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Information on Conveyor Technology 13
Drive Location
The head drive is located on the discharge end of the
conveyor and pulls the transport medium, e.g. the belt.
This is the most common, safest and most affordable
drive position. If you have location restrictions, you
can also install a head drive on the infeed end for use
as a rear drive (pushing). In this case, however, you
must provide adequate pre-tension and prevent the
transport medium from getting kinked.
Lower belt drives, which are also called centre drives,
can be installed in various locations below the transport
level. They enable limited, non-continuous reverse
operation (reversible conveying direction), because
the transport medium is constantly pulled, preventing
problems that arise when the belt is pushed. You can
achieve fixed installation lengths by selecting the design
with a tensioning roller in the centre drive. Since
two snub rollers are typically used, this drive is also
known as an omega drive. A further benefit of this
drive is the option to install knife edges on both the
infeed and discharge ends for transferring small
products.
Internal drives with a drum motor produce few obstructing
edges, making them particularly popular for
applications with limited installation space. They are
also popular in clean environments, since they feature
low particle emissions and have few surfaces on
which dirt can deposit.
Drive Type
In the most commonly used indirect drives, force is
transferred using a chain or timing belt. This additional
option to adjust the transmission ratio allows
you to achieve very fine speed increments and compensate
for alignment errors. With servo and stepper
motors, a timing belt can be used to dampen the
abrupt, jerky starting behaviour.
With a direct drive, the motor is connected directly to
the drive shaft, offering a compact and low-maintenance
alternative.
Motor Selection
Our standard product range also includes a variety
of different stock equipment motors from well-known
manufacturers. These gearmotors, consisting of
asynchronous AC motors as standard or DC motors,
combined with a Spiroplan, helical-worm or helical
gearbox, meet efficiency class 2 and IP 54. Custom
motors, servomotors, UL-CSA approval and multi-
range motors are also available as options.
From July 2021, a new EU ecological design requirement
for electric motors will come into force that will
result in a change to the dimensions of our standard
motors. The motors will generally become slightly
larger; the energy efficiency class is increased to IE 3
for this purpose.
Speeds
The maximum conveying speed depends on the
motor selected, the load on the belt, the duty type
and other influencing factors. The speeds provided
here are nominal values and may deviate due to the
speed tolerances of the motors (up to ± 10%). For
indirect drives using chains or timing belts, the tolerance
tends to be even higher, at up to 20% above
the nominal speed. Higher speeds are also achieved
when the system is operated on a 60 Hz grid, for
example in the USA. If you need a precisely defined
speed, this can be accomplished with a frequency
inverter or reglomat.
Adjustment Ranges
The frequency inverter allows you to control the
conveyor speed within a range of 1:7 (10-70 Hz),
assuming an alternating current and the nominal
speed at 50 Hz. For internal drives (drum motors),
the adjustment range is 1:3 (20-60 Hz). For direct
current with the reglomat, the range is 1:6 (0.25-
1.5 A or 0.5-3 A). See page 314.