CCred68046 wrote:

You have got to see this....
http://www.bath.ac.uk/~ccsshb/12cyl/

Wow!

I wonder what it redlines at? One cool thing about
the big commercial ship diesels is that no
reduction gear is needed, which saves cost,
weight, & maintenance.

Fair Skies- Doug King

G Probably around 105 RPM ..... more important to some would be it's
"barred speed range" (if any) and where it's at.

DSK wrote:
CCred68046 wrote:


You have got to see this....
http://www.bath.ac.uk/~ccsshb/12cyl/


Wow!

I wonder what it redlines at? One cool thing about
the big commercial ship diesels is that no
reduction gear is needed, which saves cost,
weight, & maintenance.

Fair Skies- Doug King

On Wed, 19 Nov 2003 17:03:31 +0000, otnmbrd wrote:

G Probably around 105 RPM ..... more important to some would be it's
"barred speed range" (if any) and where it's at.

I'm not familiar with *big* diesels, but I was surprised at how slowly
that sucker turned, maximum power at 102 RPM.

On Wed, 19 Nov 2003 14:46:51 -0500, thunder
wrote:

I'm not familiar with *big* diesels, but I was surprised at how slowly
that sucker turned, maximum power at 102 RPM.

================================

Big squirrels run slow...

How the heck do they crank it to get it started??


"otnmbrd" wrote in message
news
G Probably around 105 RPM ..... more important to some would be it's
"barred speed range" (if any) and where it's at.

DSK wrote:
CCred68046 wrote:


You have got to see this....
http://www.bath.ac.uk/~ccsshb/12cyl/


Wow!

I wonder what it redlines at? One cool thing about
the big commercial ship diesels is that no
reduction gear is needed, which saves cost,
weight, & maintenance.

Fair Skies- Doug King

On Thu, 20 Nov 2003 03:32:59 GMT, "Snafu"
wrote:

How the heck do they crank it to get it started??
=========================================

We had a discussion about that earlier this year, answered by Rick our
resident LARGE diesel expert. To make a long story short, they use
compressed air stored in large accumulator tanks, and admitted into
the cylinder heads through a special set of valves used only for
starting the engine.

In an emergency you can hand crank...

....but not very much.

Snafu wrote:
How the heck do they crank it to get it started??


Air .....lotsa air... most big diesels on ships, have limited amounts of
starts when maneuvering. However, this has greatly improved with newer
ship. They generally have over a dozen, before they run out and have to
wait to rebuild supplies.

On Thu, 20 Nov 2003 04:04:48 GMT, otnmbrd
wrote:

They generally have over a dozen, before they run out ...

Spot on. CFR's say there is supposed to be sufficient for 12 starts.

Rick

Snafu wrote:
How the heck do they crank it to get it started??


Air .....lotsa air... most big diesels on ships, have limited amounts of
starts when maneuvering. However, this has greatly improved with newer
ship. They generally have over a dozen, before they run out and have to
wait to rebuild supplies.

Thanks for the info.

Just looking at the pix at the massive size, it has to take incredible air
volume and pressure to get that huge crankshaft rolling. I'm guessing that
once you get one of these things running, you don't want to shut down very
often.

Snafu wrote:

Thanks for the info.

Just looking at the pix at the massive size, it has to take incredible air
volume and pressure to get that huge crankshaft rolling. I'm guessing that
once you get one of these things running, you don't want to shut down very
often.


When maneuvering in port, each time you go from ahead to astern, you
need to stop the engine, then restart it in the opposite direction.
Naturally, while docking, you'll mostly be at "stop", and occasionally
to frequently (G depending on the pilot and conditions) have to start
it for needed maneuvers .... which eats up air.

otn