Basic Vibration Terminology - Suzuki XL7 2007 Service Manual

0A-19 General Information:

Basic Vibration Terminology

The following are the 2 primary components of vibration
diagnosis:
• The physical properties of objects
• The object's properties of conducting mechanical
energy
The repetitive up and down or back and forth movement
of a component cause most customer vibration
complaints. The following are the common components
that vibrate:
• The steering wheel
• The seat cushion
• The frame
• The IP
Vibration diagnosis involves the following simple outline:
1. Measure the repetitive motion and assign a value to
the measurement in cycles per second or cycles per
minute.
2. Relate the frequency back on terms of the rotational
speed of a component that is operating at the same
rate or speed.
3. Inspect and test the components for conditions that
cause vibration.
For example, performing the following steps will help
demonstrate the vibration theory:
1. Clamp a yardstick to the edge of a table, leaving
about 50 cm (20 in) hanging over the edge of the
table.
2. Pull down on the edge of the stick and release while
observing the movement of the stick.
The motion of the stick occurs in repetitive cycles. The
cycle begins at midpoint, continues through the lowest
extreme of travel, then back past the midpoint, through
the upper extreme of travel, and back to the midpoint
where the cycle begins again.
The cycle occurs over and over again at the same rate,
or frequency. In this case, about 10 cycles in one
second. If we measure the frequency to reflect the
number of complete cycles that the yardstick made in
one minute, the measure would be 10 cycles x 60
seconds = 600 cycles per minute (cpm).
We have also found a specific amount of motion, or
amplitude, in the total travel of the yardstick from the
very top to the very bottom. Redo the experiment as
follows:
1. Reclamp the yardstick to the edge of a table, leaving
about 25 cm (10 in) hanging over the edge of the
table.
2. Pull down on the edge of the stick and release while
observing the movement of the stick.
The stick vibrates at a much faster frequency: 30 cycles
per second (1,800 cycles per minute).