Unserviceable Lorries - Jul - Sep 44

[phylo_roadking]

The other advantage of taper rings is that the combustion gas acts obliquely against the taper face, so there's a degree of pressure relief that tends to suppress the blow by to a certain extent. I'm assuming the original compression rings were rectangular faced?

I'm assuming that if the tapered outside face on the compression rings were indeed "new", then the old rings were rectangular faced...

I know this sounds somewhat primitive for Austins...but as of January 1946, their car engines were still running without oil scraper rings!

In January the Ministry of Supply tackled Austins as to why there were as yet no supplies of the 4 cylinder saloon cars ordered by the War Department; Austins replied that the dealy was due to the MoS/WD specifying that the cars had to use HD30 oil....and the Austin "technical people at Chobham" reported that this was entirely unsuitable as their four-cylinder car engines didn't have oil scraper rings! They had to rapidly spec up new pistons with oil scraper rings and submit them to four weeks of bench testing...

I can't help thinking that Austins (and by definition their various subsidiaries incuding Humber) were...um...slightly technically backward? This something I've noticed before, possibly on the British tank design thread; yes, there were various high spots of technological development through the war...but basically we fought a 1940's war with 1920's/1930's technology!

[Don Juan]

Well, British vehicles were designed to be operated at the farthest points of the empire, so I suppose there was a premium on simplicity - British equipment was designed to be durable and repairable more than efficient and reliable.

My take on this now is that the increased clearance given to the piston skirt meant that less lub. oil was retained in cylinder. My understanding is that the piston skirt is there to retain and distribute lub. oil, not to remove any excess. (Well, its primary job is to steady the piston at TDC and BDC, and oil distribution is a secondary task).

Therefore, the more spartan oil regime in-cylinder required new piston rings that wore better and distributed oil more effectively themselves. If the new HD30 lub. oil spec. was less viscous, this might have added to the problem of retaining oil in-cylinder.

As to the standardisation of the wading spec., I wonder if they looked at where they were going in NWE, and realised there was going to be a lot of water about, i.e. the ports of Calais, Dunkirk, Antwerp, the latter with the operations around the Scheldt and Walcheren, and then there's the Dutch lowlands, which the Germans could flood, then the Rhine that needed crossing, then the north German lowlands, which WERE flooded etc.

[Aber]

IIRC the wading Bedfords were replaced by 4x2s in the assault units - was the Army building up stocks of 4x4s for the winter?

[phylo_roadking]

My understanding is that the piston skirt is there to retain and distribute lub. oil, not to remove any excess. (Well, its primary job is to steady the piston at TDC and BDC, and oil distribution is a secondary task).

Here I would normally defer to your previous career and expertise as an engine designer; but for a few other interests of my own, particularly "classic" petrol-driven internal combustion engines in single-, v-twin, and parallel-twin configurations...and the two-wheeled chassis wrapped around them

For decades one of the tuning techniques for four-stroke (four-cycle for American readers) engines was to sharpen the edge of the piston skirt to allow it to "clean" the bore more - less "oil drag" on components in high-revving motors; it was the oil control ring that retained and distributed oil in that part of the cylinder ABOVE the gudgeon pin (wrist pin )...especially if there were oil feed holes IN the piston, just below the control ring's groove; and especially so as the oil control ring would be an inch or two....or three!..."above" the line of the piston skirt. In other words - the piston skirt edge could only scrape the oil off that portion of the bore that the piston skirt actually travelled up and down - ABOVE that part of the piston's stroke, the oil control ring was responsible for that task, retaining/distributing oil on the upper cylinder walls...

Therefore, the more spartan oil regime in-cylinder required new piston rings that wore better and distributed oil more effectively themselves.

Exactly! Given that the portion of the upper cylinder where the compression rings...bore...would need lubrication too...and THIS was above the travel of the oil control ring The oil control ring would control the lubrication THERE where the compression rings travelled....not the piston skirt.

Although I do also fully agree with your comments last night regarding the rocking of the piston due to increased piston skirt clearance probbably causing high wear too - especially if the earlier rings were rectangular-edged...

Hence the greatly accelerated wear over earlier K5s - SEVERAL factors simultaneously contributing to accelerated ring wear?

If the new HD30 lub. oil spec. was less viscous, this might have added to the problem of retaining oil in-cylinder.

Yes, this came to me a while back when I first read up on the HD30 issue! Unfortunately I haven't come across any comparisons yet...surely there MUST have been some done and discussed in and around the period of the Paul Pryon Agreement, the agreement by which the British agreed to take on U.S.-equivalent oil grades to greatly simplify the logistic chain!

But there must have been some great difference if Austin's "technical people" could say their engines would run on their old specified oil grade - but NOT on HD30!

As to the standardisation of the wading spec., I wonder if they looked at where they were going in NWE, and realised there was going to be a lot of water about, i.e. the ports of Calais, Dunkirk, Antwerp, the latter with the operations around the Scheldt and Walcheren, and then there's the Dutch lowlands, which the Germans could flood, then the Rhine that needed crossing, then the north German lowlands, which WERE flooded etc.

That's one for Rich perhaps - to what extent was THIS direction of travel obvious to OVERLORD planners BEFORE the events of the summer of 1944? My take was more that the first wave of operations would be to the south and south-east, to secure the Breton Peninsula and allow the USAAF to establish airfields there within a couple of weeks at most - not the couple of months as per OTL? But that was for the Americans - where had the British been planning on heading?

[phylo_roadking]

IIRC the wading Bedfords were replaced by 4x2s in the assault units - was the Army building up stocks of 4x4s for the winter?

Aber - Tom turned up a couple of examples of this happening in September...at the same time as the first indications of K5s appearing in numbers in Advanced Workshops for repair. More likely therefore that they were setting the K5s aside due to the increasing problems and pulling whatever was available with the same lading weight out of reserve and issuing them?

[phylo_roadking]

Just as an aside...

Well, British vehicles were designed to be operated at the farthest points of the empire, so I suppose there was a premium on simplicity - British equipment was designed to be durable and repairable more than efficient and reliable.

There weren't many designed specifically to do this; the various "India Pattern" armoured cars and light tanks etc. come to mind. Looking back over many years of CMV - I don't think we can say that the many and various civilian car and lorry engines and chassis pressed into service from 1939-on were specifically designed for the extremes of climate.

It's hard to put this bit into words, but...I personally think that simplicity of design was a property of many of the engines used BECAUSE they were simple already Or rather....because they were STILL simple! SO many vehicle engines were still at the side-valve level, for example. Yes, they were primitive compared to what the next few decades brought, and what we're used to - but that simplicity and durability was often what kept them going in adverse climates and circumstances...that Austin Technical Manual that contained the information on advancing or retarding the ignition timing to suit octane ratings? It ALSO specified ignition settings if the engines were run on white spirit! ...

...UNTIL issues like the changing octane rating and oil grades during the war showed up as cooling problems and hotspots around components and assemblies. This was what happened from 1943-on when the then-imminent chage to MT 80 was first flagged up; Tom turned up a report of a meeting...one of how many I wonder???...between representatives of the British motor industry and the D.M.E. (again!) where the industry representatives reported that testing HAD showed that running higher octane levels in their "old" engines designed for lower ratings WAS manifesting as overheating and thus accelerated wear on some components and areas in engines.

In other words - not only is the change to HD30 known to have caused problems, the change to Mt 80 Pool is ALSO known to have done so...and in it's case up to a year before D-Day!

[Don Juan]

For decades one of the tuning techniques for four-stroke (four-cycle for American readers) engines was to sharpen the edge of the piston skirt to allow it to "clean" the bore more - less "oil drag" on components in high-revving motors; it was the oil control ring that retained and distributed oil in that part of the cylinder ABOVE the gudgeon pin (wrist pin )...especially if there were oil feed holes IN the piston, just below the control ring's groove; and especially so as the oil control ring would be an inch or two....or three!..."above" the line of the piston skirt. In other words - the piston skirt edge could only scrape the oil off that portion of the bore that the piston skirt actually travelled up and down - ABOVE that part of the piston's stroke, the oil control ring was responsible for that task, retaining/distributing oil on the upper cylinder walls...

In reality, the distribution of oil in-cylinder is a bit more dynamic than in theory. The "working lubricant" in the cylinder is known as the hydrodynamic (isoviscous-elastic) layer, bounded by partial lubrication layers found at TDC and BDC, which are due to the reduced speed of the piston at these points. The benefit of a lower viscosity lubricant is that it presents less friction - it is easier for the piston to move through - but the disadvantage is that it can't bear as much load as a high-viscosity oil. This means that maintaining the hydrodynamic layer becomes more critical.

The benefit of the skirt is that it is subjected to low load but has a large contact area, which promotes more effective lubrication distribution within the hydrodynamic layer. And from that point, the rings can do their job.

What people do to supe up their motorcycles rarely has anything to do with good engineering, I'm afraid.

[Aber]

As to the standardisation of the wading spec., I wonder if they looked at where they were going in NWE, and realised there was going to be a lot of water about, i.e. the ports of Calais, Dunkirk, Antwerp, the latter with the operations around the Scheldt and Walcheren, and then there's the Dutch lowlands, which the Germans could flood, then the Rhine that needed crossing, then the north German lowlands, which WERE flooded etc.

That's one for Rich perhaps - to what extent was THIS direction of travel obvious to OVERLORD planners BEFORE the events of the summer of 1944? My take was more that the first wave of operations would be to the south and south-east, to secure the Breton Peninsula and allow the USAAF to establish airfields there within a couple of weeks at most - not the couple of months as per OTL? But that was for the Americans - where had the British been planning on heading?

Pre D-DAY long range planning maps are quite scarce - the most well-known is in Eisenhower's Crusade in Europe which puts 21st Army Group on the coast with a right boundary roughly Nantes - Brussels - Duisberg, and a frontline on the German border/Maas at D +330.

[phylo_roadking]

What people do to supe up their motorcycles rarely has anything to do with good engineering, I'm afraid.

True - but I'm not talking about the "back yard" school of engine performance tuning, more the Peter Williams' etc. school of engineers turned racers!

Just as a side note - Wellworthy's "Lymalloy" piston rings just by chance first came to public notice on two wheels! They were THE competition fitment of choice for the last three years of the 1930s on the Isle of Man...

The benefit of a lower viscosity lubricant is that it presents less friction - it is easier for the piston to move through - but the disadvantage is that it can't bear as much load as a high-viscosity oil. This means that maintaining the hydrodynamic layer becomes more critical.

...but I take it the present situation is much improved by the modern generation of additives etc.? Permiting low viscosity oils in modern performance engines? Remember - we ARE talking about rather primitive - by modern standards - engines here.

with a right boundary roughly Nantes - Brussels - Duisberg, and a frontline on the German border/Maas at D +330.

I.E. stopping short of all the potential problems in Holland intentionally?

[Don Juan]

True - but I'm not talking about the "back yard" school of engine performance tuning, more the Peter Williams' etc. school of engineers turned racers!

Well there you go. Racing engines are designed for maximum performance and minimum durability.

...but I take it the present situation is much improved by the modern generation of additives etc.? Permiting low viscosity oils in modern performance engines? Remember - we ARE talking about rather primitive - by modern standards - engines here.

I think it's all relative really. If Austins were concerned about HD30, then I would assume that this was either because it had a higher viscosity than the existing standard oils, and therefore added frictional load to the engine, or it had a lower viscosity, which made it less able to endure the existing loads without the lubricating face shearing, thus inducing friction and wear.

[phylo_roadking]

Racing engines are designed for maximum performance and minimum durability

...except when it comes to the Island

REAL maximum performance vs. minimum durability is for sprinters; men like George Dixon, Sunbeam's interwar development engineer and Britain's most successful sprinter/hillclimber ever...who dealt with oil drag by warming his bike up on the starting line - then dropping the contents of the sump! - having calculated that the oil actually coating the engine internals at that point would lubricate them until the end of the course!

I think it's all relative really. If Austins were concerned about HD30, then I would assume that this was either because it had a higher viscosity than the existing standard oils, and therefore added frictional load to the engine, or it had a lower viscosity, which made it less able to endure the existing loads without the lubricating face shearing, thus inducing friction and wear.

I'm about to break someone's heart right now...

Tom, I think you've partly been researching the WRONG AUSTIN PROBLEM!

I've a feeling everything we're seeing after D-Day is a result of problems encountered BEFORE that date, and possibly the actions taken (in a panic?) to clear them. What we all should be looking for is more of what you turned up on ww2talk regarding the British motor industry's issues and responses to the arrival of MT 80 Pool and HD30 oil I.E. 1943 into 1944!....and in particular exactly what caused Austin to recall and fit a revised piston design to the "assault" K5s in May 1944...

For decades everyone has been looking at the issues the K5s developed by September 1944 and what caused those; well, we can SEE what resolved them...but what happened that Austins went over TO that "problem" specification???

[Don Juan]

If the original M220 oil is to an ISO (ex BS?) viscosity standard (220), and the HD30 is to an SAE (ex API?) viscosity standard (30), then this chart indicates that to go from the former to the latter saw a pretty big drop in viscosity.

I think this would have resulted in greater oil consumption, requiring enhanced piston wiping, which is perhaps another reason why the new compression rings were tapered - they were partly "scraping" along with the scraper ring itself.

[phylo_roadking]

If the original M220 oil is to an ISO (ex BS?) viscosity standard (220),

That I'm not sure of - but I'll ask the restorers on HMVF.

EDIT: the REME Staff History has a chapter on lubricants and fuels, three pages of which deal with a brief history of the use and problems of opils in use in the british Army through the war period...

It is indeed possible that the "220" in M.220 refers to the viscosity; it reports that in Europe in 1939-40, the Army had difficulty with M.220 in its vehicles as it was too "heavy" an oil....the winter of 1939-40 was extremely cold, and long!....and they went to a lower grade, M.160. But through 1941, although M.160 was for a time the standard grade in Europe, and M.220 in the desert...before the end of the year M.220 was AGAIN in use as a general engine lubricant in ALL theatres (...with M.120 "available" as a lighter grade for winter, but it was never issued)

So - it does indeed look as if "220" and "160" directly refer to relative viscosities???

The History DOES dwell shortly on the concerns over the use of HD30 etc, and the other high-detegent oils, after the Paul-Pryon Agreement of 1942 that mandated their use in British vehicles as well; it notes that despite the many warnings of incipient engine damage due to the flushing effect lifting deposits in oil galleries etc. and re-depositing them elsewhere, blocking oilways...there wasn't in the end any reported manifestation of this. In 1942...

However - that's NOT to say that the problem of heavily-worn rings on/caused by slack-fitting (from new) pistons wasn't contributed-to by the viscosity issue in 1944, well after the experiemntation period in 1942 for HD oils. The increased piston skirt clearance would indeed have thrown an extra factor into the equation of oil films and viscosities - as well as the more obvious issues of high-wearing, rectangular-edged rings and rocking pistons.

On the whole, therefore, with all THOSE issues ranged against it suddenly in the summer of 1944 the poor K5's straight six was doomed! And THEN when you add the wear issues elsewhere in the engine due to the burned/heavily-graphited oil....and the overheating in certain areas and components due to MT 80...!

[Tom from Cornwall]

Phylo, Don Juan, Aber, Rich (if you haven't given up reading!),

I think I have followed some of your technical debates. And then:

Tom, I think you've partly been researching the WRONG AUSTIN PROBLEM!

Coincidentally, I went for a run today, and while puffing away I suddenly had one of those moments - very rare these days! Why did they choose the Austin K5 to waterproof? Easier than any other model? Which lead me on to think:

That you might be right, I do think I will have to broaden the scope of my research - but frustratingly both earlier and later than the 21 A Gp Admin History had led us to believe.

My thoughts are (and I will try to reference this tomorrow):

1. Decision is made that Austin K5 4 x 4 is best 3-tonner for Assault Force as it is easiest to waterproof (and just as importantly therefore to dewaterproof once in Normandy) - Date to be confirmed but 1943?
2. Austin modify engine on 1400 Austin K5s as you suggest to reflect need to keep them going whilst waterproofed!
3. Trials in March 44 (?) at Weymouth reveal problems with the 1400 "Assault" Austins.
4. This leads to last minute (May 44 memo!) replacement of rings (?) etc by Austin and rewaterproofed by REME.
5. 1400 "fixed" "Assault Austins" go into VRDs in UK for Assault Force and are drawn by Assault Units (number unknown).
6. Fault continues to exhibit once on the far shore.
7. Sep 44 - enough in "Crock Parks" to warrant the REME trial I found, to discover if a "local fix" can solve the problem. Trial fails and all Austin K5's frozen until Austin come up with a full solution. The single GT unit I have so far found using Austin K5 swaps them over for other vehicles.
8. By Dec 44 a solution is found and modified Austins start flowing to continent again.

One thing though, is that I think the reference to so many thousand "frozen" in VRDs refers to vehicles NOT sent to the continent. I have not seen the parks of reserve vehicles on the continent referred to as VRDs, rather they were Vehicle Parks belonging to Vehicle Companies which were part of AODs (Advanced [?] Ordnance Depots) RAOC. VRDs are a UK thing AFAIK.

Clearly we need to do a bit more work here, but I think we are beginning to build up a good timeline for the technical history.

BTW the other thing I think I can say with some confidence is that of those 1400 "Assault Austins" some were kept going into a least October 44 - no, I don't know how many.

Also, these vehicles were not used by GT units on the L of C! So, they were not doing 100's of miles back up and down from Bayeux to Brussels, for example. For example, the Inf Bde Coy RASC from 50 Div (524?) that I found using Austin K5's would have only done this trip once. All the rest of the time, they would have been running back and forth between Ammunition, Supply or Petrol Points where they handed stuff over to the Units, and then back to the Corps FMC to replenish.

Regards

Tom

[phylo_roadking]

6. Fault continues to exhibit once on the far shore.

OR....a NEW set of problems appear after the May 1944 changes??? You'd need to fully identify the PRE-May '44 problems to say whether they're the same or different

Which brings me on to -

That you might be right, I do think I will have to broaden the scope of my research - but frustratingly both earlier and later than the 21 A Gp Admin History had led us to believe.

Tom, try that (big) D.M.E. file again....around April-May 1944 this time And see if anything shows up about that FIRST fault or faults that required remedial work at Austins There might also be something in the REME files about it - seeing as they had to RE-waterproof the affected K5s!

BTW the other thing I think I can say with some confidence is that of those 1400 "Assault Austins" some were kept going into a least October 44 - no, I don't know how many.

Don't forget you turned up a reference that in mid-September 150 or so were getting their pistons and rings replaced to try and cure the "problem". WE know it wouldn't....but at the time what would have happened is that THOSE engines started wearing again from fresh Eventually, weeks down the line, they'd be back to the SAME degree of wear as before

Also, these vehicles were not used by GT units on the L of C! So, they were not doing 100's of miles back up and down from Bayeux to Brussels, for example. For example, the Inf Bde Coy RASC from 50 Div (524?) that I found using Austin K5's would have only done this trip once. All the rest of the time, they would have been running back and forth between Ammunition, Supply or Petrol Points where they handed stuff over to the Units, and then back to the Corps FMC to replenish.

But then again - you ALSO found engine failures reported after as little as 2,000 miles That's STILL not too many weeks of short journeys!

Coincidentally, I went for a run today, and while puffing away I suddenly had one of those moments - very rare these days! Why did they choose the Austin K5 to waterproof? Easier than any other model?

Good if not excellent reliability up until then in all other theatres including the Desert since 1941??? Apart from the "troublesome" CV joints, that is, the problematic "Tracta" design. Communality of spares??? Virutally the same panel of engine spares for the K5 as the K2 and the K6