Page 32 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Rotating Machinery: Practical Solutions

Examples of analyzing vibration readings are presented in
the chapters on unbalance and misalignment.
It is the primary intent of this book to allow technicians to
perform simple field corrections and inspections to correct the
majority of problems encountered. By feeling a vibrating part
rotating at 1,750 rpm, using a screwdriver, the difference between
1 × rpm and several times rpm vibrations can easily be deter-
mined.
The 1 × rpm is felt as a vibration, where the higher frequen-
cies feel like a tingling sensation. By placing the screwdriver on
different parts and in different directions, the shape and direction
of vibration can be determined.
Most often, a machine or a component will exhibit vibration
in several directions and may be vibrating at several different fre-
quencies simultaneously. It is important to understand the charac-
teristics of these vibrations in order to identify the root cause.
Various problems will exhibit different characteristics that will aid
in evaluating the cause. These characteristics are discussed in the
following chapters.
These simple techniques will be used to determine the cause
and possible corrective actions required. There is no substitute for
experience, and the more machines felt, the more confident the
technician.
In Chapter 2, additional equations are presented to determine
the forces caused by vibrating machine members.