Carryfast:
Like the 12 speed ZF just not as relatively forgiving of anything less than spot on timing and road/engine speed matching as a Fuller isn’t the same thing as engineering ■■■■ up.IE the Fuller’s exceptional ease of use still just proves the rule of the way better shift quality of the constant mesh ZF 12 speed and the Spicer Splitters over the synchro 16 speed Eco Split for example.IE any superiority in forgiving nature of the Fuller over the ZF or Spicer in terms of shift quality is all only relative and subjective with the convenience of pre select splitter arguably winning out over the Fuller’s range change.
WTF U chattin? If its worse than the other one, it’s a ■■■■ up.
What I asked was, why was it inferior? Did the dogs have a disadvantageous number of teeth, was the detent spring wrong, was some other parameter less optimal? IE I was hoping for an educated answer.
Needs relatively more care in terms of driver input regarding shift timing and engine/road speed matching isn’t ‘inferior’ at all.In just the same way that a Fuller isn’t inferior to a synchro Eco split because the synchro box obviously needs far less care than the Fuller in that regard.
cav551:
Apart from being a splitter transmission there was one significant difference between the Spicer SST10? and the Fuller Roadranger in the design of the dog clutches; although both employed the floating mainshaft principle with no bushes for the mainshaft gears.
The Spicer used a curvic coupling design to mate the dogclutch to the gear. In simple terms the Fuller dog clutches had longitudinal teeth cut inside the gear and on the outside diameter of the dog clutch. The dogclutch then mated with the inside diameter of the gear. The Spicer however had vertical teeth cut onto a boss on the face of the gear and onto the face of the dog clutch. Whereas there was more room to accommodate a taper to the teeth on the Fuller there was less for a taper in the Spicer design. This made the Spicer less forgiving to engine speed mismatch.
IIRC the Roadtrain was piped up so that you could preselect the splitter while you were not supposed to do that with the Seddon.
Superb. Ta. So the Fuller arrangement could be described as an exaggerated spline, with a lead, to make them slip into mesh easier?
^^
Exactly as you say. It is many years since I had either a Fuller or a Spicer fully apart and things are slowly coming back or playing tricks. I think I am right in saying that the large case Fuller had an internally splined tapered washer and a selective thickness internally and externally splined washer for each gear. The small Fuller omitted the tapered washer. The Spicer design was like the small Fuller at least for the SST 1010 . I never got to strip the smaller SST 8010.
Edit: Oooops. Silly boy, Mr Cooper slap handie. It wouldn’t work would it with two sets of splines! It was externally splined only and I think it was the bevelled washer which was a selective fit to set the correct end float for the gear.
That seems to suggest that the laygears are different on each side, giving the split gears.
cav is our tech correspondent with that type of in depth knowledge that’s getting rarer as time goes by.
I can only tell it as I saw it from a driver’s point of view that the Spicer didn’t deserve a lot of the unwarranted criticism thrown at it.Surprised that Pat Kennet seemed to jump on that bandwagon.Also note with interest that the Spicer wasn’t designed with preselectable clutch actuation and being rightly retrofitted with that capability by Leyland,as stated in the article to compete with the Euro type splitters.
RMC had many Leyland Constructors with the Spicer box and when they were pulling on sites, or idling, they always sounded as if the gears were about to make an exit through the casing! They were noisy, rattly things when worn.
Ok, I agree not an Interstate, but “Leyland or Scammell?”, that’s a bit academic, by this time in Leyland’s history, they were long part of the same stable, the S26 , built at the old Scammell factory at Watford was marketed as part of the Leyland T.45 range along with the Roadtrain, Cruiser, Constructor, Freighter and Interstate!
Sorry it not an Interstate, but here’s a Leyland T.45 range Scammell S.26:-
rapidgem:
Ok, I agree not an Interstate, but “Leyland or Scammell?”, that’s a bit academic, by this time in Leyland’s history, they were long part of the same stable, the S26 , built at the old Scammell factory at Watford was marketed as part of the Leyland T.45 range along with the Roadtrain, Cruiser, Constructor, Freighter and Interstate!
Sorry it not an Interstate, but here’s a Leyland T.45 range Scammell S.26:-
Thanks for the photo’s guy’s. I remember spending two weeks sleeping behind the seats in the same cab as this but on a scammell 8x6 chassis during a stint in the Former Yugoslavia.No mattress, just a solid piece of rubber on the floor.When I can work out how to upload a photo I will.I enjoyed driving it , but mind you it was an automatic !
They were noisy, rattly things when worn.
