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#1
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I would think that it is just simply a resonance factor.
Ever heard one of those old Cummins 160's? Let them idle & they are as quiet & smooth as a church mouse. Increase the revs very slowly & you'll find that at 1400, 1600, 1800 & 2000 revs they just about shake out of the chasis. (truck) Most diesels do it to a certain extent. Next time it does it, try adjusting your governer up or down a few revs & see how it goes. My guess is that under that certain load, it hits the "rattle" speed. Maybe if you can tweak it a weeny bit, it might not come down to that rattle speed under load? BruceM "Wayne.B" wrote in message ... On Sun, 5 Sep 2004 09:49:03 +0200, "Steve Lusardi" wrote: My guess is that it is not electrical. I think your flex plate drive is either loose or worn out. The alternator has bearings only on the outboard end. The engine rear main bearing acts as the other armature bearing. This mechanical connection is usually done through a flex plate which is bolted to the engine flywheel and a splined hub drives the armature or rotor. To check this, the alternator must be removed from the engine. =============================================== Thanks, your assessment of not being electrical jibes with my observations. What would explain the intermittent nature of the vibration given a more or less constant electrical load? Is the flex plate a coupling with a rubber hub? |
#2
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The problem Is VERY LIKELY to be a combination of a worn drive plate
(between flywheel and generator drive shaft) and the resonance factor mentioned here. "BruceM" wrote in message ... I would think that it is just simply a resonance factor. Ever heard one of those old Cummins 160's? Let them idle & they are as quiet & smooth as a church mouse. Increase the revs very slowly & you'll find that at 1400, 1600, 1800 & 2000 revs they just about shake out of the chasis. (truck) Most diesels do it to a certain extent. Next time it does it, try adjusting your governer up or down a few revs & see how it goes. My guess is that under that certain load, it hits the "rattle" speed. Maybe if you can tweak it a weeny bit, it might not come down to that rattle speed under load? BruceM "Wayne.B" wrote in message ... On Sun, 5 Sep 2004 09:49:03 +0200, "Steve Lusardi" wrote: My guess is that it is not electrical. I think your flex plate drive is either loose or worn out. The alternator has bearings only on the outboard end. The engine rear main bearing acts as the other armature bearing. This mechanical connection is usually done through a flex plate which is bolted to the engine flywheel and a splined hub drives the armature or rotor. To check this, the alternator must be removed from the engine. =============================================== Thanks, your assessment of not being electrical jibes with my observations. What would explain the intermittent nature of the vibration given a more or less constant electrical load? Is the flex plate a coupling with a rubber hub? |
#3
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On Mon, 6 Sep 2004 13:56:38 +0000 (UTC), "James"
wrote: The problem Is VERY LIKELY to be a combination of a worn drive plate (between flywheel and generator drive shaft) and the resonance factor mentioned here. ============================ Thanks. Any idea how much work is involved in replacing the drive plate? |
#4
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On Mon, 6 Sep 2004 21:44:37 +0930, "BruceM"
wrote: I would think that it is just simply a resonance factor. Ever heard one of those old Cummins 160's? Let them idle & they are as quiet & smooth as a church mouse. Increase the revs very slowly & you'll find that at 1400, 1600, 1800 & 2000 revs they just about shake out of the chasis. (truck) ========================================= The vibration in this case is way beyond anything normal, and the generator is designed to run at a steady 1800 RPM regardless of load. |
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