If you’ve ever worked around a tractor-trailer, then you’re likely familiar with the pain of pulling a tandem axle pin. Just getting to the pin can be a challenge. Once you’ve successfully made your way to the pin, you have to pull and push it into position. In my experience on-site with our clients, I’ve adjusted enough pins to learn that they don’t all slide and glide as easily as we want them to. This inconsistency often leads to injuries among the hard-working folks who pull axle pins on a daily basis.

Don’t get me wrong, the pin was designed for a specific purpose and makes the job easier than it would be without it; it’s an example of ergonomics. But, “ergonomics” is a word people throw around a lot without fully understanding what it means. OSHA sums it up nicely as, “...fitting a job to a person.” Ergonomics are great! Why not try to engineer as much of the risk out of the environment as possible? But until every single trailer on the road has an automatic tandem, drivers are still going to have to adjust these pins manually. At the end of the day, a person still has to interact with the environment that’s been engineered or “fit” to them. So how do we prevent injuries if drivers are still climbing under the truck every day? While I’ve pulled my fair share of pins, I’m not a professional driver; my area of expertise is human movement. To me, the solution to this pin problem starts with considering how our drivers are moving in and interacting with their environment. Simply understanding the difference between a strong body position and weak one can significantly reduce the number of musculoskeletal injuries that occur when pulling the pin. From there, knowing how to apply strong movement technique to the task will reduce those injuries further.

It’s less complicated than it sounds. Here are 2 quick tips that I’ve found can make this job a lot less painful:


I want you to feel what I’m talking about, so try this: Lift your arms out in front of you and imagine that you’re holding a pencil on either end. Now, snap the pencil in half. Let me guess, you ended up with a “thumbs up” position, right? Why is that? Everyone breaks the pencil in this direction because this is how our bodies were designed to move. You are able to exert minimal effort and engage the large muscles in the shoulder. Try breaking it the other direction so that you end with a “thumbs down” position. Can you feel the muscles engage or are you just hanging on the shoulders, giving yourself a chicken wing like a bully on the playground? This is a weak position.

I want you to feel the difference because achieving this “thumbs up” position is really just you rotating your elbows in. This rotation is important because of its relationship to your shoulders. As you rotate your elbows in, you’re able to set your shoulders back and down into a strong position; one that engages your muscles and prepares you to do work. So when it’s time to push or pull the pin, as you grab the handle, you should focus on rotating your elbow in to help set your shoulders back and down, in a strong, safe position. When your elbows are up and out, and your shoulders are “dumped” forward, we see an increased likelihood of injury. Remember how sketchy it felt to break an imaginary pencil this way? As you know, the pin is going to provide a lot more resistance than a pencil, so the stakes are a lot higher. Why give yourself a chicken wing and crank on the handle when you can just keep your elbows rotated in and shoulders back and down?


Now that we understand what a strong position for the task of pulling feels like, we need to think about the actual act of pulling. Don’t just “grip and rip”! At any given stop, we can’t know the exact resistance we are going to get from the pin. Maybe it’s a brand new pin and only provides 10 pounds of resistance. No big deal. Maybe it’s an older trailer and the pin is bent slightly, providing closer to 100 pounds of resistance. If you get under that old trailer and suddenly yank on the pin, in the event of a jam, you’ll be pulled into a weak, injury-causing position. That said, it is possible to fail safely. Establishing a strong position and applying power gradually allows you to determine whether or not you can successfully adjust the pin. If the pin isn’t going anywhere, well, you’ve still maintained strong positions and avoided injury.

The human body is an amazing and extremely complex system, however you don’t have to overthink to work in strong positions and get home safely. Try practicing these two simple strategies the next time you pull a tandem axle pin and feel the difference it can make throughout the course of a shift, week, month, and career.

By: Worklete
Tags: Movement Matters

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