What is the Moeller Click-Loc™ advanced self-locking device?

It is an external secondary locking feature which provides an enhanced relia-bility and maintainability alternative to lockwire, tab washers, cotter pins, de-formed threads, locking elements, or thread lock compound (e.g., “Locktite”).

What is it made from?

The standard material is Inconel 718.

How does it work?

As the component is assembled, the Click-Loc™ engages usually within the last two turns prior to seating. Once engaged, the flexible beam fingers of the lockring act against the detent form of the mating part to provide a unique ratcheting type prevailing torque which is sufficient to prevent loosening from all known causes.

Where is it used?

Most applications are critical components on or close to jet engines, including fuel line coupling nuts, borescope plugs, drain plugs, adjustable mechanical linkages, and engine mounts.

Who are the present users?

Customers using the Click-Loc™ include such industry leaders as GE Aircraft Engines, Pratt & Whitney, Rolls-Royce, Pratt & Whitney Canada, Allison, Al-lied Signal, Boeing, Lockheed Martin, Snecma, USAF, and many more. The Click-Loc™ has been used in commercial and military aircraft and other appli-cations since 1993.

Is it reuseable?

The Click-Loc™ is typically rated for 100-cycle reusability in applications up to 600°F; from 600°F to 1200°F the typical reusability rating is 50 cycles. Generally, the Click-Loc™ reusability exceeds the service life of the compo-nent on which it is installed.

What if the fingers break off?

The fingers are an integral machined part produced by strictly controlled manufacturing process and NDT procedures, the same as the other critical engine parts we manufacture. The material (Inconel 718) is tough and dura-ble. There has never been a reported case of a finger coming off inadvertently. However, if it were to happen, the lockring would need to be replaced.

What if a finger is damaged?

Damaged parts need to be replaced. However, the Click-Loc™ is designed with a substantial safety margin and there is a possibility, as determined on a case-by-case basis, that the Click-Loc™ will provide adequate security until re-placement can be done. This is totally dependent on the extent of the damage, the remaining prevailing torque which must be verified, and the concurrence of both Moeller and the OEM design activity.

How much does it cost?

Pricing is dependent on part size, complexity, and the production quantity. Generally, the price ranges from $50 to $200 per joint. This is the upfront ac-quisition cost. In almost all applications thus far, the Click-Loc™ becomes ex-ceptionally cost effective when life cycle costs are considered.

Can the Click-Loc™ be retrofit to my present hardware?

Sometimes yes, sometimes no. This is dependent on many factors, and the cost effectiveness of retrofit versus replacement must be considered. Thus far, our applications include some major retrofit programs that are extremely cost effective.

We are experiencing leaking fittings. Will the Click-Loc™ fix this?

If the leaking fittings are associated with the coupling nuts, loosening the Click-Loc™ will definitely fix it. If the nuts do not loosen but leak anyway, the problem is in the sealing surfaces and the Click-Loc™ will not fix it, although it will prevent it from getting worse. Note: As a coupling nut loosens, the cou-pling loses rigidity and can wear out quickly from vibration and the resultant rubbing action at the sealing surfaces. Using the Click-Loc™ will help prevent coupling wear.

Does the Click-Loc™ change the fitting torque?

Yes. The Click-Loc™ adds some prevailing torque during the last two or so turns immediately before seating. This can be compensated for by several methods.

  1. Note the prevailing torque the Click-Loc™ generates (i.e., 30 in-lbs.), and add this to the standard tightening torque the fitting would normally require (i.e., 300 in-lbs.) and tighten to sum total (i.e., 330 in-lbs). This is the most
  2. accurate method of achieving the standard tightening torque level. This method is called “torque plus” and is widely used for self-locking crimp nuts.

  3. Another method is to add a constant (i.e., 30 in-lb.) to the standard tightening torque. The Click-Loc™ is capable of generating a predictable and consistent amount of prevailing torque cycle-to-cycle and part-to-part. While this method is
  4. not as accurate as “torque plus,” it may be suitable.

  5. If tightening is done by “wrench arc” or “nut angle” methods, no change is required. This is a very accurate method of preloading fluid fittings.

Can the Click-Loc™ be used with all types of materials?

Yes. The Click-Loc™ is made from Inconel 718. Retrofit kits can be applied to couplings made of virtually any material.

Does the Click-Lock™ require any unique maintenance procedures?

No. Fluid fitting couplings and most plugs and fasteners are usually lubricat-ed with oil before tightening. A light film of oil on the Click-Loc™ will extend its service life as well.

Do retrofit kits change the wrench sizes?

Yes. Generally the next 1/16″ larger size must be used.

How do I know if a Click-Loc™ is work out?

If a pronounced ratcheting feel is no longer evident, replace the Click-Loc™. This is indicative of severe wear, but this occurs well before the prevailing torque diminishes; therefore, replacement can be done prior to losing securi-ty. If properly serviced the Click-Loc™ should not wear out.

How can I verify the Click-Loc™ is functional and the joint is secure?

Visually look at the joint to be sure the fingertips are overlapping the detent area. While this does not assure the joint is properly torqued (neither does the presence of lockwire), it will tell you the mechanic used a wrench to tighten the joint (lockwire does not indicate a wrench was used), and the joint will not loosen. Also, during servicing a positive ratcheting feel and/or measuring the prevailing torque can assure proper function. Generally, the Click-Loc™ will also produce a noticeable clicking sound as well.

Will the Click-Loc™ still work if it gets oily or dirty?

Yes. Lubrication is recommended for maximum service life. Dirt, carbon build-up, and other contaminants do not significantly affect performance.

How is the Click-Loc™ retained on the mating parts?

New components are typically retained by a controlled interference fit, suffi-cient to provide a 500 to 1,000% safety margin over the maximum forces that could be expected. Retrofit components are generally sleeves that snap in place.

What standard or specification does the Click-Loc™ conform to?

There is no industry standard that applies to the Click-Loc™ because it is a fairly new product in a field where nothing existed before. In lieu of an indus-try standard, performance criteria are specified for each application.

How was the Click-Loc™ qualified?

Initially, there was extensive lab testing (including vibration, circular flexure, reusability, pressure, and thermal cycling). This was followed by qualification testing on AMT engines, then in-flight service evaluations. It is important to note that all Click-Loc™ components use virtually the same materials, beam geometry, and locking configuration. Therefore, each new application addi-tionally substantiates all others. For more details about testing and substanti-ation please click here.

How does the Click-Loc™ compare to competitive devices?

The Click-Loc™ is by far the most widely accepted secondary locking feature for special applications such as those listed previously. No other competitive product exists which meets all the original USAF design criteria for self-locking fluid fittings. The Click-Loc™ does.

Recently some “one-sided” designs have been introduced. They are called that because they do not require any locking component on the male-threaded part. Instead these designs attempt to safety the fitting by locking the nut to the hose or tube of which it is part of. This is never done, even with safety wire! The reason why is that when the coupling nut is tightened it has a tendency to impart a twisting force to the hose or tube on which it is in-stalled. This is such a well-known problem that many hose manufacturers design their hoses with a second hex behind the coupling nut (to allow an-other wrench to be used to minimize twist-up) and a stripe painted down the length of the hose to indicate the degree of twist-up that has occurred.

Even with these precautions, any twist-up at all means the hose or tube is constantly exerting a torsional force against the coupling nut, and it is in the CCW loosening direction. The “one-sided” designs are inherently flawed be-cause under conditions of tube or hose twist-up they become self loosening!

Unlike the “one-sided” designs, Click-Loc™ actually locks the male and female threaded parts together. This is the way that safetying is to be accomplished in accordance with well-established standards (see specifications AS567 and AS4536 for illustrations). It is also the only way to positively prevent all loos-ening.

Finally, Click-Loc™ is the only readily retrofittable and repairable product on the market. The Click-Loc™ is technically superior, affordable, reliable, and flight proven in service in thousands of commercial and military aircraft. This is why Click-Loc™ is clearly the industry leader by a wide margin.

How Reliable is Click-Loc™?

Reliability data has been tracked. It’s measured in the hundreds of millions of component flight hours.

Learn how Click-Loc surpasses the ease, reliability, and reusability of other secondary locking devices.

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