Maintenance Man Math

One of the aspects of being an Industrial Technology teacher that I like the most is being able to cover a wide range of different topics and subject matter. There never seems to be a shortcoming of applicable class material to help prepare students for future careers in Industrial Technology. STEM curriculum has been incorporated into a lot of school curriculum and I fully endorse getting all students more involved in the areas of science, technology, engineering and math. Of course it is being taught using a wide variety of different methods depending on whether the teacher is endorsed in math, science, or technology. The important aspect of STEM curriculum to me is in helping students of all disciplines make the connection between the importance of knowing enough in all four subjects to be able to recognize how each applies to the other and why they "need to know" and conversely be able to do the math, science, engineering and technology that will be required for jobs in the future.
Math is one of those areas that a lot of students struggle with. A lot of research is being done into trying to determine reasons why students struggle so much with math. I have to admit that I am not real well versed on the research. I do tend to believe that in many cases it is because student's just can't relate to where they will need to use it. Most people don't really think about how much of industrial technologists and trades people rely on math every day to perform the job duties. One of the reasons why I prefer teaching industrial technology to science, math and engineering is that I am better prepared to explain the relevance of math, science and engineering to a group of individuals that need to learn industrial technology. These students usually have not excelled in applying math or science in the past and it is really a good feeling for me when I see the light bulb turn on and they "get" the reasons for doing the math in a real world problem.
So where does the maintenance man fit into my current diatribe you might ask? Most people probably don't think about maintenance men and their ability to do math but maintenance personnel use it everyday and without it a lot of our modern conveniences wouldn't continue to work and provide us with the hydraulics, pneumatics, air conditioning, working plumbing, elevators, and other services that we usually take for granted when we enter a building.
As an example I ask you to consider a simple "O" ring. Yes, there are many different sizes of "O" rings out there that are needed in residential, commercial and industrial settings. The maintenance man needs to be aware of the outer diameter (O.D.), inner diameter (I.D.), and a radial cross section or "thickness" of the o ring. This is usually pretty simple to figure out and just a matter of checking suppliers charts or the owners manual part list of the equipment needed to be repaired. Here's a link to a reference chart if you are interested http://www.allorings.com/size_cross_reference_framed.htm.  Not really much math other than recognizing the size and being able to measure size to insure proper selection. Unfortunately most maintenance men will tell you that a repair job is not always that easy and often times something as simple as a $0.35 o ring can stall a job and cause a lot of lost time by not having the right part. In a best case scenario, there is a preventive maintenance program in place that takes care of replacement parts before failure occurs but how does the maintenance man fix the equipment when failure has occurred, the o ring has broken and there is no owner's manual?

Here is an example of where knowing the math really comes into play.

 

This broken O ring needs to be replaced but I don't know what size I need. I need to take some measurements and apply my math abilities to this problem to get the part I need and make the repair. From the O ring size charts I know I need to have the O.D., I.D., an thickness of the part to order the replacement. Unfortunately this o ring in no longer a perfect circle so its not real easy to just measure the O.D. and I.D. I can try.

 

First I'll measure the longer side which is almost 6". Next I'll measure the shorter side.

That looks to be around 2-1/4". Hmm, I'll just average the two measurements out and split the difference to get the answer.

 No, that's too hard and just complicates things.


I'll just pull and stretch the o ring back into a circle before taking my measurement. 

 

 

Well that measures somewhere around 5-1/4". There is still a lot of guessing going on for my size here so I can either order several different sizes of O rings and hope I get the right one or I can step up my math game a bit and remember the relationship between diameters, radii and circumference and apply those equations to the one thing that I can take an exact measurement of the left over o ring on, the length of the  broken o ring.

 Remembering that circumference is a linear distance around a curve, I can use the distance measurement of the length of the broken O ring to determine the diameter of the O ring. That distance measures 14.5". My formula is C=2πr or in this case C=πDiameter. Plug in my numbers and I get 14.5"=(3.142) x diameter. Reduce the equation by dividing both sides by 3.142. 14.5"/3.142=diameter. Solving the equation gives me a diameter of 4.615 which is similar to 4.625 or 4-5/8" diameter O Ring.

 

This all seems pretty easy for me as I go through the math in my head to find out what I need to replace this part, but time and time again I have found that both high school students and adults in my corporate training classes are not able to do this math to get the answer they need. I've heard both educators, HR professionals and corporate trainers complain about the lack of these math skills when they get a new student in the class room. I don't know if it is that the individuals never really learned how to do it and where the math applied or if they just forgot over time from lack of use. Either way, it is a math skill that needs to be learned for success in Industrial technology applications so it is my job as a teacher/corporate trainer to make sure that individuals know how to do this math. The future of industrial technologists depend on it.

 

Oh and the next time you meet a maintenance man, take a moment and thank them for all they do to keep things running smoothly in the buildings you work in. They tend to be unsung heroes in my book.