Human Strength Evaluation - Fundamentals and Assessment Tools for Occupational Ergonomics - page 223

TABLE 10.6 Horizontal Push and Pull Forces (N) that Male Soldiers can Exert Intermittently or
for Short Periods of Time

Condition (m is the
coefficient of friction
at the floor)

Horizontal Force a
at least Applied with b

100 N push or pull Both hands, or one

shoulder, or the back

With low traction, m
between 0.2 and 0.3

200 N push or pull Both hands, or one

shoulder, or the back

With medium traction, m
about 0.6

250 N push One hand If braced against a vertical

wall, 50 to 150 cm from
the push panel and
parallel to it

300 N push or pull Both hands, or one

shoulder, or the back

With high traction, m above
0.9

500 N push or pull Both hands, or one

shoulder, or the back

If braced against a vertical
wall, 50 to 150 cm from
the push panel and
parallel to it, or if
anchoring the feet on a
perfectly nonslip ground,
such as at footrest

750 N push The back If braced against a vertical

wall, 60 to 110 cm from
the push panel and
parallel to it, or if
anchoring the feet on a
perfectly non slip
ground, such as at
footrest

a May be nearly doubled for two and less than tripled for three operators pushing simultaneously. For
the fourth and each additional operator, add about 75% of their push capabilities.
b See Figure 11.9 for example.
Source: Adapted from MIL-STD 1472.

surface may make it impossible to push a heavy object sideways with the shoulder; one can experience
this in the winter on an icy ground when trying to push a car out of the ditch. To a sitting person, the seat
provides most of the reaction that counters the forces actively exerted through the upper body and arms,
although some support may be gathered from the floor via the legs.

10.7.3 Designing for Foot Strength
If a person must stand at work, fairly little force and only infrequent operations of foot controls should be
required because, during these exertions, the operator has to support the body solely on the other leg. For
a seated operator, however, operation of foot controls is much easier because the seat supports the body.
Thus, the feet can move more freely and, under suitable conditions, can exert large forces and energies. A
typical example for such an exertion is pedaling a bicycle where all energy transmits from the leg muscles
through the feet to the pedals. For normal use, these should be located underneath the body, so that the
body weight above them provides the reactive force to the force transmitted to the pedal. Placing the
pedals forward makes body weight less effective for generation of reaction force to the pedal effort;
but if a suitable backrest is present against which the buttocks and the low back rest, the feet can
push forward on the pedals.
Foot movements are relatively slow compared to hand motions, because rather large leg messes are
involved. Yet, feet can generate small forces in nearly all directions, such as for the operation of switches,