Improving steering system for walking tractor-trailer combination to increase operator’s comfort and ease of control


  • Ali Mirzakhani Nafchi
  • Hassan Mirzakhani Nafchi
  • Iman Abdollahi Demneh


walking tractor, steering, workplace layout, vibration, heart rate, turning radius


The aim of present study was to develop the performance of walking tractor-trailer combination, increase the ability of control and steering, maneuverability, reduce the hand transmitted vibration (HTV), discomfort, stress and probability of accident for walking tractor operators.  The location of controls in existing walking tractor with respect to anthropometric suitability of operators and rearrangement for improved operator's ergonomics was analyzed.  To compare existing system with improved system, and find the affects of improved workplace layout over the existing one in terms of physiological cost and discomfort of the walking tractor operator, turning radius, operator hart rate, energy cost and HTV were measured.  The energy cost of riding walking tractor-trailer with improved workplace layout is 9.2% lesser than that of riding unmodified walking tractor-trailer.  The overall discomfort and body part discomfort of operator riding walking tractor-trailer with improved workplace layout were reduced by 38.5 and 17.9% walking tractor-trailer with and without improved work space layout.  The HTV was measured and analyzed as per the guidelines of International Standards ISO 5349 (1986 Vibration was measured using the portable four-channel multi-analyzer system.  The data collection included frequency-unweighted and frequency-weighted vibration in RMS acceleration, frequency response of the vibration.  The HTV reduction of the walking tractor with trailer at the handles for steering system was improved from 10.1 to 11.6% and from 11.9 to 17.3% on farm road and concrete road respectively at selected levels of forward speed of operation.  The turning radius decrease from 6.2 to 2.7, 6.7 to 2.8 and 7 to 3 meters for unmodified and modified walking tractor respectively at the speed of 3, 4 and 5 km/h.  Average operator hart rate has reduction at the rate of 20% for modified compared to unmodified walking tractor.  Reduction in operator heart rate was because of fixing the handle steering and convenience during the operating.

Author Biography

Ali Mirzakhani Nafchi






V-Management, Ergonomics and Systems Engineering