Laboratory investigation of seat suspension performance during vibration testing.
Mayton-AG; DuCarme-JP; Jobes-CC; Matty-TJ
Proceedings of the ASME 2006 International Mechanical Engineering Congress and Exposition (IMECE2006), November 5-10, 2006, Chicago, Illinois. New York: American Society of Mechanical Engineers, IMECE2006-14146, 2006 Nov; :177-183
Mining injury statistics show that a significant number of back, neck, and head injuries are linked to exposure from vehicle vibration. Use of a suspension seat is a common way to isolate the vehicle operator from the adverse effects of vibration exposure. Thus, researchers at the National Institute for Occupational Safety and Health - Pittsburgh Research Laboratory (NIOSH - PRL) performed laboratory studies on four passive and two semi-active seat suspension designs. These are typical of seat suspensions commonly found on large off-road heavy surface mining, construction and agricultural vehicles as either replacement or original equipment manufacturer (OEM) systems. One included a pneumatic (air bladder) spring mechanism. The fifth and sixth suspensions were based on a magnetorheological (MR) semi-active damper design used in conjunction with the pneumatic (air bladder) and one of the coil spring suspensions above. These suspensions were modified with a commercially available MR damper substituted for the OEM damper. These six seat suspension systems were tested and analyzed, for vertical vibration only, using the ISO 5007 Standard . This paper describes the laboratory vibration tests using a MTS shaker table and discusses the results obtained for the different suspension designs and highlights the rheonetic technology studied. Implications of the seat suspension designs relative to their capabilities for isolating vehicle operators from vibration exposure are discussed. Results for suspensions 1 through 3 showed frequencies of isolation from 2.1 to 3.0 Hz using the 40-kg (88-lb) mass and from 1.65 Hz to 1.8 Hz using the 80-kg (176-lb) mass. Suspension #4, in tests with only the 80-kg (176-lb) mass, showed an isolation frequency of 3.7 Hz. With the MR damper added to seat suspension #4, the peak transmissibility was lowered from 1.3 to 0.95 and showed a corresponding downward shift in frequency from 2.25 Hz to 1.4 Hz. In fact, the results for suspension #5 (the MR damper added to seat suspension #4), using test #3 conditions of the programmed control algorithm, showed isolation (attenuation of transmitted vibration) throughout the test frequency range from 1.0 to 6.0 Hz.
Vibration; Vibration-control; Vibration-effects; Vibration-exposure; Mining-industry; Mining-equipment; Ergonomics; Musculoskeletal-system-disorders; Injuries; Injury-prevention; Cumulative-trauma; Cumulative-trauma-disorders; Head-injuries; Neck-injuries; Back-injuries
National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory 626 Cochrans Mill Road, Pittsburgh, Pennsylvania 15236
Proceedings of the ASME 2006 International Mechanical Engineering Congress and Exposition (IMECE2006), November 5-10, 2006, Chicago, Illinois