Ask the Mechanic

By Steve Thompson, Contributing Columnist

READER: I have a John Deere 5510 that is playing tricks on me. It deals with the movement of the tractor. It has three ranges and three gears forward in each range. What happens is that I can start out in the tractor, and everything seems fine. Then, after a short while, the tractor begins to lose speed. I can stop and let it rest for a short while, and then it will go again then stop again. Can you help me figure this one out? I can leave on the tractor headed to the field, and then I have trouble getting back home.

STEVE: The problem is that your clutch is going out. I'll agree, these types of clutches will play tricks on anyone. It will hook up for a little while, but as the clutch lining warms up (dry clutch in this tractor), it will slip. It will go from hooked up to leaving you on the side of the road.

READER: I have always heard about the thrust side of the cylinder wall in an engine wearing at a faster rate than the rest of the cylinder wall. Can you tell me what thrust really is and where it comes from in an engine to cause more wear on one side of the cylinder, even though the piston is round?

STEVE: Thrust is defined as side force, and the thrust side of an engine cylinder wall receives major thrust when the piston is pushed down the cylinder on the power stroke by thousands of pounds of pressure from hot expanding gasses. At the same time, the piston receives resistance from the crankshaft through the rod attached to the crankshaft. Since the rod is not exactly perpendicular to the crankshaft during maximum explosion, the piston rocks to the major thrust side of the cylinder. If you are looking at the front of an engine that is rotating clockwise, the major thrust side of the cylinder wall will be on the left side. The cylinder wall also has a minor thrust side on the right side of the cylinder wall. This is caused by engine compression as the piston moves up on the compression stroke. However, it only has a few hundred pounds of pressure on the piston when it comes up on the compression stroke.

Great Idea! From Robert and William Horn, Waynesburg, Kentucky:

My brother and I struggle to get the pins in or out of the lacing on our round baler belts. One day, we were fighting the uncooperative pins and about to give up when we noticed we had accidentally left a cordless drill out from the last job. We turned the pin into a drill bit, and in a flash, the pin went right in with the help of a little penetrating oil. Then, we found that when we put it on an installed pin, it also came right out. Not only does this make changing lacing pins an easy job, but it also makes changing them out before they break a little more exciting -- if there is anything exciting about baler belts.

SAFETY TIP OF THE MONTH:

A die grinder looks like a harmless tool to use. However, without a shield in place, they are extremely dangerous. The die grinder works at speeds of about 20,000 rpm and, with a disc used for grinding or cutting, becomes very dangerous. The die grinder gets its name from the use of creating precise contours of dies or molds. Face shields and gloves are a must when using a die grinder. Always consult your welding supplier on how you plan to use your die grinder. Cutting discs come in different thicknesses and quality. Don't cut corners on these round discs.

Write Steve Thompson at Ask The Mechanic, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email mechanic@progressivefarmer.com.

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