John Deere has also increased filter performance on new equipment because of concerns about fuel contaminants. While investigating fuel injector problems, field service representative Greg Clampitt, from Deere''s Waterloo, Iowa, Engine Works, discovered good reason for that concern.Clampitt used fuel testing equipment on tractors operating in several states. The equipment counted particles as small as 2 microns both before and after the fuel filtration system (see chart below).Surprising results"The results were surprising, and we think they relate to fuel storage and handling," says Clampitt. "We tested tractors in Texas and, on average, found 25 times more particles carheaterquit in the 2-to 5-micron size range than on tractors tested in Iowa. There were 40 times more particles from 5 to 15 microns in size in Texas. Results from tests on tractors in Arizona and California fell between the Texas and Iowa findings.

The Chicago Pneumatic Air carheaterquit Scribe is a bit noisy and also produces quite a bit of dust and grit as it disintegrates the rock matrix, making both a dust mask and ear protectors necessary when the unit is in use outside a dust-collecting chamber. A silencer that fits snugly around the hand-held unit is not available from the manufacturers but can easily be made with a few common household tools. By cutting a piece of metal tubing to the length of the air scribe''s handpiece and notching one end so that it can be crimped to conform to the tapered bit end of the tool, a very simple noise insulator is produced. A foam rubber plug inserted in the bit end forms a snug fit. The only disadvantage to this noise protection is that the natural stream of air emitted from the tool end is blocked, and dust is not readily blown off the working surface. Likely some innovative tinkerer will soon solve this problem. Simple ear plugs or muffs are adequate to help provide hearing protection. Another minor problem with the air scribes is the absolute necessity of lubrication. Producing an effective reciprocal motion to any tool involves very complex valves and close-fitting parts. This is especially true when the tool is designed to be very small. Depending on the duration of use, an air scribe must be oiled from once to several times per day. This involves shutting down the system, dismantling the air supply, and inserting several drops of high-quality air-tool oil. In-line oiling systems are available that can make this process far simpler. Additionally, regularly flushing the unit with oil will eliminate microscopic particles of metal and grit and will greatly extend the life of your air scribe. Sandblasting

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