Transcript Ergonomic Assessment

Ergonomic Assessment
Josh Prince
Keith Heerdegen
Mary Cook
Stacking

We measured 3 types of boxes that are most
common it the warehouse.

We recorded the dimensions and more
importantly the force the box exerts.
Box1





Height-15 in
Length-24 in
Width-14 ½ in
Weight-18 kg
Force- 50 lbs/sq. in
Box2





Height- 20 ½
Length-25 ½
Width-17 ½
Weight-14 kg
Force-24 lbs/sq. in
Box3





Height-22
Length-20 ½
Width-9 ½
Weight-12 kg
Force-22 lbs/sq. in
Job description

NIOSH recommended
weight is 23 kg (225 N).

Employees commonly are
either stacking these boxes
off pallets or back on them.

Can stack anywhere from 5
boxes to hundreds of boxes
in a given job.

Lift boxes overhead
Evaluation and Risk Factors

Bending
–



Can cause over-exertion
(account for ¼ of all reported
occupational injuries)

Will cause increase stress
on discs in back (up to
225%)
Greater than 15° in some
incidences
Head and Neck
–
Energy consumption
increases 50% when
working bent over
Greater than 15°
Twisting
–

Ideal
Evaluation and Risk Factors

Arms
–
–

Back and disc problems

Shoulder pain

Tendinitis in elbow or
shoulder

Arthrosis (joint
degeneration)
Elbows
–
–

Reaching overhead
Over extending

Out of position
Not at 90° angle
Wrists
–
–
In and out of neutral
position
Extended greater than 10°
Evaluation and Risk Factors

Standing
–

Repetition
–

Lifting can occur more than
20 times in an hour
Force
–

Knees are straight and not
locked
Boxes can weigh over
25lbs.
Grip
–
–
Moderate pinch grip
Awkward handle

Muscle strain

Arthritis

Fatigue

Muscular- lactic acid build
up and shortage of oxygen

General (weariness)
Solution






Lift with legs, not with back
Keep arms at sides and elbows at 90 degrees (less
strenuous)
Wrists should be in neutral position at all times.
Keep the boxes on pallets to avoid extra stacking
Take breaks to avoid fatigue
Be as efficient as possible (human body only
converts 30% to energy)
Solution

Use a scissor lift with pallet

Use a vacuum lifting system
Pallet Jacks

Dimensions of a
stacked pallet:
–
Height- 82 ½ inches
–
Width- 43 ½ inches
–
Length- 49 inches
–
Weight- 789lbs
Using Pallet Jacks

Employees use pallet jacks to move pallets
that can range from 300 lbs to 1400 lbs.

Use both push and pull forces.

Distances vary but can end up pushing for an
extended period of time (up to 1 minute
without stopping)
Using Pallet Jacks

Pull Force- 26 lbs/sq. in

Push Force- 58 lbs/sq.
in
Evaluation and Risk Factors

Back and Neck
–
–

Injuries will most likely
occur at the shoulder,
arm, or upper back.

Causes a lot of muscle
strain especially in the
legs.
Straight and upright
No bending involves
Twisting
–


Minor twisting when
turning the pallet jack
Standing
–
Knees are straight and
not locked


Pulled muscles
Muscle strains
Evaluation and Risk Factors

Arms
–
–

Extended in front of body
when pulling
In good position when
pushing

Tendinitis

Arthrosis (joint
degeneration

Fatigue

Possible CTS
Elbows
–
–
In front of body and not
at 90° when pulling
At sides and close to 90°
when pushing
Evaluation and Risk Factors

Wrist
–
–

In neutral position when
pulling
Extended greater than
10° when pushing
Repetition
–
–
Can be exerting force for
up to a minute without
rest
Usually frequent stops
(times for rest)
Evaluation and Risk Factors

Grip
–
Slight pinch grip
Evaluation and Risk Factors

Static effort in the arms (prolonged state of
contraction of the muscles). This causes:
–
Less oxygen to the muscle


–
–
–
–
–
Lactic acid builds up
Muscle can’t recover
Fatigue
Higher heart rate
Higher energy consumption
Longer rest periods needed
Less efficient
Solutions

Pull the pallet jack instead of push since it
creates less of a force.
–

It keeps the wrists in neutral position.
Keep the elbows at sides and at 90° while
pulling.
–
–
More efficient.
Less stress on the arms and shoulders.
Solutions

Take frequent rest break to avoid fatigue.
–

Avoid twisting the body when turning.
–


Will also help limit the static effort.
Turn with the arms
Try to install a more adequate handle on the
jack.
Use a automatic power jack
References

Kroemer, K. H. E. and E. Grandjean. “Fitting
the Task to the Human: Fifth Edition.” Taylor
and Francis. 1997