Whole-body vibration: Measurement of horizontal and vertical transmissibility of an agricultural tractor seat

Abstract The seats may significantly reduce the exposures levels transmitted to the driver, but the European Directive 2002/44/EC (2002) requires only tests on the damping seat capacity along the vertical direction, whereas nothing is required for the longitudinal and transversal directions. Field tests were carried out using a 93 kW tractor to verify the vibrational comfort values given by seat with pneumatic suspension. The tests were executed with the tractor running on different surfaces, at two different forward speed and tire pressures and with different tractor masses. Three repetition were carried out for each configuration. Accelerations were always measured on both the seat and the cabin platform and the calculations were done using the ISO 2631 standard suggestions. The vibration total values and the acceleration transmissibility along the 3 perpendicular axes were calculated and analysed. Despite different boundary conditions (surface, tire pressure, forward speed and tractor mass distribution), along the Z axis the transmissibility was constantly around 0.7, to confirm that the seat worked well to damp the vertical exposures. Different were the situations for the X and the Y axes. Excluding the asphalt, on the other crossed surfaces high transmissibility values were observed (never less than 1), especially along the X axis. Relevance to industry . This paper describes the vibration transmissibility of an agricultural tractor seat. Tests were carried out with the tractor running on different surfaces and with different configurations. The seat transmissibility along the three orthogonal directions was acquired. Results suggest that the tractor manufacturer should consider, during the machine design, also the rolling and pitching movements, because the seat accelerations along the X and Y axes are influenced by them. The seat manufacturer could reduce the rolling and pitching effects using specific suspension systems along the horizontal and lateral directions.

[1]  M. Griffin,et al.  Discomfort caused by low-frequency lateral oscillation, roll oscillation and roll-compensated lateral oscillation , 2013, Ergonomics.

[2]  S. Sankar,et al.  Design and testing of lateral seat suspension for off-road vehicles , 1993 .

[3]  Morten K. Ebbesen,et al.  Experimental analysis of occupational whole-body vibration exposure of agricultural tractor with large square baler , 2015 .

[4]  Michael J. Griffin,et al.  Effect of seating on exposures to whole-body vibration in vehicles , 2002 .

[5]  Helmut Seidel,et al.  On the relationship between whole-body vibration exposure and spinal health risk. , 2005, Industrial health.

[6]  Michael Rygaard Hansen,et al.  Reducing whole-body vibration exposure in backhoe loaders by education of operators , 2012 .

[7]  Carel Hulshof,et al.  Whole-body vibration and low-back pain , 1987, International archives of occupational and environmental health.

[8]  J. B. Liljedahl,et al.  The Dynamic Behavior of Farm Tractors , 1961 .

[9]  Xiaojing Zhao,et al.  Evaluation of whole-body vibration exposure experienced by operators of a compact wheel loader according to ISO 2631-1:1997 and ISO 2631-5:2004 , 2014 .

[10]  Pierre Mistrot,et al.  Numerical assessment of fore-and-aft suspension performance to reduce whole-body vibration of wheel loader drivers , 2006 .

[11]  M Shyam,et al.  Ride vibration on tractor-implement system. , 2000, Applied ergonomics.

[12]  Koen Deprez,et al.  An improved design of air suspension for seats of mobile agricultural machines , 2004 .

[13]  Angela Calvo,et al.  Comparison between ISO 5008 and field whole body vibration tractor values , 2012 .

[14]  Michael J. Griffin,et al.  Transmission of vibration to the backrest of a car seat evaluated with multi-input models , 2004 .

[15]  J D Troup,et al.  Driver's back pain and its prevention. A review of the postural, vibratory and muscular factors, together with the problem of transmitted road-shock. , 1978, Applied ergonomics.

[16]  Sihong Zhu,et al.  Effects of tyre inflation pressure and forward speed on vibration of an unsuspended tractor , 2013 .

[17]  J. A. Lines,et al.  Whole Body Vibration During Tractor Driving , 1995 .

[18]  Michael J. Griffin,et al.  Transmission of roll, pitch and yaw vibration to the backrest of a seat supported on a non-rigid car floor , 2005 .

[19]  K Taattola,et al.  Whole-body vibration of tractor drivers during harrowing. , 1998, American Industrial Hygiene Association journal.

[20]  Ralph Blüthner,et al.  On the significance of body mass and vibration magnitude for acceleration transmission of vibration through seats with horizontal suspensions , 2006 .

[21]  G. Vassalini,et al.  PM—Power and Machinery: Innovative Systems to reduce Vibrations on Agricultural Tractors: Comparative Analysis of Acceleration transmitted through the Driving Seat , 2002 .

[22]  M. Griffin,et al.  MOVEMENT OF THE UPPER-BODY OF SEATED SUBJECTS EXPOSED TO VERTICAL WHOLE-BODY VIBRATION AT THE PRINCIPAL RESONANCE FREQUENCY , 1998 .

[23]  M J Griffin,et al.  Vibration and comfort: vertical and lateral motion in the range 0.5 to 5.0 Hz. , 1986, Ergonomics.

[24]  M Bovenzi,et al.  Low-back disorders in agricultural tractor drivers exposed to whole-body vibration and postural stress. , 1994, Applied ergonomics.

[25]  N. Belfiore,et al.  Analysis of driving seat vibrations in high forward speed tractors , 2007 .

[26]  M J Griffin,et al.  The apparent mass of the seated human body: vertical vibration. , 1989, Journal of biomechanics.

[27]  Subhash Rakheja,et al.  Effects of sitting postures on biodynamic response of seated occupants under vertical vibration , 2004 .

[28]  B Willems,et al.  Whole-body vibration exposure: a comprehensive field study. , 1994, American Industrial Hygiene Association journal.

[29]  Michael J. Griffin,et al.  Response of the seated human body to whole-body vertical vibration: discomfort caused by sinusoidal vibration , 2014, Ergonomics.

[30]  D J Oborne,et al.  The determination of equal comfort zones for whole-body vibration. , 1974, Ergonomics.

[31]  Subhash Rakheja,et al.  EVALUATION OF VIBRATION AND SHOCK ATTENUATION PERFORMANCE OF A SUSPENSION SEAT WITH A SEMI-ACTIVE MAGNETORHEOLOGICAL FLUID DAMPER , 2002 .

[32]  Herman Ramon,et al.  Comfort improvement of a nonlinear suspension using global optimization and in situ measurements , 2005 .

[33]  A. J. Scarlett,et al.  Whole-body vibration: Evaluation of emission and exposure levels arising from agricultural tractors , 2007 .

[34]  K. Sankaranarayanasamy,et al.  Whole body vibration analysis for drivers of suspended cabin tractor semitrailer , 2014, Experimental Techniques.

[35]  N. K. Kittusamy,et al.  Jarring/jolting exposure and musculoskeletal symptoms among farm equipment operators , 2008 .

[36]  Pedro Arezes,et al.  The influence of operator driving characteristics in whole-body vibration exposure from electrical fork-lift trucks , 2009 .