Claas

Despite the fact that noise levels in its machinery cabs are already well below the standard requirements in this respect, the German manufacturer Claas is aiming to take things a step further with its next generation of tractors.The acoustic service at its development centre in Vélizy (78) is focusing on operational Transfer Path Analysis (TPA), for this purpose. This technique can be used to determine the contribution of the active forces and the propagation paths of vibrations and noise at a given location. «This is a particularly complex method to implement, and we do not yet hold enough experience in this field, so we decided to opt for the support of experts in view of assimilation for future use», explained the Acoustic Quality Customer Services Manager for Claas Tractor, Isabelle Raye. 

A 2-phase study

On this basis, the operational transfer path analysis was entrusted to Cetim. Phase 1: identify all components contributing noise and all transfer paths. No factor must be omitted in order for the results to be conclusive. Phase 2: assess noise and vibrations. Around sixty sensors (accelerometers, microphones, pressure sen-sors) were fitted on a tractor. A series of measurements were taken in around forty operating configurations for the tractor, at various engine speeds, and involving various hydraulic systems such as assisted steering or hydraulic distributors. All of the measurements were processed using specific software. Using the results, Cetim notably determined that the noise heard in the cab is mainly structure-borne (with the transfer path determined) and that resonance exists in some hydraulic circuits and parts. Several modifications were recommended on this basis and assessed at a future stage.