Maintenance & Repair.

Q. A few weeks ago, we did an engine tune-up for one of our regular customers on an older model gasoline engine tractor. Recently he was in complaining that, in his view, the tractor's performance was worse than it was before we did the tune-up, and further, it seem to be getting worse as time went by.

Concerned that perhaps we had in some way "goofed" on this job, we brought his tractor in for a recheck. We found that the ignition timing was significantly retarded. The customer vowed he had not even touched any of the related adjustments on the engine. We tend to believe him because he tends to call on us for even minor service work that many of our customers would probably do themselves. Any thoughts on what might be happening here?

A. As you no doubt realize, among the things that affect ignition timing is the gap at the ignition breaker points. Points are designed so that the wear rate of the rubbing block and of the contact surfaces should be equal and cancel each other, thus avoiding any effect on timing. However, in some instances, the two wear rates may exactly cancel and, with use, ignition timing is gradually retarded. Thus, the fix is to simply replace the ignition point set and adjust timing to the specified setting.

Q. When a customer is considering new equipment that has greater capacity than his present equipment, how do we explain to him up front -- and avoid future dissatisfaction -- that field capacity in terms of acres per hour will not necessarily increase in direct proportion to equipment size? As an illustrative example, why is it that an eight-row planter will not plant four times as many acres per hour as will a two-row planter if both are operated at the same speed?

A. The potential capability of any piece of equipment is realized only when, and if, the machine is in actual operation. In the cage of the example corn planter, consider the time lost in turning at the row ends and in refilling the planter with seed and fertilizer. If the eight-row planter could be filled in exactly the same time as the two-row planter, and if the same time were required for turning at the row ends, the capacity of the eight-row rig would be four times as great. Thus for the customer to realize the benefits of higher capacity equipment, he must plan his operation to keep down time to the lowest possible percentage of field time.

Q. When on service calls, I occasionally encounter a farmer using a log chain to hitch to a load, with the chain attached to the tractor above the drawbar, usually wrapped around the rear axle housing. When I try to tactfully point out that this can be a dangerous procedure, he usually claims that the tractor "pulls better" than it does if he hitches to the drawbar. "Besides," he says, "if the tractor is going to tip over backwards, it rotates around the rear axle." I know this is a dangerous practice, but can you help me better understand why it is, so that I may be able to convince those who choose to do this?

A. The reason the farmer thinks that his tractor pulls better is the result of the greater weight transfer to the rear wheels that he is obtaining. However, therein lies the danger, because excessive weight transfer increases the tendency of the front of the tractor to raise off the ground when the tractor is pulling. And, a rearward tipping tractor rotates around the point of contact between the rear tires and the ground, not around the rear axle. You can think of the rearward tipping as the tendency of the tractor to pivot around this point of contact. The higher the hitch point, the longer lever the rearward force has with which to attempt to raise the front wheels.

Q. Is there any harm in operating a tractor in the summertime without a thermostat? A few of our customers insist that it's actually "better" for the tractor.

A. A thermostat should be used the year around so that the engine will reach operating temperature as quickly as possible after it's started. Before reaching operating temperature, the gaseous products of combustion tend to condense into corrosive liquids in the exhaust system. Without the correct thermostat, the tractor may operate below correct operating temperature for excessively long periods, even during warm weather.

Send Mel Long your comments or question to: Implement & Tractor, 2302 W. 1st St., Cedar Falls, IA 50613; fax: [phone], email: [e-mail].