Present results of decreased linear and areal cervical dimensions leading to decreased column stability may partially explain increased traumatic injury rates in women.

This paper investigates dynamic standing postural stability during standup forklift operation through a series of live subject tests to determine the sensitivity to loss of stability and falling. Through a set of controlled tests, the tolerance to accelerations in the lateral, oblique, and longitudinal orientations is determined. The levels of acceleration causing loss of balance are in close agreement with earlier studies and support the use of a door in the case of a standup forklift and the use of a control corridor in the case of a pallet jack (walkie-rider) during routine operation.

Rear impact sled tests were conducted using 5th, 50th, and 95th percentile Hybrid III dummies to evaluate proposed injury criteria. Different head restraint height (750, 800 mm) and backset (0, 50, 100 mm) positions were used to determine axial and shear forces, bending moments, and injury criteria (NIC, N(ij), and N(km)). The time sequence to attain each parameter was also determined. Three events were identified in the response. Event I was coincident with the maximum rearward motion of the torso, Event II occurred at the time of the peak upper neck flexion moment, and Event III occurred at the time of maximum rearward motion of the head. Parameters such as backset, head restraint height, seat-head restraint interaction, and anthropometry affected impact responses. Head rotations increased with increasing backset and increasing head restraint height. However, N(ij) and N(km) did not exhibit such clear trends. The 50th percentile dummy responded with consistent injury criteria values (e.g., the magnitude of the injury criteria increased with backset increase or head restraint height decrease). However, the 5th and 95th percentile dummies did not demonstrate such trends. These findings underscore the need to include subject anthropometry in addition to seat and head restraint characteristics for better assessment of rear impact responses.

This paper investigates the threshold of dynamic postural stability during standup forklift (lift truck) operation. Through a series of controlled tests, live subject data is gathered to determine the effect of upper extremity support during acceleration perturbation of the forklift (standing platform). The level of perturbation causing loss of balance is in close agreement with earlier studies and supports the use of a door in a standup forklift to arrest loss of balance, falling and injury during routine standup forklift (lift truck) operation.

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