EXPERT COLUMN | LEEA A load on your plate W
idely used in many heavy-duty sectors, plate clamps have the ability to safely grip, move and
position fabricated assemblies as well as individual or bundles of plates. This makes them a suitable choice of lifting equipment for moving or positioning heavy steel sheets, plates and other parts in steel fabrication and manufacturing. On construction sites these clamps can handle panels and large components. Shipbuilders may deploy them for transporting plates used on hulls as well as sections and deck parts. Plate clamps will also be seen in the automotive sector lifting frames or plates. There are two basic types of plate clamps, the first being Type 1. These use friction to grip the edge of the plate. Some are used only to lift the plate in the vertical position, others lift from the horizontal to the vertical position or vice versa. Type 2 clamps are for lifting the plate in a horizontal position only, when used in conjunction with a two-leg sling or reeved onto an endless loop, as determined by the design.
Three principles for Type 1 clamps There are three main principles for operating Type 1 clamps. The first involves a system of levers actuated by the loading of the lifting eye or chain, or where a chain or wire rope is attached to the jaws in such a way as to produce a force causing the jaws to come together and grip the plate. This gripping action is provided either by the lever system itself or by a combination of the leverage and the jaw’s cam action. The preference is for clamps provided with a spring-loaded locking device, which locks the clamp onto the plate without a force being applied to the lifting eye. Some clamps can lift plates from the
horizontal to the vertical and vice versa, but others will only maintain their grip away from the vertical one way around. This means they can only turn a plate over if the plate is first lifted to the vertical, then temporarily supported while the clamp is removed and turned around prior to the plate being lowered. Given that users are obligated
Ben Dobbs
Technical Committee
Plate clamps are frequently used for heavy-duty tasks. Ben Dobbs, head of global standards and legislation at LEEA (Lifting Equipment Engineers Association), runs through the two different types of these important pieces of lifting equipment.
Despite their simplicity of operation,
horizontal plate lifting clamps are purpose- designed to take account of the forces that occur in the line of lifting. Some of these clamps are designed for use on an endless loop, in which case it must not be changed for a two-leg sling nor should an endless loop be substituted for a two-leg sling. In both cases this would alter the geometry of the arrangement and thus the forces. Horizontal plate handling clamps can be designed to handle one plate at a time or a bundle.
to provide safe systems of work, clamps that retain their grip throughout the whole manoeuvre are preferred. There are clamps with the further advantage of being able to accommodate a lifting load applied at any angle to the side plate of the clamp. When used in this way, the clamp’s Working Load Limit (WLL) is usually reduced by a stated percentage. Seek confirmation from the manufacturer’s instructions on how their clamps perform. The second principle sees clamps that grip by the action of a wedge or cams but without lever action. The third principle is where a screw
tightened by a bar or spanner provides the gripping force. These clamps are purpose- designed items – ordinary ‘G’ clamps are not suitable – and special precautions are required for their use.
Horizontal lifting with Type 2 clamps Type 2 clamps lifting horizontally are used in pairs in conjunction with a two-leg sling. The sling can be permanently attached to the clamps or the clamps may terminate in an eye or shackle into which the hook of the sling (preferably a safety hook) is inserted. The clamps may be provided with a toe or cam to grip the plate – by far the safest type – or grip only by the inward force produced by the angle of the sling.
10 | November/December 2026 |
www.hoistmagazine.com
Selecting clamps Clamps designed to lift at an angle to the side plate of the clamp should be additionally tested at the maximum angle permitted, of twice the WLL for that angle. A design that permanently incorporates a short length of chain connecting the clamp to the crane hook is strongly recommended in preference to an eye. Proof tests should be carried out on the thinnest plate practicable within the clamp’s range. The range of thickness that may be lifted should be indicated on the clamp. Gripping cams and jaw teeth should be easily replaceable. Some designs of clamp, particularly those with a moving cam action jaw, where a spring provides the initial grip, have a minimum load and minimum plate thickness they can safely lift. Refer to the manufacturer’s instructions wherever possible, but in the absence of specific guidance the load should not be less than 20% of the SWL and the plate thickness not less than 20% of the maximum. The provision of handles on the heavier
clamps aids handling and prevents pinched hands, but if there is a tendency for the plate to sag when lifted then this type of clamp may not be suitable. Clamps designed for use on an endless loop usually exert a greater crushing force, which aggravates the problem. Having run through these two different
clamp types, I recommend reading further guidance, particularly related to their safe use, in the LEEA Code of Practice for the Safe Use of Lifting Equipment (COPSULE), which can be accessed for free at
leeaint.com.
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