Preventive Maintenance for Sweepers
Mechanics and operators work together.by Steve Miller
Steve Miller, fleet manager for Mountain View, California, would much rather keep problems from occurring than to patch things up afterward. His thought-provoking approach makes good reading for anyone who would like to find ways to get more out of their own equipment or personnel.
When I talk about having a sweeper maintenance program that is pro-active, it means that I don't wait for the dent and then pound it out. I don't want it there in the first place. Let me relate to sweeper curtain maintenance, as an example: If I make sure that everyone involved in the process knows what the curtain does and what will wear it out prematurely, then we'll be better able to avoid poor sweeping. Proactivity is also knowing what down-pressure means and how that relates to wear. It's really knowing how the total machine works.
The only way to make that happen, however, is for everybody to have a really clear understanding of how that sweeper operates. I want both mechanics and operators to know why we chose this sweeper, why we have this kind of adjustment, why we bought this option and how it was intended to work, what we'd like to see happen as far as its maintenance cost, maximum engine speeds, gear selection, etc. Then, I want constant feedback. If something doesn't work the way we think it's going to work, then with the proper feedback loop we can correct the problem.
Proactivity also means questioning. When somebody says, "We sweep at four miles per hour," for example, that doesn't make any sense at all. What makes sense is, "We sweep as fast as we can to still keep the quality of sweeping high without jeopardizing safety." To tell an operator to sweep at 4 miles per hour is not the pro-active presentation you would want to have. The machine should be run such that it safely does the job at a combination of the highest possible speed and the lowest possible cost. Then, make sure that when the operator sees a different sweeping condition up ahead he knows what changes to adjustments and speed he needs to make.
That's why we make sure that even an experienced operator we might hire from another city knows a lot about how our equipment works, what he can do to make it better so he can sweep up more material - effectively and efficiently. We've learned that by doing so we are sweeping up more tons of material at lower operating costs. We can actually do more work for less money.
That's something I like in working with the management of the people who make our sweepers - I want a continual feedback. I want to know how other people are using the same machine; the adjustments and items to look for. It was through that process that we realized how very important downward pressure on the head was to the life of the skids and the sweeping curtains. Because a sweeper changes frame heights as it's loaded, it becomes very difficult to make the machine adjust exactly to the varying conditions. This factor makes it harder to make the head counterbalance and adjust so that you can get better wear - to make adjustments for the dynamic situation.
It's very difficult when you have a huge sweeping head that weighs hundreds of pounds. In working with my manufacturer, we came up with the idea of determining an ideal weight onto the pavement (down-pressure). We decided that our standard for each corner of the head was fifty pounds of pressure in order to lift the head off the pavement. So we simply bought a fish scale that goes up past fifty pounds, and it is very easy to hook that to the head and lift up on it to get what the downward pressure is. Now, we can be accurate in terms of overall down-pressure, as well as per individual corner, and we are able to be in control in terms of counterbalancing the springs.
The balance is very important, because you want to be able to raise the front of the head prior to raising the entire head. The reason for that is to be able to accept large quantities of materials such as leaves without pushing them in front of the sweeper. So, in working with these balances and the spring tension we came up with a good setting. It allows the operator to raise the head and still maintain the proper angle.
We also realized that the skids that the head rides on, which are pretty expensive, are something we would like to maximize the life on. So, we put some stops on the outside of the sweeping head so that we would never have the skids raised high enough for damage to the blast orifices to occur. It also gives an easily visible measurement as to where we are in the adjustment process, and what increments we are making them in. An important part of this process is that we work very closely with our sweeper operators all the time. They absolutely know how the machine works, what we are doing, what we are trying to accomplish. We'll try an adjustment and then they'll test it and come back and tell us how it worked.
So many times I think that management doesn't take the time to make sure that operators know how their sweeper actually works, the big picture. Realizing that the curtain life was very important, because it's expensive and involves considerable down-time, we actually had the sweeper operator come and observe and help when we changed the curtains. That way he could see what was going on, the real nuts and bolts of how it works. We also make the adjustments in very fine increments of an 1/8 of an inch at a time, so that we could get the adjustment to the exact right point. That's where there is just enough contact in the curtains to maintain proper sweeping but not so much contact that they wear too quickly.
Through this education, understanding, and experimentation, we got to the point where we doubled the curtain life the first time and we doubled it a second time. And it's as a result of having the sweeper operators staying in close contact with us. Operators should be really comfortable with finding out what works the best for the machine in all sweeping conditions. I think the whole secret to it is that we have both the operators and the mechanics working very closely together toward common goals: to do the best job at the least possible cost; reducing the wear rate to as low as it can possibly become.
This article is reprinted from American Sweeper magazine, v3 n3.
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