Technical Article Top Drives Responding to the Challenge of Deeper Wells

How to Increase Top Drive Bearing Life Jesse R. Yorty Principal Application Engineer Responding to the Challenge of Deeper Wells A primer on proper main thrust bearing selection, maintenance, and more Table of Contents Key Bearing Positions Top Drive and Swivel Design Differences 4 Main Thrust Bearings Machine Upgrades and Bearing Requirements Seal Out Mud, Water, and Debris Case Study: 1250T Top Drive Bearing Lubrication Considerations Extend Bearing Life in Top Drives Tips for Bearing Service and Selection Depend on Timken Quality The Timken Company is a technical leader with more than a century...

Increasing Roller Bearing Life Key Bearing Positions The use of anti-friction roller bearings on the main shaft and throughout the transmission of top drives promotes optimal performance and longevity. Top drives are required to operate in extreme conditions, often making it tremendously hard on units used offshore or on land rigs. In all cases, bearings that tolerate demanding conditions are a necessity given the criticality of the top drive’s role on the rig. Rolling element bearings are selected for use in the following positions in top drive units: • Main thrust bearing • Upper radial setup...

Increasing Roller Bearing Life and Performance in Top Drives Top Drive and Rotary Swivel Design Differences Top drives and rotary swivels are the two main types of drilling and load path hoisting equipment for the petroleum and natural gas industries. Swivels were invented first, which evolved into the power swivel and later into the top drive system. Top drives can generally be described as having the main shaft bearing and the transmission in a single housing. Rotary swivel: Precision machined steel casting with streamlined contours. The kelly connects to the bottom of the main stem, below...

Increasing Roller Bearing Life and Performance in Top Drives Main Thrust Bearings Main thrust bearings are high-performance, heavy-duty tapered thrust roller bearings. These bearings are (Fig. 3) tapered thrust heavy duty (TTHD) or tapered thrust heavy-duty free lateral (TTHDFL or V-flat) types. TTHD and TTHDFL tapered thrust bearings are the most utilized type of main thrust roller bearing used on a top drive’s drive stem, quill, or main shaft. Timken has a very broad offering of these products and can accommodate customer needs from a size and performance standpoint. From the smallest land...

Increasing Roller Bearing Life and Performance in Top Drives Machine Upgrades and Bearing Requirements It is important to understand how machine upgrades can impact bearing selection; for instance, when considering an upgrade to a higher API hoisting rating. This will alter the required API bearing-load rating of top drives or swivels, expressed in short tons, and the main bearing thrust rating at 100 RPM for 3,000 hours minimum life for 90% of bearings, expressed in pounds force. A properly specified bearing can provide issue-free performance, even under increased loading, while maintaining...

Increasing Roller Bearing Life and Performance in Top Drives Seal Out Mud, Water, and Debris Washpipe assemblies are an important component of high-pressure sealing technology between the main shaft and gooseneck to combat drilling mud from entering the upper bearing cavity in the main gearbox housing. The upper bearing retainer plates use a combination of lip seals and O-rings to keep the housing sealed tight from the elements. Concentricity between multiple housings and limiting angular alignment play a major role in seal and packing performance. Rotary seals, spring-loaded lip seals, and proprietary...

Increasing Roller Bearing Life and Performance in Top Drives Lubrication Considerations a) Lubricant Film Figure 7: An effective lubricant film maintains separation between asperities on the bearing. a) Effective lubricant film with full separation of contact surfaces; b) insufficient lubricant film with asperity contact. Adhesive wear from contacting asperities reduces expected bearing life. Proper lubrication in any bearing application is critical to long-term reliability and performance. The top drive main shaft rpm is low to moderate, and loading is moderate to heavy. These factors must be...

Increasing Roller Bearing Life and Performance in Top Drives Extend Bearing Life in Top Drives Tapered thrust bearings Tapered roller bearings A properly selected top drive bearing should provide a minimum of five years of reliable field service under various drilling conditions to reach the desired time between major rig overhauls. Drilling conditions range from mild to extreme and there’s always a chance for a surprise event along the way. The replacement of main shaft or transmission bearings is completed in a certified repair facility, as a tear-down of this scope would be next to impossible...

Increasing Roller Bearing Life and Performance in Top Drives Tips for Bearing Service or Selection In addition to the many considerations above, it is also important to note the following when servicing top drives or selecting bearings: • Use an approved method to heat bearings prior to installation on a shaft. Other methods cannot achieve the same consistent, safe results. • Keep a detailed log of bearing maintenance procedures, particularly relubrication intervals. If a problem with your bearings does occur, this can make it easier to diagnose the issue. • When relocating top drives, be aware...