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Well... The fixed position clutch drive disc is solid on the crank. The flywheel is set to a gap from the slinger, thrust washer, or main bearing, depending on the model (early, late, numbered, or diesel) to set the overall endplay. When you engage the clutch, the fork pulls the collar, then the clutch bolts and then outer plate, towards the crankcase from the right, in effect pushing the crank towards the flywheel side. The pinch that results from the inner and outer clutch plates and disks under pressure traps the fixed disk and locates the crank, preventing lateral movement, so the crank does not move from side to side while the clutch is engaged. To demonstrate, with engine off, engage the clutch, and rock the lever back and forth, but not so far to the rear as to disengage. The movement you 'll see as you almost override the clutch pack is end play in the crank. It's particulary devastating to the fiber thrust washers on the diesels. I guarantee you will hear it hammer a different tune if you let the tractor run for a time with the clutch disengaged (like on a blower or pto dryer). It will affect crankshaft end movement on a conventional drivetrain, too. A conventional clutch is a normally engaged design. If you hold the clutch down on a car, the crank will float in and out, but generally the throw-out bearing will give way before the crankshaft thrust wears too much. Endplay notwithstanding, I always felt that since the pulley roller bearing which must rely on just it's packed grease for lubrication, had a better chance of failing from over use than the first reduction gear brearing which gets fresh lube when the tractor moves. It's kind of a pick your poison, but I've had to replace more pulley bearings than first reduction gear quill bearings. Old farmer's tale or not, I only disengage the clutch to shift gears. Frank-in-Tallahassee
70D // 855
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