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.
LOGIN TO DOWNLOAD THE CONVENTION PRESENTATION
EASA Technical Manual
More information on this topic can be found in EASA's Technical Manual- Section 2: AC Machines
- Section 8: Bearings
- Section 9: Lubrication
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