NIOSH equation

Load Weight (L)

weight of the object

Vertical Location (V)

distance of the hands above the floor

horizontal location (H)

distance measured from the midpoint between the ankles to the midpoint of a line drawn between the middle knuckles of both hands.

if less than 10”, set to 10”

Asymmetry Angle (A)

angular measure of how far the object is displaced from the front (mid-sagittal plane) of the workers body at the beginning or ending of the lift.

Lifting Frequency (F)

average number of lifts per minute over a 15 minute period

moderate lifting duration

1-2 hours followed by a recovery time of at least 0.3 times the work time.

Short lifting duration

1 hour or less followed by a recovery time at least as long as the lifting duration. recovery time=non-lifting, light work

long lifting duration

2-8 hours. with standard industrial rest allowances

2 breaks +lunch

RWL

Weight that nearly all healthy workers can safely lift over the course of the workday.

RWL equation

RWL= (LC)(HM)(VM)(DM)(AM)(FM)(CM)

LC

load constant (23kg or 51 lbs)

HM

horizontal multiplier

metric 25/H

US: 10/H

if >1, use 1

if H>25in or>63cm H=0

VM

verticle multiplier

inches VM=1-0.0075|V-30|

cm: VM=1-0.003|V-75|'

if V>70in,178cm VM=0

Distance multiplier

inches: DM=0.82+1.8/D

cm:DM=0.82+4.5/D

if D<=10in then Dm=1

if D>+70 in then DM=0.85

D=the vertical distance the object travels in the task

AM

angle multiplier

if significant control required at destination, also measure at destination

A>135 degrees set AM=0

AM=1-0.0032A

FM

frequency multipler

there is a table to use (LEARN IT)

if F<.1 lift/minute use the 1 hour lift category

if F<0.2 lifts/minute, set frequency to 0.2lifts/min

CM

Coupling multiplier

coupling documents

feed force equation

Max Feed Force=MVC (RF) (SF)(FF)(DF)

feed force frequency table

feed force duration table