3.2. Portable signals include:

rectangular shields in red on both sides or on one side of red and on the other white,

yellow square shields (green back),

lanterns on poles with red fire,

red flags on poles.

3.3. The requirements are imposed by portable signals:

a rectangular red shield (or a red flag on a pole) in the afternoon and red pole lantern fire at night - "Stop! It is forbidden to pass the signal" (Fig. 3.3, a);

yellow square shield day and night (Fig. 3.3, b) when a dangerous place is located:

• on the stretch - "It is allowed to move with a decrease in speed, in front of a dangerous place requiring a stop or proceed at a reduced speed";

  on the main track of the station - "It is allowed to move with a decrease in speed, in front of a dangerous place, which requires proceeding with a reduced speed";

  on other station tracks - "It is allowed to pass the signal at the speed indicated in the warning, and in the absence of it, at a speed of no more than 25 km / h."

Reverse side of the square shield (green) day and night (Fig. 3.3, c) on the stretch and on the main track of the station indicates that the driver has the right to increase the speed to the speed set after following the dangerous place with the whole train.

Fencing of places of obstacles for the movement of trains and places of work on the tracks

3.4. Any obstacle to the movement of trains on the stretch should be fenced with stop signals, regardless of whether a train is expected or not.

Places of work on the stretch, requiring trains to stop, are fenced in the same way as obstacles.

Obstacles on the stretch are fenced off on both sides at a distance of 50 m from the boundaries of the fenced area with portable red signals. From these signals at a distance B, indicated in column 4 of the table. 3.1, depending on the leading descent and the maximum permissible speed of train movement on the stretch, three firecrackers are stacked and at a distance of 200 m from the first firecracker closest to the place of work, in the direction from the place of work, portable speed reduction signals are installed.

Fencing schemes for obstacles and work sites on a single-track section are shown in Fig. 3.4, a, on one of the tracks of the double-track section - in Fig. 3.4, b, on both tracks of the double-track section - in Fig. 3.4, c.

Portable speed reduction signals and firecrackers must be guarded by signalmen standing with hand red signals 20 m from the first firecracker in the direction of the work site. The portable red signals must be supervised by the supervisor.

When performing work with a deployed front (more than 200 m), work places are fenced in the order shown in Fig. 3.4, g.

Portable red signals installed at a distance of 50 m from the boundaries of the area requiring fencing must be guarded by signalists standing near them with hand-held red signals.

If the place of an obstacle or work on the stretch is located near the station and it is impossible to fence this place in the established order, then from the side of the stretch it is fenced as indicated above, and from the side of the station a portable red signal is installed on the axis of the track against the input signal (or signal sign " Station border ") with the laying of three firecrackers, guarded by a signalman (Fig. 3.5).

If the place of the obstacle or work is located at a distance of less than 60 m from the input signal (or the signal sign "Station boundary), then the firecrackers from the station are not laid. The diagram of the obstacle fencing in front of the input signal is shown in Fig. 3.5.

Figure 3.5

When a train approaches a portable yellow signal, the driver must blow one long whistle of a locomotive (multiple-unit train), and when approaching a signalman with a manual red signal, give a stop signal and take measures to immediately stop the train in order to stop without passing the portable red signal.

Signalists to distinguish themselves from other railway workers must wear a headdress with a yellow top.

Places of obstacles for the movement of trains and places of work on multi-track sections are fenced in in accordance with the procedure established by the Ministry of Railways.

3.5. In case of a sudden occurrence of an obstacle and the absence of the necessary portable signals, a stop signal should be installed immediately at the site of the obstacle (Fig.3.6): during the day - a red flag, at night - a lantern with a red light and on both sides at a distance B, indicated in column 4 of the table. 3.1, depending on the leading descent and the maximum permissible speed of the trains on the stretch, lay three firecrackers each.

Figure 3.6

Firecrackers must be guarded by railway workers, who must stand with hand-held red signals at a distance of 20 m from the first firecracker in the direction of the obstacle.

Signals are set primarily from the side of the expected train. On single-track sections, if it is not known from which side the train is expected, the signals are set first of all from the side of the descent to the fenced-in place, and on the site - from the side of the curve or notch.

The detailed procedure for the actions of employees when fencing suddenly arisen obstacles is determined by the corresponding instruction of the Ministry of Railways.

3.6. Places through which trains can only pass with a conductor (at a speed of less than 15 km / h), as well as plexuses of tracks on double-track sections in one level, are fenced off as an obstacle to traffic, but without laying firecrackers. Written warnings are issued about the installation of these signals on trains.

If it is necessary to skip a train with a conductor, for which a warning has not been issued, laying firecrackers is obligatory.

If the passage of trains with a conductor is established for a long time, then portable red signals may be replaced with cover traffic lights left in the closed position, with warning traffic lights installed in front of them (Fig. 3.7).

Figure 3.7

The installation of these cover traffic lights is announced by the order of the head of the railway, and in this case, no train warnings are issued.

When the track posts are opened on both sides of the fenced place, the movement of trains between these posts is carried out using one of the used signaling and communication means without a conductor. At the same time, in some cases, a conductor can also be assigned to monitor the movement of a train through a fenced area at a set speed.

3.7. Firecrackers in all cases are stacked in the amount of three pieces: two on the right rail of the track along the train and one on the left (see Figure 3.6). The distance between the firecrackers should be 20 m.

3.8. Portable signals of speed reduction and signal signs "Start of a dangerous place" and "End of a dangerous place" are installed according to the diagrams shown in fig. 3.2.

If the place requiring a decrease in speed on the stretch is located near the station and it is impossible to protect it in the established order, then from the side of the stretch it is fenced as indicated above, and from the side of the station - in the order indicated in Fig. 3.8.

Figure 3.8

When approaching the portable yellow signal the driver is obliged to give one long whistle of the locomotive (multi-unit train) and drive the train so as to follow the place fenced with portable signal signs "Beginning of a dangerous place (Fig. 3.9, a) and" End of a dangerous place "(Fig. 3.9, b), with the speed indicated in the warning, and in the absence of a warning - at a speed not exceeding 25 km / h.

The signal sign "End of dangerous place" is placed on the back of the sign "Beginning of dangerous place".

Portable speed reduction signals and signal signs "Start of dangerous place" and "End of dangerous place" on station tracks and multi-track tracks can be used with short poles.

3.9. Places of work on the track that do not require fencing with stop or speed reduction signals, but requiring workers to be warned about the approach of a train, are fenced with portable signal signs "C" about the blowing of a whistle, which are installed at the track where the work is being performed, as well as at each adjacent main track (Figure 3.10).

Portable signal signs "C" are installed in the same order at adjacent main tracks and during the performance of work, fenced off with stop signals (see Fig. 3.4, b and 3.5) or speed reduction signals.

On the tracks, where trains operate at a speed of more than 120 km / h, portable signal signs "C" are installed at a distance of 800-1500 m from the boundaries of the work site.

33. A yellow disc (Fig. 68) gives a signal - it is allowed to move with a decrease in speed and readiness to follow a dangerous place, fenced off by the signal signs "Beginning of a dangerous place" and "End of a dangerous place" (Fig. 95, 96), at the speed set the owner of the infrastructure or the owner of non-public railway tracks.

With a green disc (Fig. 69) - the train passed a dangerous place. On single-track sections, the driver sees such a signal from the left side in the direction of travel.

Places installed by the owner of the infrastructure or the owner of non-public railway tracks and requiring a constant reduction in speed are fenced on both sides on public railway tracks at a distance of 50 m, and on non-public railway tracks - 15 m from the boundaries of a dangerous place with permanent signal signs "Start of a dangerous Places ”and“ End of Dangerous Places ”. From these signal signs at a distance A specified in column 3 of Table 1, depending on the leading descent and the maximum permissible speed of trains on public railway tracks, constant speed reduction signals are set, and on non-public railway tracks at a distance of the stopping distance determined and installed by the owner of non-public railway tracks (hereinafter - distance "T") - speed reduction signals.
In table 1 and in all diagrams in this annex, distances are given in meters.

Table 1

The schemes for installing permanent speed reduction disks and signal signs "Start of a dangerous place" and "End of a dangerous place" of the owner of the infrastructure on a single-track section are shown in Fig. 70, on one of the railway tracks of a double-track section - in Fig. 71, on both railway tracks of the double-track section - in Fig. 72, on non-public railway tracks - respectively in Fig. 73, 74, 75.

34. Portable signals include:
1) rectangular shields are red on both sides or on one side of red, and on the other - white;
2) yellow square shields (green back);
3) lanterns on poles with red lights and red flags on poles.

35. The requirements are imposed by portable signals:
1) a red rectangular shield (or a red flag on a pole) during the day and a red lantern on a pole at night - stop! It is prohibited to drive through the signal (fig. 76);

2) a square yellow shield during the day and at night (Fig. 77) when a dangerous place is located:
on the stretch - movement with a decrease in speed is allowed, there is a dangerous place ahead that requires stopping or following at a reduced speed;
on the main railway track of a railway station - movement with a decrease in speed is allowed, there is a dangerous place ahead that requires passage at a reduced speed;
on other station railway tracks - the signal is allowed to travel at the speed specified in the warning, and in the absence of it - on public railway tracks at a speed of no more than 25 km / h, and on non-public railway tracks - at a speed of no more than 15 km / h ...

The reverse side of the square shield (green) day and night (Fig. 78) on the stretch and on the main railway track of the railway station indicates that the train driver has the right to increase the speed to the speed set after the entire train has passed the dangerous place.

36. Any obstacle to the movement of trains on the stretch should be fenced with stop signals, regardless of whether a train is expected or not.
Places of work on the stretch, requiring trains to stop, are fenced in the same way as obstacles.
Obstacles on the stretch are fenced on both sides on public railway tracks at a distance of 50 m, and on non-public railway tracks - 15 m from the boundaries of the fenced area with portable red signals. On public railway tracks, three firecrackers are stacked from these signals at a distance B, indicated in column 4 of Table 1, depending on the leading descent and the maximum permissible speed of trains on the stretch, and at a distance of 200 m from the first firecracker closest to the place of work , in the direction from the place of work, and on non-public railway tracks at a distance "T" portable speed reduction signals are installed.
On non-public railway tracks, when cars move forward, the distance of installation of portable signals increases by the length of the train circulating in a specific section.
Diagrams of fencing obstacles and places of work on public railway tracks on a single-track section are shown in Fig. 79, on one of the railway tracks of a double-track section - in Fig. 80, on both tracks of the double-track section - in Fig. 81, and on non-public railway tracks - respectively in Fig. 82, 83, 84.

On public railway tracks, portable speed reduction signals and firecrackers should be guarded by signalmen standing with hand red signals 20 m from the first firecracker, and on non-public railway tracks - from speed reduction signals towards the place of work (obstacle site). The portable red lights must be supervised by the supervisor.
When performing work with a deployed front (more than 200 m), work places are fenced in the order shown in Fig. 85. On public railway tracks, portable red signals installed at a distance of 50 m, and on non-public railway tracks - 15 m from the boundaries of the section requiring fencing, should be guarded by signalmen standing near them with hand-held red signals.

If the place of the obstacle or the production of work on the stretch is near the railway station and it is impossible to fence this place in the prescribed manner, then from the side of the haul it is fenced as indicated in this paragraph, and from the side of the railway station a portable red signal is installed on the axis of the railway track opposite the entrance traffic light (or signal sign "Station boundary"). At the same time, on public railway tracks with the laying of three firecrackers, guarded by a signalman (Fig. 86), and for non-public railway tracks, without laying firecrackers (Fig. 87). If the place of the obstacle or work is located at a distance of less than 60 m from the entrance traffic light (or the signal sign "Station Border"), then firecrackers from the side of the railway station are not stacked, and portable speed reduction signals are not installed on non-public railway tracks. The diagram of obstacle fencing in front of the entrance traffic light on public railway tracks is shown in Fig. 86, and on non-public railway tracks - in Fig. 87.

On non-public railway tracks, the place of obstacles for the production of work on the hauls, requiring trains to travel at a reduced speed, is fenced off at a distance "T" from the boundaries of the fenced area with portable speed reduction signals.
The scheme for setting the speed reduction signal on a single-track stretch is shown in Fig. 88, on one of the double-track railway tracks - in Fig. 89, on both railway tracks of a double-track haul - in Fig. 90.

When a train approaches a portable yellow signal, the driver must blow one long whistle of a locomotive, a motor-car train, a special self-propelled railway rolling stock, and when approaching a signalman with a manual red signal, give a stop signal and take measures to immediately stop the train in order to stop without passing the portable red signal.
Signalists to distinguish themselves from other railway workers must wear a headdress with a yellow top.
Places of obstacles for the movement of trains and places of work on multi-track sections are fenced in in accordance with the procedure established by the owner of the infrastructure, the owner of non-public railways.

37. In case of a sudden occurrence of an obstacle on the stretch and the absence of the necessary portable signals, a stop signal should be installed immediately at the obstacle site (Fig. 91): during the day - a red flag, at night - a lantern with a red light and on both sides on public railway tracks at a distance of B , indicated in column 4 of Table 1, depending on the leading descent and the maximum permissible speed of trains on the stretch, lay three firecrackers, and on non-public railway tracks set a stop signal from the side of the expected train - at a distance "T".

Firecrackers should be guarded by employees of the infrastructure owner or the owner of non-public railway tracks, who are required to stand with hand red signals at a distance of 20 m from the first firecracker in the direction of the obstacle.
Signals are set primarily from the side of the expected train. On single-track sections, if it is not known from which side the train is expected, the signals are set primarily from the side of the descent to the fenced-in place, and on the site - from the side of the curve or notch.
The detailed procedure for the actions of employees when fencing suddenly arisen obstacles is determined by the owner of the infrastructure, the owner of non-public railway tracks.

38. Places through which trains can only pass with a guide (at a speed of less than 15 km / h), as well as plexuses of railway tracks on double-track sections in one level, are fenced off as a place of obstacles to traffic, but without laying firecrackers. Written warnings are issued about the installation of these signals on trains.
If it is necessary to skip a train with a conductor for which a warning has not been issued, laying firecrackers is mandatory.
If the passage of trains with a conductor is established for a long time, then portable red signals may be replaced with cover traffic lights left in the closed position, with warning traffic lights installed in front of them (Fig. 92).

The installation sites for covering traffic lights are determined by the owner of the infrastructure, the owner of non-public railway tracks.
When the track posts are opened on both sides of the fenced place, the movement of trains between these posts is carried out using one of the signaling and communication means used without a conductor. In some cases, in this case, a conductor may also be assigned to monitor the movement of the train along the fenced place at a set speed.

39. Firecrackers in all cases are stacked in the amount of three pieces: two on the right rail of the railway track along the train and one on the left (Fig. 91). The distance between the firecrackers should be 20 m.

40. Portable speed reduction signals and signal signs "Start of a dangerous place" and "End of a dangerous place" are installed on public railway tracks according to the schemes shown in fig. 70, 71, 72, and on non-public railway tracks - in Fig. 73, 74, 75.
If the place requiring a decrease in speed on the stretch is located near the railway station and it is impossible to fence it in the prescribed manner, then from the side of the haul it is fenced as indicated in this paragraph, and from the side of the railway station on public railway tracks - in the manner specified in fig. 93, and on non-public railway tracks - in Fig. 94.

When approaching a portable yellow signal, the driver of a locomotive, a multiple-unit train, a special self-propelled railway rolling stock must blow one long whistle and drive the train so as to follow the place fenced with portable signal signs "Beginning of a dangerous place" (Fig. 95) and "End of a dangerous place "(Fig. 96), at the speed indicated in the warning, and in the absence of a warning on public railway tracks - at a speed of no more than 25 km / h, and on non-public railway tracks - no more than 15 km / h.
The signal sign "End of a dangerous place" is placed on the back of the sign "Beginning of a dangerous place".

Portable speed reduction signals and signal signs "Beginning of a dangerous place" and "End of a dangerous place" on station railway tracks and multi-track sections can be used with shortened poles.

41. Places of work on the railway track that do not require fencing with stop or speed reduction signals, but requiring workers to be warned about the approach of a train, are fenced with portable signal signs "C" - blowing a whistle, which are installed at the railway track where the work is carried out, as well as at each adjacent main railway track. The arrangement of signal signs "C" is shown in fig. 97, where for non-public railway tracks the distance from the place of work to the signal sign "C" is equal to the distance "T".

Portable signal signs "C" are installed in the same order at adjacent main railway tracks and during the performance of work, fenced off by stop signals (Fig. 80, 86 - 90) or speed reduction signals.
On the tracks, where trains operate at a speed of more than 120 km / h, portable signal signs "C" are installed at a distance of 800 - 1500 m from the boundaries of the work site.

42. Any obstacle to movement on station railway tracks and turnouts should be fenced with stop signals, regardless of whether a train (shunting train) is expected or not.
When fencing a place of obstacle on the station railway track or performing work with stop signals, all arrows leading to this place are set in such a position that the railway rolling stock cannot enter it, and are locked or sewn up with crutches. At the place of an obstacle or work on the axis of the railway track, a portable red signal is installed (Fig. 98).
If any of these arrows are pointed with their wits in the direction of the place of the obstacle or work and do not make it possible to isolate the railway track, such a place is fenced on both sides with portable red signals installed on public railway tracks at a distance of 50 m, and on non-public railway tracks. use - 15 m from the boundaries of the place of obstacles or work (Fig. 99). In the case when the points of the switches on public railway tracks are located closer than 50 m, and on non-public railway tracks - closer than 15 m from the place of the obstacle or work, a portable red signal is installed between the points of each such arrow (Fig. 100).

When fencing with portable red signals the place of an obstacle or performing work on a turnout switch, the signals are set: from the side of the cross - against the limit column on the axis of each of the converging railway tracks; from the opposite side on public railway tracks - 50 m, and on non-public railway tracks - 15 m from the point of the switch (Fig. 101).

If another switch is located near the turnout switch to be fenced, which can be put in such a position that the railway rolling stock cannot enter the turnout switch, where there is an obstacle, then the switch is locked or sewn up in this position. In this case, a portable red signal from the side of such an isolating arrow is not set (Fig. 102).

When the arrow cannot be put in the indicated position, then on public railway tracks at a distance of 50 m, and on non-public railway tracks - 15 m from the place of the obstacle or work in the direction of this arrow, a portable red signal is installed (Fig. 101).
If the place of an obstacle or work is located at the entrance switch, then from the side of the stretch it is fenced off with a closed input signal, and from the side of the railway station - by portable red signals installed on the axis of each of the converging railway tracks against the limit post (Fig. 103).

When the place of the obstacle or the production of work is between the input switch and the input signal, then from the side of the stretch it is fenced with a closed input signal, and from the side of the railway station - with a portable red signal installed between the edge of the input switch (Fig. 104).

The switch post duty officer who has discovered an obstacle at the turnout switch must immediately install one portable red signal at the obstacle site (before the start of repair work) and report this to the railway station duty officer.

43. The place requiring speed reduction, located on the main railway track of the railway station, is fenced with portable speed reduction signals and signal signs "Start of a dangerous place" and "End of a dangerous place", as shown in fig. 105 and 106.

If a place requiring a speed reduction is located on the remaining station railway tracks, then it is fenced off only by portable speed reduction signals. The order of installation of these signals is shown in Fig. 107.

At railway stations of non-public railway tracks that are not equipped with devices for electrical interlocking of arrows and traffic lights, in the event of a train stopping at the neck of a railway station and there is no passage (a specified distance between the axes of the station railway tracks) along adjacent railway tracks, all exits from these railway tracks are fenced off with signals stops (fig. 108).

44. Cars repaired on station railway tracks and cars with dangerous goods of class I (explosive materials), passenger cars standing on separate railway tracks are fenced with portable red signals installed on public railway tracks on the axis of the railway track at a distance of at least 50 m, and on non-public railway tracks - at least 15 m (on through railway tracks - on both sides, and on dead-end railway tracks - from the turnout side).
If in this case the extreme car on public railway tracks is less than 50 m from the limit post, and less than 15 m on non-public railway tracks, then a portable red signal from this side is installed on the axis of the railway track opposite the limit post.
At railway stations of non-public railway tracks equipped with devices for electrical interlocking of switches and traffic lights, railway tracks on which cars are cleaned, commercial faults are eliminated, uncoupled repairs and maintenance of cars are equipped with fencing devices that exclude the entry of railway rolling stock.
When maintenance and repair of cars, devices and centralized fencing of trains can be used, while the procedure for fencing trains or individual groups of cars during their maintenance and repair, depending on local conditions, is established by the owner of the infrastructure, the owner of non-public railways.

45. In case of a forced stop on the stretch of a passenger train, the guard is made by the conductor of the last passenger carriage at the direction of the driver in the following cases:
1) requests for a recovery or fire train, as well as an auxiliary locomotive, if assistance is provided from the tail;
2) if the train was sent during a break in the operation of all means of signaling and communication on the correct railway track to a double-track or single-track track with a notification about the departure of another train for it.
The conductor of the last passenger car, guarding the stopped train, must activate the hand brake, lay firecrackers at a distance of 800 m from the tail of the train, then move 20 m from the place of the laid firecrackers back to the train and show a manual red signal in the direction of the haul (Fig. 109).

In case of a forced stop on the haul of other trains, they are fenced in cases when the departure was made in conditions of an interruption in the operation of all signaling and communication means along the correct railway track to a double-track or single-track haul with the issuance of a notification about the departure of another train for it. In this case, the fence is made by the driver's assistant, who must immediately after stopping go to the tail of the train, check for the presence of a train signal, carefully observe the haul and, if a next train appears next, take measures to stop it.
If assistance to a stopped train is provided from the head, the driver of the leading locomotive, when a recovery or fire train or an auxiliary locomotive approaches, must give a general alarm signal; turn on the searchlight at night and during the day with poor visibility.

46. ​​The conductor of a carriage guarding the tail of a passenger train stopped on the stretch returns to the train only after the approach and stop of a recovery or fire-fighting train or an auxiliary locomotive, or upon transfer of the guardrail to another employee who has approached the place where the passenger train stops.
The assistant driver, who is at the tail of a train sent when all signaling and communication means are interrupted, returns to the locomotive only after the train arrives and stops following the train, or at the driver's signal given by the locomotive's whistle, if the need for a fence has passed.

47. On sections equipped with automatic blocking, when stopping on the stretch of a passenger train, the conductor of the last passenger carriage is obliged to check the visibility of train signals, carefully observe the section, and in the event of the appearance of a following train, take measures to stop it.

48. In case of a forced stop of a train on a double-track or multi-track haul due to derailment, collision, collapsed cargo, etc., when it is required to protect the place of obstacles to train movement that has arisen on the adjacent railway track, the driver must give a general alarm signal.
In this case, in the event of a passenger train stopping, the fence is made from the side of the head of the train by the assistant driver, and from the tail - by the conductor of the last passenger car, laying firecrackers at a distance of 1000 m from the head and tail of the train, as shown in Fig. 110.

In addition, the driver of the passenger train reports the incident using the available means of communication to the train dispatcher or duty officer at the railway stations limiting the haul, as well as to the driver of the locomotive following the adjacent railway track.
On non-public railway tracks, if the train is accompanied by a compiler, the obstacle site is fenced from the side of the train head - by the assistant driver, and from the tail - by the compiler, which depart to the distance "T" and show a manual red signal in the direction of the haul from the head and tail, respectively trains. If the train is not accompanied by the originator, the fencing of the place of the obstacle on the adjacent railway track is made by the assistant driver from the side of the expected train at a distance "T". If the train driver receives a message about the departure of the train on the wrong track, he must whistle the locomotive to call the assistant train driver to fence off the obstacle from the opposite side.
When the rest of the trains stop, the fencing is made by the assistant driver by laying firecrackers on the adjacent railway track from the side of the train expected along this railway track at a distance of 1000 m from the place of the obstacle (Fig. 111). If the head of the train is at a distance of more than 1000 m from the place of the obstacle, firecrackers on the adjacent railway track are stacked opposite the locomotive. If the train driver receives a message that a train has been sent in the wrong direction along an adjacent railway track, he must call an assistant driver by radio communication or with a locomotive whistle to lay firecrackers at the same distance from the obstacle on the opposite side, and on uncommon railway tracks to fence off an obstacle from the opposite side.

In areas where passenger trains run at speeds exceeding 120 km / h, the distances over which firecrackers must be laid are set by the infrastructure owner.
After laying the firecrackers, the assistant driver and the conductor of the carriage must move 20 m from the place of the laid firecrackers back to the train and show a red signal in the direction of a possible approaching train.

49. By order of the driver of the leading locomotive, workers of the locomotive crew, conductors of passenger cars, conductors may be involved in the fence of the tail and head of a train that has a forced stop on the stretch, as well as places of obstacles for the movement of trains on the adjacent railway track of a double-track or multi-track section.
Other workers established by order of the owner of the infrastructure or the owner of non-public railways may also be involved in the fence of the tail and head of a train that has a forced stop on the stretch, as well as places of obstacles to the movement of trains on an adjacent railway track of a double-track or multi-track haul.
When servicing locomotives of passenger trains by one driver, the train fencing during a forced stop on the stretch is carried out by the head (mechanic-foreman) of the passenger train and the conductors of the carriages at the direction of the driver, transmitted by radio communication.
When servicing locomotives of freight trains by one driver, the train fencing in case of a forced stop on the stretch is carried out in accordance with the procedure established by the owner of the infrastructure, the owner of non-public railways.

The Slavic warriors, long before the appearance of Kievan Rus, according to the Byzantine authors of the 6th century. it is the shields that act as the only means of protection:
Procopius of Caesarea: "Entering the battle, the majority go to the enemies on foot, with small shields and spears in their hands, but they never put on the shell."
Mauritius Strategist: "Each man is armed with two small spears, and some of them with shields, strong but difficult to bear."

Unfortunately, it is not possible to imagine the appearance of the aforementioned Slavic shields, since there is no visual or archaeological evidence from written sources. Obviously, Slavic shields of this time were made entirely from organic materials (boards, rods) and, due to the absence of metal parts, have not survived to this day.

The earliest fragments of shields found on the territory of Ancient Russia date back to the 10th century. With rare exceptions, these are only metal parts. Thus, the information to recreate appearance and the design features of the shields are very limited.

Fragments of at least 20 shields have been archeologically recorded on the territory of Ancient Rus. The most common and clearly identifiable part of the shield is the umbon, which is an iron hemisphere attached to the center of the shield.

A.N. Kirpichnikov distinguishes two types of Old Russian umbons: hemispherical and sphero-conical. The first type includes 13 out of 16 found specimens. All of them are standard in shape - a hemispherical vault on a low neck, and in size - a diameter of 13.2-15.5 cm, a height of 5.5-7 cm. The thickness of the metal does not exceed 1.5 mm.

The second type includes three umbons, two of which originate from the Southeastern Ladoga area and one more was found in the Old Russian layer of the Tsimlyansk settlement. These are sphero-conical umbels, most clearly expressed in the Ladoga specimens. They are somewhat larger than umbons of the first type: diameter 15.6 cm and 17.5 cm, height 7.8 cm and 8.5 cm. The neck is absent. Umbon from the Tsimlyansk settlement is smaller (diameter 13.4 cm, height 5.5 cm) and the presence of a small ledge at the top of the vault.
Umbons of both types have fields with a width of 1.5-2.5 cm. On these fields, from 4 to 8 holes were punched through which nails (rarely rivets) passed, which fastened the umbon on the wooden field of the shield. Several fastening nails have survived, which make it possible to roughly calculate the thickness of the wooden field under the umbil. With a length of 2.5 to 5 cm, the nails are bent in such a way that the thickness of the wooden field is reconstructed within 7-8 mm. At the same time, on one of the booms of the second type found in the Ladoga area, a rivet with no bends, 4.5 cm long was fixed. According to A.N. Kirpichnikov, such rivets simultaneously fastened the boom edge, the shield board and the handle bar.

In addition to the umbons, the defining part of the shield is metal fittings attached to the edge of the shield. In six cases the shackles were found together with umbons, in three cases without umbons. The number of fittings ranged from a few pieces to two dozen. They are thin (0.5 mm) iron (in one case, bronze) strips about 6 cm long and about 2 cm wide, bent in half. On one of the fetters, traces of ornamentation in the form of two parallel lines have been preserved. Two small rivets were attached to the edge of the shield. Most of the Old Russian fetters on both sides had a step, which, as foreign material shows, was necessary for the location of a leather strip running along the edge of the shield. The distance between the edges of the forging in all cases was 5-6 mm, which was equal to the thickness of the wooden field at the edge of the shield.

A flat screen or shield is the simplest type of acoustic design for a loudspeaker head (speaker). Most often it is a wooden panel of a square or rectangular shape of rather large dimensions. For example, to reproduce without attenuation of sound with a frequency of 50 Hz (λ = 680 cm), it is necessary that the side of the screen is at least 0.5λ, i.e. about 340 cm. However, good results can be obtained with a smaller panel with a side about a quarter of the wavelength of the lowest frequency reproduced by raising the frequency response at low frequencies. At the same time, this frequency cannot be lower than the main resonant frequency of the head, since in this case the sound emission by the head in the screen sharply decreases (18 dB / oct.).

The symmetry of the screen relative to the axis of the diffuser is undesirable, since in this case a deep dip will appear in the frequency response of the loudspeaker as a result of an acoustic short circuit at one of the frequencies. Significant improvement in frequency response can be achieved by using an unbalanced screen or an asymmetrical position of the speaker in the screen of the correct shape.

The figure above shows the dimensions of a typical flat panel loudspeaker measurement and two ways to install them in a panel. This design is not very common due to its bulkiness and aesthetics.

Installing the screen in the corner of the room allows it to be reduced in size without degrading playback low frequencies, since the walls forming the corner serve as a continuation of the screen, increasing its effective dimensions. The shield is suspended from the ceiling, giving it the shape of a triangle or trapezoid. A wide gap must be left between the top edge of the board and the ceiling, and the space behind the board must be filled with sound-absorbing material.

Frequency response of the speaker when placed in a rectangular shield. 1 - in the center, 2 - when offset along the long side

The screen is recommended to be made of a thick board, chipboard, plywood, etc. 10-20 mm thick. Preferably, the aspect ratio of the rectangular shape is from 2: 1 to 3: 1. It is advisable to choose the absolute dimensions such that at the lower limit of the frequency range (resonant frequency of the speaker) the equivalent diameter of the screen (diameter of a circle whose area is equal to the area of ​​the screen) D is determined by the formula:

D= 0.5λ /Q where

D- equivalent screen diameter;

λ - the length of the sound wave at the lower limit of the frequency range;

Q- full quality factor.

With this screen size, the frequency response will be more uniform. If the screen is made smaller, then one should expect that there will be a drop at the lower frequency of the range, calculated by the formula:

N=20 lg(D/ D 1 ) where

N- decay at the resonant frequency;

D 1 Is the actual diameter of the screen.

Example... The resonant frequency of the speaker is 85 Hz, the quality factor is 2. Determine the drop at the resonant frequency if D 1 = 0.5 m. Determine the equivalent screen diameter: D = 0.5 · (343: 85) · 2 ~ 1 m. When D 1 = 0.5 m at the lower cutoff frequency N = 20lg (1: 0.5) = 6 dB.

It is recommended to place the loudspeaker in the center of the rectangular shield. Off-centering reduces the developed sound pressure and degrades the frequency response. For a square shield, offsetting the head mounting position improves frequency response, albeit lowering the sound pressure.

It is highly recommended to install the speaker flush with the display panel. If the speaker is installed on the inside of the panel, a cylindrical depression (a kind of short pipe) is formed in front of it, and the air column inside it can resonate at a number of frequencies, thereby degrading the frequency response and sound quality. When covering the front side of the screen with a grill, make sure that the fabric is well stretched. Behind, from the side of the magnet, it is recommended to put on a "skirt" on the speaker, for example, from coarse calico.

Meet Acustic systems in which the loudspeaker head is inserted into a hole in the wall of the room, i.e. the wall is the screen. Such a constructive solution is beneficial, but one must take into account sufficient volume in the next room. Using a wall as a screen gives a noticeable improvement frequency response and sound quality (especially at low frequencies). An additional bag behind the speaker should be made large (for example, in the form of a hemisphere with a diameter equal to that of the speaker) and filled with cotton wool to prevent unwanted resonances.

The shield can be small (side dimensions 40-50 cm) if the speaker will reproduce frequencies above 150-200 Hz, as, for example, in the case of system 2.1, where the subwoofer plays the role of sounding low-frequency sounds.

Let's consider one more calculation for the dimensions of a flat screen (shield). We need a screen that would allow at the lower boundary frequency of the reproduced range to obtain the same sound pressure level as at the upper boundary of the piston range. fgr. the area of ​​its action, i.e. equalize the sound pressure at low and mid frequencies. Value fgr. can be found from the formula: fgr.= 1.4 s / (∏d) .

Typical low frequency response at Q> 1.93

The choice of the lower cutoff frequency depends on the quality factor of the head used. Frequency response form at Q<1,93 монотонно возрастает, а при Q≥1,93 на АЧХ появляется провал на частоте ω 2 and a peak at frequency ω 1. The quality factor of the head, when placed in a flat panel, practically does not change. Frequency response at Q<1,93 и при правильном выборе размеров экрана определяется только спадом в область более низких частот. Поэтому за нижнюю граничную частоту при Q<1,93 выбирают резонансную частоту динамика ω 0 ... At Q≥1.93, the peak frequency is usually chosen for the lower cutoff frequency ω 1 The frequency response of the dynamics and the unevenness of the frequency response in this case is determined by the dip at the frequency ω 2... However, in this case, the calculated range of reproducible frequencies is somewhat narrowed in comparison with its value at Q<1,93.

Dependence of φ (Q) on Q

To eliminate this disadvantage, another method is proposed for choosing the lower cutoff frequency, which allows one to reduce its value. Its essence lies in the fact that the cutoff frequency is selected at the frequency ω<ω 2 , at which the level of the frequency response is equal to its level at the frequency of the dip ω 2... Depending on the value Q this frequency may be slightly higher or lower ω 0 ... Studies have shown that the most rational head quality factor for open speakers is 2.4. In this case, the lower cutoff frequency of the open speaker fgr. n. matches the resonant frequency of the speaker ω 0 .