Operating instructions

Principles of Rotary Encoders
12
Pepperl+Fuchs Inc. • 1600 Enterprise Parkway • Twinsburg, Ohio 44087-2245 • www.am.pepperl-fuchs.com
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PEPPERL+FUCHS
Shaft Load
Pepperl+Fuchs encoder shafts are mounted using two ball
bearings. The encoder’s service life is directly dependent upon
the bearing’s structural integrity, which is, in turn, dependent
upon five main components:
• Speed
• Temperature
• Axial load
• Radial load
• Load location (on the shaft)
Pepperl+Fuchs specifies maximum encoder shaft loading
and bearing service life based upon “worst case” permissible
conditions (i.e. maximum speed, temperature and shaft forces,
where the load is centered/applied on the shaft end).
With proper encoder mounting and selection of shaft
couplings, P+F encoders will provide a service life beyond the
stated value. Conversely, if mechanical loading is increased
beyond the catalog-specified limits, an encoder’s working life
will be reduced.
Example: At 6,000 rpm, with axial and radial shaft loads of 40
lbs, the RVI25’s specified service life is 2 x 10
8
revolutions. If
the axial and radial shaft loads are reduced to 13 lbs and 9 lbs
respectively, the guaranteed service life increases to 2 x 10
10
revolutions.
Mounting Instructions
Mounting Encoders
Mounting a solid shaft encoder using an L-bracket
Mounting a solid shaft encoder using an eccentric clamp
Mounting a solid shaft encoder with a mounting bracket
Use of Couplings
To prevent excessive loads on the encoder bearings, the
encoder and drive shaft must be linked with a flexible
coupling. Without a flexible coupling, slight misalignment
of the encoder and drive shaft or changes in alignment due
to temperature fluctuation can generate excessive axial or
radial forces. In a rigidly mounted system, this can destroy
the encoder. However, a coupling with high torsional rigidity
will reduce the torsional error between the encoder and drive
shaft.
For data on maximum radial, axial or angular misalignment,
please refer to the encoder data sheets.
L-bracket 9203
RVI58 with clamping flange
Synchro clamping element 9302-3
RVI50
Synchro clamping element
from mounting set 9311
Spring disk coupling 9404
RVI58 with
servo flange
Mounting bracket 9300
A
xial misalignment ∆a
∆a
Radial misalignment ∆r
∆r
A
ngular misalignment ∆α
∆α