Parker OEM750, User Manual

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Installation • OEM750
42
Attaching the Load – Couplers
Align the motor shaft and load as accurately as possible. In
most applications, some misalignment is unavoidable, due to
variations in component tolerance. However, excessive mis-
alignment may degrade system performance. Three misalign-
ment conditions, which can exist in any combination, are:
• Angular Misalignment: The center lines of two shafts intersect at an angle other
than zero degrees.
• Parallel Misalignment: The offset of two mating shaft center lines, although the
center lines remain parallel to each other.
• End Float: A change in the relative distance between the ends of two shafts.
The type of misalignment in your system will affect your
choice of coupler.
Single-Flex Coupling
Use a single-flex coupling when you have angular misalign-
ment only. Because a single-flex coupling is like a hinge, one
and only one of the shafts must be free to move in the radial
direction without constraint.
Do not us a double-flex coupling
in this situation : it will allow too much freedom and the shaft
will rotate eccentrically, which will cause large vibrations and
catastrophic failure.
Do not use a single-flex coupling with a
parallel misalignment : this will bend the shafts, causing
excessive bearing loads and premature failure.
Double-Flex Coupling
Use a double-flex coupling whenever two shafts are joined
with parallel misalignment, or a combination of angular and
parallel misalignment (the most common situation).
Single-flex and double-flex couplings may or may not accept
end play, depending on their design.
Rigid Coupling
Rigid couplings are generally not recommended, because they
cannot compensate for
any misalignment. They should be
used only if the motor is on some form of floating mounts that
allow for alignment compensation. Rigid couplings can also be
used when the load is supported entirely by the motor’s
bearings. A small mirror connected to a motor shaft is an
example of such an application.