Manual Material Handling Flashcards
7 cards from real CEA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Manual Material Handling flashcards as text
A worker frequently carries a tote bag on one shoulder instead of using both hands. The PRIMARY ergonomic concern is:
Answer: Lateral spinal imbalance and elevated trapezius on the loaded side
Single-shoulder carrying creates asymmetric lateral loading on the spine and sustained trapezius muscle activation on the load-bearing side.
The Waters et al. (1993) revision of the NIOSH lifting equation added which key component compared to the 1981 version?
Answer: Inclusion of asymmetric lifting via the asymmetry multiplier
The 1993 revised NIOSH equation introduced the asymmetry angle and asymmetry multiplier (AM) to address non-sagittal-plane lifts.
Which of the following task factors does NOT directly affect the recommended weight limit (RWL) in the NIOSH lifting equation?
Answer: Worker's age and gender
The NIOSH RWL equation uses task factors (H, V, D, A, F, C) and does not include worker-specific variables like age or gender.
What is the recommended maximum push/pull force for sustained cart pushing by an average worker, based on Liberty Mutual (Snook) guidelines for 75th percentile male workers?
Answer: 20–35 lbs
Snook guidelines suggest sustained push forces of approximately 20–35 lbs are acceptable for 75th percentile male workers, varying with frequency and distance.
Which type of cart or equipment modification most effectively reduces the initial force required to move a heavy cart?
Answer: Switching from small hard wheels to large pneumatic or swivel caster wheels
Larger diameter and softer wheels reduce rolling resistance and contact pressure, dramatically decreasing the initial force needed to move a loaded cart.
A warehouse ergonomist observes workers bending forward more than 45 degrees at the waist while picking items from lower shelf levels. The BEST immediate intervention is:
Answer: Raise the lower shelf height or use a lift table to bring items to knuckle height
Raising the work height to the knuckle zone eliminates extreme forward trunk flexion, the primary biomechanical risk factor in this scenario.
Which measure is the MOST direct indicator that a manual material handling intervention successfully reduced musculoskeletal injury risk?
Answer: Calculated peak L4/L5 compressive force decreases below 3,400 N
A reduction in L4/L5 peak compressive force below the NIOSH action limit of 3,400 N is the most direct biomechanical measure of reduced spinal injury risk.