Brake line of a freight car with fittings. Wagon brake system Wagon brake system

26.06.2020

Introduction

Auto brake technology is one of the most important elements of railway transport; the carrying capacity of roads and the safety of train traffic largely depend on the level of development and condition of this technology.

The braking equipment of the rolling stock must work normally under the conditions of complex processes occurring in a moving train (dry friction of brake shoes with the conversion of mechanical energy into heat, gas-dynamic processes in the brake line, rolling of wheels on rails under conditions of maximum use of adhesion forces, interaction of cars with each other with the appearance of significant longitudinal forces, etc.).

To ensure the uninterrupted operation of rolling stock auto-brake equipment in difficult meteorological conditions and with high traffic density, employees of auto-brake checkpoints and automatic departments of locomotive and car depots do a lot, constantly improving the technology of repairing brake equipment, ensuring high reliability and stability of its operation in trains.

In order to ensure the safe operation of the brake equipment, the following types of repair and inspection of the brake equipment of cars have been established: factory, depot, revision and current.

In modern operating conditions and in the near future, the automation of maintenance of various components of the brake system, its adaptation for remote control with a motorist and other devices, will acquire particular importance.

Purpose and design of the brake linkage of a freight car

A lever brake transmission is a system of rods and levers, through which the human effort (during manual braking) or the force developed by compressed air is transmitted along the brake cylinder rod (during pneumatic and electro-pneumatic braking) to the brake pads, which are pressed against the wheels. According to the effect on the wheel, lever gears with one-sided and two-sided pressing of the pads are distinguished.

Lever brake gear with double-sided pressing of the pads has the following advantages compared to a single-sided one: the wheelset is subjected to an eversion action in the axle boxes in the direction of the pressing force of the pads; the pressure on each pad is less, therefore, the wear of the pads is less; the coefficient of friction between the block and the wheel is greater. However, leverage with double-sided pressing is much more complicated in design and heavier than with one-sided, and the heating temperature of the pads during braking is 10-15% higher. With the use of composite pads, the disadvantages of one-sided pressing become less noticeable due to less pressure on each pad and a higher coefficient of friction.

Basically, all freight cars have one-sided pressing of the pads, and passenger cars have two-sided, with vertical levers located on both sides of the wheels. Therefore, triangels are used on freight cars, and beams (traverses) on passenger cars.

The device of the brake linkage of a four-axle freight car is shown in Figure 1.

Figure 1 - The device of the brake linkage of a four-axle freight car

The piston rod 6 of the brake cylinder and the dead center bracket 7 are connected by rollers with horizontal levers 10 and 4, which are interconnected in the middle part by a puff 5. Puff 5 is installed in holes 8 with composite shoes, and with cast-iron shoes in hole 9. From opposite ends levers 4 and 10 are articulated by rollers with a rod 11 and an auto-regulator 3. The lower ends of the vertical levers 1 and 14 are connected to each other by a spacer 15, and the upper ends of the levers 1 are connected to the rods 2, the upper ends of the extreme vertical levers 14 are fixed to the cart frames with the help of earrings 13 and brackets. Triangels 17, on which shoes 12 with brake shoes are installed, are connected by rollers 18 with vertical levers 1 and 14.

To prevent the triangles and spacers from falling onto the track in case of their separation or breakage, safety angles 19 and brackets are provided. Brake shoes and triangles 17 are suspended from the bogie frame on suspensions 16. The traction rod of the regulator 3 is connected to the lower end of the left horizontal lever 4, and the adjusting screw is connected to the rod 2. When braking, the body of the regulator 3 rests against the lever connected to the horizontal lever 4 by tightening .

A similar linkage, differing only in the size of the horizontal levers, have gondola cars, platforms, tanks, etc.

The action of the lever transmission of a four-axle car is similar to the action of the lever transmission discussed above. For manual adjustment of the linkage in the rods 2, earrings 13 and puffs 15 there are spare holes.

The hand brake drive is connected by means of a rod to the horizontal lever 4 at the point of connection with the rod 6 of the brake cylinder, so the action of the leverage will be the same as during automatic braking, but the process is slower.

The most critical parts of the lever transmission of freight cars are triangles with a blind fit of brake shoes 3 (Figure 2).

brake lever car repair

Figure- 2 Triangel with a blind fit of the brake shoes

Bookmark 2 is installed on the inside of the shoe. The tip 5 placed behind the shoe lies on the shelf of the side beam of the bogie in the event of a break in the suspension 4 and protects the triangle from falling onto the track. The parts mounted on the trunnions are fixed with castellated nuts 8 and fixed with cotter pins 9. The blocks 7 are fastened in the shoes with checks 6. The triangel is pivotally connected to the side beams of the bogie by means of hangers 4. All freight cars must have shoe hangers with rubber bushings in the holes (Figure 3). This allows you to remove loads from the suspension that cause fatigue cracks, prevents breaks and parts from falling onto the track.

Figure-3 Suspension with rubber bushings in holes

To increase the reliability of the linkage and prevent the fall of puffs and rods, both strips 1 of each vertical and horizontal lever are welded together with strips 2. When placed in the holes of such levers, the connecting rollers are fastened as usual with a washer and cotter pin with a diameter of 8 mm.

The rods and horizontal levers near the cylinder are equipped with safety and support brackets.

To improve the reliability of the linkage and prevent the fall of puffs and rods, both strips 1 of each vertical and horizontal lever are welded together with strips 2 (Figure 4). The connecting shafts, when inserted into the holes of such levers, are fastened as usual with a washer and a cotter pin with a diameter of 8 mm.

Figure 4 - Welded strips to improve the reliability of the linkage

Additionally, from the side of the roller head, a safety cotter pin of the same diameter is inserted into specially welded cheeks 3 to prevent the roller from falling out if the main cotter pin is lost.

Figure 5 - Cheeks to prevent the roller from falling out

The design feature of the lever transmission of eight-axle cars is the presence of a balancer that ensures the distribution of the braking force on both bogies (Figure 6). Many freight cars are equipped with a hand or parking brake with a steering wheel located on the side of the car.

Figure 6 - Features of the design of the brake linkage of 8-axle cars

The brake system of any wagon consists of pneumatic and mechanical parts. The pneumatic part of the brake system of a freight car includes: an air distributor, a brake cylinder, a reserve tank and an automatic pressure regulator in the brake cylinder (auto mode). The mechanical part includes: brake cylinder, brake linkage (horizontal levers, horizontal lever tightening, rods), automatic brake linkage adjuster and hand brake.

Rice. Pneumatic part of the brake of a freight car.

In the figure, the numbers indicate: 1 - connecting sleeves, 2 - tee-bracket of the brake line, 3 - end valves, 4 - spare tank, 5 - uncoupling valve, 6,7,8 - air distributor (two-chamber tank 7 with main 8 and main 6 parts), 9 - auto mode, 10 - brake cylinder.

Rice. Wagon braking system.

The figure shows the brake system of the car, the location of the brake equipment on the frame, and the numbers indicate: 1 - head link, 2 - automatic regulator of the brake linkage, 3 - head horizontal lever, 4 - tightening of the horizontal levers, 5 - brake line, 6 - rear horizontal lever, 7 - tee bracket, 8 - spare tank, 9 - platform for auto mode, 10 - rear link, 11 - release valve leash, 12 - air distributor, 13 - brake cylinder, 14 - brake cylinder rod, 15 - automatic drive TRP regulator, 16 - safety brackets.

The principle of operation of the brake system: when the brake line is discharged, the air distributor is activated for braking, while connecting the spare reservoir with the brake cylinder. Under the action of compressed air pressure, the brake cylinder rod comes out, while turning the head horizontal lever relative to the dead point. The tightening of the horizontal levers moves in the same direction as the stem, and pulls the rear horizontal lever towards itself. The automatic brake linkage adjuster runs over the drive, the brake linkage shrinks. The rods pull the vertical levers of the brake linkage of the bogies to the center of the car and press the brake pads fixed in the triangular shoes to the wheel tread.

When the pressure in the brake line rises, the air distributor is released, connects the reserve tank to the brake line, and the brake cylinder to the atmosphere. Under the action of the return spring, the piston with the rod moves to the brake cylinder cover, the horizontal levers move the rods towards the bogies, the brake pads move away from the wheel rolling surface.

A manual parking brake is used to secure wagons at stations or steep descents.

Rice. Diagram of the hand brake.

The manual parking brake consists of a drive 2 with a handwheel 1, a worm gear, a mechanism with an eccentric 4 and a link 5. To bring the brake into working position, the handwheel with the drive is deflected away from its original position) so that it is perpendicular to the longitudinal axis of the car. Then the worm gear engages with the rotary mechanism, which, turning, pulls the thrust along with it. The rod with its second end is attached with a roller to the head horizontal lever. When it is moved towards the manual parking brake actuator, the head horizontal lever rotates relative to the dead center and removes the piston rod from the brake cylinder, thereby bringing the brake linkage to the braking position. The second end of the manual parking brake rod, connected to the head horizontal lever, is made in the form of an eyelet, that is, it has an elliptical hole, the length of which ensures free movement of the mounting roller when the brake cylinder rod exits during operation of the brake system.

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Ministry of Railways of Russia

RUSSIAN STATE OPEN

TECHNICAL UNIVERSITY OF COMMUNICATIONS (RGOTUPS)

Test

discipline Fundamentals of technical diagnostics

"Brake equipment of freight cars"

Student Nesterov S.V.

Saratov - 2007

Brake equipment is used to reduce the speed of the car and stop it in a given place.

The most important parameter of the efficiency of the braking system is its braking coefficient or the length of the path that a car moving at a given speed will cover from the moment the braking starts to a complete stop. The design of the brake equipment is very diverse. However, if we consider it as an automated system, then we can select a number of blocks combined into a single block diagram (Fig. 1).

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Rice.1. Structuralschemebrakeequipment

The brake system works as follows. The control unit 1 ensures that the brake system is charged with compressed air through the brake line (link unit 2) and, if necessary, gives a signal to start braking or releasing. The control signal is received by the air distributor 3, which, using the auto mode 4, activates the brake cylinder 5 with a lever transmission and an automatic regulator 6. The force from the brake cylinder is transmitted to the friction pair 7, which ensures the absorption of the kinetic energy of motion, i.e. wagon braking. The braking process of the wheelset 9 is controlled and regulated by the anti-skid device 8. Therefore, the efficiency of the braking system is ensured by the high-quality functioning of all units. Moreover, the predominantly serial connection of blocks makes such a system very vulnerable, since the failure of one of the blocks leads to the failure of the entire system. This feature of the operation of braking equipment requires a clear organization of the system of diagnostics and maintenance.

Functional diagnostics of the effectiveness of the automatic brakes is carried out during the movement of the train (after departure to the station) mainly on a flat straight section of the track at a speed of 40-60 km/h. To do this, the driver performs trial braking of the train, usually by reducing the pressure in the brake line by 0.03-0.04 MPa. If a sufficient braking effect is not obtained within 20-30 seconds in freight trains, then emergency braking is performed and other measures are taken to stop the train, since the brakes do not function correctly. Experienced drivers can determine the braking coefficient by the train deceleration rate.

For example, in the United States, the following system for diagnosing train brake systems began to be applied on an experimental basis. On the last car of the train and in the driver's cab, electronic units with microprocessors are installed, which interact with each other via radio communication. According to the corresponding program, pressure and leaks from the brake line in the head and tail of the train, the process of braking and release are monitored. At the request of the driver, this information is displayed on the display located in the driver's cab.

In the wagon industry at maintenance points, quasi-functional diagnostics of brake equipment by structural parameters is widely used, which is called full and reduced testing of brakes. The essence of testing is as follows.

After charging the brake network of the train to the set pressure, the tightness of the air line is checked. To do this, for example, in freight trains, the driver's crane is set to the position II and measure the time of pressure drop in the main tanks with the compressors off by 0.05 MPa. The time rate is set depending on the volume of the main tanks and the length of the train in the axes.

After checking the tightness of the train line, the brakes are monitored. To do this, the stage of braking is performed by reducing the pressure in the line by 0.06-0.07 MPa and the handle of the driver's crane is set to the position of shutting off with power. All air distributors of the train must act on braking and not spontaneously release during the entire time of the test. The control of the action of the brakes is carried out by the inspectors of the cars, who, according to the structural diagnostic parameters, evaluate the technical condition of the brake equipment. The diagnostic parameters in this case are: the output of the brake cylinder rod, the pressing of the pads to the wheels, the correct location of the gear levers, the absence of intense air leaks in the elements of the brake equipment. If it is established that the brake system has worked normally for braking, then a signal is given to release the brakes and the driver's crane is moved to the position II. The release of the brakes is controlled. The correctness of the release is checked by the return of the rods to the cylinders, the departure of the brake pads from the wheels, the absence of intense leaks, in that case from the air distributors.

Rice. 2. Schemepointscentralizedtestingbrakes

At the end of the full testing of the brakes, a certificate of brakes of the VU-45 form is filled out. At large PTOs, there are centralized testing points for diagnosing brakes (Fig. 2). Two point schemes have become widespread. In Scheme A, all diagnostic equipment is located in the room of the checkpoint, and pipelines with end valves 1, 2, 3, 4 are connected to the Pit to connect the brake network of the trains and a two-way loudspeaker. The testing of the train brakes is controlled by the operator of the centralized point, who performs it according to the algorithm described above.

In Scheme B, autonomous semi-automatic devices 5, 6, 7, 8 are installed at each intertrack for diagnosing automatic brakes according to the corresponding program. The compressed air supply and cable lines are centralized, through which the diagnostic results are recorded on the equipment of point B. The point operator actually controls the actions of semi-automatic devices and car inspectors, and also decides on the amount of repair work and keeps appropriate records. As can be seen from the described procedure for the complete testing of the brakes, this process is quite lengthy, which makes it difficult to service trains, especially long trains, and increases their downtime at the maintenance station. To reduce the process of diagnosing brakes, VNIIZhT researchers have proposed two methods. The essence of the first method is that it is recommended to control the density of the line by measuring the flow of compressed air in the process of charging the brake network. Indeed, as operating experience shows, air leaks in the composition are concentrated mainly in places where end valves, connecting sleeves, tees, dust collectors, couplings are located. Therefore, the state of the brake line is essentially characterized by a transit flow caused by leaks concentrated in the indicated places. Therefore, by measuring the air flow rate when charging the brake network, one can first observe a large flow rate going to charge the spare tanks, and then a gradual stabilization of the compressed air flow rate. This stabilized level of air flow actually goes to replenish the leaks. Evaluating it depending on the length of the train, it is possible to determine whether the density of the brake line meets the established standards.

The second way is that the tightness of the brake line is checked after the braking stage. In this case, the wagon air distributors are activated and disconnected from the brake line. Therefore, if 15-20 seconds after braking, leaks are checked, they will characterize the density of the brake line of the train. This means that in this case it is also possible to combine two procedures for testing the brakes and reduce the time of the entire diagnostic cycle.

With reduced testing of the brakes, the diagnostic algorithm is greatly simplified. After charging the brake network, a braking stage is performed and the operation of the brakes of only the tail cars is controlled. If the brakes of the tail cars have worked, then the brakes are released and the quality of the release of the brakes of the tail cars is controlled. Consequently, with a reduced test of autobrakes, the actual integrity and serviceability of the brake line of the train and, with a certain probability, the operation of all brakes are checked when the brakes of the tail cars are activated.

Air distributors and auto modes

The method for diagnosing air distributors can be considered using the example of testing freight car devices. On the test stand, four parameters of the functioning of the main part of the air distributor and three parameters of the main part are controlled.

Moreover, tests of the diagnosed, for example, main part are carried out together with the reference main part of the same type of air distributor. Subsets used as references must comply in all respects with the requirements of the manufacturer's instructions. When testing, the operation of the main part is checked in a flat loaded mode according to the following parameters: charging time of the spool chamber; softness of action; the clarity of functioning at the degree of braking and vacation. The main part of the air distributor is checked in the mountain empty and loaded modes. In this case, the main attention is paid to the control of the charging time of the reserve tank, the correct operation of the non-return supply valve, filling and dispensing of the brake cylinder (time and pressure). At present, a test bench with automatic program control of the StVRG-PU type is being introduced at auto-brake checkpoints (St - stand, VRG - cargo air distributors, PU - with program control).

The stand works as follows. The test and reference parts of the air distributor are installed on the counter flanges of the stand and fixed with pneumatic clamps. The stand is charged and the software control unit is turned on. The step searchers of the program block, which are in the initial position, turn on the corresponding electro-pneumatic measuring instruments and start testing the air distributor according to the unconditional diagnostic algorithm. Electrocontact pressure gauges measure the pressure in the tanks and air distributor chambers, and time interval counters record the time (in seconds) of filling or emptying the tanks. The memory block also remembers the information and stores it until the end of the check.

If at any stage of diagnostics the measured parameters go beyond the established norms, then the tests automatically stop and the red signal lamp lights up. The indication block indicates on which operation a defect was detected. This allows you to quickly determine which air distributor assembly is faulty.

freight car braking equipment

auto modes.

Diagnosis of auto modes is carried out on the stand (Fig. 3). The stand consists of a pneumatic clamp, in which auto mode 1 is set and connected to tank 6 and through valve 2 to tank 3. Reducer 4, receiving power from compressed air line 7, maintains the specified pressure in tank 3. In turn, the tank 6 is equipped with a valve 5 with a calibrated hole. Imitation of the operation of auto mode 1 at different loadings of the car is carried out by cylinder 9 using crane 8.

Rice. 3. SchemeboothFordiagnosingauto modes.

Diagnosis of auto mode is performed in the following sequence. First, the reducer 4 sets the pressure in the tank 3 to 0.3 - + 0.005 MPa, i.e. tank 3 will simulate the operation of the car brake air distributor. Auto mode 1 is set to work in empty mode, i.e. with a gap between the head and the cylinder rod 9 in the released state d? 1 mm. Valve 2 is opened, and compressed air from reservoir 3 through auto mode 1 enters reservoir 6, which plays the role of a brake cylinder. In the brake reservoir 6, a pressure of 0.125 - 0.135 MPa should be established. This concludes the first stage of testing. At the second stage, valve 2 is closed, and compressed air is released from tank 6 into the atmosphere. Cylinder 9 is supplied with compressed air from line 7 by means of valve 8. Cylinder 9 is triggered and lowers the head of auto mode 1 by 24 - + 1 mm, i.e. switches it to medium mode. Next, the reducer 4 sets the initial pressure in the tank 3, open the valve 2 and measure the pressure in the brake tank 6, which should be 0.3 MPa. The time of movement of the damper piston of the auto mode down when air is released from the cylinder 9 should be within 13-25 seconds. In the same order, the operation of the auto mode is controlled at other loadings of the car, as well as when simulating a leak from the brake cylinder by opening a calibrated hole in the valve 5 of the tank 6.

Leverage auto-adjusters

The effectiveness of the brake system depends largely on the correct operation of the brake cylinder and linkage. The output of the rod of the brake cylinder must be within the limits provided for by the instructions of the MPS. An increase in the output of the rod in excess of the established norm leads to a decrease in the efficiency of the brake, since the pressure in the brake cylinder will be lower than the calculated value. Small rod extensions with non-direct acting brakes cause an overpressure in the brake cylinder, which can cause wheel seizure.

The output of the brake cylinder rod depends not only on the wear of the brake pads, but also on the correct adjustment of the linkage and its rigidity. The brake linkage must be adjusted so that, when braked, the horizontal levers occupy a position close to the perpendicular rod of the brake cylinder and rods. The vertical arms on the bogie should have approximately the same slope, and the suspension and chocks would form approximately a right angle between the suspension axle and the direction of the radius of the wheel passing through the center of the lower suspension pivot.

The rigidity of the transmission should not be below the norm. For example, on a freight car with a brake cylinder with a diameter of 14 and a gear ratio n rp = 11.3, the rod output in the empty mode is 110 mm, in the middle mode - ? 120 mm, and loaded -? 135 mm. To ensure automatic control of the linkage, auto-regulators are used, for example, 536 M, 574 B, and a pneumatic regulator RB 3. The leverage regulators are checked on the stand (Fig. 4). The stand consists of a brake cylinder 1 connected to a lever transmission, consisting of a horizontal lever 2, a tested regulator 4, a limiter 3, a simulator of the elasticity of the brake gear 5, a vertical lever 6 with a brake shoe, a wheel simulator 7 with an adjusting screw 8. Brake cylinder rod output 1 is measured by the device 9. By adjusting the position of the wheel simulator 7 with the screw 8, it is possible to reduce the gap between the wheel and the block. Therefore, the stand simulates the operation of a lever transmission on a car. The regulator is tested on the stand according to the algorithm.

Rice. 4. SchemeboothFordiagnosingautoregulatorslevertransmission.

From the beginning, set the regulator to its original position, i.e. when the linkage is adjusted correctly and the regulator should not act on either the dissolution or the contraction of the gear. In this position, the dimension a from the protective tube to the control mark on the screw shank must be between 75 and 125 mm. After that, the positional stability of the regulator is checked. For this, a longitudinal line is applied with chalk on the pipe and the thrust of the regulator screw and a number of successive braking cycles - vacation are simulated on the stand. For a working regulator, the protective tube in this position should not rotate relative to the screw, i.e. the size of a should not change. Next, check the action of the regulator for dissolution. To do this, by turning the control pipe, screw the regulator nut onto the screw by 1-2 turns and thereby reduce the size a. The braking process is simulated on the stand and the regulator must restore the initial size a, and during subsequent braking it should not change. At the next stage, the action of the regulator for contraction is checked. To do this, the adjusting nut is turned 1-2 turns to increase the dimension a, i.e. "dissolve" the transfer. After each braking, the dimension a must decrease, which is observed on the chalk line "measured by the device" marked on the protective tube and rod.

Anti-skid devices

The main function of these devices is to prevent jamming of wheel sets during braking. The anti-skid device consists of an axial sensor mounted on the axle box of the wheelset; a safety valve located on the car body and connected to the axial sensor by a flexible hose; exhaust valve located next to the brake cylinder. The devices work as follows. The axle sensor, when the wheelset is jammed, sends a signal to the safety valve, which acts as an amplifier and actuates the exhaust valve. Through the exhaust valve, the compressed air from the brake cylinder is released into the atmosphere and the brake is released for a short time. As soon as the speed of the wheelset is restored, the braking process resumes, and so on.

Three types of anti-skid devices have been used on wagons: inertial type, improved for international wagons, and electronic. Anti-skid devices of the inertial type are triggered when the rotational movement of the wheel tread is slowed down by 3-4 mm per second. Included with advanced anti-skid device type MWX includes 4 axial sensors MWX2, two actuating valves MWA15 and four safety valves. Thus, the devices control the speed of rotation of all four wheelsets of the car.

The set of electronic anti-skid device includes an electronic unit, four tachogenerators installed on each axle of the wheelset, and four resetting electro-pneumatic valves.

Rice. 5. schemeboothFordiagnosingantiskiddevices.

Power is supplied from a rechargeable battery. Despite the design differences, all types of anti-skid devices actually have similar structural schemes and they are controlled on the stand (Fig. 5). The stand for checking the anti-skid device includes: base 1, on which the axle box 2 with the sensor 3 of the anti-skid device is fixed; brake shoe 4 with cylinder 6, which is mounted on frame 5; rotator 7 with V-belt transmission; relief valve 8; air distributor 9; brake line 10; spare tank 11; brake cylinder 12, and simulator 13 linkage, in the form of an elastic element. The diagnostic technique is as follows. The stand is turned on and with the help of the rotator 7 with V-belt transmission, the specified frequency of rotation of the axle neck of the wheelset with the flywheel is reproduced. Compressed air is supplied to the cylinder 6, which receives the brake shoe 4 to the flywheel. The braking process begins. The anti-skid test is carried out from the beginning under normal braking, i.e. deceleration of the wheelset speed less than 3 m/s 2 . In this case, the anti-skid device should not work. Next, the jamming of the wheelset is simulated, i.e. the process of stopping the flywheel occurs with a deceleration of more than 3-4 m/s 2 . In this case, the sensor 3 of the anti-skid device should work to turn off the brake system, turn on the relief valve 8, which connects the brake cylinder 12 to the atmosphere. The pressure is released from the cylinder 6 and the process of rotation of the wheelset axle is resumed. At this time, the valve 8 closes and the air distributor 9 connects the reserve tank 11 with the brake cylinder 12, simulating the braking process. Then, the operation of the anti-skid sensor 3 is reproduced again, and so on.

It should be noted that the described stand consists, as it were, of two parts: the first, which simulates the jamming of the wheelset and the operation of the sensor, and the second, which reproduces the operation of conventional elements of braking equipment - an air distributor, a spare tank, a brake cylinder and a lever transmission.

Diagnosis is carried out according to the parameters of the deceleration at which the sensor is triggered, the time of emptying and filling the brake cylinder, the flow of compressed air from the reserve tank during repeated operation of the anti-skid device, and others. The anti-skid device is adjusted so that it ensures the prevention of jamming of the wheelset with a minimum decrease in the braking efficiency of the entire system.

Magnetic rail brake

Such brakes are mainly used as additional brakes for emergency braking of high-speed trains. Electromagnetic shoes are located on both sides of the cart in the space between the wheels. Each such shoe, when the brake is released, is held above the rails by springs mounted in vertical pneumatic cylinders with guides. The shoes are also equipped with shock absorbers and cross links.

During emergency braking, compressed air is supplied to the cylinders that lower the shoes onto the rails, and at the same time, current from the batteries is supplied to the windings of the solenoids of the shoes. Electromagnets are attracted, and there is friction of the shoes on the rails, which ensures the braking of the cars.

Rice. 6. SchemeboothFordiagnosingmagnetic railbrakes.

Checking the efficiency of the magnetic rail brakes is carried out on the stand (Fig. 6). For testing, the magnetic rail brake unit 1 is mounted on rotating metal circles 2, which imitate a moving rail track, and fixed with ties 3 to fixed supports. Perform a series of cycles braking - release. Braking efficiency is measured by the power consumption of electric motors rotating circles 2. When checking, they also measure the response time of the shoes for braking and release, control the efficiency of the lifting devices, dampers and connections.

Occupational safety requirements for the repair of brake equipment of freight cars

1. Repair of brake equipment must be carried out in accordance with the repair and technological documentation, the requirements of the Instruction for the Repair of Brake Equipment of Cars by specially trained locksmiths under the supervision and guidance of a foreman or foreman.

2. Before changing air distributors, exhaust valves, parts of brake equipment, reservoirs, supply pipes to the air distributor, before opening the brake cylinders and adjusting the leverage, the air distributor must be turned off, and the air from the spare two-chamber reservoir must be released.

3. Contraction of the brake linkage, when adjusting it, should be done using a special tool. To align the holes in the heads of the rods and the levers of the brake linkage, it is necessary to use a barb and a hammer. It is forbidden to check the coincidence of the holes with your fingers.

4. When purging the brake line, in order to avoid hitting the connecting sleeve, hold it with your hand near the connecting head.

5. Before disconnecting the connecting sleeves, the end valves of adjacent cars must be closed.

6. To disassemble the piston after removing it from the brake cylinder, it is necessary to compress the spring with the brake cylinder cover so much that it is possible to knock out the rod head pin and remove the cover, gradually releasing it until the spring is fully decompressed.

7. Before separating the piston rod head of the brake cylinder and the horizontal arm, the air distributor must be turned off, and the air from the spare and two-chamber reservoir must be released. Removal and installation of the piston of the brake cylinder must be carried out using a special tool.

8. Before changing the end valve, it is necessary to disconnect the brake line of the freight car from the power source.

9. When repairing brake equipment under a freight car, it is forbidden to be at the head of the piston rod of the brake cylinder on the side of the rod outlet and touch the head of the rod.

10. It is forbidden to tap the reservoirs of the working chamber and the air distributor during their cleaning, as well as to unscrew the plugs of brake devices and reservoirs under pressure.

11. Special installations and air columns for testing auto brakes and other purposes must be equipped with connecting heads. When testing auto brakes, it is prohibited to repair the running parts of the frame, the auto brake device of the brakes of freight cars.

12. When repairing equipment under a freight car, it is prohibited to sit on the rail.

Literature

1. Sokolov M.M. Wagon diagnostics.

2. Sergeev K.A., Gotaulin V.V. Fundamentals of technical diagnostics.

3. Birger I.A. Technical diagnostics. M: Mechanical engineering.

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Lever transmission of passenger cars.

The main part of all-metal passenger cars is equipped with a lever transmission of a shoe brake with a cylinder with a diameter of 35 mm and double-sided pressing of the shoes. The characteristics of such linkages are given in table. 8.2.

Table 8.2

Characteristics of lever gears of passenger cars

Note. In the numerator there are values in the presence of cast-iron blocks, in the denominator - composite ones.

The lever transmission of a passenger car differs from the transmission of freight cars in that instead of triangels, traverses are used, on the trunnions of which shoes with brake shoes are installed . Vertical levers and puffs are suspended from the frame on hangers.

Pressing of brake pads is bilateral; vertical levers are located in two rows on the sides near the wheels.

Traverses with shoes and blocks are suspended on single hangers , the ears of which pass between the sides of the shoes. In addition to horizontal levers, there are intermediate levers , connected with vertical levers by rods.

Brake shoes are supplied with a locking device consisting of a leash with a spring, nuts and a cotter pin. With the help of this device, a shoe with a block, when the brake is released, is held at a certain distance from the surface of the wheel

In case of disconnection of rods, levers and traverses or their breakage, safety brackets are provided to prevent parts from falling onto the track.

Leverage adjustment is carried out by an automatic rod-driven regulator . For manual adjustment of the linkage, holes are provided in the heads of the rods and turnbuckles .

Unlike freight cars, each passenger car is equipped with a manual brake, which is located in the tambour on the side of the conductor's compartment. The hand brake drive consists of a handle , which is placed in the vestibule of the car, screw , pairs of bevel gears and thrust , connected to the lever, which is articulated by a rod with a lever and further by a rod with a horizontal lever.

When setting composite pads, the leading arms of the horizontal levers are changed by rearranging the spacer rollers into the holes closest to the brake cylinder. To maintain the gap between the wheel and the block within the established limits, the leverage is adjusted.

Manual adjustment is carried out by moving the rollers into the spare holes of the brake rods for freight cars and with the help of turnbuckles for passenger cars.

Semi-automatic adjustment is carried out using devices in the form of a screw or a gear rack with a dog, mounted on rods or near the dead points of the levers and allowing you to quickly compensate for pad wear. Such adjustment is used on electric locomotives ChS and diesel locomotives 2TE1.

Automatic adjustment is performed by a special regulator as the brake pads wear out.

The brake lever must be adjusted so that:

In the inhibited state, the horizontal levers occupied a position close to the perpendicular rod of the brake cylinder and rods;

The vertical arms on each wheelset had roughly the same slope;

Suspension and pads formed approximately a right angle between the suspension axis and the direction of the radius of the wheel passing through the center of the lower suspension hinge.

This time-consuming process of manual adjustment is eliminated when the rolling stock is equipped with automatic regulators of the brake linkage. The regulator provides a constant average clearance between the block and the wheels, therefore, compressed air is more economically consumed during braking, the braking process proceeds more smoothly throughout the train and losses in brake efficiency are eliminated (especially when the piston rests against the brake cylinder cover).

Depending on the drive, regulators are divided into mechanical and pneumatic. Mechanical automatic regulators are equipped with rocker drives, rod or lever . The rod drive is simple in design and easy to maintain, but the compression losses of the autoregulator return spring cause a significant decrease in braking efficiency, especially in empty mode and composite pads.

The use of a lever drive is caused by the desire to reduce the influence of the autoregulator return spring. On passenger cars, it is a small fraction of the braking force and practically does not reduce the brake pressure. On freight cars with composite pads in the empty mode, this force reduces the amount of brake pressure by 30-50%. Therefore, only a lever drive is used on freight cars. The rocker drive has not been widely used on Russian railways.

The pneumatic actuator retracts the linkage after the output of the brake cylinder rod exceeds a certain value determined by the design of the regulator.

Pneumatic regulators are usually single-acting, while mechanical regulators are single-acting and double-acting.

The work of the double-acting auto-regulator lies in the fact that it automatically dissolves the linkage by the required amount in the event of a decrease in the gaps between the pads and wheels and automatically tightens it when the gaps increase.

The head is screwed into the body and locked with a bolt. A protective tube is inserted into the head and secured in it with a locking ring and a rubber ring. A sleeve with a nylon ring is installed at the end of the protective tube , protecting the regulator from contamination. In the body of the auto-regulator there is a traction cup, in which the auxiliary and adjusting nuts with thrust bearings and springs are installed.

A cover and a bushing are screwed into the traction cup, which are locked with screws. The conical part of the rod enters the traction sleeve, and at the other end of the rod, an eye is screwed, which is locked with a rivet. The return spring rests on the conical surface of the draft cup sleeve and the housing cover. The adjusting and auxiliary nuts are screwed onto the adjusting screw, which has a three-start non-self-locking thread with a pitch of 30 mm. The adjusting screw ends with a safety nut fixed with a rivet that prevents the screw from completely unscrewing from the mechanism.

The case of the autoregulator conv. No. 574B does not rotate. This reliably protects its mechanism from moisture and dust ingress, makes it possible to install safety devices that exclude bending of the adjusting screw and the tendency to self-dissolve at high speeds and vibrations, which occurred with a double-acting automatic regulator conv. No. 53. With manual adjustment, the outlet of the brake cylinder rod is reduced by simply rotating the body of the auto-regulator conv. No. 574B, without reconfiguring the drive.

For normal operation of the auto-regulator, it is necessary to observe the distance between the drive stop and the auto-regulator body - size A. It determines the amount of output of the rod of the brake cylinder during braking. Size value A depends on the type of drive of the auto-regulator, the value of the gear ratio of the leverage, the dimensions of the shoulders of the horizontal levers and the gap between the wheel and the block, with the brake released.

The value of size A is calculated by the formulas:

With a lever drive (Fig. 8.25, a)

With a rod drive (Fig. 8.25, b)

where: A is the distance between the drive stop and the autoregulator housing;

n is the gear ratio of the linkage;

k - clearance between the wheel and block with the brake released;

m - the sum of the gaps in the hinges of the levers;

a, b, c - dimensions of lever arms.

The second controlled dimension is the margin of the working screw (the distance from the control mark on the stem of the adjusting screw to the end of the protective tube). If the screw margin is less than 150 mm for a freight car and 250 mm for a passenger car, it is necessary to replace the brake pads and adjust the leverage.

Size A and propeller stock for cargo, refrigerated and passenger are given in Table. 8.5.

Table 8.5

Reference values of the distance "A" between the drive stop and the body of the auto-regulator on freight, refrigerator and passenger cars.

Wagon type	Type of brake pads	Distance "A", mm	Screw stock, mm
Lever drive	Rod drive
cargo 4-axle	composite cast iron	35 - 50 40 - 0	- -	500 - 575 500 - 575
8 axles	compositional	30 -50	-	500 - 575
Refrigerated rolling stock: 5-, - and -car sections built by BMZ and GDR ARV	composite cast iron composite cast iron	-0 40 -75 - -	55 -5 0 -0 0 - 0 130 - 150
Pass. wagons with containers: 5 - 53 t 52 - 48 t 47 -42 t	composite cast iron composite cast iron composite cast iron	- 45 50 - 70 - 45 50 - 70 - 45 50 - 70	0 - 130 90 - - 0 5 - 135 0 - 0 130 - 150	400 - 545 400 - 545 400 - 545 400 - 545 400 - 545 400 - 545

The action of autoregulator No. 574B. In the initial position, the brake is in the released state. The distance "A" between the drive stop and the end face of the regulator housing cover corresponds to the normal clearance between the wheel and the block.

The return spring presses the sleeve against the auxiliary nut. Between the end of the traction rod and the adjusting nut there is a gap "G", between the cup cover and the auxiliary nut - a gap "B".

Braking. With normal clearances between the wheel and the block (Fig. 8.28), the drive stop and the regulator body move towards each other, reducing the size "A". At the moment when a braking force of more than 150 kgf appears on the traction rod, the return spring is compressed, reducing the gap "B", the cone of the traction cup engages with the cone of the adjusting nut. Screwing nuts and thus does not occur.

The regulator works like a hard link. The braking force is transmitted through the rod to the traction sleeve, through the adjusting nut to the screw and then to the brake rod. If the outlet of the brake cylinder rod is reduced, then at any pressure in the brake cylinder, a gap is maintained between the regulator body and the drive stop. The regulator works like a hard link.

When the brake cylinder rod extends more than the norm, the contact of the regulator housing cover with the drive stop occurs earlier than the contact of the brake pads with the wheel tread. Under the action of increasing forces in the brake cylinder, the rod, together with the traction cup, moves to the right relative to the body, nuts, screw and compresses the spring. In this case, the glass moves to the right until it comes into contact with the adjusting nut and the screw begins to move through it.

The auxiliary nut moves away from the regulator body together with the screw and, rotating under the action of a spring on its bearing, is screwed onto the screw until it comes into contact with the cover of the draft cup. The maximum amount of screwing on the auxiliary nut in one braking is 8 mm , which corresponds to wear of the brake pads by 1.0 - 1.5 mm for passenger cars and 0.5 - 0.7 mm for freight cars.

If the output of the rod of the brake cylinder exceeds the norm by more than a mm, then the final adjustment of the brake linkage is made during subsequent braking.

Vacation. The decrease in air pressure in the brake cylinder leads to a decrease in effort in the rods. The stop of the drive with the body of the auto-regulator moves to the right relative to the draft cup under the action of the spring until the head of the body and the auxiliary nut come into contact. Then the drive stop moves away from the housing cover, forming a gap "A", and the traction cup moves under the action of the return spring and opens the friction connection with the adjusting nut, which, under the pressure of its spring, is screwed onto the screw.

The movement of the adjusting nut continues until it rests against the auxiliary nut. The traction cup is shifted to the stop by the bushing into the conical tip of the rod, after which all parts of the auto-regulator return to their original position.

When adjusting the leverage on cars equipped with an auto-adjuster, its drive is adjusted on freight cars to maintain the output of the brake cylinder rod at the lower limit of the established norms, and on passenger cars - at the average value of the established rod output norms.

The pneumatic part of the brake equipment (Fig. 7.11) includes a brake line (air duct) b with a diameter of 32 mm with end valves 4 of a valve or spherical type and connecting inter-car sleeves 3; a two-chamber tank 7 connected to the brake line b by a drain pipe with a diameter of 19 mm through a disconnect valve 9 and a dust collector - tee 8 (faucet 9 has been installed in tee 5 since 1974); spare tank 11; brake cylinder 1; air distributor No. 483 m with main 12 and main 13 parts (blocks); auto mode No. 265 A-000; stopcock 5 with handle removed.

Auto mode is used to automatically change the air pressure in the brake cylinder depending on the degree of car loading - the higher it is, the greater the pressure in the brake cylinder. If there is an auto mode on the car, the handle of the load mode switch of the air distributor is removed after the mode switch of the air distributor is set to the loaded mode with cast-iron brake pads and the average mode with composite brake pads. Refrigerated wagons do not have auto mode. The reserve tank has a volume of 78 liters for four-axle wagons with a brake cylinder with a diameter of 356 mm and 135 liters for an eight-axle wagon with a brake cylinder with a diameter of 400 mm.

The charging of the tank 7, the spool and working chambers of the air distributor of the reserve tank 11 is carried out from the brake line 6 with the disconnect valve 9 open. In this case, the brake cylinder is connected to the atmosphere through the main part of the air distributor and auto mode 2. When braking, the pressure in the brake line is reduced through the driver's valve and partially through the air distributor, which, when activated, disconnects the brake cylinder 1 from the atmosphere and communicates it with the reserve tank 11 until the pressure in them is equalized during full service braking.

The brake linkage of freight cars is made with one-sided pressing of the brake shoes (except for six-axle cars, in which the middle wheel pair in the bogie has a double-sided pressing) and one brake cylinder, bolted to the center beam of the car frame. Currently, on a pilot basis, some eight-axle tanks without a center beam are equipped with two brake cylinders, from each of which the force is transmitted only to one four-axle tank bogie. This is done to simplify the design, facilitate the brake linkage, reduce power losses in it and improve the efficiency of the brake system.

The brake linkage of all freight cars is adapted to use cast iron or composite brake pads. Currently, all freight cars have composite pads. If it is necessary to switch from one type of pad to another, it is only necessary to change the gear ratio of the brake linkage by rearranging the tightening rollers and horizontal levers (into a hole closer to the brake cylinder with composite pads and, vice versa, with cast iron pads). The change in the gear ratio is due to the fact that the friction coefficient of the composite pad is approximately 1.5-1.6 times greater than that of cast iron standard pads.

In the brake linkage of a four-axle freight car (Fig. 7.12), horizontal levers 4 and 10 are pivotally connected to rod b and bracket 7 on the rear cover of the brake cylinder, as well as to rod 2 and auto-regulator 3 and to rod 77. They are connected to each other by tightening 5 , holes 8 of which are designed for installing rollers with composite pads, and holes 9 - with cast-iron brake pads.

The rods 2 and 77 are connected to the vertical levers 7 and 72, and the levers 14 are connected to the dead center earrings 13 on the pivot beams of the bogies. Between themselves, the vertical levers are connected by spacers 75, and their intermediate holes are pivotally connected to spacers 17 of triangles with brake shoes and blocks, which are connected by suspensions 16 to the brackets of the bogie side frames. Protection from falling onto the path of parts of the brake linkage is provided by special tips 19 triangles located above the shelves of the side frames of the bogie. The gear ratio of the brake linkage, for example, a four-axle gondola car with horizontal lever arms 195 and 305 mm and vertical levers 400 and 160 mm is 8.95.

The brake lever transmission of an eight-axle car (Fig. 7.13, a) is basically similar to the transmission of a four-axle car, the only difference is the presence of a parallel transmission of force to both four-axle bogies on each side through rod 1 and balancer 2, as well as a shortened by 100 mm upper arm of the vertical leverage.

In the lever transmission of a six-axle car (Fig. 7.13.5), the transfer of force from the brake cylinder to the triangels in each bogie does not occur in parallel, but in series.