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Vertical Distance Multiplier Factor

How can the vertical distance affect the weight limit?

Example: A worker lifts a 15 kg load from loosely piled pieces of metal from the floor to the table five times an hour.

Example of a worker lifting

To calculate the recommended weight limit (RWL) for the task:

  • Determine the weight of the load.

Weight - 15 kg

  • ASSESS the six components of the lifting task.

H (Horizontal Distance) - 30 cm
V (Vertical Distance) - 0 cm
D (Lifting/ carrying Distance) - 115 cm
F (Frequency) - 12 min
A (Angle) - 0°
C (Coupling/quality of grip) - poor

23 Kg x 0.80 x 0.80 x 0.86 x 1.00 x 1.00 x 0.90 = 11.4 kg

  • Compare weight of the box against the determined Recommended Weight Limit for the task. The weight of the load at 15 kg is higher than the recommended weight limit calculated to be 11.4 kg.

Therefore the TASK IS DANGEROUS.

Recommendations

The components: V - starting height, D - lifting distance and H - horizontal distance and C - poor grasp contribute similarly to the risk.

  • Raise the starting height by providing materials at the best starting height (75 cm). This change also decreases D, the lifting distance.
Evaluate the Redesigned Task

Evaluate the Redesigned Task

23 kg x 0.8 x 1.00 x 0.95 x 1.00 x 1.00 x 0.90 = 15.7 kg

  • Compare weight of the load against the Recommended Weight Limit in new layout.

The weight of the load at 15 kg is lower than the recommended weight limit now calculated to be 15.7 kg.

  • Further improvement can be achieved by providing the working materials in containers with handles; this would increase RWL up to 17.5 kg.

Therefore, MOST WORKERS CAN SAFELY PERFORM THE TASK.

Document last updated on November 21, 2002
Document confirmed current on October 1, 2010

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