Belt displacement in horizontal curves.
Report 2003.TT.6779, Transport Technology.
This report provides the reader with an overview of currently used
calculation methods for belt conveyor track with horizontal curves. Next
it provides the description of a computer program formed to visualize belt
displacement in the idler set, in these curves. This program can also show
the forces acting on a side guide roll, should maximum belt displacement
The fundamental concept of a belt moving through a horizontal curve is
very simple. As an element of the belt passes through the curve it is
motivated to drift towards the center of the curve radius by unbalanced
tension forces in the belt. These unbalanced tension forces form what is
called the motivating force vector.
As the belt drifts laterally on the idlers, opposing forces induced by
gravity and friction create increasing resistance to drift. These
resisting forces form what has been termed the resisting force vector.
Since the motivating and resisting force vectors act in opposite directions,
when their magnitudes become equal the belt will cease to drift. The belt
has reached a condition of force equilibrium.
These calculations can be used to determine the belt drift, without physically
constraining the edges of the belt. These equations are based on steady
state conditions, so no dynamic behavior is involved.
If it were decided to constrain the belt at some limit of drift, the
constraining force required is the difference between the motivating force
and the resisting force at that limit.
The equations prescribing the equilibrium condition are used to form the
algorithms for the computer program. With Maple 7.0, they have been reshaped
to enable the program written in Visual Basic to calculate the displacement
concerning different input conditions. The main input is loaded via a data
file containing information on belt dynamics, and several parameters are to
be defined by the user. The program consists of several interfaces; the main
output is a graph showing the belt displacement in time.
A short look at the influence of the input parameters is given, followed
by a main recommendation that in order to validate the output data, tests
should be performed.
Reports on Transport Engineering (in Dutch)
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