This webinar recording focuses on:

• Motor assembly issues
• Electrical and mechanical inspection
• Static and run testing
• AC motors with ball, roller and sleeve bearings

Target audience: This webinar recording is most useful for service center mechanics, supervisors and engineers. The content will also be beneficial for machinists, managers and owners.

Gene Vogel
EASA Pump & Vibration Specialist

When repairing centrifugal and axial flow pumps, axial thrust is a concern. An understanding of the causes and the mitigating provisions of various pump designs will help repair technicians to ensure those provisions work properly. Various impeller designs, end suction and vertical turbine pumps will be a primary focus. 

Primary topics are: 

• Factors affecting the amount of axial thrust developed by an impeller 
• Review of some common mitigation designs 
• What repair technicians need to look for on various pump designs 

The mechanical pump components can be repaired without understanding the hydraulics of how a pump works. But it’s easy to miss important features that can affect pump performance and reliability.  

This presentation will be helpful for pump repair technicians and supervisor and engineers associated with pump repair.

Tom Bishop, PE
Especialista Sénior de Soporte Técnico de EASA

La lubricación es requerida para reducir la fricción entre los elementos rodantes y las partes estáticas de los rodamientos. Al hacer esto, el lubricante también ayuda a prevenir incrementos de temperatura excesivos y a disipar parte del calor generado. En este artículo discutiremos algunas de las características y propiedades clave de los aceites y grasas lubricantes.

Tom Bishop, P.E.
EASA Senior Technical Support Specialist

This webinar recording reviews electric motor bearing grease and oil lubrication frequency and quantity, as well as procedures – and the steps to be sure to get all of this right. 

• Grease and oil lubrication frequency and quantities for ball and roller bearings
• Grease and oil lubrication procedures for ball and roller bearings
• Oil lubrication frequency and quantities for sleeve bearings
• Oil lubrication procedures for sleeve bearings

This recording is intended for mechanical technicians, field service technicians, shop supervisors and engineering staff.

Austin Bonnett
Austin Bonnett Engineering LLC

La finalidad de este artículo es proporcionar fundamentos suficientes sobre los rodamientos para que los responsables por la aplicación, operación, mantenimiento y reparación de los motores eléctricos puedan tomar las medidas necesarias para minimizar los fallos prematuros y mejorar la posibilidad de que de los rodamientos duren hasta el “final de la vida útil”, que normalmente se denomina L10.

Tom Bishop, P.E. 
EASA Technical Support Specialist
 
Much of what will be discussed in this article applies to all rolling bearings, both ball and roller. Our focus, though, will be on issues that relate mostly to ball bearings used in electric motors. The intent is to address some of the fundamentals of rolling bearing enclosures, internal clearances and fits. We deal with rolling bearings every day, but we don’t always consider some of these fundamentals until there is a bearing related problem. 

Note: Rolling bearings were previously referred to as antifriction bearings. The American Bearing Manufacturers Association (ABMA), formerly the Antifriction Bearing Manufacturers Association (AFBMA), now terms antifriction bearings as “rolling bearings.” 

En toda reparación mecánica, la capacidad para desmontar, reparar y volver a montar el motor de forma apropiada sin dañar innecesariamente ninguna de sus piezas es fundamental. Esto suena sencillo, sin embargo, durante el proceso de desarme se cometen demasiados errores costosos.

Si todos los motores entraran “como nuevos”, la tarea sería más simple, aunque esto no sería garantía de que el montaje del motor fuera adecuado.

Cuando un centro de servicio recibe un pago por reparar un equipo, quiere que este permanezca en funcionamiento, ya que, si el equipo falla dentro del período de garantía, deberá asumir el costo de volver a repararlo. Por lo que tiene sentido realizar la reparación correcta la primera vez.

Los procedimientos de reparación, así como los propios motores, son afectados por los cambios en la tecnología. Este libro intenta incluir las últimas tecnologías comprobadas. En muchos casos, los métodos de reparación tradicionales aún pueden ser la alternativa más práctica. Las opciones presentadas a lo largo de este libro están destinadas a ayudar a los técnicos a seleccionar el método de reparación correcto, reconociendo que la decisión final recae en el propietario del equipo.

Algunas veces los métodos de reparación pierden popularidad, no porque aparezcan métodos mejores sino debido a técnicas deficientes. Otros métodos de reparación son adecuados para algunas aplicaciones, pero no para otras. Es trabajo del reparador decidir cuál será el mejor método para cada caso.

Este libro se encuentra dividido en secciones para los componentes básicos del motor con métodos de reparación y consejos dispersos por todas partes. Donde resulte práctico, se discuten también las causas de fallo. Esto ayudará a los técnicos a seleccionar el método de reparación más apropiado para cada aplicación en particular. La información presentada se basa en publicaciones de EASA y en revistas técnicas y literatura suministrada por fabricantes de motores, proveedores y centros de servicio establecidos.

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Tabla de contenido

• Terminología del motor
• Aplicaciones del motor y encerramientos
• Procedimientos de inspección y prueba
• Consejos para desmontar motores
• Rodamientos
• Alojamientos de rodamientos, orificios de eje, sellos y ajustes
• Ejes
• Rotores
• Ensamble del motor
• Accesorios y cajas de conexiones del motor
• Dinámica del motor
• Vibración y geometría del motor
• Corrientes por el eje/rodamientos
• Consideraciones especiales para motores a prueba de explosión
• Fallos en las componentes mecánicas
• Reparaciones misceláneas

Esta obra contiene muchas sugerencias sobre el manejo apropiado de las diferentes partes de un motor para minimizar los daños durante el proceso de reparación. Sin embargo, es imposible desarrollar un listado que las incluya todas.

En cambio, el principio básico de tomarse el tiempo para usar la herramienta adecuada y por lo general el procedimiento apropiado guiará a los técnicos por el camino correcto.

Art Godfrey (retired)
Birclar Electric & Electronics

Mi primera experiencia con lubricantes sintéticos para rodamientos con elementos rodantes fue durante la reparación de dinamómetros para probar motores de automóviles de alta velocidad. Durante varios años nuestro centro de servicio había reparado máquinas similares con rodamientos con elementos rodantes, pero todas ellas estaban lubricadas con sistemas de bombeo de aceite con accesorios especiales cerca de los rodamientos para suministrar solo pequeñas cantidades de aceite por minuto.

Comenzamos a ver máquinas enviadas para reparación con rodamientos con elementos rodantes lubricadas con grasa y estas indicaban en la placa de datos una marca y tipo de lubricante específicos. Compramos lo que estaba especificado en la placa y todo salió bien. Con el tiempo, comenzamos a ver más máquinas que especificaban la misma marca de grasa, pero con un tipo o grado diferente y esto me condujo a comenzar a buscar las diferencias en los productos, ya que uno era muy costoso y tenía una vida útil limitada.

Chuck Yung
Especialista Sénior de Soporte Técnico EASA

Un aspecto de nuestra industria de reparación que parece causar mucha confusión es la disposición de los rodamientos de los motores verticales. Existe una gran variedad de disposiciones de rodamientos de empuje y tendemos a intentar aplicar el mismo método para ajustar el juego axial en todos ellos. Por lo general, esta es una mala idea, por lo que este artículo analizará más de cerca específicamente aquellos motores equipados con un rodamiento de empuje de rodillos esféricos y ofrecerá consejos de reparación exclusivos para estos diseños.

DESCRIPTION
This 94-page handbook (3.5" x 6", 9cm x 15cm) contains carefully selected materials designed to assist repair firms in their everyday work. Just as important, your customers and potential customers can use this pocket handbook as a handy reference for mechanical data for motors and driven equipment. Buy this great resource as is OR custom brand your company logo and information on the cover to turn it into a great marketing piece for your salespeople!

BUY COPIES OF THIS HANDBOOK

TABLE OF CONTENTS

Alignment
Alignment Information
Suggested Alignment Tolerances
ANSI/ASA Alignment Quality

Balancing And Vibration
Single-Plane Versus Two-Plane Balancing
Vibration Tests
Unfiltered Housing Vibration Limits
FFT Vibration Analysis
Vibration Constants
Vibration Conversion Factors
Electric Motor Vibration Diagnostic Chart

Motor Application Forumlas
Output
Shear Stress
Speed–AC Machinery 
Affinity Laws–Centrifugal Applications

Conversion Factors, Equivalencies & Formulas
Conversion Factors
Temperature Conversion Chart
Common Fractions Of An Inch–Decimal & Metric Equivalents
Prefixes–Metric System
Formulas For Circles

Bearings
Nominal Dimensions For Radial Ball Bearings
Nominal Dimensions For Cylindrical Roller Bearings
Radial Ball Bearing Fit Tolerances
Cylindrical Roller Bearing Fit Tolerances
Lock Nuts And Lock Washers For Ball Bearings

Motor Bearing Lubrication
Lubricating Oil Viscosity Conversions
NLGI Grease Compatibility Chart
Grease Classifications
Grease Relubrication Intervals

Metals And Alloys
Properties Of Metals And Alloys
Weight Formulas For Steel
Thermal Linear Expansion

Bolts
ASTM And SAE Grade Markings For Steel Bolts And Screws
Precautions For Tightening Bolted Joints
Bolt Tightening Torque Values
Tap Drills And Clearance Drills For Machine Screws

Keys And Keyseats
NEMA Keyseat Dimensions–Foot-Mounted AC & DC Machines
IEC Shaft Extension, Key And Keyseat (Keyway) Dimensions
Square And Flat Stock Keys
Standard Keyseat Sizes
Metric Keys–Standard Sizes

Belts And Sheaves
Pulley Formulas For Calculating Diameters and Speeds
Belt Installation
Belt Tensioning
Belt Deflection Force And Elongation Ratio
Standard V-Belt Profiles And Dimensions
V-Belt Sheave Dimensions
V-Belt Sheave Dimensions For AC Motors With Rolling Bearings
Application Of V-Belt Sheave Dimensions To AC Motors With Rolling Bearings
Mounting Of Pulleys, Sheaves, Sprockets, And Gears On Motor Shafts
Minimum Pitch Diameter For Drives Other Than V-Belts

Welding, Brazing And Soldering
Recommended Copper Welding Cable Sizes
Types Of Weld Joints 
Brazing
Basic Joints For Brazing
Soldering
Melting Temperatures Of Tin-Lead-Antimony Alloys
Flux Requirements For Metals, Alloys And Coatings

Slings, Wire Rope, Shackles and eyebolts
Types Of Slings
Typical Sling Hitches
Wire Rope
Spreader Bars
Lifting Capacity
Forged Shackles
Eyebolt Strength

Common Signals For Crane

Austin Bonnett
Austin Bonnett Engineering LLC

The purpose of this article is to provide enough rolling element bearing fundamentals so those who are responsible for the application, operation, maintenance and repair of electric motors can take the necessary steps to minimize premature bearing failures and enhance the possibility of bearings lasting until the "end of life" predictions, which is normally referred to as L10 bearing life.

Kirk Kirkland
Electrical Repair Service Co. 
Birmingham, Alabama
Technical Education Committee Member

Editor's Note: This article is similar to a July 2006 Currents article titled "Tips for Test Running Motors With Roller Bearings." These two articles complement and supplement each other.

End users frequently demand that EASA service centers provide an array of test data at the conclusion of the service/repair process. These tests are normally to validate compliance with the customer’s motor repair specifications. It is also a good idea to have your own in-house specifications so you can prove that you’re compliant with EASA motor repair guidelines such as those found in the Recommended Practice for the Repair of Rotating Electrical Apparatus (ANSI/ EASA AR100-2006).

One of the more common tests involves running the motor no-load and providing the motor owner with electrical test information and vibration spectrums covering various frequency bands. No-load run tests are commonly applied to AC induction motors. In many cases, these motor types are designed for a belted-duty application. That means they may have a roller bearing in the drive end of the motor. The most common roller bearings utilized in belted applications are the two-piece NU type that consists of an inner race mounted on the bearing shaft journal and the rollers caged on the outer race.

This version of Principles of Medium & Large AC Motors manual is now available to address applicable IEC standards and practices. This 360-page manual was developed by industry experts in Europe along with EASA's engineering team. (The "original" version of this book based on NEMA standards remains available as a separate document.)

This manual includes drawings, photos and extensive text and documentation on AC motors, including how they work, information on enclosures, construction on components and applications. Many of the principles included apply to all AC motors, especially those with accessories that are associated with larger machines in the past (such as encoders, RTDs, thermostats, space heaters and vibration sensors).

While the manual covers horizontal and vertical squirrel-cage induction motors in the 37 to 3,700 kW (300 to 5,000 hp) range, low- and medium-voltage, most of the principles covered apply to other sizes as well. 

This valuable instructional/resource manual is available in printed and downloadable versions, and focuses primarily on IEC motors.

Sections in the manual include:
(Download the PDF below for the complete Tables of Contents)

• Motor nomenclature & definitions
• Motor enclosures
• Typical motor applications
• Safety & handling considerations
• Basic motor theory
• Motor standards
• Stators
• Squirrel cage rotors
• Shafts
• Bearings & lubrication
• Motor accessories & terminal boxes
• Test & inspection procedures
• Motor alignment, vibration & noise
• Storage procedures
• Synchronous machines

BUY A COPY FOR YOUR OFFICE

PRINTED BOOK DOWNLOADABLE PDF

This book is also available focusing on NEMA Standards — in both English and Español.

NEMA - English NEMA - Español

Chuck Yung
Especialista Sénior de Soporte Técnico de EASA

Existen ocasiones en las que una aplicación requiere que un motor soporte una carga radial para la que los cojinetes de deslizamiento no son adecuados. En casos como bajas revoluciones, carcasas inusuales, etc., puede ser conveniente convertir el motor del cliente montado sobre cojinetes de deslizamiento envés de obtener un motor de repuesto con rodamientos de bolas / rodillos. Este artículo contiene procedimientos sugeridos y advertencias sobre problemas potenciales relacionados con dichas conversiones.

Primero, inspeccione las tapas del motor para asegurarse de que tengan la rigidez mecánica suficiente para soportar la carga y suprimir la vibración (vea la Figura 1). Si las tapas carecen de rigidez, puede que sea necesario utilizar tapas nuevas fabricadas con un material más grueso. En otros casos, se puede utilizar un inserto para reforzar la tapa existente.

Chuck Yung
Especialista Sénior de Soporte Técnico de EASA

Muchos de sus clientes cuentan con buenos departamentos de mantenimiento predictivo propios y otros lo subcontratan con proveedores externos calificados. En ambos casos, ellos deben saber cuando un rodamiento presenta deterioro y sacar de servicio el motor antes que el fallo se vuelva desastroso. En términos de mantenimiento, esto ahorra mucho dinero, lo cual es excelente. Pero si el cliente se detiene ahí, sin descubrir por qué el rodamiento está mal, su motor puede regresar reparado de nuevo con el mismo problema. Los rodamientos defectuosos aportan una gran cantidad de evidencias, si solamente las buscamos.

La clave consiste en la comunicación con el cliente, dado que nosotros los reparadores, sabemos que el motor fue retirado del servicio debido a un fallo en los rodamientos, podemos ir un paso más adelante en el proceso de diagnóstico.

Especialmente debido al uso frecuente de los variadores de velocidad electrónicos (VFDs), las corrientes por los rodamientos causan un número considerable de fallos en los mismos. Si sabemos que el motor funciona con un variador de velocidad electrónico, existen medidas correctivas para prevenir fallos futuros del mismo tipo. Y esos pasos adicionales son facturación extra. Ignorar esos pasos de inspección adicionales, es como olvidar dinero encima de la mesa, tanto para el centro de servicios como para el cliente.

Chuck Yung
EASA Senior Technical Support Specialist

Many of your customers have good in-house predictive maintenance departments and others outsource that skill. Either way, they should know when a bearing is deteriorating and remove the motor from service before it turns into a catastrophic failure. That saves a lot of maintenance dollars, which is great. But if the customer stops there, without discovering why that bearing is bad, your repaired motor could be returned with the same problem again. Defective bearings often hold a great deal of evidence, if we only look for it. 

The key is communication with the customer so that we repairers know that the motor was removed for bearing faults, and so that we can go a step further in the diagnostic process. Especially with the prevalence of variable frequency drives (VFDs), bearing currents cause a significant number of bearing failures. If you know the motor is operating from a drive, there are corrective measures to prevent future failures of the same type. And those extra steps are billable extras. Neglecting these additional inspection steps is like leaving money on the table, for both the service center and the customer.

Chuck Yung
EASA Senior Technical Support Specialist

There are times when an application calls for a motor to carry a radial load for which sleeve bearings are not suitable. In cases such as low rpm, unusual frames, etc., it may be desirable to convert a customer's existing sleeve bearing motor rather than obtaining a ball/roller replacement motor. This article contains suggested procedures as well as cautions about potential problems with such conversions.  

First, inspect the end brackets to ensure they are mechanically rigid enough to support the load and suppress vibration (see Figure 1). If the end brackets lack rigidity, it may be  necessary to use complete fabricated replacements using thicker material. In other cases, gusseting can be used to stiffen the existing bracket.

Art Godfrey (retired)
Birclar Electric & Electronics

My first exposure to synthetic lubricants for rolling element bearings was during repair of high-speed, automotive engine-test dynamometers. For several years, our service center had repaired similar machines with rolling element bearings, but they were all oil lubricated by pump systems with specially-selected fittings near the bearings to deliver only small amounts of oil per minute.

We began to see rolling-element-bearing machines in for repair that were grease lubricated, and these displayed a specific make and type of lubricant on the nameplate. We purchased what was specified on the nameplate and all was well. Over time, we began to see more machines specifying the same make of grease, but a different grade or type. This led me to begin looking into the differences in the products, since each one was fairly costly and had a limited shelf life (for instance 24 months if in an unopened container).

Topics covered include:

• Details of the process
• Range of synthetic greases
• Things to carefully consider

Cyndi Nyberg
Former EASA Technical Support Specialist

Editor's Note: This article is similar to a February 2010 Currents article titled "Preloading roller bearing motors for no-load run testing." These two articles complement and supplement each other.

Ball and sleeve bearing motors can always be test run without any type of external load on the motor and bearings. 

However, when repairing a motor equipped with roller bearings that is used in an application with a radial load, such as a belted load, it is not advisable to perform the standard no-load test run for any length of time. Yet the no-load test run is a crucial step in the repair process to ensure proper operation. Without that radial load, the bearings can be damaged. This article will describe two ways to put a load on the shaft of a motor and therefore the roller bearing, so that it can be test run to ensure that it has been properly repaired. 

Chuck Yung
EASA Senior Technical Support Specialist

One aspect of our repair industry that seems to cause a lot of confusion is the bearing arrangements of vertical motors. There is quite an assortment of thrust bearing arrangements, and we tend to try to apply the same method for adjusting end play to all of them. That is often a bad idea, so this article will take a closer look specifically at those fitted with a spherical roller thrust bearing and repair tips unique to these designs.

Chuck Yung
EASA Senior Technical Support Specialist

Vertical motors differ from horizontal motors in numerous ways, yet some view them as “just a horizontal motor turned on end.” The obvious differences are the (usually) thrust bearings, with arrangements varying from single- to three-thrust bearings with different orientations suited for specific load, rpm and applications.

Less obvious differences are in the ventilation arrangements, shaft stiffness, degrees of protection and runout tolerances. This session will include:

• Bearing systems: Single, double or more?, Thrust direction, Angle of contact and rpm, Spherical thrust bearings, hydrodynamic
• Ventilation and cooling
• Operating environment, and enclosures: Enclosures (degrees of protection), ODP, TEFC, WPI, WPII (IP equivalents)
• Oil types and quantity: Bearing load and operating temperature, Consideration of speed, Sizing and adding cooling tubes
• Runout tolerances and repair methods: Upper bearing housing, Bearing carrier and shaft, Bottom bracket flange, Best practice methods for re-machining

This recording will benefit the service center owner, supervisor, technicians, sales personnel and customer.