$=- point of contact between the wheel flange and the rail); the arrow shows the guiding forces
Wedged fitting in operation is not allowed, as it leads to very high resistance to movement (high friction of the wheel flanges on the side faces of the rail head), lateral wear of the rails and wheel flanges.
When driving multi-axle vehicles with a large rigid base, to ensure a non-jammed passage of the wheels, it is necessary to widen the rail track.
Track width in curves. For the design scheme for determining the track width in curves, the scheme of a wedged fitting of a railway vehicle is taken, in which the outer wheels of the extreme axles of the rigid base with their flanges rest against the outer rail of the curve, and the inner wheels of the middle axles rest against the inner rail. The center of turn of the crew, as discussed above, is located in the middle of the rigid base (two-axle rigid bases, multi-axle rigid bases with a symmetrical arrangement of axes and their takeoffs). To the track width obtained on the basis of such a design scheme (leading to a wedged fit), a certain value should be added, which is taken as the minimum gap of 5 min between the side working edges of the rails and the wheel flanges in a straight section. This way it is possible to avoid jammed fitting.
Consider the case of determining the minimum required rail gauge width S from the condition of inscribing a three-axle bogie with a rigid base T reinforced concrete into a curve with a radius R(Fig. 7.9). This scheme was chosen because at present on the roads of the Russian Federation the bogie of a three-axle locomotive has the longest base.
Rice. 7.9.
Let us introduce the notation:
O- the center of rotation of the rigid base of the crew; with a symmetrical bogie, the center of rotation lies on the axis of the middle wheelset; q- wheel pair width;
/ - the distance from the center of rotation to the point of the crest of the first wheel, resting against the outer rail;
/-arrow of the bend of the outer rail, counted from the chord passing through the point of contact between the wheel and the rail; / = -;
- ?y - the sum of the transverse runs of the axes.
Let's write down the expression for the track width with a wedged fit 5 clas:
But from the consideration of the scheme for the straight section of the path (7.2) it follows 
The value of the arrow z will be determined taking into account (see Fig. 7.9), which is approximately / "0.5 /, wb:
If the value of 8 is calculated to be greater than zero, then it is necessary to widen the track.
It can be seen from the last two expressions that, in principle, the track width in curves should be greater than in straight lines. It also follows that the larger the rigid base and the smaller the radius of the curve, the greater the broadening required to arrange, the greater the takeoff of the wheelsets, the smaller the required broadening.
From the expression for the broadening value (7.16), one can determine the radius of the curve at which a wedged fit occurs.
Taking 8 = 0, we get
For example, with /, wb \u003d 4.6 m, 5 \u003d 7 mm, ?y=0 value R= 378 m.
Broadening with modern rolling stock begins with a radius steeper than 350 m according to the following standards: with a radius of 349 m to 300 m - by 10 mm, and with a radius of less than 299 m - 15 mm.
In the case of a non-wedged scheme, the position of the center of rotation cannot be determined unambiguously only geometrically, as in the case of a wedged fit. In this regard, it is necessary to determine the lateral forces and the center of rotation when fitting the rigid vehicle base into the curve.
The continuous rotation of the carriage relative to the center of rotation occurs under the action of forces arising at the points of contact of the wheel crests of the guide axles with the side face of the rail head. These are the guiding forces G (Fig. 7.10).
In the contacts of the wheels with the rails, friction forces arise equal to the product of forces perpendicular to the plane of contact between the wheels and rails and the coefficient of sliding friction /R ( . On fig. 7.10, instead of these forces, rail reactions that are equal in value and opposite in sign are shown. The transverse components of the friction forces are denoted H/, and the longitudinal V f .
Algebraic sum of pressed comb Y and friction forces H of the same wheel is called lateral force:
When the wheelset is located in front of the center of rotation of the rigid base for the outer wheel in formula (7.18), the difference should be taken and for the inner - the sum of forces; with the opposite arrangement - the wheelset is behind the center of the turn, the signs are also taken in reverse.
Guiding forces(see Fig. 7.10) are considered to be positive if they are directed outward of the track, and the reactions of the rail threads corresponding to them are inside the track. Lateral forces are considered to be positive if they act in the direction of the guiding forces, and the reactions of the rail threads corresponding to them act in the opposite direction.
Registration is free if, when the carriage is entered, guiding forces appear on the outer thread in contact with the first wheel in the direction of travel Y H and are absent on the inner thread of the U c.
The transverse force transmitted by the vehicle frame through the wheelset to the rails is called frame force At r. This force is considered to be applied to the geometric axis of the wheelset and positive if it is directed outward of the curve, equal to the difference in the lateral forces transmitted by the same axle to the outer and inner rail threads:
For the first guiding axle
Rice. 7.10.
Substituting these values into formula (7.19), we obtain
At Sh_ n \u003d#!_ in =fP find G \u003d Y, -2 fp.
Lateral forces G b, arising from the movement of vehicles, reach large values (sometimes 100 kN or more). The influence of lateral forces on the work of the track is very large. This explains a number of measures aimed at improving the fit of crews into curves and reducing lateral forces.
With known positions of the center (pole) of rotation O the carriage (see Fig. 7.10), the track width (measured between the axes of the rail heads) and the distances /, from the center O to any /-th wheelset, the direction of movement of each wheel becomes known. This direction is perpendicular to the radius - vector d t , conducted from the center O to the middle of the wheel-rail contact area, approximately to the point of intersection of the axis of the rail head with the geometric axis of the wheel pair.
The friction force of each wheel (outer, inner) of any /-th axis is directed in the direction opposite to the movement of the wheel. Transverse and longitudinal V f the components of this force are determined from the following expressions:
All transverse forces: friction SH T, guides Vi are considered to be applied not radially, but perpendicular to the longitudinal axis of the vehicle.
Strength T, applied at a distance from the first axis of the bogie, is the resultant of the centrifugal component of the crew weight (per one bogie), formed due to the elevation of the outer rail, and the normal component of the traction force per one bogie:
where a n is the outstanding lateral acceleration;
to t - the number of carts in the crew;
L u- train length;
Lx- the length of the tail section of the train, counting from the middle of the carriage, the entry of which is being considered;
Lc- the length of the vehicle under consideration between the coupling axes of automatic couplers;
FK- traction force developed by the locomotive on a curve (when pushing or locomotive braking F K taken with a minus sign; when pushing b x - head length).
In its turn
where v is the speed of the train;
AND - elevation of the outer rail.
damping moment M, formed by friction forces in the kingpin and side bearings, depends on the loading of the car and the position of the load relative to the longitudinal axis of the car. It provides resistance in the curve to the rotation of the first bogie (see Fig. 7.10) relative to the body, which, turning, drags the second bogie with it, contributing to its rotation. Therefore, the signs M d of the damping moment for the first and second carts will be different.
To determine the damping moment A / d, we denote: the coefficients of sliding friction in the pivot - through ts shk, in the bearings - through ts sk (the values of these coefficients are in the range of 0.1-0.2); pressure on the king pin and side bearings of each bogie - through Q lUK and QCK ; the estimated turning radius of the bogie relative to the body on the pivot - through g sk, on skids - through Mr SK. Then:
The normal position of the body on the pivot bogies is its support on the pivots, each of which accounts for half the weight of the body: QCK= 0 and (2 SHK = 0.5 (2 body. With a large roll, part of the load can be transferred to the bearings, for example,
The vertical pressure on the trolleys of the KVZ-TsNII is transmitted only through the bearings. In this case?) wk = 0; QCK = 0.5Q Ky3 -
To find the directing forces Fj_ H and F 3 _ B, we compose two equations of moments: one relative to the middle FROM j of the first axis and the second - relative to the middle C 3 of the rear axle. Having performed the necessary intermediate transformations, we obtain:
If the middle axis has sufficient transverse runs to move the desired amount, then it follows in the expressions for BUT and AT terms with a multiplier (/ 2 /^/ 2) are considered equal to zero, since there are no transverse components # 2 _ n and # 2 _ /d2 should be written 2/5] due to the fact that in this case V 2 =fP. The upper signs at A / d refer to the front bogie, the lower ones - to the rear. In the case of a two-axle cart in formulas (7.22), the terms containing / 2 and d2. The formulas are valid for any location of the pole of rotation.
From the pole distance /| only functions depend BUT and AT. For a given track width, the value / depends on the forces of interaction between the vehicle and the track and cannot be considered independent until the inner wheel of the rear axle reaches the inner thread with its crest. As soon as this wheel touches and begins to be pressed by the crest against this thread (for a given track width), the value of / becomes unchanged and does not depend on the force interactions between the vehicle and the track.
If the clearance in track 5 is known, the pole distance /j is determined by the dependence
Here 5 is determined taking into account the takeoffs along the first and last axes of the crew.
If the track width is to be determined (as in this case), then it can always be set such that, for any values of the acting forces, the rear axle wheel rolling along the inner thread touches or presses its crest against this thread, i.e. so that conditions (7.22) are satisfied.
For given R, T and L/D values Y\_ n and T 3 _ in are functions BUT and AT, and the latter - functions /,. At the same time, the function BUT has a maximum at = Lq, function AT and (A + B) - at /, = 0.5L Q . As can be seen from formula (7.23), /] cannot be less than 0.5 Lq.
It is important to have such values BUT and AT, under which YX_H and T 3 _ in would be minimal. Of particular importance is the provision of a minimum amount of U[_ n + T 3 _ in, which characterizes the resistance to the movement of carts, depending on the level of guiding forces. Usually L n = 0.5L 0 . In this case, the member TV sum Tj_ H + T 3 _ in is equal to zero. This implies an important conclusion that the indicated amount depends on the values of the outstanding part of the centrifugal force and the normal components of the thrust forces. Since the function BUT at Lq > I is less than its maximum, then, consequently, BUT at check /, Ф Lq will not be maximum, so the best force interaction between the bogie and the track will be at max/|. However /| cannot be arbitrarily large for the following reasons. The guiding force T 3 _ in physically cannot be negative, being the pressure of the wheel flange on the rail thread, therefore /, physically cannot be more than the value at which Y 3 _ in \u003d 0. Thus, within the previously accepted assumptions, the best gauge can be found from the condition Y 3 _ in = 0, i.e., from the condition of free fitting. The track width is greater than that at which Y 3 _ in \u003d 0, it is not advisable, since it does not change the size
A lot of work has been devoted to determining the transverse forces acting on the track when the vehicle moves along curves. At the same time, the creation of charts-passports for fitting crews into curves turned out to be fruitful. The determination of the main characteristics of such a passport is made depending on the outstanding acceleration and n. In this case, guiding, lateral, frame forces and pole distances are often approximated by linear dependencies:
where a, b, c, d- empirical coefficients.
As an example, in fig. 7.11 shows a graph-passport of the lateral impact on the path of a freight car on TsNII-KhZ bogies with a rigid base L Q = 1.85 m and load from the wheelset on the rails 220 kN. Coefficient of friction of wheels on rails / = 0.25.
Norms and tolerances for track width in curves. The track gauge in curves should be set in such a way that the most massive vehicles (freight wagons) can be freely entered. The track gauge should also provide the technical possibility of fitting the most unfavorable vehicles in terms of their impact on the track without jamming into the curves. This condition determines the minimum allowable track width. Maximum allowable
Rice. 7.11. Graph-passport of the lateral impact on the track in the curve of the car on TsNII-KhZ (18-100) bogies, the gauge is determined from the condition of reliable prevention of rolling stock wheels falling into the track.
Currently, on the roads of the Russian Federation, the gauge on straight sections of the track and on curves with a radius of 350 m or more is 1520 mm. The gauge on steeper curves should be 1530 mm for a radius of 349 to 300 m; with a radius of 299 m or less - 1535 mm.
At the same time, it is required that the slope of the track gauge bends is no more than:
- 1 mm per 1 m of track length in sections with speeds up to 140 km/h;
- 1 mm by 1.5 m at speeds of 141-160 km/h;
- 1 mm by 2 m at speeds of 161-200 km/h.
Removal of gauge broadening in curves is done along the transition curves.
Arrangement of the path in curves of small radii. If the radius of the curve is so small that the maximum standard track width of 1535 mm is less than the minimum required, determined according to the wedged fitting scheme with the addition of a minimum clearance of 8 min, the lateral wear of the rails and the breakdown of the rail gauge sharply increase in such curves.
To facilitate the work of the outer thread in such curves, counter rails are laid inside the track along the inner thread. In this case, the guide wheel pair with the wheel running along the inner thread rests against the counter rail without bursting the outer thread (Fig. 7.12). In very steep curves, it is sometimes necessary to lay counter rails at both threads inside the track. Counter rails increase resistance
Rice. 7.12. The position of wheel pairs in a curve in the presence of a counter rail to the movement, therefore, in practice, they are used only in curves with a radius of about 160 m or less. The groove between the counter rail and the rail of the inner thread of the curve should have a width of 60-85 mm. The counter rails must be securely connected to the running rails by means of bushings and bolts.
All new locomotives are expected to fit into curves with a radius of at least 150 m and a track width of 1535 mm.
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