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Technical data are subject to change without notice.
ISO 9001 certified. © Copyright SPM 1996-9. 71416.B
SPM Instrument AB • Box 4 • S-645 21 Strängnäs • Sweden
Tel +46 152 22500 • Fax +46 152 15075 • info@spminstrument.se • www.spminstrument.se
Machine vibration is measured with a small piezo-
electric accelerometer. The transducer is normally at-
tached with a magnetic base to a bearing housing or
some other suitable measuring point.
The transducer can be pressed by hand against non-
magnetic material, or it can be fitted with a 100 mm
long probe tip. Permanent mounting is also possible.
A vibration transducer is sensitive only along its main
axis. This allows accurate readings of radial and axial
machine vibration in any direction. Vibration readings
taken in three directions (vertical and horizontal in the
radial plane, plus an axial reading) are used to trace
the underlying causes of excessive vibration, such as
out-of-balance, structural looseness, or axial play.
Tachometer Functions
Used for non-contact measurements, the tachometer
probe directs a light beam against a piece of reflect-
ing foil attached to the shaft, wheel, or belt. The
measuring circuit counts the reflected light pulses.
Measuring distance is up to 0.6 meter. The maximum
range for optical readings is 20 000 rpm.
A contact adapter can be placed over the lens. For
rpm measurement, it is fitted with rubber tipped con-
tact center which is held firmly against the center of a
shaft.
Peripheral speed is measured with a contact wheel,
held against a belt or against the rim of a wheel or a
shaft.
Depending on the type of contact wheel used, pe-
ripheral speed is displayed in units of 0.10 m/min., 0.1
yards/min., or 2 feet/min. The maximum range of the
display is 20 000 units.
Fig. 9
Fig. 10
Measurement of Machine Vibration
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