Perhaps Giving It A Name Will Help Us To More Readily Recognize The Line-Of Fire, Balance And Ergonomic Risks Associated With Performing Certain Tasks.
By Randy Logsdon
The material is a bit too wet and it’s building up on the chute. It doesn’t happen that often, but frequently enough that the operator knows how to free-up the blockage. The dings and dents on the outside of the chute attest to the use of a sledge hammer to shake the caked material from the inside of the chute.
So once again the operator dons his gloves, picks up the sledge hammer and approaches the makeshift stand that will permit access to the chute. It’s a kind of a sideways swing, not unlike a batter reaching for a low fastball. He strikes the chute once, twice, three times. He’s making progress. One more hit should finish the job.
As he delivers that final swing, the grip loosens at his right hand. The sledge hammer misses the target, and the handle of the sledge crushes his left fingers against the supporting structure.
At the same time, in the maintenance shop of another operation, a mechanic is struggling to remove a rusted bolt. He’s applied some penetrating oil and is about to try one more time to loosen the nut.
He applies gentle pressure at first, more to test it than for any hope that the nut will turn that easily. He tries a bit harder, applying some body weight behind his grip on the wrench handle. Giving the effort a little bounce, he hopes against hope that the bond between the bolt and the nut will break. Suddenly it does break loose and the mechanic falls to the floor, but not before he struck his hand against the table vise peeling the skin back on three knuckles.
At still another plant, an electrician is tasked with replacing the power cable for a vibrator. Cables to this and other equipment in the area are neatly bundled with zip ties back to the MCC about 150 ft. away. The new power cable will have to replace the old cable in that bundle.
He has just picked up a supply of new zip ties to replace the ones he will need to cut away as he makes the cable exchange. Starting at the MCC, he realizes that he left his side cuts at the vibrator. Momentarily he considers walking the 150 ft. to retrieve the tool but then realizes that he has a good pocket knife that will cut the ties easily.
The first two pop off nicely. Just a couple more, and he can begin to swap cables and progressively re-secure the bundle. But the cable bundle appears to have a slight twist, and he’s forced to apply the knife at an awkward angle. He repositions to get better leverage and proceeds to pull the knife back through the zip tie. It takes a bit more force, but suddenly it snaps. The knife breaks away and slices across the electrician’s right wrist.
Procedure and Safeguards
We have established elaborate procedures and safeguards to help control and to provide protection from the many energy sources that are required on the course of our work in mining. We have reliable means to control in the form of electricity, hydraulics, mechanical, compressed air and even radiation.
In our focus on the obvious potential for harm from these sources, we can easily neglect the potential damaging effect of human energy – the energy that we personally apply to a task. The unexpected, uncontrolled release of human energy can also lead to serious injury as depicted by the scenarios described above.
Mechanics have recognized the phenomenon for ages. The second scenario describes what mechanics describe as a “knuckle-buster.” But the same human energy control principles apply to any number of tasks that involve the act of an individual applying force to accomplish an objective. Perhaps giving it a name will help us to more readily recognize the line-of fire, balance and ergonomic risks associated with performing some of these tasks.
I’m calling it the “Knuckle-Buster Effect.”