Analysis of the structure of liners used for the modernisation of brick collectors

Brick sewers were designed as egg-shaped, pear-shaped, bell-shaped, vaulted, and even rectangular (sometimes with granite ceilings and floor slabs). In exceptional cases, circular sections were also made of brick. Efforts were made in order to ensure optimal flow conditions, and also that the cross-section was adapted to the shape of the rock mass pressure line. This is due to the fact that the most advantageous shapes for masonry collectors are shapes in which no tensile stresses will occur in any part of the cross-section under the influence of external loads. Nevertheless, sewage conduits degrade over time. The boundary conditions of their use also change, which affects the magnitude of mechanical and hydraulic loads. Further use of a sewer in such a case requires its renewal, and less frequently, modernization that results from the necessity to change its function. This is usually done by introducing a new conduit into the interior of the renovated or modernized sewer, which in literature is called a liner. The aim of the analysis was to determine the thickness of the liners that strengthen the structures of brick channels with an inverted egg cross-section and with dimensions of 1050 × 700 mm, which are intended for gravitational sewage systems. The analysis included the performance of variant static and strength calculations for the assumption that the conduit after its modernization will be replaced with a conduit operating in the pressure system, which is a very rare requirement. It was assumed that the best solution would be to use a CIPP (Cured In Place Pipe) liner.

Mathematical modeling of the axial-piston pump power regulator

A mathematical model of the regulator was developed; a scheme for its solution in the Matlab-Simulink environment was suggested; dependencies of the spool movement (x1), piston (x2), transition time (t) and other parameters on the pressure in the pressure line (p) have been determined. The mathematical model of the regulator establishes the effect of pressure on control process parameters. When the pressure increases from 30 to 45 MPa, the regulator spool moves at a distance varying from 0.4 - 2.8 mm. The spool movement is proportional to the pressure. The piston movement is more sensitive to the change in pressure. It changes within the range of 3–19 mm, while the relationship is non-linear. The cylidner pressure and the ratio of rocker arms are proportional to the pressure and increases 1.5 times; the transition time is expressed by a non-linear dependence and decreases two-fold.

Influence of hydro-pneumatic accumulator on the hydraulic drive of the brush work body of light type track machines

The main direction of improving the repair processes of all types and the current maintenance of the track is to reduce the time and labor costs with the highest possible level of mechanization and automation of all types of track work. At the same time, a significant place is occupied by cleaning the tracks from weeds and excess ballast. The working body of the machines for performing these works is a brush picker with flexible blades, which provides cleaning of weeds and ballast below the level of the rail head. As a rule, on domestic machines, flexible blades are segments of a steel cable with a diameter of 16…21 mm. One of the main disadvantages of brush pickers with cable blades is the relatively low efficiency due to fatigue breaking of the flexible blades at the point of exit from the seal. There are also known design solutions with the use of blades made of rubber tape. The most successful is the combination of cable and belt blades on one picker. The main type of drive for such a working body should be considered a volumetric hydraulic drive, which allows you to solve the problem structurally in the simplest and most effective way. Since the picker blades interact with the object (ballast rubble) alternately ( usually there are 8-12 blades) the load on the drive is non-stationary, the pressure in the pressure line of the drive hydraulic motor changes sinusoidally, which negatively affects the reliability and durability of the drive. To smooth out pressure fluctuations, it is recommended to use a hydropneumulator.