MANUAL CHAINS | FEATURE
THE HANDS-ON APPROACH
Lifting does not have to be done by electric, hydraulic or pneumatic machinery. There is still a role for old-fashioned muscle-power, as Julian Champkin discovers.
Come-Along, Pul-lift (which is a trademark of Yale, and should be used only for their products but frequently isn’t, in the same way as Hoover has become a generic name for Vacuum cleaner.) The first group all describe the same thing: a device where you pull on an endless chain which makes another endless chain lift the load. The second group describes a device where you pull up and down, or side to side, on a rachet lever, which in turn raises the load chain. Both sets are worked by human muscle.
T
hey come with different names: hand chain hoist, chain block, chain fall, block and tackle; or lever hoist, lever block hoist, ratchet hoist,
Electric power, battery power, hydraulic
power, pneumatic power... All have been and are used to supply energy for hoists, and all of them are useful and time-saving and convenient and efficient – in their place. Do they still leave a place for the man- or woman-powered chain hoist – or is that as dead as the dodo, old-fashioned, yesterday’s tech, no longer needed in the all-singing, digital mechanised brave new world of now? Have we grown lazy, or should we use our own muscles more – or is that injurious to health, to safety and to the well-being of the people who are charged with moving objects from A to B in a factory or warehouse or place of employment?
Should one then opt for a powered hoist
or a manual one? There are places where manpower is still the best option – and some of them are unexpected. Perhaps surprisingly, the weight of the load is not the limiting factor. The force with which anyone can pull down on a chain is obviously limited. (Just for starters you cannot usefully exert a downward force greater than your body-weight, because if you did the chain would stay still and your feet would leave the ground. Say that two- thirds of your body weight is the maximum downward pull that an average human being can reasonably exert; the average body-weight of a European male is around 85kg. I leave the reader to do the sum.) But chain hoists come with a built-in mechanical advantage which can multiply the exerted force many times to lift a heavier load. (The mechanical advantage can come from both the gearing ratios inside the block, and the number of chain falls – ie how many strands of chain support the hook.) Remarkably, there are manual chain hoists available which can lift 100 tons, by manpower alone. On-line suppliers Lifting Safety offer
A Tiger chain hoist at work on an ROV 28 | June 2024 |
www.hoistmagazine.com
one, available by special order, and it looks a monster. Hoists with marginally-more modest 50-ton capacities are standard and more widely available. Yale has its VSIII range, which comes in capacities from 750kg up to the aforementioned 50t; in that version it has 18 falls of load chain and a lift height of three metres. Tiger, which has a speciality in sub- sea lifting, has a 30-ton-capacity manual chain hoist specially designed to lift ROVs (Remotely Operated (underwater) vehicles – unmanned yellow submarines to the outside world) from the water. It has twin heads and 10 falls; a new feature is a hand-wheel for
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