RE: Hard Drive Orientation in a Car [LONG POST]

["Phil Harris" <phil@xxxxxxx>]

Keefie,

10 years ago this would have mattered ... nowadays - to all practical
purposes - it doesn't.

All you need to do is to take reasonable steps to shock mount a drive (some
sort of compliant rubber mount) so that it's not firmly connected to the
cars bodywork and therefore being subjected to every bit of vibration and
they're then pretty much as reliable as you are going to get.

You can't protect against every eventuality - dropping a wheel into a deep
pothole is always going to generate huge forces and you'll never be able to
guard against that but, if you can, use 2.5" drives (they're designed
to
handle movement whilst operating better and they have less physial mass for
the shocks to affect).

I use a 3.5" 160Gb external HD hooked up to the lappy to play DVDs for
Demon
Spawn on long journeys and that's been fine just lobbed on the floor in the
back of the car...

Phil



> -----Original Message-----
> From: Keith Doxey [mailto:ukha@xxxxxxx]
> Sent: 17 September 2003 09:35
> To: ukha_d@xxxxxxx
> Subject: [ukha_d] Hard Drive Orientation in a Car [LONG POST]
>
>
> Hi All,
>
> Apologies for the long post but I have spent ages thinking about
> this...
>
> I have a question about the best orientation of a hard drive to
> provide maximum protection when mounted in a car.
>
> Having never disassembled a hard drive I am looking for answers from
> someone more destructive than me :-)
>
> Do all hard drives generally tend to have the same physical layout
> with regard to the pivoting of the head arm.
>
> To explain that better I will use a record deck as an analogy...
> generally most turntables have the tone arm pivoted from the rear
> right corner of the chassis with the arm extending towards front
> right. ( I wont say always because someone here will have an esoteric
> turntable with some wierd arrangement!) The turntable would be far
> less susceptable to movement front to rear than is would from left to
> right as this would cause the arm to skip across the disc. Any
> vertical movement would cause the arm to bounce.
>
> What I am trying to do is minimise the effects of external motion on
> the disc drive itself. I plan to mount the drive in an extruded
> aluminium case which will give it mechanical protection and an air
> space around it. There will be a small fan to ensure a continuous air
> flow through this case to keep the temperature down. The case will
> then be packed in foam to isolate it from the main chassis of the
> computer case.
>
> There are 4 main sources of movement that could affect the drive.
>
> 1. Acceleration - not too much of a problem with my car!!!
> 2. Deceleration - Emergency braking can cause severe sustained forces.
> 3. Cornering - Sustained but not violent forces to left or right.
> 4. Bumps - Far more likely to cause damage due to the sudden and
> violent nature.
>
> I once had a Car Radio/Cassette player that was damaged when I hit a
> pothole. The force was so severe that the flywheel pushed one of its
> mounting bushes out of its housing :-(
>
> As I see it there are 12 possible ways to mount the drive in relation
> to the front of the car.
>
> 1.  Horizontally - Connectors Front
> 2.  Horizontally - Connectors Rear
> 3.  Horizontally - Connectors Left
> 4.  Horizontally - Connectors Right
>
> 5.  Vertically - Front to Rear - Connectors Front
> 6.  Vertically - Front to Rear - Connectors Rear
> 7.  Vertically - Front to Rear - Connectors Top
> 8.  Vertically - Front to Rear - Connectors Bottom
>
> 9.  Vertically - Across Vehicle - Connectors Left
> 10. Vertically - Across Vehicle - Connectors Right
> 11. Vertically - Across Vehicle - Connectors Top
> 12. Vertically - Across Vehicle - Connectors Bottom
>
> The Vertical methods seem to be preferable to me as the most severe
> impact would be from bumps in the road which for a horizontally
> mounted drive could cause the heads to impact the surface of the disc.
>
> I am thinking Vertical - Front to rear would be best as the second
> strongest force - braking - would be directed across the disc, and
> the least force, cornering, would be the one that would affect the
> head/disc clearance.
>
> Is it better for the braking forces to push the heads towards the
> centre or outside of the disk ?
>
> What happens if the heads get displaced ?
> Does the PC just find the right place and resume like a walkman with
> AntiSkip or does it just crash ?
>
> Are there physical stops within the drive to prevent the heads
> falling off the disk or hitting the centre ?
>
> Thoughts on the best option gratefully received
>
> Thanks
>
> Keith
>
>
>
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