Static and Dynamic Characteristics of Scissors-Type Guiding Mechanism Work Suspension Seat

The International Organization for Standard ISO 2631-1 (1997), EU Directive 2002/44/EU, British Standard BS6841:87 and other standards of international repute have specified the acceptable levels of whole-body vibration (WBV) exposure for operators of mobile equipment and work vehicles. Compliance with these standards has not guaranteed absolute eradication or prevention of epidemiological disorders or injuries associated with low frequency vibrations, shocks, bumps, jolts and other irregularities. Therefore, effective and economic vibration isolation based on appropriate suspension seats is still necessary. This paper presents the findings of a practical study of the frequency response of a loaded X-type mechanism work suspension seat that was subjected to low frequency vertical sinusoidal vibrations in the range of 1-10Hz at three levels of amplitude on a test rig. The resulting transmissibilities of the seat due to the input excitations were analysed. The scissors mechanism work suspension seat had a static stiffness of 5.4kN/m, while the maximum travel attained was 82mm. Resonance occured mostly between 1.0 and 3.0Hz. However, the overall performance of the seat over the entire low frequency range provided an acceptable comfort level for the work vehicle operator, according to ISO standards.