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Correctly designed drive systems with Optibelt ZRM/ZRP/ZRL
timing belts will ensure a high level of reliability and optimum
service life.
It has been found in practice that unsatisfactory running time is
frequently attributable to installation errors and inadmissible envi-
ronmental conditions. As a precaution, we recommend observing
the following:
Operating hints
Timing belt drives are sensitive to the ingress of foreign matter. If
foreign material is getting into the drive then there must be a re-
examination and possibly a redesign of the drive guard.
The polyurethane timing belts of the Optibelt standard range are
suitable for operation in a temperature range of between –30 °C
and +80 °C with normal relative humidity. Furthermore, the
polyurethane timing belts are resistant to numerous corrosive
chemicals (ZRM/ZRP page 15 and ZRL page 42). In the case of
special ambient conditions, we recommend consulting our applica-
tions engineers.
Safety hints
Open and readily accessible drive systems should be guarded to
obviate any risk of injury.
Before commencing installation, the prime mover should be stop-
ped and secured against any possibility of accidental start up e.g.
by disconnecting electric power at the mains. The driven machine
should be prevented from rotating.
Installation of the drive
Installation of the drive comprises fitting the pulleys and idlers,
fitting the timing belt, adjusting the tension and aligning all shafts
and pulleys.
Fitting the timing belt
Before fitting, the centre distance should be reduced to enable the
timing belt to be lifted over the flanges without the use of force. If
insufficient adjustment has not been provided (see recommenda-
tion page 43), the timing belt may be fitted together with one or
both of the pulleys. The use of force when fitting is NOT permissible
in any instance, as this will damage the belt, this damage is often
not apparent.
5 Design Hints, Dimensions and Tolerances
5.3 Operating, safety and maintenance hints, installation
Adjusting the tension
The tension should be calculated and adjusted in accordance with
the guidelines on page 28 (ZRM/ZRP) and page 40 (ZRL). By virtue
of the zero stretch tension cord, no further checking of the tension
will be necessary under normal operating conditions after correct
adjustment.
Alignment, misalignment and angular deviation
Correct alignment of the pulleys and shafts will ensure free running
between the flanges, friction-free tooth engagement and uniform
load distribution over the entire width of the tooth.
The following alignment errors can occur (see Figure 5.4) and
should be prevented:
Axial misalignment of the pulleys:
● Misalignment of the pulleys in axial direction is only permissible
within the excess width of the pulley faces compared to the belt
width. The belt must engage with the pulley across its whole
width.
Horizontal and vertical angular deviation of shaft axes:
● The horizontal angular deviation α from parallel should be
measured in the plane of the drive shafts.
● The vertical deviation β from parallel should be measured
perpendicular to the plane of the shafts.
Horizontal and vertical angular deviation should be less than the
maximum permissible value in Table 5.5.
Table 5.5: Angular deviation from parallel
If the values listed for angular deviation are exceeded, reduced
service life of the timing belts must be expected.
Even with correct alignment of the pulleys, the belt will drift
sideways slightly. This is caused in the case of endless ZRM/ZRP
timing belts by the helical lay of the tension cord and in the case
of the ZRL open-ended belting, by the twist of the tension cord.
≤ 50 0.50
> 50 ≤ 100 0.25
> 100 ≤ 200 0.12
> 200 0.06
Pulley outside
diameter
d
a
(mm)
Permissible angular
deviation
α, β
(°)
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