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Listening To Your Tractor: Part 4
by Curtis Von Fange
One of the strangest ways to communicate with our tractor is to ask it how it feels. "Ask it how it feels," you say? Yup, ask it how it feels. Now, as with the other articles in this series one has to be able to hear what 'ole blue' is trying to say in response. The nice thing about our old iron friends is that they are usually quite consistent in their response, rather unlike some people I know who might change what they say due to the weather or other mitigating circumstances. But since this isn't a people communications class let's look at a couple of examples pertaining to our equipment.
I had a great time bushogging in the pasture the other week. It was sunny and cool and the grass wasn't so long that the seeds got in the radiator and overheated the tractor. After cutting a number of acres I sensed an occasional vibration in the tractor that just didn't feel right. My 1964 Super Dexta was speaking to me and I needed to listen. I shut off the bushog and pulled up to the barn. After inspecting the bushog drivetrain I discovered that the hub that the bushog blades were connected to had loosed on the drive box shaft. The resulting up and down movement had wallowed out the mating tines on the gearbox shaft and created a dangerous vibration which could be felt throughout the tractor. Had I had ignored the vibration the shaft would have eventually sheared in two, sending the remaining pieces like missiles up towards the tractor. It was fortunate that my sensation of something wrong was felt in the 'bad' vibrations.
Other bad vibes felt on the tractor seat can, many times, be related to the PTO shaft operations. Dried out or worn universal joints can contribute substantially to that strange 'feel'. Universals that lack lubrication will freeze up with rust and dust. As they try to roll over as the PTO shaft rotates the bearings heat up and may seize in place creating a flat spot on the race. As the engine continues to force rotation of the shaft these flat spots create what feels like a détente in the normal spin of the bearing. This 'bump' can create a tremendous vibration in the power train that can carry through the entire tractor. If left un-repaired the universal will eventually seize and fly apart sending metal shrapnel along with the PTO shaft in various directions.
Other universal joint problems may occur if the nuts on the u-bolts on the joint itself come loose. This may cause the cross of the joint to come loose in the bore and start to rapidly wear from vibration. It too might break apart under the stresses and revolution speeds of the PTO shaft.
One other area to check is the squared PTO shaft itself. In order for the implement to rise up and down with the three point hitch design the shaft must telescope in and out of a double bored shaft. Adequate lubrication will keep this in and out operation smooth and keep it from binding. Also make sure that the shaft rotates true and has no bends or fatigue cracks in it.
Other areas to check for vibrations depend on whether the tractor is in motion or not. Idling vibes while stationary can probably be traced to altered motor parts. Look for a vibration dampener that has a chunk out of it or has loosened up on the crankshaft. A bent fan blade or loose water pump bushing will also carry throughout the tractor. Internal drive parts are harder to locate and should be left to a professional mechanic. These include miscalibrated crankshaft counterweights, a broken or loose ring gear on the flywheel, loose clutch parts, a loose flywheel, or a worn pilot bushing.
If the tractor only vibrates while in motion then look for wheel related problems. A bent or loose hub, loose wheel weights or lug nuts, fluid in one tire and not the other, and mud clods on the inside of the wheel rim are a good place to start. Internal problems could include worn transmission bearings or a loose rear axle bearing or hub nut.
All in all bad vibes are bad. This can be yet another place to take the time to stop and listen as your tractor speaks to you and hopefully prevent more expensive and time consuming repairs in the future.