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ELATECH
®
M
and V
Being FU the resulting force on the slide, the positioning deviation
generated by belt elongation is:
The positioning accuracy is also depending on other parameters
and therefore for an accurate calculation, please consult our
technical department.
FWsta = 2 • FTV
The shaft load under dynamic conditions is:
FWdyn = 2 • FTV + FU
Calculate shaft load
Installation tension generates a belt elongation “ Δl” between
the shafts (for linear drives) or the clamping plates (for
"Omega" drives).
Linear drive
“Omega” drive
If the resulting elongation is not acceptable for the application, it
is possible to reduce it by increasing the belt width.
Calculate necessary static elongation
The shaft load under static conditions is:
In order to pretension a drive is possible to use one of the follo-
wing methods:
1) Measuring elongation
ELATECH® timing belts with steel cords have a constant elonga-
tion to the maximum allowable load FTzul. Therefore the correct
pretension can be set by measuring the belt elongation with a
gauge and using as a reference the graph load/elongation of the
selected belt type. This is a simple method but requires a good
accessibility of the drive.
2) Using span deflection
The pretension is checked by applying a force in the centre of
the span length and measuring the span deflection
3) Measuring frequency
The tension of the belt is calculated from the natural frequency
of vibration of the belt span which is measured by means of a
special belt tension meter. This is the most accurate and easiest
method.
A suitable belt tension meter is availabile from ELATECH®
Installation and drive pretensioning:
Determine the positioning accuracy
The stiffness coefficient of linear drives depends on the lenght of
slack and tight side in the drive. Every position of the system has
its own stiffness coefficient calculated with the formula:
For C spez value see technical data of selected belt type.
Stiffness coefficient will be minimum when slack and tight side
will have the same length during the working cycle.
With L R equal to the belt length free to elongate (excluding con-
tact length on timing pulleys).
spez
R TV
C2
L F
l ⋅
⋅
=Δ
spez
R TV
C
L F
l ⋅
=Δ
2 1 R spez
2 1
R L L L C
LL
L
C + = ⋅
⋅ =
R
spez
min L
C4
C ⋅
=
C
FU
S =Δ