1. ergonomics
steven casey, Ergonomic Systems Design Inc
Believe it or not, it’s entirely possible to design machinery for
use in confined areas that gives operators of all shapes and
sizes more space than they know what to do with
a question
of space
I
n 1959, when NASA engineers set
out to design America’s first
manned spacecraft and select the
seven men who would come to be
known as the Mercury Astronauts,
they faced fundamental trade-
offs between the physics of getting a
spacecraft into orbit and the physical
characteristics of the men who would be
along for the ride of their lives.
Each additional inch of astronaut
height or pound of weight translated
into hundreds, if not thousands, of
pounds of cabin structure and rocket
mass and, of course, millions upon
millions of dollars. NASA clearly had to
establish some limits for the ‘human’
part of the payload to meet the practical
considerations concerning what they
were capable of blasting into orbit.
The men selected from the hundreds
of applicants had to have ‘the right
stuff’ – the piloting skill, lightning
reflexes, and raw courage to face the
tasks and dangers of early space flight.
They also, as it turns out, had to meet a
few less-glamorous criteria concerning
their physical attributes. They could not
weigh, it was decided, a single ounce
over 180 lb, and they could not stand
any taller than 5ft 11in. Exceeding these
requirements (or being more than 40
years of age) would immediately
disqualify any applicant.
The astronauts’ space suits, high-g
seats, the location of controls, and
everything from there on out to the
walls of the capsule and size of the
rocket had to reflect the upper limits of
astronaut size and weight. As it turned
out, the Mercury Seven did have the
right stuff and were, on average, of
generally modest height and weight –
well under, in fact, NASA’s strict limits.
Unlike NASA in days gone by,
modern warehouse managers and lift-
truck OEMs do not have the luxury of
excluding job applicants or operators
who are above average height or weight.
By today’s standards, at least in the USA,
nearly 50% of adult men and 15% of
adult women would be excluded by the
so-called ‘design population’ used by
NASA in 1959. A more practical
approach, especially when dealing with
the population at large, is to design
equipment that accommodates as many
potential users as possible, from a
ergonomics
40 iVT International September 2007 iVT International September 2007 41
AllspaceimagescourtesyofNASA

2. diminutive fifth-percentile female to a
burly 95th-percentile male.
But just like NASA, warehouse
managers and lift-truck OEMs must deal
with the trickle-down consequences of
accommodating the full – or nearly full –
range of operators, especially those at
the high end of the scale. Accommodating
the largest users can lead to larger
vehicles, and larger vehicles can require
larger aisles and, ultimately, the need for
more space to warehouse product. Just
as reducing the weight of the payload
leads to a reduction in the size of the
rocket needed to put it into space,
reducing the footprint of a materials
handling machine can eliminate the
need for wide aisles and free up space
that can be used for storage.
This brings us to the fundamental
question posed by this article: with the
ongoing trend towards higher
warehousing densities, narrow aisles,
and vehicles that can
operate in these aisles,
how is it possible to
accommodate the full
range of users rather
than – as NASA did
with the Mercury
Astronauts – establish
strict operator size
and weight limits?
How does one handle
this trade-off between
the cost-driven need
for dense warehousing
and the physical
needs of operators?
iVT International September 2007 43
The following examples show how
one vehicle OEM has used highly
innovative and downright clever design
to address the question of space in some
of its key products. This company has
developed materials handling trucks for
use in narrow aisles, very narrow aisles,
and, for lack of an existing phrase,
super-narrow aisles – all while
accommodating all but the most extreme
examples of human physical variation.
WA vs NA vs VNA
Most standard lift-trucks require an aisle
of 11-12ft in which to operate, hence
the term Wide Aisle, or WA. Eleven feet
(3.35m) provides just enough room for
a forklift of traditional design to engage
pallets head-on in racks, back up,
and turn around. Narrow-Aisle (NA)
trucks are designed to operate in aisles
of 8-10ft, where packing density is
increased at the expense of narrower
aisles. With typical 40x48in loads, the
Narrow-Aisle system increases packing
density by 20-25% over a Wide-Aisle
system. Narrow-Aisle layouts require a
Narrow-Aisle truck, however, with a
smaller footprint and turning radius.
Side-stance or stand-up trucks are
typical Narrow-Aisle machines.
VNA, or Very Narrow-Aisle, systems
employ aisles of 6ft or less and result
in space savings and warehousing
densities that are 40-50% greater than
traditional Wide-Aisle systems. Like
Narrow-Aisle systems, Very Narrow-Aisle
systems require their own special class
of truck. Examples of VNA trucks
include man-up turret trucks with
rotating forks and counterbalanced
trucks with swinging masts.
Stand, lean and sit
Our first example of clever engineering
to address the question of space in
narrow-aisle applications is the Crown
RR 5200S electric reach truck. As the
originators of the side-stance, stand-up
narrow-aisle truck, Crown evolved its RR
line a few years back by figuring out a
way to let an operator sit down as well
as stand, all while maintaining the small
footprint and turning radius of a
narrow-aisle forklift. Furthermore, the
design maintained an exceptionally low
step height and accommodated the full
range of the ‘design population’, not
just those who weighed less than 180 lb
or stood less than 5ft 11in tall.
The key insight was the realisation by
Crown designers that the large, vertical
motor and drive unit (mounted vertically
in the space above the left wheel and
below the tiller) could be split into two
parts, but remain connected with a
driveshaft. A footwell could then be
incorporated into the space on either
side of the driveshaft, with the motor
above and the drive unit below, giving
enough room to accommodate the full
range of seated operators. With the
addition of a height-adjustable seat and
foldaway seat pan, the operator could
stand, lean or sit – and experience the
benefits of variable postures throughout
a long work day.
The seemingly impossible objective
of creating a seated workspace in a
side-stance narrow-aisle truck was
made possible by a combination of
astute design work and understanding
the operator’s desire to change his or
her posture.
ergonomics
clockwise from above: Mercury Astronauts;
why every inch and pound saved was
crucial; a similar – yet less cramped –
position in Crown’s reach trucks, where
operators can stand or sit

3. ergonomics
A pivotal solution
It is ironic that perhaps the most
spacious work platform of any materials
handling truck can be found on a VNA
forklift – the Crown TSP 6000 – thereby
invalidating the notion that top-tier
ergonomics must be sacrificed in a
narrow truck. Once again, clever
packaging is at the heart of the design.
The MoveControl seat on this ‘man-up’
truck not only folds up or down to let
the operator sit or stand, but also rotates
-20, 0, 60, and 90° so that the operator
can better see in the direction of
travel or towards the forks and
load. Mechanical and infrared light
sensors on pedals and hand controls
(respectively) help keep the feet and
hands inside the machine during
movement within tight aisles – an
important consideration in this truck’s
typical operating environment.
An additional innovation developed
in response to the tight working
conditions of narrow aisles is the Auto-
Pivot feature. Imagine that you are at a
high level within a VNA warehouse and
you have just extracted a pallet from the
rack on the right side of the aisle. Your
objective is to transport
that pallet to the far end
of the aisle and place it on
the ground to the left of
the aisle. The fastest way
to do this is to move the
truck forward down the
aisle, lower the work platform,
lower the loaded forks, and
rotate the pallet 180°, while
simultaneously traversing
the secondary mast so that
the rotating pallet stays
within the confines of
the narrow aisle. This
At the same time, the Wave was
designed to accommodate the broadest
possible slice of the potential user
population. With a maximum operator
compartment capacity of 300 lb, the
vehicle can easily accommodate in
excess of 98% of North American male
and female adults, and its surprisingly
spacious work platform provides plenty
of room for even the largest users.
In our quest to find out whether it is
possible to provide top-tier ergonomics
and adequate space for the full range of
lift-truck operators in narrow-aisle, very
narrow-aisle, and super-narrow-aisle
warehousing applications where space
limitations create considerable design
challenges, we have, in fact, answered
two questions rather than just one.
First, we have learned that it is
indeed possible to give the operator all
of the space that might be necessary
despite the tight constraints imposed by
high-density warehousing. And second,
we have also learned that – at least in
the warehouse space environment – it
is not necessary to turn away 6ft, 200 lb
potential operators. iVT
complex operation is surprisingly simple
on the TSP 6000. All the operator has to
do is activate auto guidance, push the
right-hand control forward and down,
and, with the left hand, activate the
Auto-Pivot feature that automatically
co-ordinates the 180° rotation of the
pallet and the shifting of the secondary
mast across the face of the truck so the
pallet and load stay within the aisle.
Selective automation of key task
elements unburden the operator and
make work in this tight environment
quick and easy.
Give us a Wave
Although it does not have to be used in
a warehousing facility with super-
narrow aisles, the Crown Wave Work
Assist Vehicle is ideally suited for this
purpose and has gained wide acceptance
within small parts-picking applications
in many industries. The Wave can turn
within its own radius and elevate its
operator to a working height of 17ft.
With a rail-guidance system installed, its
total width is only 35in, making it
ideally suited for high-density
warehousing of unpalletised parts or
boxes. Hand- and foot-present sensors
are designed to keep the operator inside
the confines of the vehicle and away
from racks when working in tight aisles.
above: No space to spare for Gus Grissom
far right: Crown’s TSP 6000 VNA truck provides
one of the most spacious work platforms
below: A footwell on either side of the drive-
shaft in Crown’s reach trucks frees up space
44 iVT International September 2007
The Wave can accommodate over 98% of
potential North American users