Method for analyzing parameters of single-level pneumatic elastic elements with backpressure

BACKGROUND: Trucks, as a rule, have a significate difference between the kerb and gross weights. Usual spring or leaf suspensions do not allow to have acceptable values of static running and suspension stiffness at different machine loading, and pneumatic elastic elements, despite their relative simplicity, are mainly implemented only on overseas technology samples, and designers do not pay attention to pneumatic elastic elements with counterpressure. One of determinants of truck users is the acceptable vibration loading of the driver’s seat. Trucks with a carrying capacity comparable or even overestimated to their kerb weight, when they move without cargo on public roads, especially with a dirt surface, have significant levels of vibration acceleration at using the metal elastic.

AIMS: The purpose of the present work is to reduce the vibration loading of the driver’s seat due to rational choice of parameters of the cushioning system with pneumatic elastic elements with backpressure, that ensures the non-zero static travel and saticfactory stiffness of suspension in the kerb and loaded state.

METHODS: Using the regorous mathematical tools of Mechanics, Pneumatics and Thermodinamics, scientific-based theoretical prerequisites as well confirm the validity and reliability of the presented dependencies for characteristics calculation, conclusions and recommendations.

RESULTS: According to the method developed and proposed in this article, effective characteristics of the pneumatic elastic elements with a single-level stiffness and backpressure for a KAMAZ-53215 Selkhoznik truck were obtained. At the kerb weight, the static stroke of the front and rear suspensions is approximately 0.06 m; at a gross weight it is of 0.12 m and 0.24 m, respectively. The period of normal vertical vibrations decrease by 25% versus a gross vehicle weight and by 31% at absence of backpressure, however, it occurs in the allowable range.

CONCLUSIONS: The proposed method allows to determine the base design parameters of the pneumatic elasticity of the suspension elements of wheeled vehicles, providing an acceptable periods for a normal vertical oscillations of the cushoining body with maintaining the non-zero static stroke to a large weight range.