Industrial ERG

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Course Learning Outcomes for Unit

Upon completion of this unit, students should be able to:

1. Describe characteristics of ergonomically designed workstations.

1.1 Explain ergonomics hazards related to workstations that subject workers to vibration.

1.2 Identify ways to improve workstations that pose potential ergonomics -related hazards.

3. Discuss body-centered design for mitigating common workplace stressors.

3.1 Describe solutions for back disorders associated with a seated workstation.

Reading Assignment

Chapter 10:

Vibration

Chapter 11:

Industrial W orkstation Design

Unit Lesson

The chapters within this unit’s required reading on vibration and industrial workstation design provide

important information to consider. Vibration gets very little attention when it comes to discussions associated

with ergonomics. Throughout the course, we have discussed and studied the effects of the workplace on

employees with a focus on equipment designed to accommodate a neutral posture and tools designed to limit

unnecessary, forceful movements. Vibration can be another culprit in causing chronic work-related

musculoskeletal disorders (W MSDs). Consider the whole-body vibration exposure experienced by the over-

the-road truck driver. For a maximum of 10 hours per day, the driver is sitting in his or her cab on an air-ride

seat and piloting an 80,000-pound vehicle down the nation’s highways. Ideally, the roads the driver takes are

very smooth without any noticeable permeation into the cab of the roadway and its surface. Of course, this is

not always the case. W hen the roads are bumpy or contain a lot of potholes, the driver is in a sitting position

with the vibratory effects felt every time he or she hits an imperfection in the road. The vibration of the engine

also plays a role.

To get a better feeling for the degree of vibration sustained by a driver, look down at your drink of choice

sitting in your cup holder the next time you are on the road. You will note that the surface of the liquid is never

completely still while the vehicle is moving. Each of those ripples in your drink translates into vibrational forces

sustained by the body’s structural system. W e know that bones are connected to each other by ligaments.

Muscle is connected to bone via the tendon system. Bones have fluid or discs that keep each bone from

striking the next bone. Neuromuscular junctions maintain a constant feedback loop between the outside

environment and the inside of our bodies. Each little bump forces a person to make subtle and typically

imperceptible adjustments to his or her body’s position. Even with the advent of air-ride seats and air-ride

cabs, the driver is still subjected to whole body vibration and the long-term consequences.

These whole body vibrations sustained over a period of years can result in signifi cant problems. According to

Salmoni, Cann, Gillin, and Eger (2007), the effects of vibration can include, but are not limited to, muscular

fatigue, headaches, and a loss of balance.

W hat are other occupations where whole-body vibration may occur? W hat about the people who work on

ships with large propellers that cause vibrations throughout the vessel, for instance? W hat about the

vibrations felt by airline pilots? Can you think of an occupation where vibration in the workspace could be a

UNIT STUDY GUIDE

Vibration and Industrial

Workstation Design

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UNIT x STUDY GUIDE

Title

problem for the employee? Consider heavy equipment used at construction sites. One that comes to mind is

the excavator or backhoe. This machine digs holes in the ground with a large bucket. The machine takes a

bite out of the ground and then swings that bucket to an area where the soil is piled. Load after load is

plucked from the ground while operating this piece of equipment, which usually has a very large diesel engine

running as it digs, swings, dumps, swings, and then digs again. The body is exposed to considerable forces

from vibration, noise, and centrifugal force.

W hen we typically think of the kind of work that creates a significant amount of vibration, one other job

position that frequently comes to mind is the jackhammer operator. A lot of attention is paid to this operation

due to the incidence of white finger syndrome, also known as Raynaud’s phenomenon, which is frequently

experienced by individuals who use equipment with extreme vibrational properties (Bush, 2012). There are

many other job tasks in the workspace that may expose employees to vibration hazards. Remember Adam,

the employee who works in the big-box store? Adam is one such person who experiences the effects of

vibration at his workstation. Recall that Adam works in the automotive shop of his store. One of his main tasks

every day is to remove tires and wheels from cars and trucks and replace those worn out tires with new ones

purchased by the consumer. Adam, of course, uses an impact wrench that is powered pneumatically. You

have likely heard the noise from an impact wrench many times when getting your car serviced. You even hear

it on television commercials for different auto service centers. Each wheel takes four, five, six, or more lug

nuts to remove in order to take the wheel assembly off the vehicle.

Let us do a mental exercise. Consider that Adam has to remove five lug nuts per wheel and replace those

same lug nuts when the tire is changed out. He does this for three cars per hour, in a 10-hour shift. So, we

have 20 lug nuts per vehicle to remove; 20 lug nuts to replace; 120 lug nuts to change per hour; 1,200 lug

nuts to change per day; 6,000 lug nuts to change per week; and 300,000 lug nuts to change per year. That is

a lot of vibrations to the hand, wrist, forearm, and arm. Doing a little research on this machine shows us that a

typical air impact wrench can have as much as 8,400 rotations per minute. Obviously this poses a concern

with respect to potential W MSDs that might result from performing this type of work over a period of years.

W hat type of cumulative trauma disorders (CTDs) might we be dealing with for our employees who use this

type of tool?

Industrial Workstations

Oftentimes, when one thinks of an industrial workstation, one may visualize a person who is working in front

of a machine or at a conveyor. Indeed, most ergonomics textbooks focus on particular job tasks that involve a

single workstation for the purpose of simplifying the discussion related to proper design of workstations. Your

textbook also utilizes this approach by considering hazards related to specific job tasks (Stack, Ostrom, &

W ilhelmsen, 2016).

Jobs can be diverse and may involve multiple workstations that require the worker to either sit, stand, lean

over, or lay prone. Consider positions that Adam would likely work in. His typical customer needs his or her oil

changed, tires rotated, chassis lubed, fluids checked and filled, and tire pressure checked. Adam has to get in

and out of the automobile. Adam must open the hood and elevate the car by using either floor jacks or an

auto lift system. He must remove the tires, move the tires to another location on the car, and then tighten the

lug nuts on each tire. Adam has to get under the car to remove the drain plug for the oil pan, remove the oil

filter, replace the filter, and replace the drain plug. He then uses a grease lube device to apply the appropriate

amount of grease to each fitting. The automobile is then lowered, and Adam replaces the oil and checks to

ensure that all fluids are filled.

Some auto service centers have pits for employees use while working underneath a car. The employees must

climb down into the pit via a set of stairs that may be oil-covered and slippery. The employees who are

performing oil changes have to work above their shoulders while taking out the drain plug and the oil filter. If

the facility does not have a pit to do this, then employees either use a floor jack or an auto lift system. W ith

the floor jack system, employees are lying on their backs on a creeper. W ith the auto lift system, employees

have to reach above their shoulders. In addition, the employees have to bend over the engine compartment to

fill the fluids and oil. The tires have to be lifted into and out of their position s.

Evaluating a given individual’s workstation is not always a simple, clear-cut process. If you are on a team to

evaluate Adam’s job tasks and workspaces, what considerations and recommendations might you make?

Adam is constantly on the move, climbing up and down oil-covered steps, crawling under automobiles,

working with his hands above his shoulders for extended periods of time, bending over the engine

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UNIT x STUDY GUIDE

Title compartment, and standing at the computer workstation while inputting data. There is a lot of repetitive

movement here and in some pretty awkward positions.

Of course, Adam is just one of our fictitious employees here. Let us look again at Amy and her cashier’s

workstation. Our textbook authors suggest rotating through the different positions throughout the day. W e

know that Amy is in a standing pos ition most of the day. Could we provide her with a leaning position or a

sitting position in order to rotate those positions? How would that affect the customer and the production

necessary to keep the customer happy? It always seems that whenever we get t o the store and are ready to

check out, everyone else is ready to check out as well. Nobody enjoys waiting in line. How would the

purchasing consumer feel if the checkout production slowed a little to allow the employee to rotate positions?

This, of course, represents just one type of conflict that might be encountered when recommendations are

made by a team conducting workplace ergonomic evaluations.

In these two scenarios, both of our employees deal directly with the customer, and customer service ranks

high with the purchasing public. W hile we are trying to figure out how to improve our employees’ workstations

and cut down on the vibratory effects of their environment, how are we affecting the public who are paying for

this service with their hard-earned money? Always remember to think completely through the issue to make

sure we are not fixing one problem and creating another, and always look at the problem from a safety

perspective to ensure that we are not making a safe work task less safe with our efforts.

References

Bush, P. M. (2012). Ergonomics: Foundational principles, applications, and technologies. Boca Raton, FL:

CRC Press.

Salmoni, A. W ., Cann, A. P., Gillin, E. K., & Eger, T. R. (2007). Case studies in whole-body vibration

assessment in the transportation industry — challenges in the field. International Journal of Industrial

Ergonomics, 38(9), 783-791.

Stack, T., Ostrom, L. T., & W ilhelmsen, C. A. (2016). Occupational ergonomics: A practical approach.

Hoboken, NJ: W iley.

Learning Activities (Non-Graded)

Non-graded Learning Activities are provided to aid students in their course of study. You do not have to

submit them. If you have questions, contact your instructor for further guidance and information.

After reading the unit lesson and the required reading, consider visiting the Occupational Safety and Health

Administration webpage (https://osha.gov/) to learn about its recommendations and reflect on how you could

use those recommendations as a safety professional. Remember that OSHA is an important resource for you

as a safety student.