depends on the length (number of axles)
of the configuration because the holes in
the plate correspond to a certain steering
angle. This steering information is shown
in a steering diagram that is provided by
the equipment manufacturer.
As a side note it should be mentioned
that a mechanically steered transporter
does not always have to be a pull type
transporter. Self-propelled transporters
with mechanical steering are also common
in the industry. The difference is that the
prime mover is replaced by a power pack
and a certain number of axles have to be
equipped with hydraulic drive motors.
Electronic steering is only available
Naming of parts: the knee-type joint (A),
hydraulic cylinder (B) and turntable (C) elements
of a pendular axle
on self propelled transporters. Instead
of plates and rods, each axle has its own
device to rotate it on the turntable. This
can either be a set of hydraulic cylinders
or a set of worm drive gears. There is no
mechanical connection between the axles.
Each axle receives its signal from the
operator’s control box, via the power pack’s
central processing unit (CPU) computer.
This CPU ensures that each axle receives
the correct signal as to how much the
turntable is to rotate.
Steering difference
As mentioned above, rods do not
interconnect the electronically steered
axles. This means that each axle can rotate
(steer) independently from any other axle,
as it is not mechanically bound. This is
the most important difference between
electronically and mechanically steered
axles. Electronically steered axles can be
steered in any angle whereas mechanically
steered axles are limited in steering angle.
The above limitation means that
mechanically steered transporters are less
manoeuvrable than electronically steered
transporters. Certain transport executions
may call for a steering combination that
mechanically steered transporters can
simply not achieve.
An example of such an execution is
a sideways move. Sideways means that
each axle is turned 90 degrees from the
longitudinal transporter axis. Obviously
this is a manoeuvre that mechanically
steered transporters cannot make.
At best a mechanically steered
transporter can crab steer or diagonally
steer and simulate a sideways motion by
moving forwards and backwards while
alternating the steering angles in a series of
direction changes.
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NOTE:
Every effort is made to ensure the
accuracy of the contents of these articles. If
you find any mistakes, a brief notification and
explanation would be appreciated.
The connecting rods of a mechanical steering
system seen through the openings in the deck
INTERNATIONAL AND SPECIALIZED TRANSPORT
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AUGUST 2013
37
THE KNOWLEDGE
