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Manual Handling is Associated with

Manual Handling is Associated with. 27% of all industrial injuries 670,000 injuries/yr in the United States 60% of all money spent on industrial injuries 93,000,000 lost workdays/yr. Approaches to Recommendations. Biomechanical Physiological Psychophysical. Manual Handling Variables.

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Manual Handling is Associated with

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  1. Manual Handling is Associated with • 27% of all industrial injuries • 670,000 injuries/yr in the United States • 60% of all money spent on industrial injuries • 93,000,000 lost workdays/yr

  2. Approaches to Recommendations • Biomechanical • Physiological • Psychophysical

  3. Manual Handling Variables • Individual • Technique • Task

  4. Pushing and Pulling Strength Factors • Handles • One hand vs. two hands • Body posture • Application height • Direction

  5. Push/Pull Summary • Two hands are usually better than one. • Force capability goes down as it is exerted more often. • Initial force capability is higher than sustained capability. • Pushing capability is higher than pulling. • Push at waist level; pull at thigh level.

  6. Task Modifications • Measure the force required to move all wheeled equipment; periodically check the forces. • Install vertical push/pull bars on carts. • Push rather than pull loads. • Avoid muscle-powered pushing and pulling for ramps, long distances, and frequent moves. • Use mechanical aids and momentum. • Reduce force by reducing friction.

  7. Holding • Problems • Holding gives a static load combining body weight and object weight. • Low-back pain arises from spine biomechanics. • Solutions • Reduce the magnitude and duration of the torque. • Use balancers. • Limit high loads to short durations.

  8. Carrying Guidelines • Replace carrying with pushing or pulling. • Minimize the moment arm of the load relative to the spine. • Consider carrying large loads occasionally rather than light loads often. • Use teamwork. • Consider using balancers, manipulators, conveyors, or robots. • Reduce lifting by raising the initial location. • Avoid carrying objects up and down stairs.

  9. Lifting Guidelines • 51 lbs is the maximum that can be lifted or lowered (load constant). • Recommended weight limit (RWL) is load constant multiplied by various factors. • Lifting index = load weight / RWL

  10. NIOSH lifting example • At initiation, • Horizontal location, H1 = 10 in. • Vertical location, V1 = 40 in. • Vertical location, V2 = 51 in. • Angle of asymmetry, A = 0 • Frequency, F = 12 /min. • Load = 14 lbs. • Duration = 2 hr. • What is the RWL? • What is the Lifting Index, LI?

  11. Basic NIOSH Lifting Formula (pg. 269) RWL = LC × HM × VM × DM × FM × AM × CM • RWL = recommended weight limit • LC = load constant (51 lbs.) • HM = horizontal multiplier • VM = vertical multiplier • DM = distance multiplier • FM = frequency multiplier • AM = asymmetry multiplier • CM = coupling multiplier

  12. Multiplier Formulas Horizontal multiplier HM = BIL / H • BIL = Body interference limit • H = Horizontal location Vertical multiplier VM = 1 – VC × | V – KH | • VC = Vertical constant = 0.0075for inches, 0.003 for cm. • V = Vertical location • KH = Knuckle height (assume 30 in.)

  13. Multiplier Formulas (cont.) Distance multiplier DM = .82 + DC/D • DC = Distance constant = 1.8 for inches, 4.5 for cm. • D = Vertical travel distance Asymmetry multiplier AM = 1 – .0032A • A = Angle of symmetry

  14. Multiplier Formulas (cont.) Frequency multiplier See Table 15.9. • Lifting frequency = mean number of lifts in a 15-minute period • Lifting duration /session in hours may be: • Short = .001 h to ≤ 1 h • with recovery time of ≥ 1.2 × duration • Moderate = >1 h ≤ 2 h • with recovery time of ≥ .3 × duration • Long = >2 h but ≤ 8 h

  15. Multiplier Formulas (cont.) Coupling multiplier See Table 15.10, 15.11, Fig. 15.13 • Depends on: • Height of initial and final hand–container coupling • Whether coupling is good, fair, or poor

  16. Force Limits FL = A × F × DIST • A = Age factor • F = Frequency factor • DIST = Distance factor • Differences between force limits and NIOSH guidelines. • Different factors • Different criteria • FL permissible load ~1.8 times that of NIOSH

  17. Resources • Manual Handing Guide (Mital et al.) • Biomechanical software • ErgoIntelligence MMH • 2D Static Strength Prediction Program • 3D Static Strength Prediction Program

  18. Guidelines for Manual Handling • Three categories: • Select individual • Select strong people based on tests. • Teach technique • Bend the knees. • Don’t slip or jerk. • Don’t twist during the move. • Design the job • Use machines. • Move small weights often. • Get a good grip. • Put a compact load in a convenient container. • Keep the load close to the body. • Work at knuckle height.

  19. Examples to discuss

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