A cleco, also spelled generically cleko, is a temporary

fastener A fastener (US English) or fastening (UK English) is a hardware device that mechanically joins or affixes two or more objects together. In general, fasteners are used to create non-permanent joints; that is, joints that can be removed or disman ...

developed by the Cleveland Pneumatic Tool Company. Widely used in the manufacture and repair of

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...

-skinned

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engine ...

, it is used to temporarily fasten sheets of material together, or to hold parts such as stiffeners, frames etc together, before they are permanently joined.

Operation

Clecos are installed in holes drilled through the workpieces (usually holes intended for permanent fasteners installed later). They expand on the far side of the workpieces and then draw and clamp them together while maintaining the desired alignment and preventing distortion of the pieces. Clecos should fit snugly in their holes to prevent shifting of the workpieces and maintain the alignment of fastener holes which do not have Clecos in them. They are blind fasteners; so they can be installed in assemblies where the worker does not have access to the other side. If permanent fasteners are installed in Cleco holes, a Cleco will be removed when its hole is needed. If the workpieces are bonded or welded, then the Cleco holes may need to be filled later.

Fastener and tool

The basic type consists of a steel cylinder body, a plunger on the top, a

spring Spring(s) may refer to: Common uses * Spring (season) Spring, also known as springtime, is one of the four temperate seasons, succeeding winter and preceding summer. There are various technical definitions of spring, but local usage of ...

, a pair of step-cut locks, and a spreader bar. A special type of

pliers Pliers are a hand tool used to hold objects firmly, possibly developed from tongs used to handle hot metal in Bronze Age Europe. They are also useful for bending and physically compressing a wide range of materials. Generally, pliers consist ...

are used to push in the spring-loaded plunger. This pushes down on the step-cut locks, which pushes them away from the spreader bars and allows them to come together. This allows the user to slip the locking jaws through a hole made through multiple sheets of material. When the plunger is released the spring pulls the locking jaws back towards the spreader bar, which separates the two jaws. The material sheets are then squeezed in between the step-cut area and the steel cylinder. This keeps the holes in the separate sheets aligned.Jeppesen Sanderson, Inc. (2002) "A&P Technician Airframe Textbook", Jeppesen Sanderson

Design variations

Cleco-type fasteners are also available with a threaded mechanism to draw the spreader bar up. Clecos of this type take more time to install and remove, but can pull parts together more tightly than the spring-type clecos. They are commonly available with a wingnut for hand tightening, or with a simple

hex nut A nut is a type of fastener with a screw thread, threaded hole. Nuts are almost always used in conjunction with a mating bolt (fastener), bolt to fasten multiple parts together. The two partners are kept together by a combination of their threads ...

so that they may be spaced more closely together. In either case they will usually have a

hexagon In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A '' regular hexagon'' has ...

al body that may be better gripped to tighten or release the spreader bar.

Sizes and color-coding

Regardless of their form, they are typically

color-coded A color code is a system for displaying information by using different colors. The earliest examples of color codes in use are for long-distance communication by use of flags, as in semaphore communication. The United Kingdom adopted a color c ...

for ready identification of their size.

References

{{Reflist Fasteners