You have a load to lift, you have a hoist to lift it with, and you may even have a hook on the end of your hoist rope, but there are times, and loads, when a hook is just not up to the job.
Drums, coils of wire, sheets of metal and concrete kerbstones are just a few commonly lifted loads for which standard hooks are inadequate. Specialised below-the-hook devices and designs, custom-made or off-the-shelf, come in huge, almost endless, varieties. ASME B30-20, the US standard that covers the tagging, load testing, maintenance and inspection requirements of below-the-hook attachments, divides them into six different categories: structural and mechanical lifting devices, vacuum devices, close proximity-operated lifting magnets, remotely operated lifting magnets, scrap and material-handling grapples, and clamps. There must, however, be very many that are put into the first of those categories only because they fit none of the others. Some lifting attachments are powered, some are passive, some ingenuously use the weight of the load to enhance their frictional grip upon it; some are simple, some are very ingenious, and sometimes the simplest ones are also the most ingenious.
Consider a common and age-old problem: that of lifting a block of stone or, these days, of precast concrete. Stonemasons since at least the time of the Romans have used the self-locking scissors action of lifting tongs, and identical devices are still made and used today. GGR, for example, offers among several other such attachments its Stone-Grip 1000. It has a capacity of 1.0t and rubber-lined clamping faces – a refinement unknown to the Romans – and GGR advises using a secondary safety strap if lifting at height, but an ancient Roman engineer building an aqueduct in the centuries before Christ would have recognised the device and been able to use it. The boulder and stone scissor grab, also from GGR, can handle stone units – they don’t have to be shaped – up to 200kg. The Boulder Stone Lifter is even simpler: it is described as “a flexible tool that can be used as a below-the-hook lifter”, and is identical in design and in principle to that used by the Romans.
For heavier stone units GGR suggest its powered vacuum lifter range. Vacuum lifters were originally developed to lift panes of glass, and that is still a primary application, but suction-pad technology has improved to the extent that vacuums can now lift rough surfaces (unfinished stone, as above), porous surfaces (cardboard boxes full of production-line goods), and heavy loads (notably steel plates), which makes them ubiquitous in fabrication workshops. GGR’s Stone Slab Vacuum Lifter GSK1000 can lift 1,000kg loads of polished or porous stone as well as other porous materials such as drywall, plasterboard and structural insulated panels (SIPs). It comes with a range of pads from 90kg to 1,000kg depending on the shape and size of the load.
Kilner Vacuumation claims to be the longest-established vacuum lifting company in the UK and has been supplying standard or bespoke glass lifters, steel plate lifters, concrete lifters, and lifters for wood, plastics, coils, sacks and much more for over 50 years. This autumn it introduced a new, small, versatile battery-operated vacuum lifter to its range. The product has a capacity of 600kg and is recommended for loads such as plates, slabs and rigid panels. It is powered from a 12V battery and can be used to lift horizontally or vertically.
Although now part of Columbus McKinnon, Camlok is a UK company with a long history of making below-the-hook attachments, in its case plate clamps. The company history stems from a general industrial need to lift and transfer steel plate – its product design has evolved from that to the vast spectrum of handling devices it currently offers.
For lifting steel plates – the original focus of the company – it has vertical plate clamps, horizontal plate clamps, lifting magnets, screw clamps and hand clamps. To lift and transport steel drums – a particularly common need throughout industry – it has its DC500 drum clamp. The product clips to the upper rim of a drum, and the drum’s self-weight locks it into position. The device carries a sealed drum at an angle – to carry it level, Camlok’s DCV500 Vertical Lift Drum Clamp carries open or sealed drums vertically. For confined spaces the company has a low-headroom drum grab.
Sticking with drums, Morse Drum is based in Syracuse, New York, US, and since 1923 it has, as its name suggests, been specialising in manufacturing drum-handling equipment. Offerings include hand drum trucks, industrial drum handlers, machines for turning drums end-over-end to mix the contents, drum handling forklift attachments, and heavy-duty drum lifts for forklift mounting or below-the-hook drum handling. Its lift-and-pour below-the-hook attachments let you pour controllably from your drum: the hoist lifts the drum and attachment, and the tilt-to-pour motion can be directed by hand, or by hand-operated chain, or powered either pneumatically or by AC electric motor. Anyone who (like your author) has tried to get fuel from an oil drum into a vehicle without a hand pump or similar would have wanted such a device – though, of course, its main application is for small production lines and workshops.
Concrete sewer and water pipes are another type of sometimes-awkward load. Faced with the task of attaching one to a hoist you might be tempted to pause for a cup of tea before tackling the job. Caldwell has the product for you. It is called the Tea Cup. Yes, seriously – it’s a lifting attachment.
Caldwell created the Tea Cup pipe carrier specifically to streamline the handling of concrete pipes. You can more or less guess roughly what shape it is. To use it you drill an appropriately sized hole in the pipe. You lower a wire rope that has a metal cylindrical stopper on its end through the hole. You reach inside the pipe, with the Tea Cup in your hand – it has a handle on the side, like its namesake, for exactly that purpose – and fit the rope and stopper into a slot in the side of the Tea Cup. Use your hoist to pull upwards on the wire rope and the stopper wedges itself into the Tea Cup and tries to pull it through the hole. The rim of the Tea Cup is larger than the hole. Result: the concrete pipe with the Tea Cup inside it gets securely lifted into the air.
The device is available in three sizes with load capacities of up to 18 tons. The wire-rope slings come in six lengths. Caldwell has many other attachments, none so marvellously named, but they include spreader beams, wire mesh slings, wheel nets, coil hooks and others.
Spanish company Elebia is known for its specialised self-attaching hooks, especially for extreme-environment applications such as steel foundries, where attaching or releasing a hook by hand could be hazardous in the extreme. One of its many offerings is the eTrack lifting clamp for raising sections of railway track. It is an ingenious mix of the age-old self-clamping mechanism with high-tech monitoring and safety added in.
The device replaces or hangs below the hook on a hoist or crane. It looks like an inverted ‘U’, with a spring-loaded probe that sticks down from the one of the bottom edges. When the probe is dragged against the rail it makes the clamp swivel on its lifting rope so that the U-shaped opening is in the right orientation for the rail to fit inside it – that is, across the length of the rail rather than along it. The crane then lowers the device onto the rail – the probe contacts the flange of the rail and is pushed inside the device, releasing the clamp mechanism. When the ascending manoeuvre begins the tension in the rope passes through the clamping mechanism, making it automatically lock onto the rail allowing it to be lifted safely. Once the rail has been safely lowered in the right place and there is no tension on the rope the release order can be given by the operator via a remote control, and the clamps unlock and retract.
A battery-operated colour-coded LED status indicator on the body of the device shows blue when the load is locked and safe to lift, red as an intermediate ‘Do Not Lift’ warning, and green when the clamp is unlocked and the load released. White is a warning of a low battery. For a video animation of how the system works, see https://bit.ly/3UBQumf.
Bushman, based in Menomonee Falls, Wisconsin, are specialists in below-the-hook attachments, both off-the shelf and made-to-order. Think C-hooks, coil grabs, coil lifters, spreader beams, hook blocks, ladle hooks, sheet lifters, plate lifters, bundle lifters, pallet lifters, roll-handling equipment… and that does not begin to exhaust its product list.
The company’s sheet lifters handle single or multiple bundles of metal sheets or plates and can be operated by a hand wheel, chain wheel, electric motor or hydraulic cylinders. The firm has a unique ring lifter, which loads forged rings several meters in diameter into and out of vertical lathes, gripping them by either the inside or the outside of the ring. To lift coils of rod, wire spools, paper rolls and the like, C-hooks are a cost-effective tool, but for the heaviest coils, such as flat-rolled steel coils, the company suggests motorised coil grabs as an efficient solution – from Bushman, they are custom-designed to handle the widths and diameters that clients require. Options include coil protection features, motorised rotation, weighing systems, automation, and controls for AC or DC motors.
Bushman points out that an important factor in heavy-duty lifting applications is the weight of the attachment: the more it weighs, the more it will reduce the hoist’s useful payload. Since Bushman offers equipment for mill duty and industrial applications where capacities can range from a few kilogrammes to hundreds of tons, at the high end of that range the equipment weight becomes seriously significant. The company claims its proven designs offer lower tare (unladed) weights for its products, which, of course, relieves the load on the hoist.
Magnetic lifting is another of the ASME categories that we mentioned at the start – or rather, two of its categories. ASME distinguishes between “close proximity-operated lifting magnets” and remotely operated ones. The first category would include permanent magnets, which need some mechanism to make them release their load. Frequently on light lifting applications a hand lever moves the magnet away from the metal lifting plate, making an air gap. That reduces the magnetic field so that the load drops away from the lifting plate. The second category would cover electromagnets.
Electromagnets have been around a long time in applications such as scrap metal loading at steel mills or for lifting steel plate. They need, of course, current running through them to pick up and hold their loads, and the current must run all the time the load is in the air. They therefore consume a large amount of power. A recent development is the so-called electro-permanent magnetic lifter. The design has a clever arrangement of hard iron (i.e. permanent magnets) and soft iron (i.e. non-permanent ones) arranged in a ring with a coil wound round the soft iron component. The result is a combination of permanent and electromagnet that can be switched on with just a single short pulse of electricity – and that remains switched on even after the electric pulse has ceased.
The great advantage is that they use so much less electricity – the pulse lasts less than a second, after which the magnetic field remains on and active. A second short pulse, in the other direction, reverses the polarity of the electromagnetic part of it resulting in a net-zero magnetic field and the release of the load. This means that these magnets do not need electric power to hold loads in the air, and in case of power failure, the load will remain attached to the magnet. Electro-permanent lifting magnets appear as battery-powered models and as mains electricity versions. In the UK, Lifting Safety of Leeds offers models with capacities of 1,250kg to 2,400kg. Spanish company Airpes (now part of the Crosby Group) has a modular electro-permanent magnet system thaat allows an increasing or decreasing number of magnets according to the needs of each lift. The system also allows pre-programming to adapt the magnets to the type or shape of object or material that needs to be lifted – a plate, a pole a coil, or round or flat objects. The lifting beams that support the magnets are custom-designed and can be telescopic (hydraulic or mechanically operated) or fixed beams.
They can be adapted to high service factor plants, harsh environments such as high temperatures, and can be upgraded to perform extra functions such as data collection, integrated load weighing and wireless transmission.
That might perhaps have begun to scratch the surface of devices that you can attach below your hook. The conclusion would be that whatever your load, and however awkward it may be to handle, there is, somewhere out there, an attachment that will lift it.
