Solution Summary: Quick-Threading Lock Nuts
When you tighten a standard lock nut around the thread on a long rod, you have to twist your hand, wrist, and forearm over and over. Making these twisting movements can strain the muscles and tendons in your hand, wrist, and elbow. The strain can become more serious if you do this work a lot and you repeat the same movements for a long period of time. You can eventually develop pain and even a serious injury.
Your chance of injury depends on the amount of finger pressure you use to hold the nut, the distance the nut is threaded, and the number of nuts threaded. Working in positions where you have to reach above your shoulders to thread the nut increases your chance of injury.
The photos below provide an example the problem (conventional tightening of nut on all thread) and a solution (slip on lock nuts):
Description:
When you tighten a standard lock nut around the thread on a long rod, you have to twist your hand, wrist, and forearm over and over. Making these twisting movements can strain the muscles and tendons in your hand, wrist, and elbow. The strain can become more serious if you do this work a lot and you repeat the same movements for a long period of time. You can eventually develop pain and even a serious injury.
Your chance of injury depends on the amount of finger pressure you use to hold the nut, the distance the nut is threaded, and the number of nuts threaded. Working in positions where you have to reach above your shoulders to thread the nut increases your chance of injury.
The photos below provide an example the problem (conventional tightening of nut on all thread) and a solution (slip on lock nuts):
(Photo courtesy of NIOSH)
(Photo courtesy of NIOSH)
There are two types of quick-threading lock nuts—Slip-On® Lock Nuts and Morton Button Thread Nuts. The Slip-On® types have two parts. You twist the two sections of the nut apart until the slot is open, then place the nut on the all-thread rod where you need it. Then twist the two sections together again until the slot is closed and the sections are snug against each other. Finally, tighten the nut with a wrench until the openings on the two sections face in opposite directions.
Morton Button Thread Nuts slide up and down the all-thread rod. You first push the button to loosen the nut from the thread. Then slide the nut to the spot you want. Let go of the button to make the nut reconnect with the thread. Then tighten it as you would any nut.
Risks Addressed:
Strain to the muscles and tendons in your hand, wrist and elbow.How Risks are Reduced:
Use a quick-threading lock nut. Depending on the type of nut, these can either snap onto an all-thread rod at any position, or slide up and down the rod freely. They eliminate the repeated hand, wrist, forearm, and elbow twisting. They can also reduce the time you spend working above your shoulders because they go on faster.
If you reduce exposures such as the number of repetitions, frequency, and force in a repetitive wrist and finger movement, and reduce the duration of work overhead, then the probability of injury should be reduced.
Effects on Productivity:
Using quick-threading lock nuts should reduce the strain on your hand, wrist, and forearm. It should therefore lessen the chance of pain and musculoskeletal injury. Because you spend less time working above your shoulders, there is also less overall strain on your shoulders, neck, and back during a shift.
In addition, these nuts should lead to a gain in productivity because they take less time. They make certain kinds of work much easier, such as threading nuts in locations that are diffcult to access. Quick-threading lock nuts may not be appropriate for all jobs, and their use may require the approval of the building owner, architect, engineer, or general contractor.
