‘If’ I’ve got it right Ro the 13 speed was actually contemporary with the 15 speed.People were re valving/ removing the low range interlock on 13 speeds to make them 18 speeds at that time long before the factory did it.Bearing in mind the 13/18 speed has no wasted/duplicated gear ratios.
Just going by the video driving a 15 speed seems to do some cognitive damage to its operator ( joke ).
To add the blue deep reduction range change switch will only switch between deep reduction and mid range by switching it first then shifting through neutral to make the change.That certainly is, by definition, preselecting the shift.Just like a 9 speed or 13 speed or 16 speed eco split etc range change shift .
Firstly you have to preselect a Euro type splitter because it’s clutch actuated IE switch, then declutch then rev match then re engagement clutch on everything from eco split to Mercedes to DAF to Spicer ?.
From memory I was also taught to drive some early 13 speed Fullers the same IE they were clutch actuated.
Having got all that out of the way apologies to SDU but the content of the video I posted shows how misleading and downright inaccurate even experienced 15 speed Fuller drivers are in their understanding and terminology.No wonder that unenlightened Europeans would be totally misled by his musings and he drives the thing in it’s land of origin.
The blue button is the bottom 5 deep reduction range change control.
Switching the blue button out of deep reduction automatically puts it back into the mid range of 5 so long as the mid/high range switch is in mid range position protected by a switch interlock.
So do I pass my 15 speed assessment SDU ? and never even needed to get in the cab let alone leave the yard.
No, it is a Fuller 10-speed 'box in essence, having 10 ratios available for normal haulage running plus the extra 5 deep reduction for special types work.
No, the 10 / 15 sp Fuller is an older 'box. But they all overlap on the timescale.
The 13 / 18 are different boxes from each other. The 9 and 13-sp boxes are the same basic box but the 13 sp had splitters on the top four shift positions. But they are set up differently so the torque settings will differ.
Yes, I’ve re-read my bit (miles up the page) where I said you couldn’t pre-select a range-change. I didn’t make it at all clear that I meant you shouldn’t pre-select deep-reduction on the move. Better to stop, select and go - like on a Landrover or older tractors.
No, not ‘because’ but ‘if’. The later type I described you needed only to back off the throttle to break the torque and the split would go through. IIRC MAN 13-speed Fullers did this, but DAFs didn’t. ERFs did.
At this rate it’ll be three days before you leave the yard. Fullers aren’t complicated to use, but they’re easy to over-think 
Opening the exhaust valves early will enable more time to evacuate the exhaust gases, but that will be at a power cost. They are opened as late as possible to keep the gases pushing on the piston, not escaping to the atmosphere.
There is still residual pressure in the cylinder. Not all of the gases escape. It is above atmospheric pressure so a higher than atmospheric pressure is needed. It is needed to blow it in.
There is no partial vacuum made as gases “rush out”. They are not being expelled by a rising piston as with a 4T cycle. They are only rushing out because of a pressure difference. They are not being pulled out by any means. They are rushing out because they are at very high pressure. There is not enough time in a truck size engine to expel them all. In big ship’s diesel engines 2T seems to work much better.
Are there many current truck or smaller 2T engines around? Are they efficient compared to current 4T diesels?
Whether it is called a blower or a supercharger, there needs to be a device of some type to ensure that the inlet side has higher pressure than the exhaust side.
Call it what you want, without charge pressurisation over atmosphere, the engine will not work.
@franglais your all over it mate.
@carryfast serious question, what does the blower (air pump) do and where does the compressed air go?
Trouble is it takes ages to try to post a reasonable explanation of summat, whereas bollox can be posted in half a second.
Brandolini’s Law
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Ain’t that the truth?
Another truth is that I’d rather be happy than right all the time!
To add ‘bollox’ would also be creating a 15 speed, 5 over 5 over 5, range change box, in which the mid range of 5 is called low range and in which, if I’ve finally got it right ?, at least 3 of the gear ratios in, what should be, low range, duplicate the ratios provided in the mid range ?.
Bollox would be trying to make the case that the Detroit two stroke blower supercharges the induction and blows out the exhaust, despite the designers putting a turbocharger in the way to strangle the whole process.
It would also be defining a 15 speed range change box as deep reduction, low range and high range and then the American farm hands and tipper drivers predictably calling the ‘deep reduction’ a deep reduction splitter.
My mistake was believing them apologies to SDU and Ro in that.
I’m actually enjoying the topic it’s actually good laugh including admitting my own mistake regarding the 15 speed Fuller but can be forgiven for not understanding what it’s designer was trying to achieve…
I refer to the example of the 40t trailer coupled to the mobility scooter without overloading it’s drive axle as being the definition of and one of the advantages of drawbar train weight, v artic combination weight.
Blimey Franglais the power stroke of a two stroke and a 4 stroke is over well before BDC.
There is no further effort to be obtained from the combustion and expansion.
At that point the cylinder is just full of high pressure spent exhaust gasses ‘before’ BDC’
The exhaust valves on both are opened before BDC.
Surely you don’t think those high pressure exhaust gasses then just sit there in the bore waiting for something to push them out to atmosphere.
Your ideas totally contradict the principle of scavenging which, combined withe help of the blower, is how it works.It can also be utilised in a 4 stroke to help drag in the inlet charge.
Two strokes are obviously compromised in regard to the time available between exhaust and induction and compression.But not compromised enough to be outweighed by the advantage of having twice as many power strokes per revolution.Forced induction, in the form of turbocharging, is obviously a game changer in that.
Which obviously wouldn’t work if the exhaust flow driving it was dependent on and provided by the blower.
While if the blower was a supercharger what would be the point of turbocharging the induction.
A 13 speed is in essence a 9 speed range change with an extra 4 ‘split’ gears on the high range ?.
This odd ball by the same logic is a 10 speed range change with an extra ‘range’ of 5 gears ?.
Much more logical to call them low, mid and high range with low using a different switch.Can understand the scope for confusion even among its drivers in its place of origin, which threw me.
At last! You are beginning to understand the Fuller gearbox. There is no confusion, as you suggest. The 15-sp 'box is indeed a 10-speed five-over-five arrangement. But you cannot call the three sets of five ratios ‘low, mid and high’ because the bottom set is unrelated to the range-change set above it. Go back to the old Landrovers - it a ain’t rocket science.
Those ratios are coincidental. It’s OK to have a five-over-five box in which some of the ratios in the deep-reduction 'box tacked on to it actually overlap FFS!
Of course they do not “sit there”. The high pressure gases will flow to lower pressure areas. If the inlet and outlet are both the same (atmospheric) pressure, the gases will flow into the exhaust and outlet equally. That is why the inlet side needs to be charged at a higher than atmo pressure so that the burnt gases are displaced to the exhaust side only, rather than to both sides.
Yes.
Forced induction, that is charging the inlet side to a superior pressure than that of the exhaust is indeed game changing: it enables the engine to function. Without the super-charging it would not work.