I have been in the market for some time to get hold of some winch lighting/speaker stands, I spotted a pair of Adam Hall SWU 400 T Winch stands for sale on eBay. For the un-informed, these stands are of telescopic design, and approx 4m in max height with a lifting capacity of 85kg. I purchased the stands with the intention of replacing the wire rope straight away, however the wire rope was already damaged on both stands. I contacted Adam Hall's support team asking for any exploded diagrams, or wire rope specifications. I received a prompt response but they were not able to supply any of that information for "safety reasons". Fair enough I thought, they don't want in-experienced people repairing lifting equipment. So I proceeded to dismantle the stands, the wire to termination to winch was as expected (greater than 3 wraps around the drum) and acceptable, however I was very shocked by the method employed to terminate the wire rope to the stand. The engineering team at Adam Hall had unfortunately 'cheaped out' for lack of a better expression and terminated the end of the wire rope around a cross pin (granted it is a heavy duty pin) in the telescopic tube by using one wire rope clamp . Due to the lack of space within the tube, the wire rope experiences severe bending using their method of termination; definitely beyond any wire ropes specifications! Also the lack of space meant they could only fit one wire rope clamp, rather than the recommended three on lifting systems. It is likely that the method used would quite happily deal with the rated max load of 85kg, however dynamic loading can do interesting things to mechanical systems and it just did not 'look right'. A picture speaks a million words so I have included a few below taken during dis-assembly: I tried to sketch the path of the wire rope This discovery stunted the re-build of these stands, as I thought of an alternative method to terminate the wire rope, as I was not happy to re-build as they were. After discussions with my colleagues I decided to remove the cross pin completely and replace with a mild steel 'bung' in the bottom of the tube with a eye bolt in the centre. (note: eyebolt shown in image was never used, a 'collar' forged one was used in the final assembly). The two 'bungs' were easily turned on a lathe within an hour or two. Replacement rigging hardware was purchased and 4mm 7x19 galvanised steel core rope was used to replace the old wire rope. Those with a keen eye will notice the side of the eyebolt have been filed flat slightly. This is to allow the eyebolt to fit into the tube. I mulled over this decision quite a lot, however the cross sectional area at each side of the eyebolt is still much greater than the size of the thread (M6 rated for 100 kg) The old cross pin was drilled out, ground flush, and bung installed. A small set screw keeps the bung in position. A small section of clear heatshrink is fitted around the rope where is passes through the tube to reduce wear. The stands are now ready to re-assemble and perform a quick load test ready for their first use on the road! (Featuring duck watering can) The benefit with the bung, is it allows for much easier annual inspections of the system without having to break the wire rope joint. Hopefully this forum post makes someone else at least aware of the potential design problem with the stands from the OEM. Stay safe!
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