Specifications

Chapter 1. Installation 25
Coupling the Motor
Align the motor shaft and load as accurately as possible. In most applications, some misalignment is
unavoidable, due to tolerance buildups in components. However, excessive misalignment may degrade your
system’s performance. The three misalignment conditions, which can exist in any combination, are illustrated
below. The type of misalignment in your system will affect your choice of coupler (described below).
Aligned
Parallel Misalignment
Combined Parallel & Angular Misalignment
End Float
Angular Misalignment
Single-Flex Coupling
Use a single-flex coupling when you have angular misalignment 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
use 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 or load 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.
Coupling Manufacturers
HUCO ROCOM CORP.
70 Mitchell Blvd, Suite 201 5957 Engineer Drive
San Rafael, CA 94903 Huntington Beach, CA 92649
[phone] [phone]