Evaluation of the efficiency of systems to reduce vibration on modern tracklaying tractors

Agricultural operators run a very high risk of exposure to mechanical vibration. To improve comfort, many different devices have recently been fitted to agricultural self-propelled machinery, especially on the most modern high-powered wheeled tractors. In contrast, agricultural tracklaying tractors are not equipped with a suspended cab floor and frequently poor or no seat suspension is fitted. Consequently, the levels of vibration measured in the driving seat of tracklaying tractors often widely exceed the limit stipulated by official national standards. The manufacturers of tracklaying tractors are currently trying to improve the level of comfort at the drivers place by reducing both the production and the transmission of vibration. The vibration levels at the driving seat of a group of tracklaying tractors produced by some leading Italian manufacturers were so measured. The models examined in the study differed in having either 5-or 6-roller track support, different types and stiffness of seat suspension, and in whether or not they were coupled to an implement. The type of seat suspension, and above all its correct adjustment, dramatically influenced the level of vibration, as did the increase in the number of track rollers. In contrast, whether or not the tractor was coupled to an implement at the rear 3-point linkage did not make any significant change to the vibration comfort during transport. Also on the best modern trackalying tractor models, vibration levels frequently exceed stipulated limits, so that a further reduction is urgently required. Possible solutions that could be developed may involve the universal adoption of rubber tracks and/or the fitting of silent blocks on the cab floor and suspension devices on one or both axles.