Norms for gauge width and widening in curves. Rail track on railways
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Crew entry diagrams in curves. Movement of the crew trolley with 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 consisting of a translational movement performed in the direction of the longitudinal axis of the rigid base of the carriage, and its rotation relative to some point 0, called the center (pole) of rotation, which is taken to be the point at the intersection of the longitudinal axis of the rigid base of the trolley with a radius perpendicular to it ( or perpendicular radius).
Depending on the ratio of the dimensions of the rail track and the wheel pair, the forces applied to the vehicle, the radius of the curve and the speed of movement, there may be various schemes fitting (installation) of the crew into the curves. You can distinguish between jammed and non-jammed. Non-jammed inscription, in turn, is divided into forced and free.
Jammed circuit occurs at the minimum theoretically possible track width for a given vehicle, when, with the selected axle runs, the vehicle is not able to move transversely in the rail track (Fig. 7.8, A). For biaxial and triaxial bogies, when the fitting is jammed, forces arise between the wheel and the rail for the outer axles of the bogie along the outer rail threads. The third force occurs along the internal thread for the rear axle of the cart with a biaxial design and for the middle axis with a triaxial design. When the fit is jammed, due to this installation of the wheels along the outer thread, the rotation pole 0 is located in the middle of the rigid base 1 of the reinforced concrete.
A non-jammed fit pattern 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 the wheel pairs. Center of rotation ABOUT at the same time shifted to the rear axle.
When transverse forces occur in the first axis along the outer thread and in the rear axis along the inner thread, forced fit is observed (Fig. 7.8, b); if the last force is zero, then such an inscription is called free (Fig. 7.8, V).
Rice. 7.8. Schemes for fitting rigid crew bases into curves: A- jammed; b- forced; V- free (“$=- point of contact between the wheel flange and the rail); the arrow shows the guiding forces
A jammed fit is not allowed in operation, as it leads to very high resistance to movement (high friction of the wheel flanges on the side edges of the rail head), lateral wear of the rails and wheel flanges.
When moving multi-axle vehicles with a large rigid base, to ensure unjammed passage of the wheels, it is necessary to widen the rail track.
Track width in curves. The design scheme for determining the track width in curves is taken to be a wedged fitting scheme for the railway carriage, in which the outer wheels of the outer 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 rotation of the vehicle, as discussed above, is located in the middle of the rigid base (biaxial rigid bases, multi-axial rigid bases with a symmetrical arrangement of the axes and their runways). To the track width obtained on the basis of such a calculation scheme (leading to a jammed fit), a certain value should be added, which is taken to be the minimum gap of 5 min between the side working edges of the rails and the flanges of the wheels on a straight section. In this way, jammed insertion can be avoided.
Let's consider the case of determining the minimum required rail track width S from the condition of fitting a three-axle trolley with a rigid base T reinforced concrete into a curve with a radius R(Fig. 7.9). This scheme was chosen because currently on the roads of the Russian Federation the bogie of a three-axle locomotive has the longest wheelbase.
Rice. 7.9.
Let us introduce the following notation:
ABOUT- 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 wheel pair; q- wheel pair width;
/ - the distance from the center of rotation to the flange point of the first wheel resting on the outer rail;
/ - arrow of bending of the outer rail, measured from the chord passing through the point of contact of the wheel and rail; / = -;
- ?у is the sum of the transverse axes.
Let us write down the expression for the track width when the 5th line is jammed:
But from considering the diagram for the straight section of the path (7.2) it follows 
The boom size z will be determined taking into account (see Fig. 7.9), which is approximately /» 0.5/, reinforced concrete:
If the calculated value 8 is greater than zero, then it is necessary to widen the track.
From the last two expressions it is clear 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 widening required, the greater the run-up of the wheel pairs, the smaller the required widening.
From the expression for the magnitude of broadening (7.16), one can determine the radius of the curve at which a jammed fit occurs.
Taking 8 = 0, we get
For example, with /, reinforced concrete = 4.6 m, 5 = 7 mm, ?y=0 value R= 378 m.
Widening with modern rolling stock begins with a radius steeper than 350 m according to the following standards: with a radius from 349 m to 300 m - by 10 mm, and with a radius of less than 299 m - by 15 mm.
In the case of a non-jammed circuit, the position of the center of rotation cannot be determined unambiguously only geometrically, as in the case of a jammed fit. In this regard, it is necessary to determine the lateral forces and the center of rotation when fitting the rigid base of the vehicle into the curve.
Continuous rotation of the carriage relative to the center of rotation occurs under the influence of forces arising at the points of contact of the flanges of the wheels of the guide axles with the side edge of the rail head. These are the guiding forces G (Fig. 7.10).
In contacts between wheels and rails, friction forces arise equal to the product of the forces perpendicular to the plane of contact of the wheels and rails and the coefficient of sliding friction /R ( . In Fig. Instead of these forces, Fig. 7.10 shows rail reactions equal to them in value and opposite in sign. The transverse components of friction forces are indicated N/, and longitudinal ones - V f .
Algebraic sum of ridge pressing Y and friction forces N of the same wheel is called lateral force:
When the wheelset is located ahead of the center of rotation of the rigid base, the difference should be taken in formula (7.18) for the outer wheel and the sum of forces for the inner wheel; with the reverse arrangement - the wheelset is located behind the center of rotation, the signs are also taken in reverse.
Guiding forces(see Fig. 7.10) are considered to be positive if they are directed outside the track, and the corresponding reactions of the rail threads are directed inside the track. Lateral forces are generally considered positive if they act in the direction of the guiding forces, and the corresponding reactions of the rail threads act in the opposite direction.
Free entry if, when the crew enters, 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 V.
The lateral force transmitted by the carriage frame through the wheel pair to the rails is called frame force At the r. This force is considered to be applied to the geometric axis of the wheelset and is positive if it is directed outward of the curve, equal to the difference in the lateral forces transmitted by the same axis to the outer and inner rail threads:
For the first guide axis
Rice. 7.10.
Substituting these values into formula (7.19), we obtain
At SH_n =#!_ V =fP let's find Г=У, -2 fP.
Lateral forces Гb arising during the movement of vehicles reach large values(sometimes 100 kN or more). The influence of lateral forces on track performance is very great. This explains a number of measures aimed at improving the fit of crews into curves and reducing lateral forces.
At known positions of the center (pole) of rotation ABOUT crew (see Fig. 7.10), track width (measured between the axes of the rail heads) and distances /, from the center O to any /-th wheel pair, the direction of movement of each wheel becomes known. This direction is perpendicular to the radius - vector dt, carried out from the center ABOUT to the middle of the contact area between the wheel and the rail, approximately to the point of intersection of the axis of the rail head with the geometric axis of the wheelset.
The friction force of each wheel (external, internal) of any i-th axis is directed in the direction opposite to the movement of the wheel. Transverse and longitudinal Vf the components of this force are determined from the following expressions:
All shear forces: friction SH T, guides V i are considered to be applied not radially, but perpendicular to the longitudinal axis of the vehicle.
Force T, applied at a distance from the first axis of the bogie, is the resultant of the centrifugal component of the weight of the crew (per bogie), formed due to the elevation of the outer rail, and the normal component of the traction force per bogie:
where a n is the outstanding lateral acceleration;
to t - number of trolleys in the carriage;
L u - train length;
L x - the length of the tail section of the train, counting from the middle of the crew whose fit is being considered;
Lc- the length of the carriage in question between the clutch axles of the automatic couplers;
FK- traction force developed by a 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 frictional forces in the kingpin and sliders, depends on the loading of the car and the position of the cargo relative to the longitudinal axis of the car. It resists the curved rotation of the first cart (see Fig. 7.10) relative to the body, which, when turning, drags the second cart along with it, facilitating its rotation. Consequently, the signs Md of the damping moment for the first and second bogies will be different.
To determine the damping moment A/d, we denote: the sliding friction coefficients in the king pin - through c shk, in the sliders - through c sc (the values of these coefficients are in the range of 0.1-0.2); pressure on the kingpin and sliders of each bogie - through Q lUK And Q CK ; calculated radius of rotation of the trolley relative to the body on the kingpin - through g ShK, on slides - through g SK. Then:
The normal position of the body on kingpin trucks is that it rests on the kingpins, each of which accounts for half the weight of the body: QCK= 0 and (2 ШК = 0.5(2 body. With a large roll, part of the load can be transferred to the side slides, for example,
Vertical pressure on the KVZ-TsNII bogies is transmitted only through the sliders. In this case?) shk = 0; QCK= 0.5 Q Ky3 -
To find the directing forces Fj_ H and F 3 _ B, we compose two moment equations: one relative to the middle WITH j of the first axle 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 required amount, then it follows in the expressions for A And IN terms with a multiplier (/ 2 /^/ 2) are considered equal to zero, since there are no transverse components # 2 _ n and # 2 _ in the force of R e tion - Instead of the term /d 2 should be written 2/5] due to the fact that in this case V 2 =fP. The upper signs for A/d refer to the front trolley, the lower ones - to the rear. In the case of a biaxial cart, the terms containing / 2 and d2. The formulas are valid for any location of the rotation pole.
From pole distance /| only the functions depend A And IN. For a given track width, the value of / 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 its ridge to the inner thread. As soon as this wheel touches and begins to press its ridge against this thread (for a given track width), the value of / becomes constant and independent of the force interactions of the vehicle and the track.
If the gap 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 vehicle.
If the track width is to be determined (as in in this case), then it can always be set such that for any values active forces the wheel of the rear axle, rolling along the inner thread, touched or pressed its ridge against this thread, i.e. so that conditions (7.22) are satisfied.
For given R, T and L/d values U\_ n and T 3 _ in are functions A And IN, and the latter - by functions /,. In this case, the function A has a maximum at = Lq, function IN 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 A And IN, at which Y X_H and T 3 _ in would be minimal. Especially great importance has a minimum sum of U[_ n + T 3 _ v, which characterizes the resistance to the movement of carts depending on the level of guiding forces. Usually Ln = 0.5L 0 . In this case, the member with TV the sum Tj_ H + T 3 _ in is equal to zero. This leads to the important conclusion that the indicated amount depends on the values of the outstanding part of the centrifugal force and the normal components of the traction forces. Since the function A at Lq > I is less than its maximum, then, consequently, A at check /, Ф Lq will not be maximum, therefore the best force interaction between the bogie and the track will be at check/|. 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 = 0. Thus, within the limits of the previously accepted assumptions, the best track width is found from the condition V 3 _ в = 0, i.e. from the condition of free inscription. A track width greater than that at which U 3 _ in = 0 is not advisable, since it does not change the size
Many works have been devoted to determining the transverse forces acting on the path when the vehicle moves along curves. The creation of graphs-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, guides, 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 of the lateral impact on the track of a freight car on TsNII-KhZ bogies with a rigid base L Q = 1.85 m and the load from the wheel pair on the rails is 220 kN. The coefficient of friction between wheels and rails is / = 0.25.
Norms and tolerances for track width in curves. The track width in curves should be set so as to ensure free fitment of the most massive carriages (freight cars). The track width must also ensure technical feasibility fit into the curves of the most unfavorable crews in terms of impact on the path without jamming. This condition determines the minimum permissible track width. Maximum permissible
Rice. 7.11. Graph-certificate of the lateral impact on the track in the curve of the car on TsNII-KhZ bogies (18-100); the track width is determined from the condition of reliably preventing the wheels of the rolling stock from falling into the track.
Currently, on the roads of the Russian Federation, the track width on straight sections of the track and on curves with a radius of 350 m or more is 1520 mm. The track width on steeper curves should be 1530 mm for a radius from 349 to 300 m; with a radius of 299 m and less - 1535 mm.
In this case, it is required that the steepness of the track width bends be no more than:
- 1 mm per 1 m of track length in sections with speeds up to 140 km/h;
- 1 mm at 1.5 m at speeds of 141-160 km/h;
- 1 mm at 2 m at speeds of 161-200 km/h.
Removal of track widening in curves is done along transition curves.
Path construction 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 fit scheme with the addition of a minimum gap of 8 min, in such curves the lateral wear of the rails and the breakdown of the rail gauge sharply increases.
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 wheelset, with its wheel running along the inner thread, rests against the counter-rail without pushing apart 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 the wheel pairs in a curve in the presence of a counter rail interferes with the movement, therefore, in practice, their installation is used only in curves with a radius of approximately 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 using inserts and bolts.
All new locomotives are designed to fit into curves with a radius of at least 150 m with a gauge of 1535 mm.
1.5.
Rail track railway tracks
Interaction between track and rolling stock. Rail track is calleddistance between the inner working edges of the rail heads, measuredlocated 15 mm below the tread surface (at the level of wheel contact with rail head). The main condition for constructing a rail track isensures the safety of trains with installed speedgrowths. The design of the rail track, its dimensions and the magnitude of permissible deviations from the norms depend on the design of the running gear of the moving system.stav and, in turn, affect their design, dimensions and tolerances. The features of the rolling stock chassis are as follows:
- the presence of ridges on the wheels (Fig. 1.78);
- blind attachment of wheels to the axle;
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constancy of distances between int
early wheel edges;
- parallelism of axes;
- conicity of the rolling surface.
Combs are necessary in order tocontrol the movement of wheels along the rail and prevent derailment.
Blind attachment of a wheel to an axle, in which the wheel rotates along with the axle,eliminates wear on the wheel hub and axle hub and thanks to thisThe wheel must not be in an inclined position, which is dangerous for movement.
Constancy of the distances between the inner edges of the wheels of all axles is necessary to ensure the safety of rolling stock movementalong the track. The distance between the track threads is constant and the compositionis 1520 mm. With this track width, the distance between the inner edges of the wheels is 1440 mm with tolerances of ±3 mm and is called the nozzle
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(see Fig. 1.78). For rolling stock traveling in trains at speeds of more than 140 km/h, tolerances are +3, -1 mm.
Parallelism of the axes is necessary to avoid misalignment of the axes and failurewheels inside the track. To ensure parallelism of the axis, a gesture is combined what frame? Distance between extreme axes remaining parallelOur movement in both straight and curved sections of the path is called
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rigid crew base. Distance between the outer axles of the carriage - the full wheelbase (Fig. 1.79).
The longer the rigid base, the more complexher crew movement in curves. For abouteasier fit into crooked cars,diesel locomotives and electric locomotives with more than three axles are placed on a bogiekakh, combining two or three axes. Gesturewhich crew base will be the distance betweenalong the outer axles of the trolley (see Fig. 1.79). Conicity of the rolling surfaceensures more even wearwheels and rail heads due tolateral movements of the wheel at vicrew laning with bevel wheelsmi in straight sections of the route. Wheelrolls along the rail mainlysloping rolling surface 1:20, which therefore wears out much more than part, I have The final slope is 1:7 (writing 1.80). Poi one-
A similar surface inclination of 1:20 would result in uneven wear To rapid education local saddle wear (groove). Passage along the crosspiece, transition from the frame rail to the point and back, if availableGrooved wheel wear is accompanied by sharp shocks and impacts. An inclination of 1:7 promotes uniform wear on the tread surface. In Fig. 1.80 is shown as a dotted line and prevents groove wear. A 1:7 slope and a 6:6 bevel also create favorable conditions for rolling wheels from the pressed tip to the frame rail and back. Comb thickness wheels are allowed according to the PTE (Table 1.6).
Table 1.6
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Track width in straight sections.
Normal track width in straightIn areas and curves with a radius of 350 m or more, there should be 1520 mm between the inner edges of the rail heads (PTE, clause 3.9). The deviations should not exceed -4 mm for narrowing, +8 mm for widening, and -4 mm, +10 mm in areas with speeds of 50 km/h or less. Consequently, the track width ranges from 1530 mm to 1516 mm. In order to to prevent the wheels of the rolling stock from jamming in the rut, in which
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The table shows that the maximum gap for locomotives is 39 mm, and the minimum is 7 mm. For cars, 29 and 5 mm, respectively. The more for sight, the more the rolling stock wobbles in straight lines and the stronger the sidewayshigh impacts of the ridges when running onto the rails.With smaller gaps the movementthe process occurs more smoothly. This is what determined the normal width gauge 1520 mm (reduction by 4 mm compared to the previously existing one).
The top of the rail heads of both rail lines of the track on straight sections must be at the same level. Allowed on straight sections of the routepress one rail thread 6 mm higher than the other throughout the straight section. When one rail thread is raised by 6 mm, the crew slightly it tilts and from this tilt a lateral force will appear, which will lightly press the wheels against the lower thread and make it difficult for them to wobble and move The movement of the rolling stock will be smoother.
Construction of rail tracks in curved sections. For that to fitlearn how to fit rolling stock into curves and move along them, railThe owl track in curves has the following features:
- track widening for radii less than 350 m:
- elevation of the outer rail above the inner rail;
- transition curves in places where straight sections meet curves;
- shortened rails on internal rail threads;
Increased distances between paths when there are two or more paths.
Track width in curves.
Widening the rail gauge in curves is done
For that so that rolling stock with a long rigid base can passalong curves without jamming of wheel sets. Rules of technical operationtations (PTE, clause 3.9) set the track width in curved sections of the track at a radius
From 349 to 300 m.................................................... ................................1530 mm
From 299 m and less................................................... ................................1535 mm
On sections of railway lines where a comprehensive replacement of the rail and sleeper grid has not been carried out, it is allowed on straight and curved sectionsOn tracks with a radius of more than 650 m, the nominal gauge size is 1524 mm. At In this case, on steeper curves, the track width is assumed to be:
At radius
From 650 to 450 m.................................................... ................................1530 mm
From 499 to 350 m.................................................... ................................1535 mm
From 349 m and less................................................... ................................1540 mm
Tolerances on curved sections, as well as on straight sections, should not exceednarrowing -4 mm, widening +8 mm. Track widths less than 1512 mm and more than 1548 mm are not allowed. The transition from the widened gauge to the normal one is made within the transition curve with a deviation of 1 mm/m.
Fitting the rolling stock into the curve can be free,linear and forced. Most favorable for interactionrolling stock and tracks free fit into a rigid base curvelocomotive or carriage (Fig. 1.82). When fitting freely, the comb is front axle wheel is pressed against the outer rail thread and guidesmovement of the crew, and the ridge of the rear axle touches the inner rail thread,in this case, the rear axle is located along the radius of the curve. In this case the gestureThis base is located completely freely in the rail track.
The most unfavorable is jammed fit(Fig. 1.83), in which the outer wheels rest against the outer rail with their ridges thread, and the inner wheels rest against the inner rail thread. Jammed inscription is not allowed, since it is accompanied by significant increased resistance to train movement, excessive wear of the rowing
Track width – 1520 mm. Permissible deviations are +8 and -4 mm, and in areas where the speed limit is 50 km/h or less - no more than +10 and -4 mm. On roads all over the world, the operational length of which is about 1200 thousand km, about 30 track width dimensions. It is generally accepted that the track width is 1435 (1430) mm normal - it makes up 62% of the world's length of the road network, more of it - wide and less of it - narrow gauge. After a track with a width of 1435 mm, the most common track sizes are 1675, 1524 (1520 mm), 1067 mm, 1000 mm. Other track widths together amount to about 5%.
Features of rail gauge in curves. Rail gauge width in curves.
Widening of the rail track for radii less than 350m.
An elevation is established along the outer rail track at a curve
Straight sections with circular curves are connected by transition curves. Transition curves are also arranged between curves of different radii.
Shortened rails are laid along the curved internal rail thread to ensure that the joints are located opposite each other.
In curved sections of the track on double-track lines, widened inter-tracks are installed. Broadening is carried out within the transition curves.
The widening or width of the track in the curve is determined by calculating the fit of railway carriages into the curve, based on the following two conditions:
The track width should be optimal, i.e. provide the least resistance to the movement of trains, the least wear of rails and wheels, protect the rails and wheels from damage and the path from distortion in plan, and prevent the wheels from falling between the rail threads.
The track width should not be less than the minimum permissible, i.e. should prevent jamming of the carriages' undercarriages between the outer and inner rail threads.
Definition optimal width ruts in a curve.
In all cases, the calculated rail gauge width should not exceed maximum width gauge S max = 1535mm.
If the calculated track width S receives a value greater than the maximum value S max, you should proceed to determine the minimum permissible track width by adopting the appropriate design scheme.
If the calculated track width S turns out to be less than the normal width on a straight section of the track (S 0 = 1520 mm), then this will mean that the design dimensions and features of the undercarriage of the vehicle in question allow it to pass a curve of a given radius without widening its track. In this case, the track width S should be taken according to the PTE depending on the radius.
Determination of the minimum permissible track width.
S min = q max = T max + 2h max + 2µ (5)
When determining the minimum permissible track width, the following cases are possible:
If S min ≤ S pte, then inclusion is ensured. At the same time, comparing all three track width values S min , S pte and S opt with each other allows us to roughly estimate the conditions under which actual fitting will take place, i.e. what type of fit it will be closer to, free or wedged.
If S min > S pte, then this case in turn splits into the following two:
If S min the wheels fall into the track, then to allow the crew in question to pass, the track must be rebuilt from the size S pte to the calculated value S min (according to permission H).
If S min S max , then to allow the crew to pass, the track must be changed by the calculated amount; at the same time, to prevent the wheels from falling inside the track, counter rails are laid.
Elevation of the outer rail, based on the characteristics of equal vertical wear on both rails.
To avoid these phenomena, the outer rail thread is raised above the inner one.
To ensure equal vertical wear on both threads, it is necessary that the sum normal pressure from all trains on the outer thread was equal to the sum of normal pressures from the same trains on the inner thread
Therefore it is necessary that:
ΣE n = ΣE in
The centrifugal force when a vehicle of mass m moves along a curve of radius R with a speed V will be determined by the expression:
Where G is the weight of the crew
Elevation of the outer rail, based on ensuring passenger comfort.
From (25)
Here and nd – permissible value unsuppressed centrifugal acceleration. According to the standards, a and nd is assumed to be equal to passenger trains 0.7 m/s 2 (in some cases a an = 1.0 m/s 2), and for freight trains a nd = ±0.3 m/s 2.
Taking S1 = 1.6 m, g = 9.81 m/s 2 , V – km/h, h – mm, we obtain:
163a nd (26)
The maximum height of the outer rail on domestic roads is taken to be 150 mm. If the calculation results in a large value, take 150 mm and limit the speed of movement along the curve from equation (26)
With a nd = 0.7 m\s 2 and h = 150mm
External rail elevation standards.
For passenger trains
For freight trains
For train flow
Where, V max p and V max gr – maximum speeds respectively, passenger and freight trains, established by order of the head of the road.
V pr is the average superficial speed of the flow trains.
R – radius of the curve.
When determining the elevation using formula (29), rational track operation is ensured at freight train flow speeds lying within
Which corresponds to the level of outstanding accelerations of passenger trains a np = 0.7 m\s 2 and freight trains a n gr = ±0.3 m\s 2 .
Basic requirements for the design and content of transition curves.
Within the transition curve, the elevation of the outer rail gradually increases from 0 to h in the CPC; a deduction is made for the widening of the track, if the latter is present in the circular curve.
The basic requirements for the design and content of the PC are that the appearing, developing and disappearing force factors (accelerations, forces, moments) within the length R of the PC change gradually and monotonically, with a given schedule, and at the beginning and end of the PC they are equal zero, which is ensured if the requirements are met.
In the NPC y,φ and k = 0, the CPC these parameters are not limited.
In NPC and CPC these derivatives are equal to zero.
The first three requirements about the inadmissibility of sudden changes in the NPC, CPC and throughout the transition curve (Fig. 2) ordinates at, turning angles φ and curvature To by the monotony of their changes. Fulfilling all five requirements creates best conditions passage of rolling stock along curves, which is especially important when high speeds movements.
Physical parameter of the transition curve.
At l = l 0 in the CCP ρ= R And
(6)
Here C is the (geometric) parameter of the transition curve.
Design of transition curves using the displacement method.
FT = AO = Ptg β/2
Where
m 0 = m + Ptg β/2
The unknown quantities m and P are determined as:
Knowing the position of the beginning of the transition curve of the NPC, the coordinates of its end (X 0,y 0) at the point of the CPC are calculated using the equation of the radio-distance spiral in parametric form
Shortened rails on the inner thread.
For each curve, the type of shortening, the number and order of laying the shortened rails are selected. There are two types of shortenings for P65 rails: 80mm and 160mm.
The choice of the type of shortened rails for a given curve is made according to the formula:
Where S 1 is the track width along the axis of the rail head within the circular curve:
S pte – standard track width in curves depending on the radius;
Having calculated the value of shortening using formula (1), we accept the nearest larger standard shortening. Required amount shortened rails of the accepted size are determined from the expression:
Shortened rails are laid in those places of the curve where the accumulated run of the joints reaches half of the accepted standard shortening.
Widening track distances in curves.
This increase is carried out different ways. One of the methods is to increase the track distance from 4.1 m to 4.1 + A 0 on straight lines before each transition curve by introducing additional S-shaped curves.
This method is rarely used, since it has a major drawback: on the path being moved, two curves appear on each side of the main curve, albeit of a large radius. Another method (the method of different shifts) is to use different parameters From the transitional curves of the outer path. Satisfied in the usual way, parameter C of the transition curve of the internal path is selected in such a way that the shift of the internal circular curve P in is equal to the shift of the circular curve of the external path plus A 0, i.e.
R in = R n + A 0
Classification of connections and path intersections.
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Connections and intersections |
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Turnouts |
Blind intersections |
Path connections |
Rotating devices |
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Singles |
Rectangular |
Switch streets |
Triangles |
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Double |
Oblique |
Conventions |
Loops |
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Cross |
Curvilinear |
Plexus |
Circles |
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Combined | |||
Classification of turnouts and blind intersections.
Singles
One-way ordinary (most common on the road network and most often used on main and station tracks)
Versatile symmetrical
Asymmetrical one-sided curvature
Double
Unilateral
Versatile symmetrical
Versatile asymmetrical
Cross
Singles
Double
Combined
When combining two tracks of different sizes
When weaving turnouts
Basic elements of ordinary turnouts.
The main elements of an ordinary single turnout include:
Arrow
Crosspiece with counter rails and track counter rails.
Connecting paths
Under-rail bases
Transfer mechanism and its fittings
Design features of turnouts and requirements for them
Turnouts are key track structures for increasing train speeds and increasing freight capacity. bandwidth railways. Research has shown that without the presence of turnouts that allow the speed set on the stretch to be realized, it is practically impossible to solve the problem of increasing the speed on the section as a whole, and on the stretch in particular.
Definition of main geometric dimensions ordinary turnouts with a straight point.
Determine the radius of the transfer curve R.
Length of direct insertion k in front of the mathematical center of the cross
Theoretical L T translation length
Practical L P transfer length.
Axial dimensions of translation A And b.
n- length of the front – mustache – part of the cross
m– length of the tail part of the cross
O k – mathematical center or point of the cross
S 0 – normal track width
l sharp – wit length
β – arrow angle
q – front frame rail overhang
L T - theoretical length of the switch - the distance from the beginning of the points to the mathematical center of the cross, measured along the working edge of the frame rail or along the axis of the straight track.
O c – center of the turnout – intersection of the axes of the direct and side tracks
a – distance from the front joint of the frame rails to the center of the switch, measured along the axis of the straight track
b – distance from the center of the S.P. to the tail joint of the cross, measured along the axis of any translation path.
O – center of the conversion curve
L P – total or practical length of S.P. from the front joint of the frame rails to the tail joint of the cross.
Let us take the Y-Y axis in a rectangular coordinate system, passing through the mathematical center of the cross, and X-X axis compatible with the working edge of the outer thread of the straight path.
Let's project the ABCO K contour onto these mutually perpendicular axes. But first for this we will make the following additional constructions.
From the center of the conversion curve, i.e. from point O, restore the radius - perpendicular to the working edge of the frame rail; From points B and C we lower perpendiculars to this radius - the perpendicular at points B 1 and C 1, respectively. What will happen as a result right triangle OB 1 B with a right angle β at the vertex O, as well as OS 1 With a right angle at the vertex C 1 and with a cross angle α at the vertex O.
Theoretical transfer length , as can be seen from the figure, is a projection of the ABCO K contour onto the horizontal axis, i.e.
(1)
But B 2 C = C 1 C – B 2 C 1 = C 1 C – B 1 B
From triangle OS 1 C: WITH 1 C =R sinα
From triangle OB 1 B: IN 1 B =R sin
From triangle O to C 2 C: WITH 2 ABOUT TO = k cosα
Therefore, after substituting the values of B 2 C and C 2 O K into equation (1), we obtain:
L T = l sharp withsβ + R (sinα - sinβ )+ k cosα (2)
Projection of the same contour ABCO K onto vertical axis will be the normal gauge against the cross, i.e.
S 0 = l sharp sinβ + B 1 WITH 1 + SS 2 (3)
But B 1 C 1 = OB 1 - OS 1
From triangle OB 1 B: OB 1 = R cosβ
From triangle OS 1 C: OS 1 = R cosα
From triangle O K C 2 C: SS 2 = k sinα
Thus, substituting the values B 1 C 1 and СС 2 into expression (3), we find the track width in the cross: S 0 = l sharp sinβ + R (cosβ - cosα ) + k sinα
Total or practical length of the turnout: L P = q + L T + m (5)
The radius R and the length of the straight insert in front of the cross k are determined depending on what parameters are known or specified.
21 22 24 ..Construction of rail tracks in straight sections of track
A rail track is two rail threads installed at a certain distance from one another and attached to sleepers, beams or slabs. The design and maintenance of the rail track depend on the design features of the running parts of the rolling stock.
These include the presence of flanges (ridges) on the wheels, which hold the wheels on the rails and direct the movement of locomotives and cars. The wheels are tightly pressed onto the axle and form a wheel pair together with it. The axles of the wheel pairs, united by a common rigid frame, always remain mutually parallel.
The rolling surface of the wheels is not cylindrical, but conical, 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 maximum tolerances+ - 3 mm. The distance between the extreme axles fixed in the frame of one cart is called the rigid base.
The distance between the outer axles of a car or locomotive is called the full wheelbase of that unit.
Thus, the total wheelbase of the BJT-8 electric locomotive is 24.2 m, the rigid wheelbase is 3.2 m.
The distance between the working edges of the wheel flanges is called the width of the wheelset.
The thickness of the wheel flanges must be no more than 33 mm and no less than 25 mm. In order for the wheelset with the widest nozzle and unworn wheel flanges to fit inside the track, its width must be 1440 + 3 + 2 x 33 = 1509 mm, but in this case the wheelset will be clamped (jammed) between the rails.
The track width is the distance between the inner edges of the rail heads, measured at a level of 13 mm below the rolling surface. The track width on straight sections of the track and in curves with a radius of 350 m or more should be 1520 mm. On existing lines, until they are transferred to a 1520 mm gauge, a track width of 1524 mm is allowed on straight sections and in curves with a radius of more than 650 m. In curves of smaller radius, the track width increases according to the Rules technical operation.
Tolerances for track width are set for widening plus 8 mm, for narrowing of the track minus 4 mm, and in areas where speeds are set at 50 km/h or less, tolerances of +10 for widening are allowed - 4 for narrowing. Within tolerances, the track width should change smoothly.
Rail bending. In straight sections of the track, the rails are not installed vertically, but with an inclination into the track, i.e., with a cushion to transmit pressure from the bevel wheels along the axis of the rail. The conicity of the wheels is due to the fact that rolling stock with such wheel pairs offers much greater resistance to horizontal forces directed across the track than cylindrical wheels, and the “wobble” of the rolling stock and sensitivity to track faults are reduced.
Variable conicity of the wheel rolling surface from 1:20 to 1:7 is given to avoid the appearance of grooved wear of the wheels and for a smooth transition from one track to another through the turnout. The rail threads must be at the same level. Permissible deviations from the norm depend on the speed of trains.
On long straight lines it is allowed to keep one rail thread constantly 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 an inter-track thread, and on single-track sections, as a rule, it is the right thread along the kilometers.
Rail track- these are two rail threads installed at a certain distance from one another and attached to sleepers, beams or slabs. The design and maintenance of the rail track depend on the design features of the running parts of the rolling stock.
These include the presence of flanges (ridges) on the wheels, which hold the wheels on the rails and direct the movement of locomotives and cars. The wheels are tightly pressed onto the axle and form a wheel pair together with it. The axles of the wheel pairs, united by a common rigid frame, always remain mutually parallel.
The rolling surface of the wheels is not cylindrical, but conical, 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 maximum tolerances ± 3 mm.
The distance between the extreme axles fixed in the frame of one cart is called the rigid base.
The distance between the outer axles of a car or locomotive is called the full wheelbase of that unit.
Thus, the total wheelbase of the VL-8 electric locomotive is 24.2 m, the rigid base is 3.2 m.
The distance between the working edges of the wheel flanges is called the width of the wheelset.
The thickness of the wheel flanges must be no more than 33 mm and no less than 25 mm. In order for the 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 in this case the wheelset will be clamped (jammed) between the rails.
Track width- this is the distance between the inner edges of the rail heads, measured at a level of 13 mm below the rolling surface. The track width on straight sections of the track and in curves with a radius of 350 m or more should be 1520 mm. On existing lines, until they are transferred to a 1520 mm gauge, a track width of 1524 mm is allowed on straight sections and in curves with a radius of more than 650 m. In curves of smaller radius, the track width increases in accordance with the Technical Operation Rules (RTE).
Tolerances for track width are set for widening plus 8 mm, for narrowing of the track minus 4 mm, and in areas where speeds are set at 50 km/h or less, tolerances of +10 are allowed for widening, -4 for narrowing (PTE TsRB-756.2000). Within tolerances, the track width should change smoothly.
Rail bending. 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 transmit pressure from the bevel wheels along the axis of the rail. The conicity of the wheels is due to the fact that rolling stock with such wheel pairs offers much greater resistance to horizontal forces directed across the track than cylindrical wheels, and the “wobble” of the rolling stock and sensitivity to track faults are reduced.
Variable conicity of the wheel rolling surface from 1:20 to 1:7 (Fig. 4.35) is given to avoid the appearance of grooved wear of the wheels and for a smooth transition from one track to another through a turnout. The rail threads must be at the same level. Permissible deviations from the norm depend on the speed of trains.
Res. 4.35. This is a new version of Sasha S.P. óðã - MÌnêêàà: 1 - î÷èùåííûé ùáåíü; 2 - son, ykst
synthetic size 40 mm
On long straight lines it is allowed to keep one rail thread constantly 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 thread along the kilometers.
Path work 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. Features of the track arrangement in curves include: increasing the track width in curves of small radii, raising the outer rail thread above the inner one, connecting straight sections with circular curves through transition curves, laying shortened rails on the inner thread of the curve. On double-track lines in curves, the distance between the track axes increases. Widening of the track on curved sections of our roads is done with radii less than 350 m.
Need for expansion 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 rolling stock bogies to pass along curves. In the absence of widening, 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 great resistance to the movement of the train, as well as additional wear on the rails and wheels, and traffic safety is not ensured.
The smaller the radius of the curve and the larger the rigid base, the wider the track should be.
Elevation of the outer rail. When the crew moves along a curve, a centrifugal force is generated, directed outward of the curve. This force creates additional impact of the wheel on the outer rail thread, greatly wearing out the rails of this thread. If both rail threads are installed at the same level in a 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 from unpleasant sensations, an elevation of the outer rail h is arranged (Fig. 4.36).
Res. 4.36. THE SYMPTOMS OF THE SYSTEM IN THE RESULTS kurya
In this case, the crew 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 action of centrifugal force. Consequently, the tilt of the carriage due to the device of raising the outer rail balances the centrifugal force. This equalizes the impact on both rails.
For 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. Removal of the elevation of the outer rail, i.e. the gradual reduction of the increased outer thread to zero is done smoothly. Deviation of the calculated elevation in 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 radius R at the point where the circular curve begins. The need to insert transition curves is caused by the following. If a train from a straight section of track enters a circular curve, where the radius of curvature immediately changes from ¥ to R, then it is instantly affected by centrifugal force. At high speeds, the rolling stock and track will experience strong lateral pressure and wear out quickly. When constructing transition curves, the radius slowly decreases, and accordingly the centrifugal force slowly increases - there will be no sharp lateral pressure on the train and the track. On railways RF transition curves are constructed along a radioidal spiral, i.e. a curve with a variable radius of curvature is used. They are accepted standard length from 20 to 200 m.
Within the transition curves, the elevation of the outer rail and the widening of the track, arranged in circular curves, are smoothly removed, and the gap between tracks is also widened.
There are special tables for breaking down 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 are laid along the inner thread of a curve of the same length as along the outer one, then the joints along the inner thread will begin to run ahead relative to the joints on the outer thread and it will not be possible to arrange them along a square, as is customary on our network. To eliminate the large run of joints in a curve, rails of a shortened length are laid along the internal 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. Larger shortenings are used on steep curves. The laying of shortened rails is alternated with rails of normal length so that the overrun or underrun of the joints does not exceed half of the standard shortening, i.e. respectively 20; 40; 60 and 80 mm. When operating the track, overrun or underrun of joints is allowed in curves - 8 cm plus half the standard shortening of the rail in a given curve.