
How to Make Sure Your Camera Tractor can go the Distance
There are strategies, techniques, and technologies to help your camera tractor travel further in the pipeline during inspections. We all know that sewer pipelines are not the most hospitable environment to be sending a robotic crawler into, and conditions inside the pipe can result in loss of traction and reduced performance of the inspection system.
The first, and perhaps the most important thing you can do is clean the pipe prior to inspection if it is dirty. Over the years I’ve heard many clients complain about doing this. I understand that the cleaning crew might not be readily available, but the purpose of an inspection is to look at the pipe for defects. To do this, the pipe should be clean, so that you can see those defects clearly. Inspecting an extremely dirty pipe is somewhat useless as debris and dirt is covering up the things you want to look for, and you already know it needs cleaning the moment you see the poor condition of the pipe. Sometimes it is unavoidable, but whenever possible, clean the pipe. If you cannot clean the pipe effectively or conditions within the pipe are not optimal, then you need to rely on setting up your robotic crawler effectively so that you have the best chance of success.
Sewer inspection robots should be manufactured to be heavy with a low center of gravity, and you will need to choose and install the right wheels and spacers to position the crawler in the right position within the pipeline. The goal is to produce the most traction possible when weight and wheelset are combined. Sewer camera systems are not under the same conditions as a car or truck, but you take some valuable lessons from larger vehicles. For example, when your pickup truck is losing rear traction, you add weight to the bed. Sometimes adding additional weights to a sewer crawler is a good idea as it increases traction in slippery conditions, just like that weight in the back of your truck.
Wheel and tire selection is important. Your camera manufacturer should provide all manner of wheels designed for different applications. Large pneumatic wheels that grip and propel over larger debris, granulated rubber wheels that have a rough surface to help in grease, or knobbed wheels to help climb over offset joints or debris. The selection of these wheels for the individual application is more of an art than a science, but just make sure that you have different wheelsets available, so that if you encounter these conditions, you have the tools you need.
Most every camera system is designed as a tethered system, with the cable being pulled in by the tractor. The cable, robot and cable drum should all work in concert to maximize your available pulling power. This is an often-overlooked part of the system that has a tremendous effect on the distance your system can travel. As the crawler pulls cable into the pipeline, it becomes responsible for pulling more and more cable. The weight of the cable, and the drag it is encountering on the pipe surface become greater and greater until the system can no longer pull it down the line. That is why you want a heavy crawler set up to maximize traction and pulling force, a light cable that minimizes the amount of weight needing pulled, a cable with a coating that minimizes drag, a downhole roller system to further reduce drag on the cable as it enters the pipe, and if possible a synchronized cable drum that is smart enough to both pay out and retract cable so that the system isn’t fighting itself.
As with any technological system, there is rarely any one solution to a given challenge. The best you can do is understand your system’s capabilities and make sure that you have a few extra tools in your toolbox. Having a few various wheel systems and maintaining your equipment well is the first step to maximizing your performance. Also don’t forget that the cable has as much to do with the distance you travel as the robotic crawler does. Keeping that cable clean and supported by rollers to reduce drag will not only reduce potential damage but will give you consistently better performance.
Matthew W. Sutton, RapidView IBAK North America