This Safety Alert is being issued as a result of a recent chain shot accident on a harvesting site.
Chain shot can cause serious injury or death to the machine operator, ground personnel and bystanders. It occurs when the chain breaks within the harvesting head and ejects a piece or pieces of chain at high velocity (similar to the speed of a bullet).
Site pre-start check, picked up a radio glitch
As part of a standing sale thinning we had some roadside harvesting to undertake on a B road. Our estate staff were set up to do the traffic management (Stop/Go boards) whilst the contractor for a local timber merchant felled the trees within the roadside zone.
The signs where set up and the teams had just run through a tool box talk to go over the method of working when it was discovered that the transmit button on the short wave radios that were to be used to communicate with the traffic controllers and the harvesting operator was setting off the cut function on the harvester head. On discovering this we changed the radios to shorter range walkie talkie radios which presented no further problems.
I spoke to our Estate radio system supplier who had not come across the problem himself, but had heard of a similar radio system interfering with a rear linkage of an agricultural John Deere tractor and a pea harvester in Fife. He suggested that the problem may be down to inadequate screening in the harvester from radio interference. The harvester was a Ponsse.
While this incident is an agricultural one, it shows how a life changing accident would result in a large fine.
The Forestry Contracting Association has recently reported the death of a fitter while welding a wheel on a tractor. The risk from tyre explosions during inflation have been well publicised and large/industrial tyres should be inflated within a restraint. The risk from welding wheels with tyres still in place is less well known. As the rubber is heated a chemical reaction known as pyrolosis, which liberates hydrocarbon gases creating an explosive atmosphere.
The FCA Report:
“There is a theory that tyres which have been in place for a long time, which makes forestry machines likely to be affected, can contain a gas created when air and something in the tyre compound react over time. This gas can explode if ignited. The recommendation is that tyres should be removed, not just deflated, before using a gas torch, stick or mig welder or a disc cutter or grinder during any repairs. We did think this was a tad difficult to believe at first but it would appear evidence is mounting so we will be doing further research and will be back with more information in the future”
Thanks to the FCA for bringing this to the industry's attention.
For more information please see
FC Learning from Experience Alert