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, PE
EASA Senior Technical Support Specialist

Lubrication is needed to reduce friction between the rolling elements and stationary parts of a bearing. By reducing bearing friction, lubricants also help prevent undue temperature rise and dissipate some of the heat that is generated. This article describes some of the key characteristics and properties of lubricating greases and oils.

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.

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.

This video shows the proper way to lubricate the deep-groove, open ball bearing before assembling a horizontal induction motor. With horizontal induction motors, we normally do this step after we've installed the bearings on the shaft, and just before we install the end brackets.

Some of what is covered includes:

•  Steps for lubricating the shaft-mounted open bearing and
•  How to lubricate the bearing housing as the last step before we put the end bracket on

Note that in this video we're lubricating an open ball bearing. But the procedure for roller bearings or grease-lubricated thrust bearings is going to be essentially the same.

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

Jim Bryan (deceased)
Technical Support Specialist
Electrical Apparatus Service Association
St. Louis, MO

In his presentation at the EASA 2011 Convention, Jim Bryan provides a comprehensive overview of motor lubrication, focusing on the types of bearings, lubrication methods, and best practices to ensure optimal motor performance and longevity. Bryan begins by categorizing bearings into two main types: rolling element bearings and hydrodynamic bearings. Rolling element bearings, which include ball and roller bearings, are characterized by rolling elements that separate the stationary part from the rotating part. Hydrodynamic bearings, such as sleeve and plate bearings, rely on an oil wedge to separate the stationary and rotating parts.

Bryan highlights the advantages and disadvantages of each bearing type. Rolling element bearings are less expensive, easier to assemble, and can handle both axial and radial loads. However, they require more frequent lubrication and are less tolerant of misalignment. Hydrodynamic bearings, on the other hand, offer greater reliability and can be inspected and replaced without removing the motor. They also provide better damping characteristics and can operate at higher speeds, but they are more expensive and require precise maintenance.

The paper delves into the specifics of grease and oil lubrication. Grease lubrication is preferred for its ease of maintenance and ability to prevent contamination, making it suitable for industries like food, textile, and chemicals. Oil lubrication, while more complex, allows for complete replenishment and better cooling of highly-loaded bearings. Bryan provides detailed guidelines for grease lubrication, including recommended quantities and intervals based on bearing size and motor speed. He emphasizes the importance of not over-greasing, as this can lead to elevated temperatures and potential failures.

Bryan also addresses the compatibility of different greases, noting that mixing incompatible greases can result in rapid lubricant failure. He provides a compatibility chart and recommends flushing old grease or consulting manufacturers to ensure compatibility. The paper includes practical tips for maintaining proper lubrication, such as turning the shaft periodically during storage and using space heaters to prevent condensation.

For oil lubrication, Bryan explains the importance of maintaining the correct oil level and selecting the appropriate viscosity based on operating conditions. He discusses the challenges of maintaining oil levels in vertical motors and the need for regular oil changes to prevent contamination and degradation. Bryan also highlights the importance of monitoring bearing temperatures and setting appropriate alarm and shutdown limits to prevent damage.

In summary, Jim Bryan's paper offers valuable insights into motor lubrication practices, emphasizing the importance of proper lubrication to prevent bearing failures and ensure motor reliability. His detailed guidelines and practical tips provide a comprehensive resource for service centers and maintenance professionals.

Key Points Covered:

• Types of bearings: rolling element and hydrodynamic
• Advantages and disadvantages of each bearing type
• Grease and oil lubrication methods
• Guidelines for grease lubrication quantities and intervals
• Importance of grease compatibility
• Tips for maintaining proper lubrication
• Oil lubrication practices and challenges
• Monitoring bearing temperatures and setting limits

Key Takeaways:

• Proper lubrication is essential for preventing bearing failures
• Different bearing types have specific advantages and maintenance requirements
• Grease lubrication is easier to maintain but requires careful quantity control
• Oil lubrication allows for complete replenishment and better cooling
• Ensuring grease compatibility is crucial to prevent lubricant failure
• Regular maintenance and monitoring are key to motor reliability
• Maintaining correct oil levels and viscosity is critical for optimal performance
• Monitoring and managing bearing temperatures can prevent damage and extend motor life

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

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

For most service centers the traditional repair services such as electric motor rewinding have been and will continue to be in a state of decline over time. Among the factors leading to this reduction in business are conversions to more efficient motors, improved maintenance of existing motors, incentives to replace with more efficient motors and in some regions a reduction in the industrial customer base. A consequence of this is that there is more competition for a “shrinking pie”. Service center reaction can be to make a comparable reduction in size or become pro-active and seek new business. The objective of this paper is to suggest and detail some of these alternatives, namely value-added repair and service opportunities for service centers that carry with them the added benefit of contributing to optimizing motor reliability.

The opportunities for value-added repairs and services are ever-increasing. Topics covered here are:

• Bearing isolators, increased winding wire area, ball-to-roller/roller-to-ball bearing conversions
• Preventive and predictive maintenance (PM & PdM) services: vibration analysis, condition monitoring, bearing lubrication, electrical testing (IR, amps, volts, kW)
• Motor management
• New premium efficient motors vs. repair and retrofitting of existing motors

Jim Bryan (deceased)
Technical Support Specialist
Electrical Apparatus Service Association, Inc.
St. Louis, MO

The paper "Vertical Motors" by Jim Bryan, presented at the EASA Convention 2011, provides an in-depth analysis of the construction, classification, and application of vertical motors, emphasizing their unique bearing configurations and the importance of proper maintenance for optimal performance. Vertical motors are distinguished from horizontal motors primarily by their thrust bearings, which are designed to handle axial loads. These motors are typically used to drive pumps and are mounted without feet, unlike horizontal motors which may have various mounting configurations. The thrust bearing, usually located at the top of the motor, can be an angular contact bearing, a spherical roller bearing, or a hydrodynamic bearing, depending on the thrust load requirements.

The paper categorizes vertical motors into solid-shaft and hollow-shaft types. Solid-shaft motors couple to the pump at the lower end and are common in shallow pumps and tanks, while hollow-shaft motors, which allow the pump headshaft to pass through the motor shaft, are used in deep well pumps. The thrust bearings in vertical motors can handle different levels of thrust: normal, in-line, and high thrust, with high thrust being a multiple of normal thrust. Angular contact ball bearings are the most common, with configurations ranging from single bearings for normal thrust to multiple stacked bearings for higher thrust levels. Spherical roller bearings and hydrodynamic bearings are used for even higher thrust loads.

The guide bearing, located opposite the thrust bearing, stabilizes the shaft and handles momentary upthrust. Proper lubrication is crucial for the longevity of these bearings, with oil being preferred over grease for larger bearings. The paper also discusses the importance of setting the correct end play in the thrust bearings to prevent damage and ensure efficient operation. Special cases, such as motors with high momentary upthrust, require specific bearing arrangements to handle the additional load.

The paper concludes with practical advice on the assembly and maintenance of vertical motors, emphasizing the need for proper lubrication, correct end play settings, and regular inspection to prevent common issues such as overheating and bearing failure. The use of synthetic oils is recommended for higher temperature operations, and the importance of not mixing different oils is highlighted to avoid compatibility issues.

Key Points Covered:

• Differences between vertical and horizontal motors
• Types of vertical motors: solid-shaft and hollow-shaft
• Thrust bearing configurations and their applications
• Importance of guide bearings and their role
• Lubrication requirements for vertical motors
• Setting end play in thrust bearings
• Special thrust cases and bearing arrangements
• Practical assembly and maintenance tips

Key Takeaways:

• Vertical motors are specialized for handling axial loads with specific bearing configurations.
• Proper lubrication and maintenance are critical for the performance and longevity of vertical motors.
• Different types of thrust bearings are used based on the thrust load requirements.
• Setting the correct end play in thrust bearings is essential to prevent damage.
• Regular inspection and adherence to manufacturer guidelines can prevent common issues and ensure efficient operation.