"Larry Jaques" wrote in message
...
On Sun, 8 Oct 2017 16:09:44 -0700 (PDT), Christopher Tidy
wrote:

Interesting. How about these holes and weld tails (see below)? These
must be for additional strength and fatigue resistance, right?

Must be.


https://www.flickr.com/photos/138493...posted-public/
https://www.flickr.com/photos/138493...posted-public/

Fascinating that the part has 3 weld tails and no (visible) welding
on
the bottom left side. Those tabs are under extremely high pressure
as
pivot points. Historical failure surely led to this practice. I'll
bet Caterpillar, Kubota, Case, Hitachi, Komatsu, Volvo, etc.
engineers
have some stories to tell about them. If you write to them and they
respond, please share it with us. I always got Gibbs-slapped as a
kid
because I constantly asked for more details about everything.


Before computers the practice was to design as carefully as existing
theory and manual calculation permitted and then test to destruction.
WW2 aircraft engines that had to be as light (=weak) as possible are a
good example.
http://spitfiresite.com/2010/04/the-...in-engine.html
"Only 175 had been built and these were considered to be rather
unreliable. As a result, Rolls-Royce introduced an ambitious
reliability-improvement programme to fix the problems. This consisted
of taking random engines from the end of assembly line and running
them continuously at full power until they failed. Each was then
dismantled to find out which part had failed, and that part was
redesigned to be stronger. After two years of this programme the
Merlin had matured into one of the most reliable aero engines in the
world, and could sustain eight-hour combat missions with no problems."

These overly optimistic submarine engine designs were never perfected:
https://oldmachinepress.com/2014/08/...diesel-engine/
"The 16-338 engines proved somewhat unreliable in service and required
excessive maintenance. Some of the 16-338's issues were due to the
Navy using standard diesel lubricating oil rather than the special oil
specified for use in the engine. Ultimately, the Tench- and Tang-class
submarines were re-engined and their 16-338 parts were used as spares
to keep the USS Albacore running until it was withdrawn from service
in 1972."

It was withdrawn from service when the supply of spares ran out. I
happened to visit the Albacore when the Navy Yard's retired chief
engineer was aboard to prepare for a film crew.

The Navy's opinion was that the crankcase was too lightly built and
flexed excessively.

https://en.wikipedia.org/wiki/Hooven-Owens-Rentschler
It was originally a German design that didn't work out well for them
either.

-jsw