Donald E. Bently

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Donald E. Bently (October 18, 1924 - October 1, 2012[1]) was an American entrepreneur and engineer, best known as the founder and former owner of Bently Nevada Corporation where he performed pioneering work in the field of instrumentation for measuring the mechanical condition of rotating machinery. He founded Bently Nevada in October, 1961, and served as its CEO until February, 2002, when he sold the company to GE Energy. GE continues to design, manufacture, and market the products and services under the Bently Nevada name.

Donald E. Bently
Born Donald E. Bently
(1924-10-18)October 18, 1924
Muscatine, Iowa
Died October 1, 2012(2012-10-01) (aged 87)
Carson Valley, Nevada
Occupation Engineer

Following the sale of the company, Bently has subsequently remained active in his other family-owned businesses representing a diverse range of interests including rotordynamics, agriculture, biofuels, real estate, externally pressurized fluid bearings, and machinery diagnostics.

Education and military service[edit]

Born in Muscatine, Iowa, Bently served in the armed forces during World War II[2] as a member of the Seabees. He attended the University of Iowa, receiving a Bachelor of Science degree in Electrical Engineering in 1949, followed by a master's degree in Electrical Engineering in 1950.[3] He later did graduate-level coursework at UC Berkeley[4] while working for an aerospace company, and it was during this time that he became exposed to the eddy-current sensing technology that would later give birth to Bently Nevada Corporation.

Bently Nevada history[edit]

During Bently's brief employment in the aerospace industry in the mid-1950s, he assisted with research into the use of electronic sensing technologies for aircraft control systems. At the time, his employer concluded that there was limited use for the eddy-current technology in aircraft controls. Bently, however, felt the technology showed commercial promise elsewhere and received permission to use it in his own endeavors. In 1956, he left to form Bently Scientific Company, manufacturing and selling eddy-current products via mail order from his garage in Berkeley, California.[5] In 1961, Bently relocated the company to Minden, Nevada, and renamed it Bently Nevada Corporation.[6] The business's headquarters and primary operations remain there to this day.

Bently's primary application of eddy-current technology was for non-contacting displacement sensors. Often thought of as a type of electronic dial indicator, such sensors are typically used to measure very small distances between the tip of the sensor and a conductive surface, such as rotating shaft. The displacements measured are extremely small, typically on the order of several thousandths of an inch.

Initially, Bently's sensors were sold mainly for laboratory rather than industrial measurements. However, beginning in the early 1960s, users began to experiment with eddy-current sensors for measuring vibration on turbines, compressors, pumps, electric motors, and other turbomachinery. This application proved to be extremely successful, allowing machinery operators a practical method of observing actual shaft vibratory motion for the first time. Soon thereafter, Bently augmented his sensors with monitoring instrumentation that accepted his sensors as inputs and provided simple visual indication of the amount of vibration. Users could set alarm levels for annunication and machine shutdown purposes when vibration levels became excessive. From that time forward, Bently began to focus his company's efforts almost exclusively on instrumentation for rotating machinery condition measurements.

This specialized focus resulted in substantial growth of the business. By the time he sold Bently Nevada to GE Energy in 2002, the company had 1800 employees worldwide, operated in more than 40 countries, and had global sales exceeding $250 million USD.


In 1981, Bently established a pure research organization called Bently Rotordynamics Research Corporation (BRDRC or "Birdrock"). BRDRC's objective was to conduct rotordynamic research, furthering the knowledge of rotating machinery behavior, modeling techniques, and malfunction diagnostic methodologies. Its mission was considered complementary to Bently Nevada, with BRDRC focused on understanding how machinery behaved, and Bently Nevada focused on understanding and building instrumentation to measure machinery behavior.

BRDRC made a number of important contributions to the field of rotordynamics such as a better understanding of fluid-induced instabilities, advanced models for understanding shaft crack behavior, insight into rubbing malfunctions between stationary and rotating parts, and enhancement of the rotordynamic equations via introduction of a new variable lambda (λ) which denoted the fluid circumferential average velocity ratio and more accurately modeled hydrodynamic effects. Bently was personally responsible for many of these developments, publishing his work under the auspices of BRDRC.

BRDRD also introduced several new data presentation formats, such as so-called "full" spectrum plots and "acceptance region" trend plots. Its research findings were published extensively in relevant technical journals, and the research that had practical commercial applications often found its way into the Bently Nevada product line.

In 2002, BRDRC was sold along with Bently Nevada to GE Energy.[7]


A significant amount of Bently's rotordynamic research efforts have pertained to the topic of stability. In 2001, he established a bi-annual event known as ISCORMA (International Symposium on Stability Control of Rotating Machinery). Bently has remained an active organizer and participant for all subsequent ISCORMA conferences.[8]

Work with NASA[edit]

His expertise also led to work for NASA. He spent 2½ years studying the area where the oxygen and hydrogen fuel pumps connect to the main engines on the space shuttle following the January 1986 challenger disaster.[9]


Bently has authored more than 140 papers and articles dealing rotordynamics and/or condition monitoring technologies.[10] Many are peer-reviewed and have been published in various technical journals such as those of the American Society of Mechanical Engineers (ASME). Bently has also co-authored one textbook, Fundamentals of Rotating Machinery Diagnostics which is being used as a textbook at major universities.[11]

Businesses Owned[edit]