1. Psy 552 Ergonomics & Biomechanics Lecture 11

2. Lifting findings  Squatting yields a lower shear force than bending over.  Squatting…  Pretensing…

5. 3 Dimensional Models  Are predictive, but are limited…  Shultz et al. (1982) – 10 muscle model including the L/R rectus abdominus, external/ internal obliques, erector spinaes, and latissimus dorsi.  This model has been modified

6. Model Findings  Torsional loading…  SpeedIncrease over static slowno increase normal… fast…  Granata & Marras (1995)…

8. Pushing & Pulling  Compression varies little with handle height.  Compression forces vary when: …

9. The wrist  Place of common work related musculoskeletal disorders  Tunnel is made up of the: Hamate Capitate Pisiform Scaphoid Trapezium Lunate Retinaculum

11. Wrist forces  Depend on: Type of grasp – large or small Size of the hand -- large or small Type of movement Bend radii

12. Grasp Type

13. Bend Radii  The radii of the “pulley” changes the area over which the force is applied

14. Supporting force