It’s lightweight, mediumweight and heavyweight. The lightweight ones are mostly rigids. The S26 brochure surprisingly shows the 4x2 tractor unit as heavyweight but up to 65t which sort of contradicts the rest.
Yes, I would agree that it appears to be Mediumweight 65t.
You may well be right - I don’t know. Bear in mind that at those weights they’re often double- or even triple-headed with other S26 or S24 tractors (or older Contractors).
Well it has the shorter wheelbase of the mediumweight but looks as if it might be spec’d for heavy. Here’s a couple of spec-sheets to pore over. One shows the S26 LWB heavy and the other shows the SWB medium:
I can’t make much sense of those figures Ro.
Firstly in artic configuration it should have axle/bogie weights and GVW for the unit and the ‘GCW’ for the outfit.
But the tractor unit axle/bogie weight and GVW seem wildly Conservative for a 65t GCW ?.
How would you possibly distribute any load to put a remaining around 40t on the trailer and without exceeding the trailer bogie weight ?.
While ballast tractor configuration should show the tractor axle/ bogie weights and GVW and GTW of the outfit to deduce the ballast loading and the remaining allowable weight capacity for the load and trailer.
I’m surprised they don’t seem to differentiate the two totally different types of outfit to get the required calculations.
Or in fact how a 65 tonner artic outfit could possibly be, or need to be, loaded lighter on the bogie than a 100 - 300 tonner ballast tractor ?.
I’d be surprised if that tank transporter outfit is within the type of bogie weights shown whether medium or heavy.
But would really have expected the brochure to clearly differentiate the required GCW for artic v GTW for ballast tractor operations.
Strange.
These are spec sheets, not a brochure. I suspect there’s more info on the reverse side of these sheets, as is usual for truck spec sheets. I agree with you that they appear to have conflated GCW with GTW but I think the clue for the reason for this lies in the 26t gross GVW, which like Mercedes trucks, shows its weight as 6x4 rigid whether its a tractor or not. You’ll notice that they don’t even give the GVW for the heavy tractor, only the medium.
They appear to be generalising to cover all bases, considering that many of these S26s will be bought to order for very specific jobs.
I’m going to move the goalposts a bit here CF, as you’ve got me thinking. The 1985 S26 brochure gives the following classification:
Lightweight – rated up to 38 tonne GCW covering 6x2, 6x4 and 8x4 configurations with engine powers up to 265 bhp.
Middleweight – rated up to 65 tonne GCW, covering 6x4, 6x6 and 8x4 configurations with engine powers up to 350 bhp.
Heavyweight – rated up to 300 tonne GCW, covering 4x2, 6x4 and 6x6 configurations with engine powers up to 350 bhp.
Now, we know that bigger engines were available (400 bhp) in the medium and heavy categories; so the 265 bhp in the Lightweight category may only be nominal. If so, might units like the Scud actually be lightweight 38-tonners with double-drive (and not Middleweight heavies, as I’ve assumed)? Really, we need someone who knows about Scammells on here to clarify.
The big problem with a lot of these glossy brochures is that they were written and published at the start of the production run. After a short time they become over-simplified because they don’t reflect the continuous development of the truck over its production period.
In some cases, engines that were made available options at the start never materialised because no one wanted them (as was the case in one of ERF’s models), or larger engines and alternative gearboxes were made available that aren’t mentioned in the brochure or on earlier spec-sheets. Sobering thought!
I haven’t got the S26 brochure but it can be viewed here as an already sold item on ebay. They’ve conveniently left pics of all the pages for us to see and they’re readable!
Agreed some ball park figures just related to prime mover/locomotive/ tractor in isolation would be the logical explanation Ro.
But surely by default medium weight 65 tonner would have to be artic configuration not prime mover ?.
In which case the weight capacities provided, running as an artic tractor unit, don’t seem significantly different to those expected of a standard 3 axle unit or rigid and 6 axle 44 tonner today ?.
In all cases you’d expect to see far more design weight capacity for the specialist bogies obviously designed for relatively heavy haulage as shown in the military example.
Was the Scud a medium weight 65 tonner ?.
400 Cummins, 15 speed Fuller ( now I’ve learnt what the thing actually is ), but prime mover and drawbar spec not artic, seems like an ideal middle easter and alpine mountain climber like the 8v92 TM 4400.Ironically both made within 20 miles of each other.We had a great and sadly underrated truck manufacturing sector here in the South East.
Pics online and in books show them to be in both forms, as many ballast boxes are detachable leaving the turntable undisturbed beneath.
We have to be careful with that one! The Scud and at least one other very similar S26 I’ve found were part of a cancelled M/E order. That means a Middle-East spec truck designed for operation in the shifting sands of the desert and the heat etc. A Middle-Easter on the other hand is a truck suitable (rather than designed) for the highly varied run via high mountains, Euro-winters, Turkish snows and desert sands to the Gulf. It seems to me that the Scud was a shrewd choice.
I suspect that in practice, you went to Scammell and worked out which bogie you needed from which manufacturer at which weight. Remember, Kirkstall, Rockwell, Scammell, SOMA et al were each turning out their own range of axles to suit different conditions.
I asked the same question a couple of posts above yours. I had assumed it was but I’m now asking whether it was a ‘lightweight’ 38-tonner, which it could well have been!
Hard to read close up. But yes it supports what I have been saying about the S24 being basically the same as the S26 but bonnetted etc. Same driveline etc
And thank you for posting it! 
It looks like only the Scammell bogie option on the S24 ?.
But either way a 65t GCW artic outfit is realistically going to need at least 30-32t of that weight to be put on the tractor unit ? and the steer looks like it can only take less than 7t of that ?.Call it a 25t bogie.
My guess is heavyweight by definition would be ballast tractor operation only.
Can also see why the 15 speed Fuller would be the default choice of gearbox.Would there even be any need for it on the lightweight spec ?.
Yes, if it leaves the road or has to work on a construction site.
You may be right. I don’t know.
