A Beginner’s Guide to How Hydro Bearings Work

We are all familiar with the standard industrial bearing, hardened steel ball bearings enclosed in round metal rings or races (top and bottom). Everything is then lubricated to make it spin more freely. When fitted around a shaft, the bearings allow the shaft to rotate freely. Depending on the quality of the bearing, the shafts can rotate at very high speeds. There are some variations, but these bearings all work on the same principle.
Hydro bearings are substantially different.

The Challenge for Hydro Bearings

According to the US Energy Information Administration, 5.7% of US electricity comes from hydroelectric systems that are part of dams. These dams use the power of flowing water to turn large hydroelectric turbines that generate electricity. Hydroelectric systems are complex and require bearings in many of their subsystems.

Lubrication is problematic since these bearings are underwater all or part of the time. The flow of water will eventually break down the lubricant to the point where it is ineffective. There are also environmental considerations. These hydroelectric dams are part of an ecosystem that includes fish, plants, and other aquatic organisms. It’s important not to pollute this environment with petroleum-based oils and greases from hydroelectric turbine bearings. Metal bearings also have the potential for oxidation and corrosion.

Contact CRC Distribution today to learn more about Orkot®

and how it can perform in your application.

A Solution: Greaseless Composite Bearings

As a remedy to this problem, hydroelectric turbine designers use water-lubricated bearings. One of the most effective brands of these bearings is the Orkot® hydro bearing from Trelleborg Sealing Solutions Streamwood. CRC Distribution is the official Distribution Channel Partner for Trelleborg’s Orkot® hydro bearings in North America, including Mexico.

How Orkot® Is Manufactured

Orkot® is a proprietary material made from a combination of polymers that include Teflon® (PTFE), Molybdenum disulfide (MoS₂, which is similar to graphite), and other solid lubricants. Woven fabric is then immersed into the resin bath, rolled onto a mandrel, then moves through the oven during the thermosetting process. 

The result is Orkot®, which engineers can machine into various shapes and precise dimensions, much like metals. Orkot® material also comes available in tubes, sheets, or other custom shapes. It is self-lubricating and can safely interact with water and other lubricants without losing its performance, making it suitable for hydroelectric turbine bearings. Orkot®’s properties are at the molecular level. They are irreversible, even under extreme heat or cold. For more information on Orkot®, read the CRC Distribution blog post, How Is Orkot® Manufactured?

Advantages of Orkot®Hydro Bearings

Because of its composition, Orkot® has a few unique advantages over other bearing materials.

Low Friction

The ingredients and the curing process result in a material with a bearing surface that is self-lubricating and interacts with water as a lubricant. This gives Orkot® hydro bearings reduced friction in wet or dry applications alike.

Dimensionally Stable

Orkot® has virtually no absorbency, and as a result experiences almost zero swell in water.

High Load Capabilities

Orkot® materials and components have high compressive and yield strength. Generally, Orkot® can be machined to replace traditional bronze bearings without additional alterations to other components.

Edge-Loading Capabilities

Orkot® hydro bearings operate under severe edge-loading conditions. This allows flawless operation while protecting expensive components.

Easily Machined

Orkot® is a substantial material and is capable of being machined in processes similar to brass, aluminum, or lignum vitae. Orkot® is also suitable for drilling, boring, and honing if the application requires it.

Ease of Installation

Orkot® can be freeze-fitted with liquid nitrogen, press-fitted, bonded, or mechanically mounted in your application. CRC Distribution works closely with the engineers at Trelleborg to ensure you get the proper guidance for your application.

Proven Service Life

You can find Orkot® in thousands of hydroelectric turbine applications throughout the world. The material provides years of service and is approved by the Army Corps of Engineers for hydroelectric applications. 

Environmentally Friendly

No petroleum-based ingredients or asbestos are used in the manufacturing of Orkot®. The material is non-toxic and environmentally friendly with no pollution concerns. It is safe to use in hydroelectric applications on an open river or other body of water. Orkot® can even be used in saltwater applications.

Contact CRC Distribution today to learn more about Orkot®.

Choose From Two Orkot® Variations

Orkot® comes in two variations: Orkot® TLMM and Orkot® TXMM. Their formulations are the same, except that TXMM includes a Teflon (PTFE) lining on the portion that acts as the bearing surface. This provides added protection against wear and friction. For more information on the materials, refer to the CRC Distribution blog post, The Difference Between Orkot® TLMM and TXMM.

Orkot® is Versatile

Orkot® hydro bearings are not used just as hydroelectric turbine bearings. The material is ideal for many other hydroelectric applications, including the following as just a few examples.

Spillway Gates

Spillway gates in hydroelectric applications come in several different designs. Orkot® trunnion bearings in these applications provide easy operation and long life, even under the harshest conditions. Read the CRC Distribution blog post, Orkot® Trunnion Bearing Friction Analysis for more information about this application.

Main Guide for the Turbine Shaft

Orkot® TXMM hydro bearings prevent metal-to-metal contact between the main shaft and the guide, preserving the life of these valuable components and allowing for the maximum electricity generation. To see how Orkot® compares against bronze hydroelectric turbine bearings, read the Orkot® blog post, Orkot® TXMM vs Greased Bronze Bearing: 300MW Pump Turbine.

Distributor Ring

As this system distributes the electricity generated from the hydroelectric process, Orkot® wear pads protect the contact points against friction.

Wicket Gate Guide Vane

An assembly of Orkot® TXMM hydro bearings and Turcon Variseals on the intermediate and lower assemblies of the wicket gate forms a barrier against suspended solids that could damage the wicket gate stems and bearings.

Control Linkages

The control linkages in hydroelectric applications allow for adjustment depending on the flow and other conditions. Orkot® hydro bearings enable smooth operation, even in these limited motion applications.

Runner Blade Hub

Runner blade hubs are where the hydroelectric process begins, spinning the turbines to generate electricity. Orkot® hydro bearings allow for the blade angle’s adjustment to maximize production based on the volume of water flow.

Trelleborg named CRC Distribution as the official Distribution Channel Partner for Orkot® Hydro bearings in North America. Contact us today to order yours.

Maintenance of Composite Bearings

Orkot® hydro bearings are virtually maintenance-free. One consideration comes if they are anchored in place using screws or bolts. The head of the screw or bolt must be sunk deep enough into the bearing’s outer surface to prevent contact with the shaft or journal. 

Where to Buy Orkot® Hydro Bearings

Numerous opportunities exist to use Orkot® composite bearings and components in hydroelectric applications. CRC Distribution has been involved in hydroelectric projects throughout the world using Trelleborg Orkot® Hydro Bearings. CRC’s personnel are experts in customizing Orkot® for applications, including machining this composite bearing material for specialized applications. Request a quote for your next project by visiting the CRC Distribution website today.