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Spontaneous actuation of brakes on a train: causes, prevention, minimizing consequences

[ U ]V.G. POGUDIN, head of the brake testing car of the October Infrastructure Directorate,
A.V. ISAEV, Ph.D. technical, science, associate professor of Federal State Autonomous Educational Institution of Higher Education SPbPU,
AZ. GERBEK, engineer, first class driver of the October Traction Directorate[/ U ]

[ I ]“Increasing the density of the brake network of freight trains and reducing the charging pressure in the brake network not only helps to reduce the energy costs of driving the train, but, most importantly, improves the controllability of the train brakes, which play a critical role in ensuring traffic safety.”
P.T. Grebenyuk. “Longitudinal dynamics of a train”, proceedings of VNIIZHT, 2003[/ I ]

One of the most common types of brake equipment failures is spontaneous operation of train brakes. According to the ASUT-NBD system, on the Oktyabrskaya Railway, when decoding data from the CLUB, BLOK, KPD files for 2022, 2733 cases (in 2021 - 2607) of spontaneous operation of the brakes on a train with a pressure drop in the brake line of more than 0.02 were identified MPa and activation of the sensor for monitoring the integrity of the brake line No. 418. In 345 cases, the driver performed the actions provided for in paragraph 179 of the Rules for the maintenance of brake equipment and control of brakes of railway rolling stock (hereinafter referred to as the Rules) according to the procedure for the spontaneous operation of the train brakes and restoration of the functionality of the control sensor integrity of the brake line, led to the train stopping on the stretch and disrupting the schedule.
Of these 345 cases, according to the KASANT system for 2022, 110 cases of train delays due to spontaneous brake activation were registered on the Oktyabrskaya Road, resulting in train delays lasting more than 5 minutes on a stretch or station. The reasons established by the official investigation of the owner of public railway transport infrastructure are as follows:
> 43 cases - due to faulty fittings (end or isolation valve);
> 39 cases - due to malfunctions of air distributors (AD) identified during a control check of train brakes;
> 16 cases - due to concentrated leaks in the brake line (at T-type connections and couplings);
> 12 cases of disconnection and breakage of brake connecting hoses.
In 64 cases, the TM integrity monitoring sensor was triggered during the departure of the train during the period of elimination of overcharge pressure in the brake line (TM), which arose when the driver fulfilled the requirement of paragraph 1 of Appendix 3 of the Rules (increasing the pressure in the brake line (TM) by placing the driver's control valve in position I at 3 - 4 s) and longitudinal dynamic reactions (LDR) that occur when the train departs.
The main reason contributing to the spontaneous operation of the brakes is the unsatisfactory technical condition of the brake equipment of train cars. However, the prerequisites for reducing the reliability of the braking equipment of rolling stock are created by the requirements of regulatory documents (in particular, the Rules) and other factors.
[ LIST ][*] ♦ Requirement paragraph 1 of appendix 3 of the Rules ( overstatement pressure V brake highways staging manager organ crane driver for 3 - 4 s V position I ) for identifying blocked end cranes V train at departure trains leading _ To violation paragraph 100, table . V.1 in _ parts installations charger pressure V train . Consequence this is following trains on overpriced pressure V TS , and This leads To emergence differences pressure between working And mainline cameras more than 0.03 MPa . The indicated pressure difference causes, under certain conditions, the activation of individual air distributors of cars for braking, followed by non-release, which is revealed by the readings of the KTSM.[*] ♦ Requirement paragraph 100, table . V.1 of the Rules By installation charger pressure V loaded train at inclusion carriages on laden mode ( not installed , when which quantity carriages V train included _ on laden mode , necessary install charger pressure V train 0.53 - 0.55 MPa ).[*] ♦ Requirement paragraph 10 of appendix 3 of the Rules V parts mandatory applications auxiliary brakes locomotive at vacation brakes cargo loaded trains _ This local increase resistance movement V head parts causes compression and _ then guy carriages V train With emergence PDR .[*] ♦ Constructive flaws B.P. No. 483 A , inclined at overpriced pressure And emergence PDR V train call actuation air distributor on braking With additional détente TM .[*] ♦ Concentrated leaks V connections TMs emerging _ at mechanical influence on connection . At this is formed a fall pressure V brake highways more than 0.02 MPa And How _ consequence , trigger sensor control integrity TM with withdrawal traction locomotive _[/list]To establish the reasons for the spontaneous activation of the train brakes, which resulted in its delay, at the request of the locomotive crew or the heads of the carriage depots, a control check of the train brakes is assigned.
In accordance with the requirements of Appendix 5 of the Rules (clause 9), checking the operation of the brakes must be carried out under the conditions that caused the failure of the train brakes (perform braking and release in accordance with the speed tape data recorded on the stretch).
However, in fact (in violation of the requirements of the specified document), a control check of the train brakes is carried out under extreme operating conditions of the air distributor at an excessive pressure of 0.6 MPa and mechanical impact on the main and main parts of the air distributor No. 483. This method for identifying a faulty air distributor was proposed by Doctor of Technical Sciences, Professor MIIT V.G. Inozemtsev and officially approved by order TsT-60 dated April 2, 2013.

This method makes it possible to identify an air distributor that, under unfavorable operating conditions, is prone to cause spontaneous operation of the brakes (conditions created by the driver driving the train - increased pressure and increased longitudinal-dynamic reactions in the train).
The following actions of the locomotive crew when controlling the train brakes also contribute to brake equipment failures:

• 'b installation of increased charging pressure at high density of the brake line (charging pressure at the upper limit established for this type of train);
• b excessive overestimation of pressure in the brake line after braking and releasing the brakes at a high density of the train's brake line (increased pressure in the brake line by more than 0.03 - 0.05 MPa);
• 'Ъ use of an auxiliary brake of a locomotive to regulate the speed of a train at a turning point, causing compression of the train with subsequent tightening of its tail section, as a result of which spontaneous activation of the brakes may occur;
• 'Ъ violations of the train traction control mode and control of the electrodynamic brake of the locomotive (sharp set of positions or their reset);
• actions of the driver to comply with paragraph 179 of the Rules in the event of spontaneous activation of the brakes in the absence of an intense drop in pressure in the brake line, resulting in the train stopping on the stretch due to the driver using braking stages of 0.06 - 0.08 MPa to restore the functionality of the sensor for monitoring the integrity of the brake line , as well as long-term presence of the operator’s crane control body in the braking position.

The use of an overestimation of pressure in the brake fluid above the charge pressure by more than 0.03 - 0.05 MPa when releasing the brakes also affects the high density of the train brake line, which leads to re-activation of the brakes on the train.
The analysis of the CLUB files of trains that had delays due to spontaneous actuation of the brakes confirms the above reasons that contributed to the occurrence of spontaneous actuation of the brakes:
E excessive pressure in the brake line of the train with a high density of the brake line;
О peak overestimation of pressure (more than 0.1 - 0.12 MPa above the charging pressure) when the train departs using the brake line pressure gauge with a charged brake line;
This is an overestimation of pressure when releasing the brakes above 0.03 MPa according to the pressure gauge of the equalization tank or a peak overestimation of pressure of more than 0.1 - 0.12 MPa above the charging pressure according to the brake line pressure gauge.
Based on the above, in order to prevent cases of train delays due to the activation of the sensor for monitoring the integrity of the brake line, to ensure favorable operating conditions for air distributor No. 483, excluding non-release of the brake and its spontaneous operation, as well as to expand the powers of the driver to create favorable operating conditions for the brake devices of rolling stock, it is necessary to: In the opinion of the authors, the following changes will be made to existing regulatory documents in the near future:
in paragraph 1 of Appendix 3 of the Rules - eliminate the mandatory requirement to increase the pressure when the train departs, transfer it to the recommended one when the density of the brake line changes more than 20% upward from the original;
in paragraph 100, table. V.1 on setting the charging pressure in a loaded train when the cars are turned on in loaded mode: if there are more than 30% of the cars in the loaded mode, set the charging pressure in the train to 0.53 - 0.55 MPa, and also expand the range of permissible charging pressure for driving empty trains and set it within 0.46 - 0.5 MPa.
To prevent cases of a train stopping during a stretch, to prevent repeated spontaneous activation of the train brakes, or to trigger the sensor for monitoring the integrity of the brake line in the absence of an intense drop in pressure, it is necessary to ensure that the driver performs the actions provided for in paragraph 178 of the Rules:
❖ establish a requirement to perform an all-season minimum braking step to restore the functionality of the brake line integrity monitoring sensor of 0.04 MPa and the amount of pressure increase after braking of no more than 0.03 MPa.
Taking into account the positive experience of driving empty trains without the use of an auxiliary locomotive brake when releasing the train brakes and reducing the longitudinal-dynamic reactions in the train when releasing the brakes, it is advisable to consider the issue of abolishing the mandatory use of an auxiliary locomotive brake when releasing the brakes in loaded freight trains from mandatory to permissible (according to the conditions driving the train depending on the track profile).
It is also advisable to establish the brake release range specified in paragraph 10 of Appendix 3 of the Rules to the charging range for a train length of up to 150 axles with a brake line density exceeding the permissible by 30% or more (release of the driver's crane control body by the train position). As is known, a positive property of the driver’s crane No. 395 is the provision of a “pressure push” when released in the train position, but this design property of the crane is not used in operational practice.

Taking into account the economic losses from the actions of the driver to comply with the requirements of paragraph 179 of the Rules, to restore the functionality of the integrity monitoring sensor No. 418 in the absence of intense leakage when placing the control element in the “overlap without power” position (excluding a drop in train speed during braking and energy costs for restoring the speed of movement trains) it is proposed to consider an energy-saving method of restoring the functionality of the integrity monitoring sensor by switching the electrical power circuits of the sensor without placing the driver's crane control element in the brake position.

The decision to abolish the requirement for overincreasing pressure when a train departs, limiting the amount of overpressure after regulatory braking to more than 0.03 MPa above the charge level will increase the reliability of the braking devices, reduce the preconditions for failures in the operation of the braking equipment by 30 - 50% while ensuring traffic safety and traffic schedules trains The result of this, according to the authors, will be a reduction in operating costs for operating a train and compliance with train maintenance technology.

Bibliography

1. Inozemtsev V.G. Brakes of railway rolling stock: questions and answers. M.: Transport. 1984.
2. On the influence of the requirements of regulatory documents on technological processes and traffic safety / V.G. Pogudin, A.V. Isaev, P.V. Menshikov, A.E. Gerbeck // Lokomotiv. 2022. No. 4. P. 39 - 43.

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