Re: RAID Class Drives`

[Richard Scobie <richard@sauce.co.nz>]

Leslie Rhorer wrote:

> 	I would not expect a hard drive to use any fluid lubricant at all in
> its bearings, although it is possible.  Nonetheless, 55C is *NOT* a high

Google "disk drive fluid bearing". Many current drives use fluid rather 
than the previously used precision ball bearings.

> temperature for any industrial lubricant, dry or fluid.  Most petroleum
> based and organic lubricants can easily withstand temperatures well in
> excess of 140C indefinitely.  The motor oil in your car's engine is
> subjected to much higher temperatures than that daily, and if it were not
> for the blow-by of hot gases laden with graphite particles and un-burned
> gasoline from the engine cylinders, the oil would last for many years.  I

Off topic , but a significant cause of motor oil degradation is 
increasing viscocity due to the lighter fractions evaporating over time 
at high temerature.

> would expect the drives to use delron or teflon bearings, or possibly
> aluminum on brass, without any fluid lubricant at all.  Any of these can
> easily withstand close to or more than 200C.

Prior to the relatively recent practice of disk drive heads being parked 
  off the surface of the platter, it was not uncommon for drives that 
had been run for extended periods, at high teperatures, to not restart 
after having been shut down.

In many cases this was caused by stiction, brought on due to 
vaporisation of bearing lubricant depositing back onto the platter surface.

Regards,

Richard