Whole-body vibration in underground load-haul-dump vehicles

Abstract

Whole-body vibrations (WBV) were measured at the seatpan of load-haul-dump (LHD) vehicles of 3.5-, 5-, 6- and 8-yard capacity at two underground mines. Twenty-two sets of measurements were made involving 11 vehicles, 8 operators and 4 work locations. In each set frequency-weighted rms and peak accelerations were measured in the x, y and z directions, as defined by the ISO (1982), during mucking, driving full, dumping and driving empty. Significant differences in rms accelerations were found between vehicle sizes and between operational tasks (less than or equal to 0.05). The smallest (3.5 yd) vehicle produced the greatest accelerations in the x and z directions. Accelerations in the x and z directions were also greater when driving full and empty than when mucking and dumping. The highest frequency-weighted rms accelerations of 2.0 to 2.8 m/s-2 were recorded in the z (longitudinal) direction. Peak accelerations ranged from 1.2 to greater than or equal to 20 m/s2, resulting in crest-factor ratios in excess of six. The exposure periods for each task were used to calculate mean daily acceleration exposures (m/s2). Of the 22 sets of measurements, 20 exceeded the International Standards Organization (ISO) six-hour daily exposure limit in the z direction of acceleration, and 9 exceeded the six-hour daily exposure limits in all three directions. Acceleration exposure ratios calculated using resultant acceleration vectors as described in ISO (1982), were found to exceed the ISO exposure limit for health or safety in all 22 cases. One-third octave band frequency analysis of the weighted signals indicated that the dominant frequencies were usually 1.6 to 3.15 Hz, except when the vehicles were idling and higher frequencies predominated.

Influence of Vehicle Size, Haulage Capacity and Ride Control on Vibration Exposure and Predicted Health Risks for LHD Vehicle Operators

“…In a 1989 study by Village and colleagues 2 , WBV experienced by LHD vehicle operators was measured for 11 LHD vehicles ranging in size from 2.7-6.2 m 3 bucket haulage capacity.…”

“…Despite health concerns related to WBV exposure, a limited number of studies have evaluated the health risk associated with WBV during the operation of underground LHD vehicles 1,2 .…”

A comparison between methods for assessment of whole-body vibration exposure: A case study in a limestone quarry

“…About the quarry activities, numerous studies have explored WBV exposure levels during the operations of large earth moving equipment [17]. The loadhaul-dump (LHD) vehicles are a potential dangerous source of hazards health human due to the rough terrain, heavy loading and haul travels [18]. The long-term exposure to WBV has multiple shocks during the unloaded travels can lead to adverse effects on the lumbar spine.…”

Performance Analysis of Suspension Seats under High Magnitude Vibration Excitations: II. Design Parameter Study

“…Off-road vehicles, which are often unsuspended, are known to cause high magnitude vertical ride vibration in the vicinity of the resonant frequency of the vehicle supported on large and soft tires. Some examples of such vehicles include agricultural tractors that could cause frequency-weighted peak acceleration in the 8.5 to 53.2 m/s 2 range; forklift trucks driving over obstacles with frequency-weighted rms acceleration up to 2.5 m/s 2 , load-haul dump vehicles with peak frequency-weighted acceleration exceeding 20 m/s 2 (Sandover, 1998;Lovat et al, 1995;Village et al, 1989). Such high magnitude excitations induce not only repetitive contacts of the suspension seat mechanism with the elastic end-stops, but may also cause intermittent loss of contact between the seated body and the seat.…”