Holes in welded and galvanised structures

Must be.

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.

- I've figured out why we have Dems. Uncle Siggy told me:

Most people do not really want freedom, because freedom involves responsibility, and most people are frightened of responsibility. --Sigmund Freud

Unfortunately, some Reps are that way, too. (see CONgress)

Reply to
Larry Jaques
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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.

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"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:

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"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submarines were re-engined and their 16-338 parts were used as spares to keep the USS Albacore running until it was withdrawn from service in 1972."

It was withdrawn from service when the supply of spares ran out.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.

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It was originally a German design that didn't work out well for them either.

-jsw

Reply to
Jim Wilkins

In the early decades of the last century, that's how Rolls-Royce developed their automobile engines, too.

Royce took measurements from the best engines of the day and then averaged them. That's how he arrived at, for example, the odd bore/stroke dimensions of their early engines.

The 1904 Grey Ghost was developed that way. To this day, many historical automobile experts consider it to be the best engine for its day, of all time.

The bar was rather low in 1904, however. d8-)

Reply to
Ed Huntress

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-jsw

Reply to
Jim Wilkins

Wow! But will it fly?...

If you looked at that without knowing what's going on, you'd think that Boeing was building an ornithopter -- a wing-flapping airplane.

Reply to
Ed Huntress

Am Montag, 9. Oktober 2017 15:15:55 UTC+2 schrieb Larry Jaques:

Those are JCB loader pivots. Interesting thing is, the early pivot plates d id not use this arrangement of welds (instead they were welded all the way around and had no central hole) and they did not regularly fail. However, t he early pivot plates were about twice as big and heavy. I figure it's an o ptimisation process which demands this kind of weld design.

Might write to them if I have time. Not sure that will happen though. The J CB Facebook group would be quicker for an informal answer.

Best wishes,

Chris

Reply to
Christopher Tidy

Am Montag, 9. Oktober 2017 15:15:55 UTC+2 schrieb Larry Jaques:

Looks like Volvo does exactly the same thing:

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Reply to
Christopher Tidy

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