The Bureau of Mines has developed an in-house test facility to evaluate some of the effects of whole-body vibration levels experienced by underground mobile equipment operators. Vibration data were collected from a coal haulage vehicle via a uniaxial accelerometer (vertical direction) attached to the machine frame under the operator's seat. The data were analyzed and processed so a computer-controlled vibration platform could approximate the vibration signals. Six men (36.0 Yr of age +/- 6.9 Sd) participated in a pilot study to evaluate the effects of shock and whole-body vibration on heart rate (hr), blood pressure (bp), back extensor strength, stature, manual dexterity, and subjective discomfort. The subjects were exposed to vibration for 30-min periods while seated in a typical operator's seat (with the backrest angle at 90 deg. Or 130 deg.) That was plain steel or modified with 2 in of foam padding. To control for diurnal variations in stature, hr, and bp, each subject repeated the same order of tests on a separate day, but without the vibration. Results indicated that vibration significantly increased the hr, systolic bp, mean bp, and the overall subjective discomfort rating (p<0.05). Also, the number of times subjects reported discomfort increased significantly during vibration (p<0.05) and when seated in the steel seat (p<0.005). The seat back angle had no significant effect on any of the dependent measures.
Chinese Soc. Met., V. 1, 1988, PP. 182-194