Controlling Whole-Body Vibration
Vibration is an occupational hazard in the workplace. It is separated into two sub categories – Hand-Arm vibration (HAV), which is usually associated with the use of vibrating hand tools, and Whole-Body Vibration (WBV), which is experienced when the operator or driver sits or stands on or in a vibrating machine. Such operations include truck and tractor driving, forklift operating, and driving earth moving machines
The health effects from vibration is caused by the energy wave that is transferred from the energy source (i.e., a hand tool or vehicle) into the body of the operator and is transmitted through the body tissues, organs, and systems of the individual. The body can tolerate certain levels of vibration, but eventually starts to deteriorate and fail as long-term damage is done and natural processes and systems of the body are disrupted.
The most pronounced and common effect of WBV is lower back pain, resulting from the degeneration of the intervertebral discs in the spinal column. Muscle fatigue also occurs as the muscles try to react to the vibrational energy to maintain balance and protect and support the spinal column. Other health effects that have been associated with WBV, and especially the driving environment, are hemorrhoids, high blood pressure, kidney disorders, and even impotence and other adverse reproductive effects in both men and women.
Prevention or mitigation of exposure to WBV is generally accomplished by eliminating the vibration source, reducing vibration at the source, reducing the transmission of vibration to the body, or reducing the duration of vibration exposure. The following are recommendations to control the exposure to WBV.
Train workers to recognize the warning signs of WBV injury.
Medically monitor workers who routinely use products associated with WBV.
Consider rotating jobs to limit worker exposure to WBV, but beware of increasing the number of workers exposed to risk.
Check, lubricate, and maintain seat, cab, and chassis suspensions according to manufacturer’s recommendations.
Keep suspension seats in vehicles in good working order and replace when worn out. A seat usually has a shorter working life than that of the vehicle.
Replace vibration dampers in suspension seats when worn out.
Show drivers how to adjust seats so that they are able to easily reach the vehicle’s pedals.
Show drivers how to use and adjust back supports.
Show drivers how to adjust the seat so it provides support for their thighs.
Show drivers how to adjust the suspension mechanism correctly. A suspension seat is usually adjusted in the middle of the suspension range for a particular driver’s weight.
Balance all machinery to eliminate unwanted vibration.
Change machinery speed so the resulting vibration frequency is not in a range that affects the human body.
Use additional mass to shift the natural frequency of the machine.
Level all roads or tracks that heavy machinery uses as a platform for movement.
Fill in all potholes that might cause problems for powered industrial trucks.
Adjust bridge cranes to ensure the rail track of a bridge crane provides a smooth ride.
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