AS9120B, ISO 9001:2015, AND FAA AC 0056B ACCREDITED

A Comprehensive Guide on One-Way Clutch Bearings

One-way clutch bearings are a category of bearing types that feature reverse stop motion and a one-way rotation function (which is where they got the name “one-way bearing”). The one-way clutch bearing is designed so that when its movement opposes the intended one-way direction, an immediate locking or disengagement motion occurs, arresting the system in place. In general, one-way clutch bearings boast low frictional torque, saving energy by avoiding losses.

One-way bearings are also known as sprag style bearings, and their design contains drawn cups with needle roller bearings. They are used in automobile and industrial applications such as speed compensation devices, aircraft, overrunning clutches, e-bikes, and motorbikes. With that said, let us now look into the design machinations of one-way clutch bearings in greater depth.  

What Is the Working Principle of One-Way Clutch Bearings? 

The design of one-way clutch bearings involves the use of wedge-type, one-way clutches and ball bearings. One-way clutches are well-designed structures consisting of identical machine elements: thin-walled outer rings (drawn cups), complete with a sequence of ramps, plastic cages, needle rollers, and springs.

The structural design of sprag bearings is nothing more than a collection of roller pins, which upon rotation “climb” the case walls of the bearing, pushing the center shaft away. The locking mechanism results from this very “climbing” by the rolling pins, those of which exert pressure on the center shaft. When rotated in the other direction, the pins “climb down,” loosening their grip on the center shaft. This design contrivance helps reduce fuel wastage and minimize exhaust emissions during the “engine-idle” phase. Apart from the general application of one-way clutches as described above, there are three specific ways by which sprag clutches regulate and support an application’s motion:

  •  Backstopping     

Backstopping is a design mechanism that is used as a safety precaution, such as in the case of an industrial winch. If a machine fails, the backstopping clutch helps keep the load in its place. In this context, a winch clutch bearing acts as a vital part of the winch which securely locks the brake assembly within the motor shaft so that when the motor is turned off, the spool which carries the load does not get unwinded.

  • Indexing  

An indexing sprag clutch is a device that encourages motion in a single circular direction before allowing it to stop or get idle. Factory production lines employ these indexing clutches wherein they move to a position, wait for some time, and then move to the next. In the case of an electrical or motor failure, an indexing sprag clutch can act as an additional precautionary measure. 

  •  Overrunning  

An overrunning sprag clutch adds to the speed of a unidirectional rotating component, allowing it to spin faster than it would have in its absence. An overrunning clutch keeps a component spinning without the requirement of an external force. Torque converters, gearboxes, and conveyors primarily employ overrunning sprag clutches for their day-to-day operations. 

What Happens When a One-Way Clutch Bearing Fails?   

If the one-way bearing loses functionality or gets damaged over time, the pilot will lose control of gears, even if the clutch is pressed down. This implies that there will be a total loss of acceleration or control of engine performance in such a scenario, ultimately jeopardizing aircraft safety to the extent of a possible crash.   

How Should One-Way Clutch Bearings Be Maintained?   

If the one-way clutch bearings in the starter system are not adequately looked after, the engine can develop irreparable damage and complications. For example, lubricants from improperly-burned fuels, such as castor oil, can seep through the starter shaft, end up in the bearing, and ultimately clog it. This will lead to the slipping of the starter shaft, preventing the engine from starting up at all. Furthermore, a lack of proper lubrication between the starter shaft and the bearing can cause it to produce excessive heat and get locked up.   

The shaft and bearing should be immediately replaced if it is discovered that the bearing has gotten trapped within the starter shaft. Furthermore, the starter shaft of the engine should be thoroughly cleaned so that all congealed oil deposits are removed from the backplate and the shaft. The one-way bearing should be cleaned with either an electric motor cleaner or denatured alcohol. Lastly, if the shaft sports any grooves or scratches, it should be immediately replaced to avoid damage reaching the bearings.   

In Conclusion   

The longevity of one-way clutch bearings depends on their quality, and reputed suppliers such as Aerospace 3Sixty are well-known in the aerospace sector to deliver parts of only the highest quality. We are proud to maintain a legacy of timely delivery and customer satisfaction. You can browse through our extensive catalog of parts, run on our highly streamlined user interface, to experience the top-notch parts procurement process that there can be. Get an RFQ quote today and we will be glad to assist 


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