Lifting Clamp Maintenance is at the Heart of Best Practice at the Point of Use

By Dale Kelly, Engineering Manager at The Caldwell Group.

Clamps for lifting come in many designs and are used in a myriad of applications, including working with plate steel, ingots, slabs, concrete barriers, pipe, coil steel, paper bales and paper rolls. It is important to source them from a reputable manufacturer.

Clamps are designed to generate a clamping force perpendicular to the surface of the load. These clamping forces are generated from the clamp geometry by the pulling force on the lifting shackle of the clamp or tightening of a screw. Clamps can be used for attaching loads to a hoist, or for other load handling purposes, such as anchoring or positioning. Importantly, the load being lifted must be able to support the amount of squeeze that the clamp applies to the load.

At the top end of the market, a single manufacturer might make 200 types of clamps. One area where we see repeated misuse is picking the wrong clamp for the application, so it is necessary to understand the application before selecting the clamp.

Common types include:

• Friction, pressure-gripping clamps
• Indentation, pressure-gripping clamps
• Anchoring clamps, used for suspending or attaching detachable rigging hardware
• Positioning clamps, used to hold or locate parts during assembly operations
• Hybrid clamps, which are a combination of the others.

Clamps for lifting come in many designs and are used in many applications.

Looking after clamps

Bad practice endures, as knowledge on inspection, repair, testing, and maintenance is often lacking. Further, clamps have parts — the teeth, primarily — that wear over time, which is impacted by environment of use, types of steel, storage, and operator care. Worn teeth can cause disengagement with the load. It is important therefore that end users realise the importance of supporting ownership with a reputable factory maintenance and repair program.

Ideally, there will be a trained maintenance person or team at a facility that keeps track of all the clamps — and other rigging gear — that they use. They will understand that it is necessary to conduct a thorough inspection both before and after using a clamp. Thorough, periodic inspection should also be completed in line with service class, a process that should include removal from service protocols.

Inspection is useless if those inspecting the equipment don’t know what they are looking for. Defects should be recorded by serial number and clamp model, and a record kept for tracking purposes. These defective clamps must be clearly marked, removed from service, and placed in a designated area for further inspection, repair, or disposal.

Caldwell customers can phone our service department and arrange for the clamp/s to be returned. They can even be shipped back to the point of use with a new certificate of proof test.

Rebuilding clamps

End users should source lifting clamps from manufacturers that supply rebuild kits, while offering guidance on product replacement and best practice.

Damage to welded bodies requires replacement, but most other issues can be rebuilt. This isn’t always possible with every clamp on the market, and it can lead to costly and unnecessary replacements. Some lifting clamp parts for example are forged or welded, or put together in a way that they can’t be taken apart.

Clamps should be viewed as safety products; they keep people safe, after all. Diligent users want to have the control to maintain those safety perimeters themselves. In turn, reputable manufacturers understand that users want the ability to maintain this important piece of equipment in the field; in other words, all parties want to avoid throwing clamps away and buying new ones. Renfroe supports its lifting clamps with rebuild kits and can even supply a single cam jaw if that will see the item safely returned to service.

In order for rebuild to be an option, the right rebuild kit must be sourced at the time of purchase and kept in a place where it is easily found. Different kits have different parts because the clamps themselves are not the same. Even within a single model, kits will vary by size and clamp capacity. All rebuild kits for one model will have the same pieces, but a separate kit will be available for 1 ton, 2 ton and 3 ton capacities. A rebuild kit should include all required hardware to install components, such as shackle pin, gripping cam, cam pin, swivel jaw, lock spring, shackle pin bushing, cam stop pin, and fasteners.

Different rebuild kits have different parts because the clamps themselves are not the same.

Modifying clamps

We urge users and industry generally to proceed with great caution when it comes to considering modifications to clamps. We’ve looked at the many different scenarios that use clamps and each of these applications present their own specific requirements.

However, it is never ok to modify a clamp without consulting the manufacturer. Even at the very first consideration that a modification might enhance productivity or efficiency as it relates to that application, the manufacturer of the clamp should be contacted. In some cases, an alternative solution already exists.

As stated, so much of safe operation starts with selecting the right tool for the job in hand. Modifying the right tool can turn it into the wrong one.

The Caldwell Group has grown into one of the largest manufacturers of below-the-hook lifting devices in North America, selling beams, clamps and lifting points all over the world. https://www.caldwellinc.com