Leyland Marathon...The "Nearly" Truck of The 1970s?

[railstaff]

Carryfast:

[zb]
anorak:

Carryfast:
.The BG ‘range’ was ‘available’ from 1976.

It was only available in GB chassis from 1978. We’ve already been down this route, and I’m not going to dig out the same stuff twice for you. The Marathon 2 was launched in 1977 or '78, and was available with the E290 at some stage.

The fact that the Brits were adopting available technology unnecessarily late and when they did limited,to the advantage of the foreign competition,is my point.In this case obviously allowing DAF and Volvo for two examples to get an early foothold with superior products.Although you obviously won’t accept that the DAF 2800 was a better truck than a TL12,let alone 250 NA ■■■■■■■■■■■■■■■ Marathon.As opposed to an SA 400 type cab with a ■■■■■■■ 350 under it.

Oh wait we’re supposed to believe that it would have been slower and thirstier,with a supposed more fragile engine,with 280 hp + produced at around 1,500 rpm,than the TL12 producing 280 hp max at 2,200 rpm.If not the lie that a 335 let alone 350 ■■■■■■■ didn’t even exist.

Who were they trying to kid and why.On that note remind us what the TL 12’s piston speed was at 2,200 rpm and its SFC at peak power v the ■■■■■■■■ at 1,600 rpm and therefore how could the thing possibly have provided a better overall journey time,at a better overall fuel consumption,at a lower piston speed,than a ■■■■■■■ 335 let alone 350.

The small cams made peak power at 2100 rpm.

A spirited driver could drop an SC to 5mpg.They hammered fuel,one reason as ive explained of the adoption of big cam.

Another issue which ive never mentioned is the power and torque outputs were very inconsistent,and this is still more true today of the electronics.

As said regarding the TL12,maybe the pump timing and phasing was perfect out of the works and simple they performed.

[carryfast]

railstaff:

Carryfast:
The fact that the Brits were adopting available technology unnecessarily late and when they did limited,to the advantage of the foreign competition,is my point.In this case obviously allowing DAF and Volvo for two examples to get an early foothold with superior products.Although you obviously won’t accept that the DAF 2800 was a better truck than a TL12,let alone 250 NA ■■■■■■■■■■■■■■■ Marathon.As opposed to an SA 400 type cab with a ■■■■■■■ 350 under it.

Oh wait we’re supposed to believe that it would have been slower and thirstier,with a supposed more fragile engine,with 280 hp + produced at around 1,500 rpm,than the TL12 producing 280 hp max at 2,200 rpm.If not the lie that a 335 let alone 350 ■■■■■■■ didn’t even exist.

Who were they trying to kid and why.On that note remind us what the TL 12’s piston speed was at 2,200 rpm and its SFC at peak power v the ■■■■■■■■ at 1,600 rpm and therefore how could the thing possibly have provided a better overall journey time,at a better overall fuel consumption,at a lower piston speed,than a ■■■■■■■ 335 let alone 350.

The small cams made peak power at 2100 rpm.

A spirited driver could drop an SC to 5mpg.They hammered fuel,one reason as ive explained of the adoption of big cam.

Another issue which ive never mentioned is the power and torque outputs were very inconsistent,and this is still more true today of the electronics.

As said regarding the TL12,maybe the pump timing and phasing was perfect out of the works and simple they performed.

It’s obvious that running the ■■■■■■■ at its peak power or for that matter even at lighter load than that at 2,000 rpm + would have massacred the fuel consumption figures.

However what is also certain is that to provide the same ‘spirited’ 280 hp of the TL12’s 2,200 rpm power peak the 335 at least was turning over at only 1,600 rpm,at a piston speed of 26.6 feet per second,at a Specific Fuel consumption of less than .350 lb/bhp/hr.Or 300 hp at 1,750 rpm at a piston speed of 29 feet per second still without exceeding an SFC of .350 lb/bhp/hr.

Those are the only figures that matter here which you’ll have to beat if you want to show that the TL12 could have possibly beaten the journey time/fuel consumption/piston speed comparison with the ■■■■■■■■■■■■ we know that the 280 hp figure is set in stone and is as much as the TL12 could provide.As is the fact that its piston speed at that or any other equivalent output was also far higher than the ■■■■■■■■■■■ that’s the journey time and piston speed issue settled in favour of the ■■■■■■■ at least.Which just leaves that SFC question at the equivalent output in which again it’s my bet that the ■■■■■■■ was also ahead.

While the fact that driving the thing in the wrong gear at the wrong engine speed and/or making unnecessary use of all the available power at any point,while not making correct use of the available torque,is the point ‘if’ someone was actually setting out with the aim of artificially creating a worse journey time/fuel consumption figure v the TL12.As would making a pointless irrelevant comparison of the TL12’s v the ■■■■■■■■ piston speeds at an equally irrelevant equivalent high idle speed.

While we’ve already got documented evidence that even the road test regime only started to supposedly realise and apply the technique of ‘letting the ■■■■■■■ lug’ with the introduction of the BC.When the SC’s obvious real world working rev range was between 1,350 rpm - 1,800 rpm with absolutely no need to take it above 1,800 rpm for an easy 300 + hp by just a quick glance at the torque and SFC curves.Again that unbelievable erroneous inference,of it supposedly being ok to rev the nuts of the SC,being more explainable by conspiracy than ■■■■ up.While the type of driver who wants to thrash a motor way outside of its optimum operating range will get bad fuel consumption figures regardless of the engine type.

Which still leaves the question as to how did the 780 lb/ft and 280 hp max TL 12 powered Marathon supposedly get better journey times anywhere than the 335 and E290 powered Marathon and 355 powered Transcon and Volvo F12.That’s obviously not coincidence that’s total bs.Probably like the comparative fuel consumption figures.Leaving the next question who gained from that sand bagging of the competition and biging up the Marathon.

images41.fotki.com/v1634/photos … 001-vi.jpg

[zb_anorak]

railstaff:
The small cams made peak power at 2100 rpm.

A spirited driver could drop an SC to 5mpg.They hammered fuel,one reason as ive explained of the adoption of big cam.

Another issue which ive never mentioned is the power and torque outputs were very inconsistent,and this is still more true today of the electronics.

As said regarding the TL12,maybe the pump timing and phasing was perfect out of the works and simple they performed.

I think I’ve read elsewhere that the 14 litre ■■■■■■■ needed regular “tuning” to release its potential, otherwise its performance and fuel consumption were below par. If the TL12 was more foolproof, that is surely a significant advantage. Given Leyland’s reputation for poor build quality, I am moderately surprised to read that the engines were consistently well-made. The more I read about the TL12, the more I am impressed with the engineering wrapped up in it.

[railstaff]

[zb]
anorak:

railstaff:
The small cams made peak power at 2100 rpm.

A spirited driver could drop an SC to 5mpg.They hammered fuel,one reason as ive explained of the adoption of big cam.

Another issue which ive never mentioned is the power and torque outputs were very inconsistent,and this is still more true today of the electronics.

As said regarding the TL12,maybe the pump timing and phasing was perfect out of the works and simple they performed.

I think I’ve read elsewhere that the 14 litre ■■■■■■■ needed regular “tuning” to release its potential, otherwise its performance and fuel consumption were below par. If the TL12 was more foolproof, that is surely a significant advantage. Given Leyland’s reputation for poor build quality, I am moderately surprised to read that the engines were consistently well-made. The more I read about the TL12, the more I am impressed with the engineering wrapped up in it.

That is correct,■■■■■■■ advised two top sets a year if engine under hard use,that means double shifted or an hours based schedule.

Taking the covers of an 855 without training in 1972/3 would have been daunting to the average fitter.There was so much to take in, using the timing marks on the auxhillary drive,then of course the three different methods of setting the injector preload,IBC,OBC,DTI.The adjustment of the fuel pressure on a snap reading,you had to have a degree in brain surgery to maintain them.Things got left understandable,but yeah when on song they flew or maybe in reality could be made to fly.

[dave_docwra]

Going back a year or two I worked for a company who run a mixed fleet of British vehicles & three 2800 DAFs, my experience at the time with the fleet was that the ■■■■■■■ powered vehicles were reliable & we did have to do rebuilds on the engines which were pretty much straight forward, The Rolls Royce diesel engines took much more time to rebuild & were done more often, The Gardner 240s or as some people describe them boat anchors, only ever needed exhaust (bag pipes) down pipes replacing & as far as I can remember we never rebuilt one, the two Marathons we had, were reliable and only one of them had a head gasket replaced which was on the one which was driven by a racing driver who never quite understood it was a truck, the same vehicle had brake linings replaced at an average of three to one compared to the proffessional drivers that were employed at the time, the second Marathon was pretty much trouble free, the five Roadtrains they had were all powered with the TL12 engine & were reliable, but I do recall they all had various niggling electrical issues but nothing that stopped them getting back to our workshop. The DAFs were brand new & obviously pretty much trouble free, the only negative I would say on the DAF was that one of them rolled into the back of a loaded trailer in the yard, after the driver started it released the hand brake to find the air was down then wandered off, the rest I am sure you can work out, anyway the down side was the chassis it twisted & had to go to Truckalign (may be wrong on the name) at Charlton, South London to be repaired, I am sure the British stuff would have not have suffered in the same way. The Guy who drove the second Marathon was allocated a new DAF and constantly complained what seemed for ever that he would have preferred to have kept his Marathon, so I guess not everything was bad about them. Obviously all the above mentioned vehicles suffered with the normal issues of the time.

With the road test Marathon reports, were Leyland clever enough to have matched engine, gear box, tyres & drive axle to give the best results which they achieved?

Happy new year to all, Dave…

[carryfast]

dave docwra:
With the road test Marathon reports, were Leyland clever enough to have matched engine, gear box, tyres & drive axle to give the best results which they achieved?

Happy new year to all, Dave…

To be fair both the Trancon 355 and the Volvo F12 seemed to have a very reasonable gearing match.It would have taken something impossibly stupid to have possibly got a slower journey time result,or possibly even a worse fuel consumption,against something with the 280 hp max at 2,200 rpm of the TL12.

Although the 335 powered Brits were often lumbered with silly low final drive gearing and/or a media road test regime which seemed to go along the lines of drive an SC ■■■■■■■ like a torqueless Bedford 6 v 71 powered TM 32 tonner. No surprise with a fuel consumption result to match.Which leaves the question was that deliberate to put the 335 and 350 out of the frame when it mattered to the benefit of the foreign competition.All being part of the intentional,planned,progressive run down of the uk truck manufacturing industry,which is my argument and I’m staying with it.

[erf-ngc-european]

Carryfast:

dave docwra:
With the road test Marathon reports, were Leyland clever enough to have matched engine, gear box, tyres & drive axle to give the best results which they achieved?

Happy new year to all, Dave…

To be fair both the Trancon 355 and the Volvo F12 seemed to have a very reasonable gearing match.It would have taken something impossibly stupid to have possibly got a slower journey time result,or possibly even a worse fuel consumption,against something with the 280 hp max at 2,200 rpm of the TL12.

Although the 335 powered Brits were often lumbered with silly low final drive gearing and/or a media road test regime which seemed to go along the lines of drive an SC ■■■■■■■ like a torqueless Bedford 6 v 71 powered TM 32 tonner. No surprise with a fuel consumption result to match.Which leaves the question was that deliberate to put the 335 and 350 out of the frame when it mattered to the benefit of the foreign competition.All being part of the intentional,planned,progressive run down of the uk truck manufacturing industry,which is my argument and I’m staying with it.

As always, CF, you appear to be parading your pet fixed ideas from thread to thread. It has already been explained to you that final drive ratios provided by manufacturers are neither ‘silly’ nor thirsty; rather they are designed for the use to which the truck is intended to be put. We’ve already covered the fact that Continental and UK speed limits might justify different final drive ratios. We’ve already established that a final drive ratio for that period on the Continent was commonplace at about 4.71:1. Even export Morris Minors were made with three different ones to cater for urban, long-haul and mountainous terrains in the '50s.

I’ve just found a piece at the back of Eric Gibbons’s history of Scania. It states that ‘for optimising engine and final drive ratio for a given task, Scania’s answer was to plot fuel consumption for a certain drive ratio over a particular route, in this case from Stockholm to Gothenburg, and chart the results on vehicles of an otherwise identical specification. This showed that there was a minimal point in the fuel consumption for that drive ratio. However, the best compromise had to be sought between fuel consumption and driveability.’ You see, these chaps were working in the real world! It goes on, ‘This showed for example that the DS11 engine combined with a final drive ratio of 4.71:1 offered a fuel saving of 3.5 litres per 100 kms when decreasing the speed from 80 kph to 70 kph and 2.5 litres per 100 kms when decreasing from 90 kph to 80 kph.’ Notice that 4.71:1 is exactly the same ratio that ERF was already using with its NTC 335-powered ‘Europeans’. Robert

[carryfast]

ERF-NGC-European:
As always, CF, you appear to be parading your pet fixed ideas from thread to thread. It has already been explained to you that final drive ratios provided by manufacturers are neither ‘silly’ nor thirsty; rather they are designed for the use to which the truck is intended to be put. We’ve already covered the fact that Continental and UK speed limits might justify different final drive ratios. We’ve already established that a final drive ratio for that period on the Continent was commonplace at about 4.71:1. Even export Morris Minors were made with three different ones to cater for urban, long-haul and mountainous terrains in the '50s.

I’ve just found a piece at the back of Eric Gibbons’s history of Scania. It states that ‘for optimising engine and final drive ratio for a given task, Scania’s answer was to plot fuel consumption for a certain drive ratio over a particular route, in this case from Stockholm to Gothenburg, and chart the results on vehicles of an otherwise identical specification. This showed that there was a minimal point in the fuel consumption for that drive ratio. However, the best compromise had to be sought between fuel consumption and driveability.’ You see, these chaps were working in the real world! It goes on, ‘This showed for example that the DS11 engine combined with a final drive ratio of 4.71:1 offered a fuel saving of 3.5 litres per 100 kms when decreasing the speed from 80 kph to 70 kph and 2.5 litres per 100 kms when decreasing from 90 kph to 80 kph.’ Notice that 4.71:1 is exactly the same ratio that ERF was already using with its NTC 335-powered ‘Europeans’. Robert

We know that the thing wasn’t geared for 80 kmh at 1,500 rpm more like 2,000 rpm so obviously way outside the optimum point of its SFC curve and we know that they only started making a big song and dance about let it lug with the arrival of the Big Cam.The inference of both being obvious regarding the fuel consumption figures at least.Which leaves the question how could a 335 ■■■■■■■ powered vehicle and an F12 have possibly ended up with a slower average journey figure v a 280 hp TL12 powered Marathon.The inference being obvious let’s hide the fact that we’re deliberately crippling our products to the advantage of the foreign imports.On that note there’s not much point in manufacturers providing SFC curves if the assemblers were going to make it up as they went along.

[jelliot]

Oh I feel like such a dummy!!! all that time I was running my own trucks and there I was not realising that every time I changed terrain I should have stopped and changed my final drive ratio to optimise my fuel consumption… Here I was thinking that the truck supplier was just being polite asking me what kind of work I was doing and what sort of weight I was intending to run when I was sitting in the sales office ordering a new truck .
Unlike certain operators the difference between my profit and loss was a lot more than the difference between 7.8 and 7.9 mpg. If your margin was so tight why did you even go for the contract.
As long as it starts up in the morning, and does it’s job I really don’t care what speed the piston going, or if the con rod has a bit of an angle on it.
The product speaks for it’s self and makes it’s own reputation. If it runs cost efficiently and doesn’t cause many problems then that is what most of are / were looking for…

I started reading this thread because like many on here I have a nostalgic soft spot for Marathons, I quite like the design of them and can look back on them with rose tinted glasses. Unfortunately for the most of us the last few pages have descended into a bit of an incoherent meaningless drivel.

As I said before my dad ran Marathons along side Big Fiats and Mercs, they were Mid Brunswich Green with red chassis and traditional yellow block sign writing with complementary shadows… Like most on here some days he loathed them and other days he just hatted them, but for some reason he just kept going…as did I…

Jeff…

[lespullan]

At last sanity.

[gingerfold]

lespullan:
At last sanity.

+10 Thank you

[ramone]

lespullan:
At last sanity.

Didnt they have some Marathons at Renwicks Les

[lespullan]

ramone:

lespullan:
At last sanity.

Didnt they have some Marathons at Renwicks Les

Yes we got 2, cant remember much about them, they came new Dixie Dean and Frank Breslin got them.

[james_908]

lespullan:
At last sanity.

Phew…at last

Sent from my SM-G900F using Tapatalk

[gingerfold]

I have been in touch with a former Leyland graduate engineer, now a Chartered Engineer, who worked in Leyland’s Advanced Powertrain Department in the early 1980s, and who was actively involved in development testing of the T45 Roadtrain. When engine production was discontinued by Leyland he joined the Ricardo Engineering Consultancy and he has also worked for ■■■■■■■■ He is happy to have his name published and I have quoted the salient observations he makes about the TL12 engine. These comments of Gary Dwyer are meant to “box off” some of the points about the TL12 raised in this thread and they are from “the horses mouth” so to speak. I do hope that any replies made to Gary’s comments are sensible and objective. There is no need for the thread to degenerate again to where it went previously.

Gary Dwyer writes: -

For the T45 Roadtrain the 273 bhp output was retained, but it was achieved at 2,000 rpm. To reduce fuel consumption and also as a response to market forces from competitors.

The TL12 was judged to be a good workhorse engine that gave more than acceptable durability. The majority of feedback comments were always positive.

After the production machinery was moved from Southall to Leyland the first Leyland built TL12s were not entirely successful and they did have some quality issues. These were quickly resolved but there were rumours that AEC employees had sabotaged the machinery before it left Southall. The rumours of sabotage were never proven.

AEC had a reputation for not exactly following production drawings to the letter, but they would “tweak” things to make them work. These “tweaks” were never recorded.

Leyland at the time was not perfect but they achieved a lot from limited available resources…the continuous draining of funds to car divisions restricted product development at a time of increased competition.

Ricardo did plenty of durability testing on the T45 variant (of the TL12). They also did some thermal testing to measure metal and component temperatures. No major issues were found after the standard 1,500 hour durability test.

Inlet valve wear was slightly excessive as AEC used a design (masked inlet valve) which did not permit the valve to rotate and even out wear.

Leyland built TL12s did have a modified cylinder head design, but the TL12 remained a very competitive engine in its day.

AEC and Leyland were developing an air-to-water intercooled version at 325 bhp, but the engine never got beyond development testing. Further piston development was thought to be needed…the dry liner design could have limited any further development…but modern air-to-air intercooling would have been beneficial for further development. At the time intercooling was in its infancy.

The chassis engineering guys were not in favour of higher power outputs…larger radiators were needed that meant a re-design of the front of the chassis…but DAF managed it with their engine in the 80 series.

The only other application for the TL12 was in the Leyland Landtrain

One prototype horizontal TL12 was built at Southall and taken to Leyland when Southall was closed.

I am grateful to Gary for sharing the above comments with me and publicly record my thanks to him.

[railstaff]

gingerfold:
I have been in touch with a former Leyland graduate engineer, now a Chartered Engineer, who worked in Leyland’s Advanced Powertrain Department in the early 1980s, and who was actively involved in development testing of the T45 Roadtrain. When engine production was discontinued by Leyland he joined the Ricardo Engineering Consultancy and he has also worked for ■■■■■■■■ He is happy to have his name published and I have quoted the salient observations he makes about the TL12 engine. These comments of Gary Dwyer are meant to “box off” some of the points about the TL12 raised in this thread and they are from “the horses mouth” so to speak. I do hope that any replies made to Gary’s comments are sensible and objective. There is no need for the thread to degenerate again to where it went previously.

Gary Dwyer writes: -

For the T45 Roadtrain the 273 bhp output was retained, but it was achieved at 2,000 rpm. To reduce fuel consumption and also as a response to market forces from competitors.

The TL12 was judged to be a good workhorse engine that gave more than acceptable durability. The majority of feedback comments were always positive.

After the production machinery was moved from Southall to Leyland the first Leyland built TL12s were not entirely successful and they did have some quality issues. These were quickly resolved but there were rumours that AEC employees had sabotaged the machinery before it left Southall. The rumours of sabotage were never proven.

AEC had a reputation for not exactly following production drawings to the letter, but they would “tweak” things to make them work. These “tweaks” were never recorded.

Leyland at the time was not perfect but they achieved a lot from limited available resources…the continuous draining of funds to car divisions restricted product development at a time of increased competition.

Ricardo did plenty of durability testing on the T45 variant (of the TL12). They also did some thermal testing to measure metal and component temperatures. No major issues were found after the standard 1,500 hour durability test.

Inlet valve wear was slightly excessive as AEC used a design (masked inlet valve) which did not permit the valve to rotate and even out wear.

Leyland built TL12s did have a modified cylinder head design, but the TL12 remained a very competitive engine in its day.

AEC and Leyland were developing an air-to-water intercooled version at 325 bhp, but the engine never got beyond development testing. Further piston development was thought to be needed…the dry liner design could have limited any further development…but modern air-to-air intercooling would have been beneficial for further development. At the time intercooling was in its infancy.

The chassis engineering guys were not in favour of higher power outputs…larger radiators were needed that meant a re-design of the front of the chassis…but DAF managed it with their engine in the 80 series.

The only other application for the TL12 was in the Leyland Landtrain

One prototype horizontal TL12 was built at Southall and taken to Leyland when Southall was closed.

I am grateful to Gary for sharing the above comments with me and publicly record my thanks to him.

Very good post.

[windrush]

Gardner and BMC both used the non rotating masked inlet valves as well, I don’t remember them having excessive guide wear on the inlets but the exhaust guides were replaced at overhaul as a matter of course. Every engine is different though.

Pete.

[railstaff]

Tends to be more the seat and port area of the valve.Of course air filtration plays a major part in it.
Many years ago I met an ex Gardner development engineer.He had just retired and we got talking about Gardners in general, I was quite intrigued over the Gardner,and then he started talking about the masked inlet valves amongst other things,his speciality was piston ring development.He then told me that back in the late 60,s a couple of Leyland development engineers came to work at Gardner.They could not understand the need for the masking and removed it,this had an ill effect on the running of the engine.They later had valves made with the mask moved degress counter clockwise and clockwise,again with ill effects on the running of the engine.Needless to say they then reverted to how Gardner originally designed the engine.

[cav551]

I probably see more AEC, Leyland and more recently to a lesser extent Gardner engines on a day to day basis than a lot of other fitters do these days. It is now the AEC masked inlet valve restrainer which tends to show the heaviest wear, followed closely by the exhaust valve guides and the pushrods.

[carryfast]

gingerfold:
I have been in touch with a former Leyland graduate engineer, now a Chartered Engineer, who worked in Leyland’s Advanced Powertrain Department in the early 1980s, and who was actively involved in development testing of the T45 Roadtrain. When engine production was discontinued by Leyland he joined the Ricardo Engineering Consultancy and he has also worked for ■■■■■■■■ He is happy to have his name published and I have quoted the salient observations he makes about the TL12 engine. These comments of Gary Dwyer are meant to “box off” some of the points about the TL12 raised in this thread and they are from “the horses mouth” so to speak. I do hope that any replies made to Gary’s comments are sensible and objective. There is no need for the thread to degenerate again to where it went previously.

Gary Dwyer writes: -

For the T45 Roadtrain the 273 bhp output was retained, but it was achieved at 2,000 rpm. To reduce fuel consumption and also as a response to market forces from competitors.

The TL12 was judged to be a good workhorse engine that gave more than acceptable durability. The majority of feedback comments were always positive.

After the production machinery was moved from Southall to Leyland the first Leyland built TL12s were not entirely successful and they did have some quality issues. These were quickly resolved but there were rumours that AEC employees had sabotaged the machinery before it left Southall. The rumours of sabotage were never proven.

AEC had a reputation for not exactly following production drawings to the letter, but they would “tweak” things to make them work. These “tweaks” were never recorded.

Leyland at the time was not perfect but they achieved a lot from limited available resources…the continuous draining of funds to car divisions restricted product development at a time of increased competition.

Ricardo did plenty of durability testing on the T45 variant (of the TL12). They also did some thermal testing to measure metal and component temperatures. No major issues were found after the standard 1,500 hour durability test.

Inlet valve wear was slightly excessive as AEC used a design (masked inlet valve) which did not permit the valve to rotate and even out wear.

Leyland built TL12s did have a modified cylinder head design, but the TL12 remained a very competitive engine in its day.

AEC and Leyland were developing an air-to-water intercooled version at 325 bhp, but the engine never got beyond development testing. Further piston development was thought to be needed…the dry liner design could have limited any further development…but modern air-to-air intercooling would have been beneficial for further development. At the time intercooling was in its infancy.

The chassis engineering guys were not in favour of higher power outputs…larger radiators were needed that meant a re-design of the front of the chassis…but DAF managed it with their engine in the 80 series.

The only other application for the TL12 was in the Leyland Landtrain

One prototype horizontal TL12 was built at Southall and taken to Leyland when Southall was closed.

I am grateful to Gary for sharing the above comments with me and publicly record my thanks to him.

I’d guess the question of exactly which ‘objective’ comparison,of specific torque figures,would justify the idea that the TL12 was ‘competitive’ with its DAF DK,Volvo TD 120,and ■■■■■■■ 335/350 and Rolls Eagle rivals in the day.

If inter cooling was supposedly in its infancy in the mid 1970’s let alone 1980’s,to the point of needing to be avoided,wouldn’t that have removed the DKS option from DAF’s armoury at least ?.

If cooling issues were a limiting factor in the Marathon or T45 how do you explain the fitting of the ■■■■■■■ 335 in the Marathon and even bigger power ■■■■■■■ and Rolls options in the T45 after the TL12’s removal from the scene ?.

What would the mechanical stress levels ( as opposed to engine temperature stress levels ) of the TL12’s piston to crank component chain,have been given a 70-80 lb/ft + per litre requirement and what was the TL12’s stress capacity in that regard before something broke in that chain ?.

What was the reason for the TL12 seeming to have been avoided in the Scammell Crusader in favour of Rolls Royce ?.