Diesel Engine Design Life

[rotrax]

Also dont forget we have moved in to shafts running directly on high engineered aluminium alloys, again they last fir ever as long as the oil etc is changed. The overhead cam in my MD22 is in perfect condition after 18 years and many thousands of hours.
Stu

Not neccessarily moved on-Edward Turners 500cc and 650cc twins pre 1954 had a Hiduminium alloy-RR spec material IIRC-con rod with a steel cap. The cap was lined with babbit metal and the rod and cap were then machined assembled to be the correct fit on the jourmal. They were very reliable.

 

[afterpegassus]

Not neccessarily moved on-Edward Turners 500cc and 650cc twins pre 1954 had a Hiduminium alloy-RR spec material IIRC-con rod with a steel cap. The cap was lined with babbit metal and the rod and cap were then machined assembled to be the correct fit on the jourmal. They were very reliable.

Keep this coming - fascinating stuff.
The last time I heard of "hiduminium" was when Hamish McInnes used it for axe shafts in the late sixties.

 

[rotrax]

Keep this coming - fascinating stuff.
The last time I heard of "hiduminium" was when Hamish McInnes used it for axe shafts in the late sixties.

OK-the connecting rod bolts were also made of very good steel and before most commercial workshops used torque wrenches the workshop manual brief was to measure the bolts with a 2 to 3 inch micrometer, taking carefull note of the length. After assembly the nuts were tightened to stretch the bolts by a certain amount-.004" to .005" IIRC.

This is, of course, what a torque wrench achieves when fastners are tightened to the correct torque.

One reason the 500cc and 650cc Truimph engines were long lived in the big end bearing area was turners clever use of the bolt together crankshaft as a centrifugal oil filter. The crank webs were bolted into a central flywheel leaving a hollow space where sediment from the old fashioned straight non detergent oils available then would collect. It was absolutly essential to clean this at overhaul and mixing the detergent type multigrades could-and did-allow this sediment into the oilways with disasterous results.

I believe the VW beetle air cooled flat four engines used a plain duralumin bush as the crankshaft bearing imediatly behind the helical timing gear.

 

[Daydream believer]

so going back to my question
is "rolling element" the same as "roller bearing" or does it apply to the way in which the bearing is loaded

 

[macd]

so going back to my question
is "rolling element" the same as "roller bearing"

By my understanding, not quite. All roller bearings are rolling element bearings, but not the other way round: a ball bearing, for instance, is obviously not a roller bearing, but does have rolling elements. 'Rolling element bearing' is the cover-all, 'roller bearing' the special case -- although there are of course many different types of roller, so many sub-sets of special case.

I imagine Vyv just wanted to cover all bases with the economical yet accurate form of words favoured by engineers.

 

[vyv_cox]

Very good point, I was indeed using info on roller bearings. But are you sure that the wear of plain bearings is NOT a funtion of number of rotations? Reductio ad absurdum, are you saying that 1 hour at 3,000 rpm at maximum load produces tye same wear as 1 hour at 1000 rpm with no load? Surely their wear must be somewhat higher at high engine speed and associated power than it is at low speed?

During hydrodynamic operation there is no contact between the plain bearing and the journal, the two are totally separated by a film of oil. The only time there is metal to metal contact is at start-up before the film has been established. The revs required for hydrodynamic lubrication are very small, e.g. ships' engines doing 100 rpm are perfectly OK and even as low as 10 rpm will suffice.

Rolling element bearings (balls, parallel or taper rollers) experience elasto-hydrodynamic lubrication, in which the races deform minutely to establish a slightly circular form for hydrodynamic lubrication to occur. Having worked quite a lot with SKF, their latest info was that improvements in steel cleanliness have now made the life of most small bearings infinite, provided operating conditions are ideal, i.e. free of contaminants.

 

[Heckler]

Not neccessarily moved on-Edward Turners 500cc and 650cc twins pre 1954 had a Hiduminium alloy-RR spec material IIRC-con rod with a steel cap. The cap was lined with babbit metal and the rod and cap were then machined assembled to be the correct fit on the jourmal. They were very reliable.

Remember in the 60s, there was still a place in Chester doing exactly that!
Stu

 

[ghostlymoron]

It seems to me that this is a bit of a pointless discussion. An engine lasts until it's knackered then you either rebuild it or get a new one.

 

[ghostlymoron]

In a major utility company I once worked for the asset life of mechanical items was taken to be 20 years (buildings were 60).

 

[chrishelen]

Very interesting thread. My perkins perama has a hard life running around on average 8 hours a day. It's the original engine from 1994. It must have at least 8000 hrs on it. I change the oil every 250 hrs (I guess this) I put a large oil filter on instead of the tiny standard thing. But it runs like a Swiss watch, and even when an oil change us due the oil light stays off for about two seconds after switch off. So I guess use it or lose it.

 

[Motor_Sailor]

But it runs like a Swiss watch . . .

Ishikawajima Shibaura Machinery Company made good engines.

 

[Fmicol]

Does somebody have some experience of life time of the volvo d 4 engine in terms of hours?

 

[fisherman]

I suspect that will be a piece of string, depending on usage and maintenance. In ideal conditions could be many thousands of hours. Consider the Ford Dover 6 cyl mermaid taken out of a boat with 42000 hours on the clock, the clock had stopped working several years ago, and which was displaying no adverse indications. Then another which gave trouble after only 7000, but had been sadly neglected and mistreated.

 

[Tranona]

Does somebody have some experience of life time of the volvo d 4 engine in terms of hours?

That is a high performance engine (relatively) compared with the sorts of engines being discussed here and is usually fitted in boats that run low annual hours in leisure use.

You may get better response posting on the Mobo forum.

 

[benchmark]

I wonder how many small boat diesel engines have such a long life that they die of old age and wear out? ( The engine 'life' question).
In the small boat category I suspect most suffer catastrophic failure related to salt water getting into the engine - at a time when they are merely 'middle age'.

My dock neighbour has a small 35 hp Saab in his 7 meter fishing boat that is from the 70ies . Even though he is now 86 yrs old and considering selling his boat, In the past he sailed out every other day to check and reset his nets.
I doubt that my 200hp Nanni diesel( toyota landcruiser base) will be able to last that long.

 

[rubbishman]

Just been reading about new diesel outboard from yanmar notable for it's two conrods per piston.That has a long life .

 

[davidej]

Two conrods per piston - how does that work?

 

[RichardS]

Two conrods per piston - how does that work?

Pistons in parallel presumably?

Richard

 

[fisherman]

There are engines and engines. There are several Gardners among the local fleet. One, fitted in 1978, had already gone twice round the world in a London Bus. Max revs probably 800. Don't think hours come into it.

 

[davidej]

Pistons in parallel presumably?

Richard

I googled it.

It has two parallel crankshafts, geared together so contra-rotating. A conrod to each, so these sort of do the splits as the shafts turn.

Two advantages as I see it. The shafts iron out vibration in the horizontal plane , but not the vertical. And the two conrods avoid wear on one side of the piston due to the firing stroke.

But at the cost of lots of extra weight and complexity