Abstract
The purpose of this paper is to calculate kinematic parameters of a railway car moving with a tailwind for designing a classification hump. The calculation of kinematic parameters is based on the d'Alembert principle, and the physical speed and distance formula for uniformly accelerated or uniformly decelerated motions of a body. By determining a difference between two components - gravitational force of a car and the resistance force of all kinds (frictional resistance, air and wind resistance, resistance from switches and curves, snow and frost resistance), which take place at different sections of a hump profile, the authors calculated the car acceleration at various types of car resistance, as well as time and speed of its movement. Acceleration, time and speed were plotted as a function of the length of a hump profile section. The research results suggest that permissible impact velocities of cars can be achieved by changing profiles of projected hump sections or by using additional hump retarders.
Highlights
A review of studies dedicated to dynamics of cars rolling down humps [1,2,3,4,5,6,7] and the applicable design guidelines for classification facilities [8] suggest that there is no method for determining kinematic parameters of a car moving along the entire length of hump profiles, including sections with retarder positions (RP)
Using the calculation program mentioned above [12], we studied the influence of the hump profile grade and placement of the third retarder position on a curved track on kinematic parameters of a car rolling down the hump
The proposed refined method for calculating kinematic parameters of cars moving along longitudinal profiles of humps and the related calculation program make it possible to determine efficient shunting conditions
Summary
A review of studies dedicated to dynamics of cars rolling down humps [1,2,3,4,5,6,7] and the applicable design guidelines for classification facilities [8] suggest that there is no method for determining kinematic parameters of a car moving along the entire length of hump profiles, including sections with retarder positions (RP). In [1], the total energy of the car is determined as a sum of kinetic energy E0 and potential energy Ep, kJ: E0 + Ep, where E0 = M(v0)2ρ/2 (where M is the car weight, t; v0 is the initial speed, m/s; ρ is the wheel rotation correction factor) and Ep = gMhhump (where hhump is the required hump height, m). It is commonly known [9] that the total energy remains constant: this state is called the law of conservation of energy. In [1], in contrast to the law of conservation of energy, the total energy E0 + Ep is equated to the work of a projected gravitational force component (Gsinψ) of the moving car, i.e. the law of conservation of energy is violated (see page 293 in [9])
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