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Unify split braking systems

D.E. Klushantsev, a leading expert at Rolling Stock Engineering Center LLC


Currently, brake systems for freight wagons with separate trolley drive are becoming more widespread in Russia. Such systems are commonly referred to as split braking systems.

Separate braking is used for bunker-type wagons, long-wheelbase wagons with an axial load of 23.5 tons and for all wagons with an axial load of 25 tons. A special feature of this design is the presence of two brake cylinders located on the carriage frame and two lever gears acting independently on two trolleys.

Over the past decade, more than 20 new models of freight wagons of various types equipped with split-braking systems have been put into production at factories in Russia and Ukraine. However, they all have different designs and parameters. The lack of requirements for the unification of brake systems with separate braking complicates their design, as well as the development of operational and repair documentation.


Thus, today, in order to improve the quality and simplify the processes of designing, operating and repairing newly developed braking systems, it is important to create a standard-sized range of them. It will depend on the type of car and its parameters.

To solve this problem, the specialists of the Engineering Center conducted research on the development of a standard-sized range of split-braking braking systems for freight wagons with an axial load of 23.5 tons. In the course of the work, a general overview was carried out, the Russian experience in designing brake systems with separate drive on trolleys was analyzed, and multivariate calculations were made on the choice of gear ratios of brake lever gears depending on the mass characteristics of the wagon.

As a result, a standard-sized range of brake systems with separate braking has been formed for wagons with an axial load of 23.5 tons. The development procedure is shown in Fig. 1.

At the first stage, a review of existing split-braking systems was carried out to identify their main functional schemes and parameters (Table 1). According to the results of the review, it was found that the scheme of the brake lever transmission depends on the design features of the wagons on which it is installed, as well as on the type of autoregulator and brake cylinder.

The design features of the carriage determine the location of the lever gears and the plane of the levers. So, for gondola cars, platforms and covered wagons, lever gears are placed under the wagon frame, and the levers are in the horizontal plane, for hopper wagons - in the cantilever part, and the levers are located in both horizontal and vertical planes.

The parameters of the autoregulator determine the number of links of the lever gear. For example, when using an autoregulator with a stroke of 675 mm in the braking system, the lever gear usually has one lever (except for hopper cars, for which the increase in the number of levers is due to the location of the lever gears).

The use of autoregulators with an adjustment stroke of 300 mm makes it difficult to use single-lever gears due to the insufficient stroke of the autoregulator screw. As a result, two levers are used in lever gears.


The diameter of the brake cylinder affects the gear ratio of the lever gear. The use of smaller diameter cylinders required an increase in the gear ratio of the brake lever, but at the same time allowed to reduce the weight of the braking systems, reduce charging time, and reduce air consumption. Therefore, in the future, when forming a standard-sized range, the use of small-sized brake cylinders was adopted as the main option.

As a result of the review, it was also revealed that even with the same diameter of the brake cylinders, container and load capacity of the wagons, the gear ratios of the existing lever gears differ. These differences are explained by the lack of unification of braking systems with separate braking.

For each type of car, the main schemes and ranges of gear ratios of existing lever gears were identified. An analysis of the technical parameters of wagons equipped with split braking systems made it possible to determine the ranges of tare weight and load capacity required for carrying out computational studies.


At the second stage of the work, lever gear schemes were selected. At the same time, the main criteria were the placement, the minimum number of lever gears, and the ability to adjust the brake gear over the entire range of shoe thicknesses up to the minimum allowable value.

At the third stage, multivariate calculations were performed for each type of wagon and the selected brake lever transmission scheme. They allowed us to determine the gear ratios based on the boundary conditions.

The maximum and minimum values of tare weight and load capacity, obtained as a result of the analysis of the technical characteristics of the wagons, were taken as the initial data in the calculations for each type of wagon. The minimum allowable pressure coefficients of the brake pads and the conditions for the absence of a skid were taken as boundary conditions.


The calculations were carried out both taking into account the compression losses from the autoregulator spring and without taking them into account. The pressure in the brake cylinders was taken in accordance with the existing regulatory requirements, while several options for completing the braking equipment were considered for each type of car.

The gear ratios were calculated using standard methods used in the design of braking systems. First, the actual forces of pressing the brake pads on the wheels were calculated to use the boundary conditions. Then, according to the actual pressing forces and characteristics of the braking equipment (diameter of the brake cylinder, pre-compression forces, stiffness of the springs of the brake cylinder and the autoregulator), the gear ratios of the lever gears for loaded and empty wagons were determined.

As a result, the ranges of brake lever gear ratios for composite and cast-iron pads were calculated. They meet the regulatory requirements for the entire range of mass characteristics of the considered types of wagons.

For example, for platform wagons equipped with composite pads, an autoregulator with a screw stroke of 300 mm and a gear ratio of the autoregulator drive brought to the stem of the brake cylinder and equal to 0.56, the range of gear ratios ranges from 5.64 to 5.85 (Fig. 2).

For hopper wagons, it was found that with a tare weight of less than 20.2 tons (composite pads) and less than 21.5 tons (cast iron pads), it is impossible to select a gear ratio when using small-sized equipment. This is due to the fact that the maximum allowable value from the no-skid condition is lower than the minimum allowable gear ratio obtained based on the conditions for ensuring braking efficiency (Fig. 3).

Consequently, for hopper wagons with a tare weight of less than 21.5 tons and a load capacity corresponding to an axial load of 23.5 tons, when using small-sized equipment, it is impossible to design a braking system that meets regulatory requirements. There are three ways to solve this problem:

- reduction of regulatory requirements for the braking performance of a loaded wagon;

- reduction of braking losses on a loaded wagon;

- increased losses during braking of an empty car.

During the research, two ways of solving this problem were considered. The first of them is to reduce losses from the autoregulator drive and, as a result, reduce the permissible gear ratio from the efficiency condition. The second way is to increase the loss of brake pad pressure due to the use of cylinders with a stiffer release spring and, consequently, an increase in the permissible gear ratio due to the absence of a skid.

Based on the calculation results, the second path was chosen, since using the first requires a significant increase in the gear ratio of the autoregulator, which is impossible from the point of view of the kinematic transmission scheme. When implementing the second track for hopper wagons with a tare weight of up to 21.5 tons, the use of brake cylinders with a diameter of 356 mm with an appropriate gear ratio is proposed.


To form a standard-sized series of the obtained ranges of lever gear ratios for each type of car, one gear ratio value was selected based on an expert assessment. Thus, the complex of works carried out made it possible to create a standard-sized range of braking systems with separate braking for wagons with an axial load of 23.5 tons (Table 2).

This size range simplifies the processes of designing, operating and repairing brake systems and makes it possible to unify brake systems with separate braking by types of wagons. In the future, it is necessary to conduct a more detailed study of the standard-size range to determine the parameters of the gear levers, as well as to develop a similar standard-size range of braking systems for wagons with an axial load of 25 tons.

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