Revised NIOSH Lifting Equation - Fundamentals and Assessment Tools for Occupational Ergonomics - page 882

TABLE 46.6 Hand-to-Container Coupling Classification
Good Fair Poor

For containers of optimal design, such
as some boxes, crates, etc., a “good”
hand-to-object coupling would be
defined as handles or hand-hold
cut-outs of optimal design a-c

For containers of optimal design,
a “fair” hand-to-object coupling
would be defined as handles or
hand-hold cut-outs of less than
optimal design a-d

Containers of less than optimal design
or loose parts or irregular objects that
are bulky, hard to handle, or have
sharp edges e

For loose parts or irregular objects,
which are not usually containerized,
such as castings, stock, and supply
materials, a “good” hand-to-object
coupling would be defined as a
comfortable grip in which the hand
can be easily wrapped around the
object f

For containers of optimal design
with no handles or hand-hold
cut-outs or for loose parts or
irregular objects, a “fair”
hand-to-object coupling is
defined as a grip in which the
hand can be flexed about 90

Lifting nonrigid bags (i.e., bags that sag
in the middle)

d

8

a An optimal handle design has 0.75 to 1.5 in. (1.9 to 3.8 cm) diameter,

4.5 in. (11.5 cm) length, 2 in. (5 cm) clearance,

cylindrical shape, and a smooth, nonslip surface.
b An optimal hand-hold cut-out has the following approximate characteristics:

1.5 in. (3.8 cm) height, 4.5 in. (11.5 cm)

length, semioval shape, 2 in. (5 cm) clearance, smooth nonslip surface, and 0.25 in. (0.60 cm) container thickness

(e.g., double thickness cardboard).
c An optimal container design has

16 in. (40 cm) frontal length, 12 in. (30 cm) height, and a smooth nonslip surface.

d A worker should be capable of clamping the fingers at nearly 90

8 under the container, such as required when lifting a

cardboard box from the floor.
e A container is considered less than optimal if it has a frontal length

12 in. (30 cm), rough or
slippery surfaces, sharp edges, asymmetric center of mass, unstable contents, or requires the use of gloves.
f A worker should be able to comfortably wrap the hand around the object without causing excessive wrist deviations or
awkward postures, and the grip should not require excessive force.

16 in. (40 cm), height

. .

Object Lifted

Container Loose Object

YES

Optimal
Container?

NO

Bulky
Object?

YES

NO

POOR

Optimal
Handles?

Optimal
Grip?

YES NO

NO NO

YES

Fingers
Flexed
90 degrees?

YES

FAIR

GOOD

FIGURE 46.3 Decision tree for coupling quality.