The silence indicares that you have never used a Detroit or RoadRanger and you don’t like being wrong.
Your whining about my so called silence just shows as much ignorance of my pre mod status as how a Detroit two stroke works.IE it ain’t supercharged forced induction and the blower isn’t there to remove the exhaust gasses.It’s just an aid to scavenging in compromised scavenging situations.
As for the 15 speed Fuller I’m obviously not alone in my confusion and disbelief regarding the thing.
Which isn’t surprising who would have thought that Fuller would have made such an oddball as a 15 speed 5 over 5 over 5 range change box effectively with only 12 speeds ? .In which even those who would be expected to know better often call the deep reduction range switch a splitter control.
Sorry if that scepticism and disbelief offended you for some reason.That wasn’t the intent just as in the case of the replies to Ro in that regard.
What has ‘revenue service’ got to do with anything.
The fact that I can’t get my head around a 15 speed range change Fuller is precisely because my experience has been 9 and 13 speed and you were contradicted by numerous other, if incorrect but no less if not more credible, references to the 15 speed ‘splitter’.
But now I also realise that the Detroit two stroke is supercharged, which also blows the exhaust out of the cylinders and which would have been far more powerful if they hadn’t made the mistake of turbocharging it.
I was referring to the torque break type splitter control v clutch actuated preselect splitter in European types and from memory even some Fullers which I drove having a liking for the latter preselect type.The torque break type obviously can’t be preselected.
But range change is always preselected and interlocked and actuated and automatically synchronised during the shift through neutral into the higher range.
The issue of the naturally aspirated Detroit was obviously directed to SDU and Franglais.By definition it’s not supercharged the blower doesn’t compress the charge above atmospheric pressure.The exhaust gasses don’t need to blown out of the cylinder.
They exit the cylinder of their own accord through the open exhaust valves with more than enough force to drag in the new inlet charge and drive a turbocharger and then some.
The plot thickens.
Sorry Ro I don’t buy it, at least yet.This clearly describes a 5 over 5 with a splitter on the low range.
What do you mean by you can’t/don’t pre select a range change ???.
Pre select is exactly how you select a range change.
The range shift is interlocked and actuated by the shift through neutral.
Only a split shift can be non pre select.If not maybe you can tell me the exact procedure for a non preselected range change.
By some accounts the second switch is just the deep low range switch.Effectively you were right it seems to be a 5 over 5 over 5 range change box with a separate range change control for the lowest range.
I can be forgiven for taking descriptions of a ‘splitter’ at face value.Why anyone would choose it over a 13 or 18 speed is a mystery.
Which leaves the question what do they mean by don’t preselect a range change ?.How wouldn’t you ?.
Exactly what overwhelming proof is there when even those who drive the thing call it a 5 over 5 with a splitter on the low range.You also won’t find the deep reduction or it’s control called a low range controlled by a range change control switch.They call it a splitter.
Yes agreed they are probably if not definitely wrong.
Just like the idea that the Detroit two stroke blower is a supercharger and an exhaust blower with the design flaw of being strangled by putting a turbocharger put in its way.
To be fair it’s going to take more than a search engine to find any accurate description of what the thing actually seems to be and how to categorise it.
There are drivers that have been driving the things for years who don’t seem to know themselves what it actually is or the terminology of it’s type and control.
Having put 5 and 5 together I’m prepared to agree with Ro.
It’s a 5 over 5 over 5 range change box with a separate range change control for the lowest range of 5.
My guess is SDU got it right more by luck than judgement I can be forgiven for misunderstanding the box of bolts but would have sorted it out before leaving the yard.
The general consensus among it’s users varies from pile of dog zb to can’t do anything that a 13 or 18 speed can’t do better.I agree with the latter.
Both types are pre-selectable. They just advise you not to pre-select until you are close to shifting gear, to save wear and tear.
Everything can be pre-selected. The issue is whether or not it’s being sympathetic with your machine to do so too far in advance of the the next shift.
The 15 sp Fuller is an older, earlier 'box dating from the 'sixties. It was flimsier, in a sense, than the later 9 and 13 sp 'boxes, in that it was designed for lower torque loads. It was designed using the old 10-sp Fuller (which preceded the 9sp one), so it was 5-over-5. They added the deep-reduction extra 5 gears for heavy haulage and off road use. The mystery of why anyone would choose it over a 9 or 13 sp is solved by knowing that neither of those boxes existed when 15-speeders first ruled the earth, and by knowing that you only needed it for special applications.
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As, SDU has already pointed out, they are referring to the valve not the switch.
That’s called progress. The 13-sp is a later, stronger design. The 18-sp came out at least 20 years later and is built to withstand the vastly increased power and torque loads of today’s trucks. You can’t compare apples with pears.
EDIT to add that talking of apples and pears, we should beware of going to 2025 manuals / vids of Eaton/Fuller 'boxes of yesteryear. Modern Fullers are very different from some of the older 'boxes. They were all developed over the years in the same way as Cummins engines were. The 9-sp 'box became very much more sophisticated in the early '80s with the intro of the RTX. Torque settings and loadings have been beefed up hugely along with the increase in engine size.
@Carryfast That bloke has no idea how to use a 15 speed. Note the dangers of relying on the internet for knowledge that you want to convert to your own expertise.
Granted, what they mean is it should be selected immediately before the shift, rather in anticipation of the next shift.
Only on the modern knobs that incorporate the valves.
On older models I’ve seen a dash mounted valVe, as shown in my previous photo and two valves on the gear stick, like the one in the same photo.
Yep, I took a stab in the dark and stumbled on the correct information. 
You really can’t cope with someone else having more knowledge than you or that which you try to convince others you have.
I find it remarkable that you failed to finish your apprenticeship, yet refer to youself as an engineer.
You the claim to have been plucked from the production line to be a test driver, where you became an expert in firefighting and aviation, awesome!
Next you get a simple and mundane driving job, where you become the virtuoso of all things road transport. Here you got a gold star, safety award that merely shows you managed to go for a year without getting caught breaking a traffic law, wow! What an achievement, you carry on as if it is the Lorry Driver of the Year cup.
I’m surprise you failed to secure continental employment. Why weren’t all the companies involved in that sector clamoring to secure the services of such an expert? (Rhetorical question)
You then go to the lowest rung on the transport ladder for the next thirty odd years.
Carryfast, take a step back and look at yourself, is it any wonder you’re not taken seriosly, attract ridicule and get put on pre-mod?
You seem like a decent fellow, with some interesting knowledge but you let yourself down when you try to prove you have the most knowledge and want to argue with people who genuinly have expert knowledge in a particular field.
In two-stroke Detroit diesel engine, there is no intake valves, so the blower serves as intake valves which allows air to come into the engine. Although, the blower is not a supercharger because it doesn’t compress the air as much as a supercharger, it still works like a supercharger.
The air cannot move unless it is pushed by a higher pressure or pulled by a lower pressure.
What is the blower (that term tells me it’s making pressure) there for? Its not decoration.
Call it what you like, blower, supercharger or scavenger pump, it’s the same thing for all intents and purposes, despite the technically wrong terminology.
A 6V53 blower can be plonked on top of a V8 petrol engine, as a supercharger. In hot rodder’s slang it is a blower, or a blown engine (not to be confused with a grenaded engine)
There was no need for you to be so condescending to Frangers, he was merely seeking knowledge and asking questions. Like you and the rest of the world, he wasn’t born with knowledge.
The piston is the inlet valve.It closes off the inlet ports in the sides of the lower bore.The piston only clears the inlet ports at around BDC.The exhaust valves open ahead of that before BDC while the inlet ports are still covered by the piston and obviously the much higher pressure exhaust gases rush out of the exhaust ports to atmosphere when the exhaust valves open.
As you say the inlet charge needs some persuasion to enter the uncovered inlet ports.That persuasion is mostly created by the effectively vacuum conditions left in the bore behind the very fast evacuating/ed exhaust gases.
That’s the scavenging part of the equation.
Agreed that often has to be augmented by the blower but at no more than atmospheric pressure.As stated the energy contained in the out rushing exhaust gasses is more than enough to drive a turbocharger.
Obviously if the blower played any large part in that process its efforts would effectively cancelled out by the energy taken to drive the turbocharger.
Bearing in mind that the exhaust gasses even in a four stroke evacuate the cylinder to atmosphere similarly virtually explosively, leaving behind a pressure less than atmosphere in the bore after the exhaust valves open rather than being driven out by the rising piston.
That’s also scavenging of a 4 stroke engine which can also be utilised to help draw in the inlet charge using clever exhaust flow management and valve timing overlap.
To be fair in the case of the accelerator pedal actuated splitter it’s going to be virtually impossible not to send an uncommanded split shift, by preselection, v clutch pedal actuated.
I thought it was a flaw in that regard.From memory the TM Fuller 13 speed splitter was preselected and clutch actuated in the same way as other European types.
Possibly a deliberate design for driver familiarity.
Although from memory the MAN installation was accelerator pedal actuated.
Generally I preselected all range change and split shifts well in advance easily aborted by just a flick of the switch if not required, or deciding on a full skip shift rather than a sequential split.
Ironically it’s actually proof that I have to rely on the word of those, who I’d think, would know what they are talking about in the case of a bag of bolts which I’ve never seen here let alone driven.Not so in the case of 9 speed range change and the 13 speed range change and splitter Fullers.
Why do you then try to conflate admittedly no clue regarding the 15 speed with 9 speed and 13 speed ?.
Equally ironically it’s taken me to refine Ro’s, correct, diagnosis with the description of it being a 15 speed 5 over 5 over 5 range change with low, mid and high ranges.Deep reduction range, low range and high range is as illogical as calling it a deep reduction splitter.
That’s not my fault.
So far.Weve confirmed that you could theoretically couple up a 40t gross drawbar trailer to a mobility scooter without overloading it’s drive axle because of the benefits of train weight v combination weight.
A 15 speed Fuller is a 15 speed 5 over 5 over 5 range change box but with only 12 worthwhile ratios.
IE low range, mid range and high range.Forget the deep reduction bollox and it’s certainly not a splitter.
A Detroit two stroke is naturally aspirated unless it’s turbocharged.The blower by definition isn’t a supercharger and it’s not there to blow out the exhaust gasses let alone drive the turbocharger.
Do you agree SDU and Frangers.