The other night I had to drive a Foden six wheeler (the one with the DAF 85 cab). I got in it and looked at the gearstick and thought “great!, an Eaton Twin Splitter - no problem!”, except it wasn’t. It had the same gearstick (with the three split switch) but it was a synchromesh gearbox instead. I managed to “find the gears” OK and managed to get to/from my destination with few problems.
Can anybody tell me how it actually works so I know for next time?
Yes m8
One of the variations of the foden box
Low to mid is a range change & mid to high is a hi & lo on each of the top block of 4.
Some of the earlier ones had a 4th low that was slightly higher than 5th (1st mid). I had one in a 8 legger with a 200 gardner 
Not a bad gearbox when you get used to it, but if the clutch brake is knackered, it will play tunes just getting it into gear 
******** just re-read it********* You sure it was a synchro box ■■? It sounds a lot like the one i describe above, but I have only ever seen them as crash boxes 
Toy, the one I drove in a Foden 8 legger was a crash (constant mesh really) box, and worked as you described.
I’ve used crash boxes before, such as the Road Ranger and Twin Splitter, and this was definitely a synchro box.
With the switch in the first position, you select the gears 1, 2, 3, 4 and then flick the switch to the second position and go back into “first” like most range changes. You then go through the gears 5, 6, 7, and 8…
When you flick the switch into the third position and select “first” again, its like you’re actually going back into first - the engine screams and the vehicle decelerates violently (nearly putting you through the windscreen)!
Instead you put the gearstick into “third” (with the switch in the third position) and you progress through the final two gears. Its really weird and don’t understand it fully, hence the question. Why are the first two gears in the top range so low and the last two gears so high, I don’t understand it?!!!
the old military foden eight legger tankers had a gearbox similar to your description.
a conventional 4 over 4, but you had the third split.
this extra split was infact an overdrive gear.
whilst in 8th gear move the switch to the third position, then come out of eigth gear then go back in to eigth for the overdrive gear.
a very good box if you did,nt rush it.
Eaton Twin Splitters are the best box ever made. Fully laden you can in theory travel from Dover to Birmingham without moving the stick. (traffic permitting) 
Wot about …
If you were in 5th (position 2 on the range/split) & moved the lever to the “hi” position, would it over rev the engine then ■■
I just can’t see how the O/D position in 5th can be that low when it’s obviously higher when in 8th
Not contradicting you m8, just trying to get my head round it ■■?
working the way you describe, it means that 8th mid is lower than 7th high
If it does work that way, it’s certainly one to excersize the arm moveing the stick back & forth !
Does it work as an O/D if you move the button from mid to high & dip the clutch 9without moving the stick) ■■
Does it work as an O/D if you move the button from mid to high & dip the clutch without moving the stick) ■■
on the ones i used to drive, you had to go into neutral then back in to get the overdrive gear.
Toytown, I’m totally confused…! With the switch in the second position and the stick in the bottom right of the ‘H’, you flick the switch into the third position and move the stick to either the top left or bottom left of the ‘H’ it does over rev. However, if you move the stick to the top right of the ‘H’ instead, the gears change up normally. Why?
Could this be a decendant of the old 13 speed Fuller box? (Popular in a lot of british trucks in the 70’s and 80’s)
I am sure that this box was a standard range change but with a splitter on the top few gears.
I agree with Pat Hasler about twin splitters though. Almost like an automatic if you drive them right! (Spent a lot of time in neutral the first time I drove one!)
hi all
i had one of these boxes for a while its just a 4 over 4 and you split the top 4 = 12 speed box and it is a syncro.
killsville:
Could this be a decendant of the old 13 speed Fuller box? (Popular in a lot of british trucks in the 70’s and 80’s)
I have a 2001 Volvo VN (see under my name) this ‘Highly advanced’ US built vehicle has a Fuller 13 speed crash box, … OLD 
Cat, Killsville & Pat,
No it can’t be a 13sp fuller because as you say, they were 4 over 4 with “hi” on each of the top 4 (I would call it overdrive on the top 4 but someone with a pedantic head on will correct me as it may or not technically be an overdrive, i.e. a ratio of less than 1:1).
Forget the 4 lows for a mo.
If I understand it right, you got thru 5,6,7,8 & then flick the switch to the right & go back into 7th position, which is then a bit higher than 8th in the mid position 
Seems very ■■■■ eyed to me & certainly nothing I have come across !
Will have a poke round & see what I can find out. Got me interested now 
Sussed it! Its called an Eaton 12 speed RTSO (whatever RTSO means…) and it is a synchromesh gearbox.
With the switch in the first position, you select the gears 1, 2, 3, 4 and then flick the switch to the second position and go back into “first” like most range changes. However, when flicking the switch between the second and third position it then acts like a splitter. So, with the switch in the second position and the gearstick in “first”, you’ve got 5th gear. Flick the switch into the third position, dip the clutch and you’ve got 6th. Flick the switch to the second position again, dip the clutch and move the gearstick down to “second” and you’ve got 7th. Flick the switch into the third position, dip the clutch and you’ve got 8th, and so on up the gearbox until you’re in 12th!!!
Thanks everyone for you help!
brummie:
Sussed it! Its called an Eaton 12 speed RTSO (whatever RTSO means…) and it is a synchromesh gearbox.With the switch in the first position, you select the gears 1, 2, 3, 4 and then flick the switch to the second position and go back into “first” like most range changes. However, when flicking the switch between the second and third position it then acts like a splitter. So, with the switch in the second position and the gearstick in “first”, you’ve got 5th gear. Flick the switch into the third position, dip the clutch and you’ve got 6th. Flick the switch to the second position again, dip the clutch and move the gearstick down to “second” and you’ve got 7th. Flick the switch into the third position, dip the clutch and you’ve got 8th, and so on up the gearbox until you’re in 12th!!!
Thanks everyone for you help!
So it’s like a range change at the bottom and a splitter at the top of the box- very unusual. Bet only foden use this box!
Sounds like an updated 13 speed Fuller then.
Anyway, once you get used to it, its a very good gearbox!
Simon:
Sounds like an updated 13 speed Fuller then.
Without a crawler gear perhaps.
I had one of those once, it’s a ZF 12 speed.
4 position lever, 3 position switch. Position 1 is low range, posit 2 is high range low split, posit 3 is high range high split. And all synchro too… And exactly the same control as the twin split… boy did it complain when I drove it like one
Has to be better than the current roadranger I’m playing music on here…
My Mack is fitted with a 18 speed eaton low torque…excellent when you are 50+ tons (company policy 
) and going up hill, she’ll purr along at 75mph (company policy ) at just over 1300rpms.
Bully