Calculation and laboratory testing of the rotation resistance of a bogie

Abstract

The rotation movement between bogie and carbody is studied using vehicle system dynamics theory and formulas for the rotation resistance factor are derived for different air spring states. Laboratory tests are conducted and the obtained results are compared with calculations. The rotation resistance factor for motor and trailer cars experiencing AW0 and AW4 loading conditions when air springs are in inflated, deflated and over-inflated states are considered so as to validate the proposed formulas and test and discuss error sources. The rotation resistance factor of the bogie is related to the rotation angle and speed. The faster the rotation speed, then the greater is the rotation resistance factor. The greater the rotation angle, then the greater is the rotation resistance factor. The maximum rotation resistance factor is 0.094 for a trailer car at a rotation speed of 1 deg/s and experiencing AW0 loading conditions and with the air springs in the deflated state. The maximum rotation resistance factor when the air springs are deflated is much greater than that when the air springs are in the inflated state for a rotation speed of 1 deg/s. The maximum rotation resistance factor obtained at a rotation speed of 1 deg/s is much greater than the one obtained at 0.2 deg/s. The over-inflated state of air springs has little influence on the rotation resistance of the bogie. The calculated results obtained when considering air springs in inflated and over-inflated states are slightly smaller than test results with a maximum difference of 0.02. For the deflated state of the air springs, the calculated and test results for a trailer car are equivalent and the calculated results are slightly larger than the test results for a motor car with a maximum difference of about 0.02. The theoretical formulas should consider the dynamic nature of stiffness properties and damping effect of air springs. The effects of other suspension components should also be considered. A laboratory test or field test after assembly is an essential requirement. The comparison of test and calculated results validates the proposed formulas and allows sources of error to be discussed.