A properly maintained hoist, used as it should be by a trained and competent operator, is generally speaking a safe machine. Nevertheless its purpose is to lift a load to a height, which is an inherently dangerous situation. Regulations on the construction and use of hoists, and a generally greater awareness of risk, have in recent years reduced the number of workplace accidents involving lifting gear; even so, accidents still happen, as the recent examples of OSHA reports from the past 18 months show – and OSHA has several others from the same period. They include non-fatal injuries ranging from amputated fingers and toes to a crushed pelvis.
In the US, ASME is the body that sets standards. In the UK, the Lifting Operations and Lifting Equipment Regulations, commonly known as LOLER, is the relevant safety legislation. These, and other regulations in force elsewhere, generally cover the same ground.
Most of the safety precautions for operating a hoist are common sense ones: plan your lift ahead of time, make sure the machine is in good condition before you use it, do not make it lift anything heavier than its safe working load, ensure that the load is securely attached, and make sure also no one can walk underneath a suspended load. The regulations put these and other requirements into formal language and they add another one: make sure the operator is properly trained.
In the UK that last requirement, like the other LOLER directives, is the responsibility of the employer, whether or not he owns the hoist directly. Employees do not have specific duties under LOLER but they do have general duties under the Health and Safety at Work (HSW) Act and the Management of Health and Safety at Work Regulations 1999 (the Management Regulations). These require employees to take reasonable care of themselves and others who may be affected by their actions, and to co-operate with others.
The UK Regulations cover workplaces where the HSW Act applies. These include factories, offshore installations, agricultural premises, offices, shops, hospitals, hotels, and places of entertainment.
An obvious disclaimer here: Everything in this article is an outline survey only: it is by no means exhaustive. Any owner or operator of a hoist should satisfy themselves that they are complying with all relevant legislation, and are taking all sensible precautions, when operating a hoist.
We have mentioned that the hoist must be in good working order. That means it has to be inspected. In the UK, inspections must take place at least annually, by a competent person, who must submit a report to the employer to take any appropriate action. If the hoist is used to lift people, that inspection must take place more frequently, at least every six months.
Fixed safety guards, clear markings, emergency stop controls within easy reach, and equipment being well maintained are also mentioned in the LOLER document ‘Lifting Equipment at work – a brief guide’ – downloadable free from https://www.hse.gov.uk/pubns/indg290.htm.
LOLER themselves summarise it as: ‘Safe lifting needs to be properly planned by a competent person, appropriately supervised and carried out safely. Any equipment you use must have been properly designed, manufactured and tested. Don’t forget maintenance.’
MAINTENANCE:
Those last three words may seem like an afterthought, but they are not. ‘Unsafe maintenance has caused many fatalities and serious injuries either during the maintenance or to those using the badly or wrongly maintained/repaired equipment’ is how the LOLER guide expands on it. This is one area where digitisation, Industry 4.0 and the Internet of Things (IoT) has brought improvements. Big Data collection applied to information from sensors on hoists routinely now gathers data on weights lifted, speeds, hours of use, lubrication, wear on wheel rims and dozens of other parameters and sends it to software which collates and analyses it to produce predictive maintenance schedules – warning operators of parts which need repair or replacement well ahead of any actual failure.
Another area where digital automation has increased safety is in collision avoidance. No-fly zones can be programmed into the control systems of a hoist. They prevent it and its load approaching too close to a wall or internal structure or building, or to walkway routes which pedestrians may be using. Columbus McKinnon’s Magnetek LaserGuard Mini collision avoidance system, for example, allows distances – such as the layout of the factory walls – to be programmed directly via a PC or tablet into the software, where it is combined with distance data from the laser sensor device. A dual set-point sensor gives an initial slowdown point, and then a stopping point if the hoist is on a collision course.
More advanced options such as their LaserGuard 2 have self-monitoring optical lasers that automatically relay required adjustment information to cranes to prevent crane-to-crane and crane-to-walls collisions.
Since the system is wireless, parameters and active zones can be changed in real time from the plant floor as changing process, plant, or crane conditions require.
Where two or more gantry cranes use the same runway sensing systems can detect near approaches and automatically bring one or both cranes to a stop.
Demag’s Smart Safety Control system gives independent and continuous monitoring of a crane; it uses a ‘largely redundant’ control concept to bring both cranes to a standstill independently if any irregularities occur. Potentially dangerous conditions can be identified and prevented in advance. The cranes can be intuitively controlled by radio, which is also very efficient; the safety control system combined with radio control can ensure gentle handling and precise positioning and set-down of loads – which also increases safety. Note that two of the OSHA-reported fatalities at the start of this article occurred when an operator tried to adjust the set-down position of the load; in at least one of these cases it would seem he was attempting to do this by hand.
Anti-load-sway technology is a similar digital control technology, designed to improve efficiency and make operating a hoist easier for all but the most skilled of operatives, but which delivers safety gains as well. Similarly, vertical lifting control, otherwise known as off-centre pick prevention, automatically prevents a hoist from lifting a load from the ground at an angle. It will not let lifting start unless the hook is directly over the load, preventing dragging and subsequent swinging as the load leaves the floor. A heavy load swinging wildly at the end of a chain is clearly not something that is advisable, especially at head height on a potentially busy factory floor. These are increasingly inexpensive systems to install and if are not yet the norm they are certainly now everyday fitments to any new hoist, and can be retro-fitted as well.
BELOW-THE-HOOK
There is another link in the load-path that is easy to overlook but which is just as important: it is the below-the-hook device that attaches the load to the hook. (Again, see the part that this played in the second of our reported OSHA fatalities, even though in that case the below-the-hook device behaved as it was designed to.) Slings, shackles, rigging hardware, even vacuum lifters are all included here.
Henry Brozyna is an industry product trainer at Columbus McKinnon specializing in crane and hoist inspection and repair, rigging, and load securement; he is also a former member of the Board of Directors for the WSTDA (Web Sling & Tie Down Association) , which writes the standards that are used by the material handling industry, the transportation industry, and also law enforcement.
“In the US, when it comes to below-the- hook lifters, there are standards in place, including ASME B30.20 and BTH-1, that outline the design, manufacture, use and inspection of this equipment,” he says. Riggers and operators frequently attach the load to the hook onsite using combinations of slings, shackles and spreaders. “While many of these lifters are “homemade,” that in itself does not disqualify them from service,” says Broznya. “What typically disqualifies a lifter from service is the lack of labelling, ID tags or engineering to back up the design.
“ASME BTH-1 details the design” he says. “Two of the most important things that help dictate the design of a lifter are the load that will be lifted and the environment the lifter will be used in.
“The most common design classification is Design Category B, which has a minimum 3:1 safety factor. Design Category B should be designated when the magnitude and variation of loads applied to the lifter are not predictable or where the loading and environmental conditions are severe or not accurately defined. This category would include most engineered spreader beams.
“Once the design is established, BTH-1 specifies the lifter must be rated for a service class. The service class takes into account the number of load cycles a lifter will see during its lifespan.
“Every time a lifter is used, it flexes, and if it flexes enough times it will fracture – this is called Fatigue. Fatigue needs to be taken into consideration to ensure safety and long life of the lifter. Three questions that will help the engineer determine Fatigue and the Service Class of the lifter are: How long do you plan on using this lifter? How many times a day will the lifter be used? And: What capacity loads do you expect to be lifting? In BTH-1, the most common Service Class is 2, which rates the lifter for 100,001 – 500,000 load cycles.”
“Once the lifter is designed and built, it must be tagged. If a lifter weighs more than 100 lbs., the weight of the lifter must appear on the tag. The tag is a very important part of any lifter. It shows who built it, what its Working Load Limit (WLL) is and the design criteria used. If the lifter employs motors, electrical information must also appear in the tag, including amps and voltage requirements.”
Although safety in lifting may seem to be largely common sense, it also requires the best of design and technology, the best in training, and ceaseless vigilance at all times. As the OSHA accident reports show, a moment’s inattention can bring appalling and irreversible harm.
“At 10am on August 05, 2021, an employee was moving material with a P&H 15 ton overhead crane. The employee was struck by the load while moving the crane. The employee was attempting to adjust the load, of 5 round steel bars weighing approximately 3,700 pounds,(1.7t) after placing the load in the nesting area. The employee was operating the overhead crane and during the work assignment the load became dislodged and struck the employee. The employee died from the blunt force trauma injuries sustained. No other employees were involved in the work operation.”
OSHA accident report number 137886.015 Employee Is Killed When Struck By Steel Bars
“At 11:30am on July 10, 2021, an employee was using a North American Industrial, 7.5-ton bridge crane to move two stone slabs weighing 800-1000 pounds (360 – 450kg) each across an aisle to consolidate similar product together. The employee was operating the crane using the crane controls. The load was moved into position at the storage rack and lowered. When the load was fully lowered, the Little Giant Lifter, model ALG75, clamp opened as designed. The slabs were still in the upright position when they slipped out of the clamp and fell toward the employee. The slabs struck the employee and killed him.”
OSHA accident report number 137102.015 Employee Is Killed When Struck By Stone Slabs
“At 9:30pm on April 21, 2021, an employee was using an overhead crane to set a press die on a bolster. While attempting to adjust the die’s position on the bolster, the die swung out toward the press crushing the employee between the die and the press. The employee died from his injuries.”
OSHA accident report number 135004.015 Employee Is Killed When Struck By Swinging Press Die
LOWERING IS SAFER
All work at height involves serious risks for both workers and their employers. You can give some protection by using safety harnesses and the like. Or you can avoid the risk altogether by not having people working at height at all. You don’t need to employ robots or remote-control to do it, just a little lateral thinking: instead of raising the operative to the object they are working on, you lower the object to the ground and let them work on it there.
Lighting fixtures in public buildings are a typical example. Bulbs may need changing, the entire fixture will need regular cleaning. The usual method is to construct a scaffold tower or use a mobile elevating work platform such as a scissor lift.
A lighting lift is a self-contained winch that instead lowers and raises chandeliers and other types of luminaire or sculptures to give ground-level access for cleaning and maintenance.
Rather than incorporating a general-use winch system, lighting lifts are specially designed to completely hide the winch mechanism, usually in the space above the ceiling. This is important since installations are commonly in historic or architecturally-important building such as theatres and cathedrals. As well as safety, other advantages are cost – operatives do not need expensive working-at- height training – and savings in job and disruption time: large areas of a palace or museum need not be cordoned off from public access for long periods while the task is undertaken.
Most light lifts are tailored to the individual chandelier and the building infrastructure. Contact Suspension Units safely lock the chandelier to the ceiling when raised. At this point, the electrical connection is automatically made, and a ‘mechanical lock’ is formed which acts as a failsafe. They are operated by a remote, hand operated, or motorised winch; a series of pulleys carry the wire cable along designated rope runs. Once a light lift is installed, a single employee is able to easily lower the chandelier in minutes.
Leeds Town Hall is an historic building at the heart of Leeds City Centre, originally built in 1858 and now used as a concert, dance and dinner venue. It has seven ornate chandeliers, each weighing around 600kg. The original builders had installed a hand-cranked lowering system for them; each was operated by three men from precarious wooden walkways in the roof void. “It could take a week to lower them all, another week to clean them, and then yet another week to raise them all back into place,” says Simon Stockton, the Town Hall’s operations manager. This costly annual clean left the popular Victoria Hall unusable during that time.
Not only did it pose a safety threat to the team carrying out the work, but there was no protection in place for the chandelier itself, meaning they could hit the ground at speed through human error. The chandeliers are rooted in the history of the building; it was essential to have an automatic stop system to prevent damage. As an historic building, it was also crucial to keep the installation neat without obscuring the ornate décor.
To solve these issues Penny Hydraulics installed its chandelier winch system. One man can lower the chandeliers in minutes, using a hand-help remote control. Automatic stop mechanisms on the chandeliers prevent ground impact. "The system improved safety for our staff. It also cuts annual cleaning and maintenance time down to just one week and frees up staff for other duties and gives more time for the venues to be used,” says Stockton.
