The Carryfast engine design discussion

UK PROFESSIONAL DRIVERS FORUMS OLD TIME LORRIES, COMPANIES AND DRIVERS (INTERACT
1

posting.php?mode=quote&f=35&p=2703005

As I said I can’t give you an answer because I don’t get the premise on which your question is based.

Which if I’ve got it right is that the inertial/kinetic ? tensile load of the piston and rod assembly at TDC, between the compression stroke and power stroke, or exhaust stroke and induction stroke, equals, if not exceeds, that of the compressive load on the assembly during the power stroke ?. :confused:

Or that the mechanical/leverage advantage provided by a longer stroke in that regard and resulting specific torque output, is cancelled out by supposed piston speed issues and their result on the supposed tensile loads ?.

jstor.org/stable/44579567?se … b_contents

When as I’ve said the design of Rolls Eagle, Mack 673 , to ■■■■■■■ ISX to Paccar MX etc all prove the case for maximising the stroke dimension.

Also the fact that AEC engine designs were compromised on that basis.

2

Lets not get concerned with all that ■■■■, the real technical question is, how much to get it from A to B and how long will the thing last before it costs me money…

Dave…

3

viewtopic.php?f=35&t=166099&start=240#p2703082

Scammell at this point were part of the Leyland Group just like AEC.
Leyland as a Group obviously had a policy of using components which it could make in house including engines.
It’s clear that Scammell was avoiding the use of AEC’s L12/TL12 in favour of Rolls or the 680 in far from ‘specialist’ products like the Crusader and the Trunker/Handyman etc.

As for AEC employees denigrating their own employers’ products and investment cash compromised designs it’s not difficult to see how that wouldn’t have ended well.

It’s clear that not only was the Ryder Report way wide of the mark.Even the few bits it got right were ignored by Leyland’s upper management obviously deliberately in the case of identifying where blame belonged and needed fixing and acting on.So what did they do they effectively committed foreseeable commercial suicide among both the car and truck divisions.

An outdated comparison of operating maintenance costs wasn’t going to make the L12 powered Buffalo or TL12 powered Marathon/Roadtrain any better in that regard than meeting the might of the foreign onslaught, with the Triumph Acclaim or Rover SD1 and then dumber 820 and keeping on pouring more cash into the basket case of BMC did.

4

viewtopic.php?f=35&t=166099&start=210#p2702874

Yes I know just disagreeing with others on a forum ■■■■■■ many of them off and isn’t ‘acceptable’. :confused:
That’s why I’ve been on pre mod for ages.No complaints if the post is ‘unnacceptable’ just nuke it without posting it that’s what it’s for.

Anyway more like they all want to use lanes 1, 2 and 3 at 55 mph, 55.5 mph and 69 mph respectively.I’ll try the M6 toll and see if that’s any better then every one might be happy. :bulb: :wink:

5

dave docwra:
Lets not get concerned with all that [zb], the real technical question is, how much to get it from A to B and how long will the thing last before it costs me money…

Dave…

All moot if your perception, of ‘getting from A to B and not costing you money’ is 10 or more years out of date and then takes out the firm that was supplying your trucks, in trying to meet it.

6

Carryfast:
http://www.trucknetuk.com/phpBB/posting.php?mode=quote&f=35&p=2703005

As I said I can’t give you an answer because I don’t get the premise on which your question is based.

Which if I’ve got it right is that the inertial/kinetic ? tensile load of the piston and rod assembly at TDC, between the compression stroke and power stroke, or exhaust stroke and induction stroke, equals, if not exceeds, that of the compressive load on the assembly during the power stroke ?. :confused:

Or that the mechanical/leverage advantage provided by a longer stroke in that regard and resulting specific torque output, is cancelled out by supposed piston speed issues and their result on the supposed tensile loads ?.

jstor.org/stable/44579567?se … b_contents

When as I’ve said the design of Rolls Eagle, Mack 673 , to ■■■■■■■ ISX to Paccar MX etc all prove the case for maximising the stroke dimension.

Also the fact that AEC engine designs were compromised on that basis.

I freely admit i haven’t a clue about any of the above but i do take exception from your last sentence.
AEC were known throughout the world for their products and their reputation was second to none at the time. Which engine or if you like all AECs engine were compromised what were the consequences of these compromises. Which engine in particular gave trouble? You mention the Pacaar MX a relatively new engine that didn’t even exist when AEC were in their pomp. Again you compare apples with pears . On that basis how does the Rolls Eagle compare with the MX or the latest from Volvo or Scania. The millions that were taken from AEC Leyland and the rest of the commercial side to prop up the ailing car debacle could have been used to sanction new engines but the powers that be decided otherwise

7

Carryfast:
http://www.trucknetuk.com/phpBB/posting.php?mode=quote&f=35&p=2703005

As I said I can’t give you an answer because I don’t get the premise on which your question is based.

Which if I’ve got it right is that the inertial/kinetic ? tensile load of the piston and rod assembly at TDC, between the compression stroke and power stroke, or exhaust stroke and induction stroke, equals, if not exceeds, that of the compressive load on the assembly during the power stroke ?. :confused:

Or that the mechanical/leverage advantage provided by a longer stroke in that regard and resulting specific torque output, is cancelled out by supposed piston speed issues and their result on the supposed tensile loads ?.

jstor.org/stable/44579567?se … b_contents

When as I’ve said the design of Rolls Eagle, Mack 673 , to ■■■■■■■ ISX to Paccar MX etc all prove the case for maximising the stroke dimension.

Also the fact that AEC engine designs were compromised on that basis.

Please produce your “fact” to support your outrageous suggestion.

AEC during the 67 years of its existence produced and sold close on 750,000 engines. These were used in its own vehicles and in many other makes of commercial vehicles at home and overseas. In addition to road going commercial vehicles it supplied diesel engines to just about every application that used diesel engines: - pumps, generators, marine main propulsion and auxiliary units, rail traction, excavators, mobile cranes, static cranes to name some of them. If the AEC engines were compromised because of design failings then this major British company that exported world-wide would never have achieved the success that it did.

I will give you a fact. It is this. You do not have a clue about AEC, the company, the products, the people and personalities that managed it and worked there. So before you write another incorrect statement about AEC, I suggest that you do some proper research, and I will gladly point you in the direction of the vast archives about this great company that exist.

Try the National Archive at Kew, not too far from your home at Leatherhead. Here you will find minutes of monthly board meetings for every month of the company’s existence, both as an independent entity and also as part of British Leyland. Board meeting minutes detail monthly warranty claims and payments, so maybe you might find evidence of the occasional engine failure… it did happen as happens in every engine manufacturing company.

And try the British Commercial Vehicles Museum at Leyland. There you will find build sheets for virtually every AEC PSV and lorry built. You will also find service bulletins issued by Southall to its regional depots and service engineers. These documents give details of problems occurring in service and the remedies for them. Strangely enough, problems still occur with new trucks today. I have had three '69 plate DAFs notified for recall in the last week.

And if you still haven’t found the fact to support your supposition that every AEC engine design was flawed, then try the Motor Industry archives at the University of Warwick. Many leading automotive industry experts and senior managers, including Bob Fryars, have placed their own personal memoirs and papers in the care of this archive.

Instead of googling dubious information on the internet get out there and conduct your research in “hard copy” archives. You will find it fascinating, but when you are doing your research be prepared to allocate a lot more time to it than you think it will take. Because in these archives, whilst you will go with an intention to research a specific topic, you will find that some other gem of information catches your attention and it will take you into another area of investigation.

So, good luck with your research, and when you have learned about AEC, feel qualified to state you opinions about the company, its vehicles, and its engines.

8

The question I posed on the other thread was quite straightforward. You could have done the research, IE asked some of the other members what the piston weight was, then done the calculation. If the answer was, as Newmercman guessed, 1400rpm, then that would have shown that, at that peak cyl pressure, the greater bearing loads above that speed would have been due to inertia. It would not matter that your original theory, that the engine should have had a longer stroke, was proved wrong- we would have some basis on which to agree, and you would have earned the respect of everyone, for doing the work. You could then have worked out what the actual full load peak pressure was, and shown that combustion loads over the whole rev range of the engine were actually higher than inertial ones. That would have proved you right, in the first place. Then someone could have stepped in and said that conn rod fatigue was a more likely failure mode than bearing slop, during the life of the engine, and so on and so on. It would then have been a “design discussion.” Until you support your guesswork with facts and mathematical deductions, you have even got the title of this thread wrong. I’m out, as they say on the telly.

9

[zb]
anorak:
The question I posed on the other thread was quite straightforward. You could have done the research, IE asked some of the other members what the piston weight was, then done the calculation. If the answer was, as Newmercman guessed, 1400rpm, then that would have shown that, at that peak cyl pressure, the greater bearing loads above that speed would have been due to inertia. It would not matter that your original theory, that the engine should have had a longer stroke, was proved wrong- we would have some basis on which to agree, and you would have earned the respect of everyone, for doing the work. You could then have worked out what the actual full load peak pressure was, and shown that combustion loads over the whole rev range of the engine were actually higher than inertial ones. That would have proved you right, in the first place. Then someone could have stepped in and said that conn rod fatigue was a more likely failure mode than bearing slop, during the life of the engine, and so on and so on. It would then have been a “design discussion.” Until you support your guesswork with facts and mathematical deductions, you have even got the title of this thread wrong. I’m out, as they say on the telly.

BMEP is based on peak specific torque in the case of the L12 that occurrs at 1,400 rpm.I didn’t guess it I said it and posted it before nmm.

You’ve provided no figures to support your claim that inertial/tensile loads ever exceeed those of compressive ones during the power stroke of a low revving truck diesel engine and that’s why AEC’s engines were never going to match those of Rolls, ■■■■■■■■ Volvo etc etc who’s longer stroke designs added more leverage to that equation.

So L12 v Rolls 220.

7% more piston speed ?.

4.5 % less engine speed at peak power ?.

12.5% more specific power ?.

7% more specific torque ?.

So tell me what was the compressive loading on the L12’s rod assembly at peak torque as opposed to the Eagle 220’s.As for taking that to a BMEP of 240 psi + in the case of the TL12 don’t even go there.

Then tell me what was the intertial tensile loading at TDC on the Eagle’s between the Exhaust and Induction stroke at 2,100 rpm as opposed to the L12’s at 2,200 rpm.

Also you didn’t answer the question what was meant in the video concerning ‘‘mechanical advanmtage’’ of the longer stroke.

10

ramone:
You mention the Pacaar MX a relatively new engine that didn’t even exist when AEC were in their pomp.

No but the Mack 673 was introduced at the same time as the TL12.The inference being that the Mack’s type of specific output was where AEC’s designers wanted/intended to be with the TL12.
I don’t/can’t believe that AEC’s designers thought for one minute that they were going to get it from the TL12’s bore stroke ratio which is the basis of the comparison with the MX.

11

Had you actually noticed thar Mr Myers was writing his paper in 1911? The year before the AEC officially came into existence and over 20 years before the AEC were at the forefront of diesel engine development under the guidance of Cedric Dicksee and Sir Harry Ricardo, two of the most widely respected authorities in their field. Of Mr Myers five bullet point advantages for the long stroke diesel engine quoted, three are incorrect if comparing the 12 litre size N/A engines under discussion with the AEC diesel equivalent. The AEC is marginally more economical, certainly lighter, and definitely quieter. The additional point about longer life does not sit well with the earlier quoted table regarding the cost of non routine maintenance in practice rather than theory.

12

cav551:
Had you actually noticed thar Mr Myers was writing his paper in 1911? The year before the AEC officially came into existence and over 20 years before the AEC were at the forefront of diesel engine development under the guidance of Cedric Dicksee and Sir Harry Ricardo, two of the most widely respected authorities in their field. Of Mr Myers five bullet point advantages for the long stroke diesel engine quoted, three are incorrect if comparing the 12 litre size N/A engines under discussion with the AEC diesel equivalent. The AEC is marginally more economical, certainly lighter, and definitely quieter. The additional point about longer life does not sit well with the earlier quoted table regarding the cost of non routine maintenance in practice rather than theory.

Ironically I could also say that at no point did he seem to list the advantage of leverage.
The forefront of diesel engine development which obviously the designers of the Maxidyne ( which you yourself said was considered by AEC as a benchmark for the TL12 ? ), Eagle, TD120, ■■■■■■■ 220 - N14,.Then from that point stroke dimensions were mainly going one way North.
As for your reliability survey we can safely disregard anything which puts Gardner at the top of it.Just as anything can look good if you keep its specific output well within its stress capabilities.Also even the Gardner isn’t going to help any argument making the case for a compromised stroke.
Neither was going anywhere in a world heading for a reliable around 100 lb/ft per litre expectation and AEC weren’t ever going to get there with the TL12 unlike the Rolls.

13

Gentlemen,
Just to bring a slice of engine size ,bore,stroke,firing order,what size key in the end of the cam shaft,OR ALL THE OTHER engine size requirements speaking as a driver who over 35 years probably have driven more different types of lorries with different engine sizes than most members on here,not all, from 1967.-2002

I will reflect, 100% of the drivers i knew had a few important things on their minds when behind the wheel and one was!! they could not have given two monkeys zbs, if the engine had elastic bands,OR cotton reels ,or whatever to power machine ,all you wanted to do was get tipped ,get home, and get zb.ed.long stoke or short,your choice.NO ONE CARES.pdb.

14

peggydeckboy:
Gentlemen,
Just to bring a slice of engine size ,bore,stroke,firing order,what size key in the end of the cam shaft,OR ALL THE OTHER engine size requirements speaking as a driver who over 35 years probably have driven more different types of lorries with different engine sizes than most members on here,not all, from 1967.-2002

I will reflect, 100% of the drivers i knew had a few important things on their minds when behind the wheel and one was!! they could not have given two monkeys zbs, if the engine had elastic bands,OR cotton reels ,or whatever to power machine ,all you wanted to do was get tipped ,get home, and get zb.ed.long stoke or short,your choice.NO ONE CARES.pdb.

Ah! Is that why this thread is receiving so much oxygen? :laughing:

15

peggydeckboy:
Gentlemen,
Just to bring a slice of engine size ,bore,stroke,firing order,what size key in the end of the cam shaft,OR ALL THE OTHER engine size requirements speaking as a driver who over 35 years probably have driven more different types of lorries with different engine sizes than most members on here,not all, from 1967.-2002

I will reflect, 100% of the drivers i knew had a few important things on their minds when behind the wheel and one was!! they could not have given two monkeys zbs, if the engine had elastic bands,OR cotton reels ,or whatever to power machine ,all you wanted to do was get tipped ,get home, and get zb.ed.long stoke or short,your choice.NO ONE CARES.pdb.

Yes but it matters a lot to anyone with the slightest interest in the history and fortunes of our automotive industry and how the things are put together and what makes them work in addition to driving them.
Why bother posting on the topic if you have no interest in that regard.It was more directed towards Anorak calling him out to back his aggressive idea of ‘discussion’ because he seems to have more or less met his match regarding technical interest and questions.

As for driving different types everything from 1940’s Matador and 70’s Clydesdale to 18 litre + 16 cylinder two strokes on and off public roads as part of a routine day’s work at the age of 21 and within months of getting my licence your point being what.

16

Well, C F Is certainly not a good old Gardner man my like myself, I dont think what he knows about any kind of engines, But I made a very good living running wagons with the 150 Gardner engines in, I dont want to insult him, But whats he allways on about I wonder :question: :question: :question: ,But I wish him well during the Virus ■■■■, Stay safe C F Regards Larry.

17

ERF-NGC-European:
Ah! Is that why this thread is receiving so much oxygen? :laughing:

Peak cylinder combustion pressure 2 x BMEP yeah right.
What difference does it make anyway to the inertial tensile load on the piston and rod assembly between the exhaust and induction stroke at peak power/governed rpm because it can’t possibly be more than at that point.
The big end bearing cab and fastenings are all that’s stopping the whole lot from flying away from the crankshaft at that point.I’ve never heard of four bolt big ends being used to stop the piston and rod flying away.
But deffo four bolt mains to stop the crankshaft being pushed down through the sump.
Sounds like pure methane. :laughing:

18

Carryfast:

cav551:
Had you actually noticed thar Mr Myers was writing his paper in 1911? The year before the AEC officially came into existence and over 20 years before the AEC were at the forefront of diesel engine development under the guidance of Cedric Dicksee and Sir Harry Ricardo, two of the most widely respected authorities in their field. Of Mr Myers five bullet point advantages for the long stroke diesel engine quoted, three are incorrect if comparing the 12 litre size N/A engines under discussion with the AEC diesel equivalent. The AEC is marginally more economical, certainly lighter, and definitely quieter. The additional point about longer life does not sit well with the earlier quoted table regarding the cost of non routine maintenance in practice rather than theory.

Ironically I could also say that at no point did he seem to list the advantage of leverage.
The forefront of diesel engine development which obviously the designers of the Maxidyne ( ? ), Eagle, TD120, ■■■■■■■ 220 - N14,.Then from that point stroke dimensions were mainly going one way North.
As for your reliability survey we can safely disregard anything which puts Gardner at the top of it.Just as anything can look good if you keep its specific output well within its stress capabilities.Also even the Gardner isn’t going to help any argument making the case for a compromised stroke.
Neither was going anywhere in a world heading for a reliable around 100 lb/ft per litre expectation and AEC weren’t ever going to get there with the TL12 unlike the Rolls.

Do you ever read what you have just written? some of the above is unintelligible because you haven’t finished the sentence. Neither do you read what others have written - rather you read something entirely different but which suits your argument :eg you quote me as " which you yourself said was considered by AEC as a benchmark for the TL12"

What I actually wrote was: "There was one manufacturer they (Leyland) had been observing from afar whose ideas might be worthy of possible consideration for their own experimentation - Mack and the concept of turbocharger tuning and torque rise." Nothing about any benchmarks.
I mentioned Mack and the concept of turbocharger tuning and torque rise because it was a principle which was to be followed by many manufacturers. It had nothing to do with the internal dimensions of the engine. Mack wanted to uprate their Thermodyne engine and make it more driveable. They wanted to do away with the multispeed transmissions needed to keep the typical american engines of the day spinning at the upper end of the rev range which was necessary to maintain progress. By a clever and novel balance of turbocharging, manifolding, fuelling and timing they managed to broaden, boost and shift the torque curve of the engine so that it became more flexible and ‘powerful’ across its rev range. In doing so they transformed their old engine into the Maxidyne and did away - for Mack - with the necessity for a multispeed transmission.
As said this principle was at least partially followed by many manufacturers as de-speeded torque rise engines appeared. In fact the final production versions of the TL12 engine were described as ‘Flexitorque’ engines.

19

cav551:
Do you ever read what you have just written? some of the above is unintelligible because you haven’t finished the sentence. Neither do you read what others have written - rather you read something entirely different but which suits your argument :eg you quote me as " which you yourself said was considered by AEC as a benchmark for the TL12"

What I actually wrote was: "There was one manufacturer they (Leyland) had been observing from afar whose ideas might be worthy of possible consideration for their own experimentation - Mack and the concept of turbocharger tuning and torque rise." Nothing about any benchmarks.
I mentioned Mack and the concept of turbocharger tuning and torque rise because it was a principle which was to be followed by many manufacturers. It had nothing to do with the internal dimensions of the engine. Mack wanted to uprate their Thermodyne engine and make it more driveable. They wanted to do away with the multispeed transmissions needed to keep the typical american engines of the day spinning at the upper end of the rev range which was necessary to maintain progress. By a clever and novel balance of turbocharging, manifolding, fuelling and timing they managed to broaden, boost and shift the torque curve of the engine so that it became more flexible and ‘powerful’ across its rev range. In doing so they transformed their old engine into the Maxidyne and did away - for Mack - with the necessity for a multispeed transmission.
As said this principle was at least partially followed by many manufacturers as de-speeded torque rise engines appeared. In fact the final production versions of the TL12 engine were described as ‘Flexitorque’ engines.
[/quote]
Sorry somehow edited out didn’t agree with.Not difficult to deduct that was meant.
They didn’t just ‘shift’ any torque curve what they actually got was around 100 lb/ft per litre torque ‘output’ and around similar peak power at 1,800 rpm as the TL12 was producing at 2,200 rpm.
The fact that they got that torque as low as 1,200 rpm was also a bonus which ironically also showed what the Rolls Eagle would ultimately be capable of in TX form.Like the TD120 leverage obviously mattered.
Maths says you just ain’t going to get match that from the TL12 without it going bang in a big way because of the extra boost pressure you’ll need.( Yes we know there are exceptions which prove the rule ).
I thought that AEC developed the TL12 and that was what you were referring to. :confused:
But generally the industry rightly entered into a specific torque, obviously needing to be helped by leverage, arms race from that point.Whether Volvo, Scania or ■■■■■■■ or Detroit.
I’ll now await Anorak to provide the figures showing that piston/con rod assembly inertial loads are relevant anywhere much other than in an F1 engine at peak power and certainly nothing to do with peak torque rpms.
In a truck diesel engine specific torque advantages combined with reduction in engine speeds generally outweigh piston speed concerns.Which explains why Mack did more with 11 litres than AEC could do with 12.4.

20

Carryfast:
Leyland Buffalo - OLD TIME LORRIES, COMPANIES AND DRIVERS (INTERACT - Trucknet UK

Yes I know just disagreeing with others on a forum ■■■■■■ many of them off and isn’t ‘acceptable’. :confused:
That’s why I’ve been on pre mod for ages.No complaints if the post is ‘unnacceptable’ just nuke it without posting it that’s what it’s for.

Anyway more like they all want to use lanes 1, 2 and 3 at 55 mph, 55.5 mph and 69 mph respectively.I’ll try the M6 toll and see if that’s any better then every one might be happy. :bulb: :wink:

Not me mate, personally I love a line of slow moving traffic on a single carriageway, picking em off one or two at a time, that’s why I loved running the old roads in Europe and why I like going over the Rockies now. In a car I’m never in anybody’s way and I’ve seen Vmax in every car I’ve owned, on a private road of course… honest.