BELOW THE HOOK | PRODUCT REPORT
hardness level below HRC 30/Brinell 300. Similar clamps from other manufacturers have similar requirements. Also note that such lifting will of course leave marks, probably visible ones, on the load. Alternatively, you could use Camlok’s HG (High Grip) plate clamp, which has an extremely high clamping force making the clamp suitable for plate with a surface hardness up to HRC 40/Brinell 375. There is also its TSB non-marking friction plate clamp (WLL 40–1,250kg), which does in this case work through the process of friction, achieved by a special material on the jaw and pad which is similar to brake linings. Another benefit of the TSB is that the same grab can be used for lifting different materials, such as concrete, wood and stone, as well as hardened steel. Camlok also manufacture the LJ non- marking plate clamps (WLL 25 – 1,500kg), which have rubber or leather pads according to application and are for structural steel plates, stainless steel, iron, timber and aluminium. They can also be used for steel plates with extremely hard surfaces. An obvious message from that huge variety of non-marking and hard steel devices is that they are highly specialised for particular applications and that it would be wise to take ad-vice before choosing your option – which is exactly what Camlok recommends. Its sales team, they say, will be happy to advise.
A single Camlok horizontal clamp.
There is a similarly wide range in their clamps for lifting sheets horizontally. Here the gripping issue is not so acute. The lower surface of the clamp can provide support without the help of friction. As long as the sheet is rigid, clamps on each side of the sheet can be joined by a two-legged chain sling which will provide the necessary inward force to keep them in place and to toggle the jaws closed. For handling larger plates it is recommended to use two such pairs in conjunction with a spreader beam. The CH clams have WLL from 1,000 to 10,000 kg; the CH is their industry standard model. Camlok’s horizontal-lift clamps are supplied as standard with smooth jaws. More specialised versions are available. There is the option of hardened steel serrated jaws for special applications; the RH/WH clamps have steel roller set into the jaws for non-marking applications. The ACH has adjustable jaws for lifting stacked plates; and so on. Of course, Camlok (based in the UK but
owned since 1999 by Columbus McKinnon) is far from alone in offering plate-lifting attachments. Tractel have its Topal range, of clamps, beams, and similar below-the- hook attachments, and their full range of lifting clamps is similarly wide. They have devices for horizontal and vertical lifting of plates, horizontal transportation of bundles or construction parts, lifting loads with parallel sides such as steel, concrete,
Caldwell offers a range of products in this area.
The RH clamp from the same firm.
wood or plastic, and for lifting smooth and polished materials such as stainless steel and natural stone. The Topal NX is Tractel’s clamp for lifting horizontal or vertical loads without damaging the surface. As an example application, these clamps have been used in a German plant in painting steel plates. The plates, approximately 4x4m wide and 6mm thick and weighing around 350kg are painted on one side, and once dried the Topal NX clamp allows the damage-free turning of the plates to allow the other side to be painted in turn. Other devices are available in a variety of configurations and applications, including for maritime and offshore use. The range can be customized and can reach capacities of 500t and beyond. We have described how horizontal clamps can be kept in position by the pull of the rigging chain that connects them to the hook. To work safely, the sheets that they are lifting must be rigid enough not to bend under that pull. Thinner sheets may sag, under that force and under their own weight, to leave the edges pointing at an angle upwards – which is not ideal for the clamps that are supposed to be holding them. An alternative is to use a more rigid below-the-hook device, of a framework with legs extending beneath it. The legs have flanges at their ends and move in or out to so that the flanges go beneath the load and support it. Caldwell is one manufacturer of such attachments. Even with these more
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