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 – Greater than 15° Twisting – Greater than 15° in some incidences Head and Neck – Ideal  Energy consumption increases 50% when working bent over  Can cause over-exertion (account for ¼ of all reported occupational injuries)  Will cause increase stress on discs in back (up to 225%)

Evaluation and Risk Factors Arms – Reaching overhead – Over extending Elbows – Out of position – Not at 90° angle Wrists – In and out of neutral position – Extended greater than 10°  Back and disc problems  Shoulder pain  Tendinitis in elbow or shoulder  Arthrosis (joint degeneration)

Evaluation and Risk Factors Standing – Knees are straight and not locked Repetition – Lifting can occur more than 20 times in an hour Force – 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 – Straight and upright – No bending involves Twisting – Minor twisting when turning the pallet jack Standing – Knees are straight and not locked  Injuries will most likely occur at the shoulder, arm, or upper back.  Causes a lot of muscle strain especially in the legs.  Pulled muscles  Muscle strains

Evaluation and Risk Factors Arms – Extended in front of body when pulling – In good position when pushing Elbows – In front of body and not at 90° when pulling – At sides and close to 90° when pushing Tendinitis Arthrosis (joint degeneration Fatigue Possible CTS

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. – Will also help limit the static effort. Avoid twisting the body when turning. – 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