Differences

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--- pld:start [2011/05/30 11:05] – jason
+++ pld:start [2011/05/31 13:41] – chris
@@ Line 12: / Line 12: @@
 The Alcatel turbo pump has a more complicated maintenance schedule.  There is no oil sump in the turbo pump like the roughing pump, and so there is no oil to be changed.  However, it is essential that the internal bearings are regreased every 5000 Hours.  The bearing life specification is 30,000 hours; however this assumes a constant operating condition (100% duty cycle) at high vacuum.  The nature of operation for this pump does not meet that specification, since its speed is ramped up and down often.  The greatest amount of wear to a turbo pump occurs when its rotational speed is changing, especially at low speeds.
-Bearing failure of this particular pump is known to happened at late as 20,000 hours, and as early as 6,000 hours.  This is why the bearing maintenance should be performed at 5000 hours.  The turbo pump controller is configured to to remind the user when this interval is met or exceeded.
+Bearing failure of this particular pump is known to have happened as late as 20,000 hours, and as early as 6,000 hours.  This is why the bearing maintenance should be performed at 5000 hours.  The turbo pump controller is configured to to remind the user when this interval is met or exceeded.
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