It is crucial that we spread this knowledge throughout the lift industry and that it is communicated to the relevant lift users as well. If your supplier hasn’t been informed of your intention to load a goods hoist with a forklift, your goods hoist will not be compliant, and there is a serious risk of horrific injury.
“Surely you are exaggerating?” you might ask. Well, if you can guarantee, with complete certainty, that the forklift front wheels will never touch the goods hoist car under any circumstances, then yes. However, if the forklift front wheels might touch the car sill, then you have an issue.
“So if I have goods hoist with a 2500kg capacity and a forklift rated for the same load, how bad is it if just the front wheels enter the goods hoist? The back wheels won’t come in at all, just the front wheels.” Unfortunately, the front wheels of the forklift carry most of the load. For example, let’s say you have a Doosan B25X-7 forklift with a 2500kg capacity. If you have a 2500kg load on it, and the front wheels of the forklift enter the goods hoist car, you apply a load of…6275kg, or two and a half times your rated load…Your goods hoist was designed based on a potential overload of 10%, so 2750kg maximum mass inside the goods hoist. Let’s say the back wheels of the forklift enter the goods hoist as well. In this case, it only adds another 848kg, which compounds the problem for sure, but not to the same extent as the loading on the forklift’s front wheels.
“Are the goods hoist’s ropes going to snap then?” Fortunately not, provided that your ropes are in good condition. In South Africa, the goods hoist rope must have a minimum safety factor of 8 by law, and you aren’t even close to that load situation despite the significant overload. However, if your rope is quite old already and your tension equalisation system isn’t fully functional for whatever reason, if the rope is being bent around a tight radius or has experienced significant shock loading already, if the rope is going through lots of bends and has generally degraded over time/use, then it is possible that it could snap. Although this is still unlikely. Also, let’s not forget the thimbles, thimble supports, diverter pulleys and shafts…All of those are at risk too, along with the thimble springs which were not designed for the load they are experiencing.
“So then the goods hoist will briefly be overloaded, but it might still be fine, just non-compliant on the rope safety factor?” No. You may well break or at the very least shorten the life of one of the components mentioned above, but even if you don’t, you still have to consider the car frame, car base, guide rails, guide shoes, rope stretch, and the winding unit assembly. Additionally, if the worst were to happen and the goods hoist actually fell, the safety gear would need to stop a load that in most circumstances would exceed its rated load…
“Why would the guide rails be a problem?” One of the most common issues on lift drawings is that the horizontal loads on guide rails are often ignored/not shown. This is a significant issue for structural engineers, but that’s a topic for another time. Let’s say the forklift’s front wheels are positioned exactly on an imaginary line drawn between the guide rails on either side of the car, with the rear wheels of the forklift still outside of the car. In this case, the forklift will only cause horizontal loads during its braking/acceleration movements. However, if those front wheels are positioned somewhere near the car door/gate, that will create a moment on the goods hoist car which needs to be counteracted by a horizontal load at the guide shoe – guide rail interface. For most car sizes, this load will result in non-compliant guide rail setups based on the required safety factors for guide rail deflection and stress. The car frame must also be able to handle these loads, and since it was designed for a load that is just 40% of what is being applied, and based on a load distribution that was far less concentrated, most car frames are going to bend beyond their allowable limits, and will most likely fail completely.
“Okay that’s enough, I get it. So what can I do if I can’t run my facility without using forklifts to load my goods hoist?” If pallet jack loading truly isn’t viable, and your car dimensions are such that you can’t prevent the forklift front wheels from entering the car, the problem can only be partially resolved. Assuming that you can’t stop your facility again to strip out the under spec’d unit and replace it with a product that is compliant, safe, and fit for purpose, then you could reduce the capacity of your unit and the forklift that is loading it, and then upgrade the unit to suit the new requirement. The extent of the upgrade will depend on the unique situation and won’t necessarily be viable, but the option is worth exploring.
This upgrade will be extensive, so the natural approach will be to request quotes from multiple companies, which in itself is not an issue at all. However, the concern comes in when lift companies claim they can do the work, but their solution doesn’t actually involve any engineers, or alternatively involves external engineers who don’t operate in the lift industry on a daily basis and consequently do not know the relevant lift regulations/operations/assemblies well enough to produce a solution that is both safe and legally compliant. It will also be tempting to award the contract to the cheapest supplier since the project is likely significantly over budget at this point already. The risk, however, is that even after all of this hassle, you may well end up in the same position as before, where your unit is actually still a hazard, and still not compliant. To avoid this risk, it is highly recommended that you involve a reputable lift consulting company to assist, since they will know which lift companies in your area employ suitably qualified engineers and which companies are not actually equipped to run with a project with this kind of complexity. Additionally, it is also crucial that the painful lessons learned through this experience are communicated throughout your own company and to other companies who will undoubtedly end up in similar situations on their own properties.