Simulation of dynamics and experimental studies of the characteristics of the system “vibration protection seat - industrial tractor operator”

The article is devoted to the study of the dynamic characteristics of the vibration protection chair and the mechanical system “operator seat” of an industrial caterpillar tractor. The studies were carried out for the Sibeco anti-vibration chair. The seat suspension system includes a pneumatic elastic element and a hydraulic shock absorber, as well as a pliable cushion. Pneumatic elastic element is adjusted according to the weight and height of the driver. The aim of the work is to determine the nonlinear elastic characteristics of the suspension system and cushion, as well as the characteristics of the equivalent viscous friction. Elastic characteristics were obtained during static tests. At the same time, loads were sequentially placed on the chair and movements were recorded. The elastic characteristic of the suspension system was recorded at various settings of the air spring. Based on the test results, a non-linear regression dependence was obtained that relates the force on the seat to its movement and the parameter characterizing the setting. The static elastic characteristic of the chair cushion is obtained. To determine the characteristics of the equivalent viscous friction, dynamic tests were carried out. The chair with the weights installed on it was placed on a vibration stand. During the test of the suspension system, the seat cushion was dismantled. When research of the characteristics of the seat cushion, the air from the air spring was released, the seat suspension system was fixed. During the tests, the amplitude-frequency characteristics (AFC) of the system were determined. The coefficients of equivalent viscous friction were determined based on a comparison of calculated and experimental frequency responses. According to the test results, it was found that the dynamic rigidity of the chair cushion significantly exceeds the static one. The obtained characteristics will be further used in the development of a dynamic model of the “caterpillar tractor - vibration protection chair - operator's body” system. Computational studies using the model will make it possible at the early stages of design to predict vibrations at the driver's seat caused by the movement of road wheels along the track links and to adjust the system parameters in order to comply with sanitary standards.