SPM leonova emerald, User Manual

Page: 90 / 170

D
D:4
Shock pulse measurement
Rules for SPM measuring points
The rules for the selection of SPM measuring points have a
very practical purpose.
We are trying to catch low energy signals which are getting
weaker the farther they travel and the more they are bounced
about inside a piece of metal.
We know that they lose strength when they cross over from
one piece of metal to another (oil between the pieces reduces
signal losses).
We cannot know, for all bearing applications, how much of the
strength of the bearing signal will reach the measuring point.
However, by necessity we try to apply general evaluation rules, i.
e. treat all measured signals as if they were of the same quality.
The rules for SPM measuring points try to assure that most
signals are comparable, with sufficient accuracy, and that the
green-yellow-red condition zones are valid.
1 The signal path between bearing and measuring point
shall be as short and straight as possible.
2 The signal path must contain only one mechanical interface,
that between bearing and bearing housing.
3 The measuring point shall be located in the load zone of
the bearing.
3 – In the load zone of the bearing
Measuring
point
Load
1 – Straight and short path
2 – No interface!