My old lorry. It possessed that superb piece of automotive engineering, the Eaton Twin Splitter twelve-speed gearbox. There’s no synchromesh, so you had to match the speed of the lorry to the engine speed using your own skills. It had an inertia brake at the end of the clutch pedal travel, which slowed down all the cogs so that you could make really slick upshifts when climbing hills. The constant-mesh was thrown out with the eco-legislative bathwater. And I, for one, lament its passing; which apparently is exactly what the Euro 3 decibel tester did during the “drive by” test. I cannot think of a finer, more versatile gearbox. All right, I admit I’ve played the odd tune on them, usually the “Eaton Doting Song” — who hasn’t? I’ve had them in ERFs, MANs, Seddon- Atkinsons and Ivecos. I’ve done Europe, Africa and Asia with them on long-haul work. Some drivers swear by them; some shun them as “the box of a thousand neutrals”. And that’s the point; we used to have a choice. Now we have less choice. Yes, I appreciate the need for change, and I wouldn’t want to return to starting handles and “armstrong” steering, but it does seem a shame to discard a beautifully engineered and virtually indestructible lorry transmission. Given mountainous terrain and treacherous roads, I know without hesitation which box I would choose. Now that driver trainers have abandoned teaching the gentle art of double-decrunching, the old Twin Splitter is becoming a useful anti-theft device. If the absence of synchromesh doesn’t get them, the clutch brake undoubtedly will. Fresh-faced crims probably think a Twin Splitter is a surgical implement for separating Siamese twins. Robert
With a Twin-splitter there was no range-change to think about. It had a simple H-pattern like a car. Each corner of the H had three positions on the splitter switch. So in the first stick position were gears 1, 2 and 3. In the second stick position were gears 4, 5 and 6. In the third stick position were gears 7, 8 and 9. In the fourth stick position were gears 10, 11 and 12.
The Eaton Twin-splitter was probably the most brilliantly devised gearbox ever, but it did require skill and expertise to use it. That didn’t stop it being brilliant. This was a highly versatile, virtually indestructible gearbox that a competent driver could be really creative with. It demanded concentration and I always found that I only missed gears when I was tired at the end of a long shift. Another thing I noticed was that the Twin-splitter performed far better in hilly country with a heavy load, because the gearbox was always working hard and therefore responding to strong torque. This is why a tractor with a Twin-splitter was often harder to drive than one with a fully-freighted trailer. I also found that they needed warming up to perform properly. For the first fifteen minutes of a cold morning the Twin-splitter never worked as well as it did for the rest of the day. Robert 
Here’s another one I drove with a Twin-splitter. The magic of the Twin-splitter was entirely due to its sensitivity to torque-load, and it achieved this without any recourse to micro-chips: just mechanical wizardry. To make a splitter up-shift, all the driver had to do is to release the accelerator a fraction to break the torque and the next gear engaged when he re-applied the throttle. This was applied physics at its best in the world of truck gearboxes. Changing down the ‘box when climbing a hill under strong torque was exactly the same; but changing down when descending a hill or entering a roundabout was entirely different because the torque had already been broken. This was where the ‘bunny-hop’ technique really came into its own.
The ‘bunny-hop’ technique was mostly used for downshifts when not climbing a hill. It entailed selecting the next lower gear on the splitter switch, moving the stick into neutral, blipping the throttle to bring up the revs and slotting the stick back into its original position. This was done in a flash but it guaranteed a fast, clean change. The technique could be used in very low gears when making a hill-start with a heavy load. This entailed moving off in 1st, selecting 2nd, knocking the stick into neutral and immediately back into first without using the clutch or blipping the throttle; then progressing through the lowest gears in a similar fashion until about 4th gear by which normal clutch-less changes could be made without risk of lurching, rearing or breaking half-shafts.
Robert 
all twin splitters
And here’s another (superb) one I did Continental work with, that had a Twin-splitter. Many seasoned Twin-splitter users took considerable pride in being able to change up and down the entire ‘box without using the clutch. I often did this myself if the load was light (with a garment trailer, for example). But if the load was sensitive to movement, laminated chip-board on a flat-bed trailer for example, I would always employ double-declutching and the ‘bunny-hop’ technique for down-shifts, to ensure super-smooth changes, thus avoiding that little lurch that often occurred when the torque kicked back in, especially when descending a hill or entering a roundabout. In any case this protected the drive-line.
On steep mountain descents, use of double-declutching in conjunction with ‘bunny-hopping’ was essential. I remember crawling down mountains in southern Turkey, matching gears to the optimal efficiency of the exhaust-brake and on rare occasions changing right down to first gear to avoid using the service brakes more than necessary. Alright, I knew the unit had disc brakes but trailer brake-fade could still be disastrous.
Going uphill on dual carriageways in hilly countries like Spain could be hard work, but with a Twin-splitter the upshifts were fast, and they were even slicker with judicious use of the clutch-brake. And that is another reason why the Twin-splitter was so good: the clutch-brake (or inertia-brake, as it is sometimes called) enabled very fast upshifts. It simply slowed down the cogs to obviate the problem of delay while the revs die down. The clutch-brake killed the revs to enable instant upshifts when travelling up hill. This device was usually activated by pushing the clutch pedal to the bottom of its travel. But it could never be used for downshifts because it was entirely counter-productive to do so. Robert
Cheers Dan!
Twin-splitter gearboxes varied enormously according to their installation. I found that Twin-splitters in ERFs, MANs and Ivecos were very precisely installed. In the Seddon-Atkinson they were notoriously difficult to use. I once drove a Seddon-Atkinson Strato, which was a good lorry but the cable operated Twin-splitter demanded such precise timing that it took ages to grow accustomed to. It has often been said that the Twin-splitter was a ‘one truck, one driver’ gearbox because it did vary from truck to truck. However, I found this not to be the case in ERFs because the gearboxes were so well installed in the first place. The best installation I encountered was in the Iveco Eurostar I drove for some years to North Africa and the Arabian Gulf. The Twin-splitter in that vehicle became an extension of my arm, my brain and eventually my driver-personality. To this day I can sit in an airport lounge and ‘drive’ over difficult mountain terrain in my head and still sense all those subtle changes of torque that informed me about the optimal gear-changing moments. In really severe mountainous terrain, the Twin-splitter was second to none.
In eulogising the Twin-splitter, it may come as a surprise to know that I actually prefer a stick-change-for-each-shift gearbox such as the 9-speed Fuller Road-Ranger, but a Twin-splitter driver can use his ‘box as one of these simply be using the ‘bunny-hop’ technique. No driver in his right mind would do this, of course, but it is nonetheless possible to change every gear using this method. Robert
And here’s another I used. The first time I ever used a Twin-splitter was in the late ‘80s when I did a little seasonal work for Portway of Faversham. Most of their wagons were MAN 281s with 13-speed Fullers, but one day I was given a new MAN F90 with a Twin-splitter. In those days nobody ever trained drivers in the use of new technology and I had to learn by trial and error how to use it. It must have been a superb installation because I had no trouble working it out, and I soon drove others like it.
Later on I used the Twin-splitter in ERF E14s on continental work for BOC Euroshield. Again, they were a joy to use and I would gladly drive one today.
Some Twin-splitters had a mysterious ‘overdrive’. If the driver took his vehicle up to the speed-limiter, quickly knocked the stick into neutral and then eased it backing into top, just short of full engagement, he could feel the bottom of the stick move onto a sort of ledge or flange and hold it there. This would override the limiter for about two minutes maximum and enable the driver to overtake a knot of slow-moving vehicles and make progress. The best part was that it miraculously failed to show any speed above 100 kph on the tachochart. It got me out of trouble on innumerable occasions abroad.
The Twin-splitter was only ever popular in Britain and for some reason it never really caught on in America, Canada, Australia, New Zealand or South Africa where the Eaton-Fuller Road-Ranger was the default gearbox. Robert
twin splitter probably soon to be transplanted to Foden Alpha .
Is that an ex-Read wagon, Dan?
Believe it not, this Bedford had (still has I think) a Twin-splitter in it! Robert
Don’t think so ,iam pretty sure mr Auker could of had it from new ,may be no rush or the boys own would know?
and another !
My first experience of driving a HGV1 was in the army. It was a Seddon Atkinson Strato and all of the Royal Engineers Stratos had the Eaton Twin Splitter. After my first couple of drives, which were disastrously tuneful, I become quite skilled at bunny hopping my way up through a twin splitter. I got great satisfaction out of pulling an out of gauge load, block changing up and down and not missing a gear. It’s a real shame they are not fitted in modern vehicles. I find it strange that the emissions laws have outlawed the constant mesh boxes, I can only guess because you need to blip the throttle when changing gear? However, the modern auto boxes blip the throttle when changing up and down? Now how does that work?? 
That’s a beaut, Dan!
Early DAF 85s had Twin-splitters as an option. These might not have been ‘premium’ motors but 85s were very nice to drive and I would certainly put up with one with a Sky-cab and Twin-splitter like the one advertised below, rather than drive an auto! Robert
Pirate:
My first experience of driving a HGV1 was in the army. It was a Seddon Atkinson Strato and all of the Royal Engineers Stratos had the Eaton Twin Splitter. After my first couple of drives, which were disastrously tuneful, I become quite skilled at bunny hopping my way up through a twin splitter. I got great satisfaction out of pulling an out of gauge load, block changing up and down and not missing a gear. It’s a real shame they are not fitted in modern vehicles. I find it strange that the emissions laws have outlawed the constant mesh boxes, I can only guess because you need to blip the throttle when changing gear? However, the modern auto boxes blip the throttle when changing up and down? Now how does that work??
Ha-ha, your’re right Pirate, the automated Eurotronic 2 double-declutches all by itself (I can do that: gissa job!) but alas the Twin-splitter wasn’t outlawed for air pollution but for sound pollution - it was too noisy!
To cheer you up, here are some Twin-splitting armed services Seddon Atkinson Stratos like the ones you drove. Robert
robert1952:
My old lorry. It possessed that superb piece of automotive engineering, the Eaton Twin Splitter twelve-speed gearbox. There’s no synchromesh, so you had to match the speed of the lorry to the engine speed using your own skills. It had an inertia brake at the end of the clutch pedal travel, which slowed down all the cogs so that you could make really slick upshifts when climbing hills. The constant-mesh was thrown out with the eco-legislative bathwater. And I, for one, lament its passing; which apparently is exactly what the Euro 3 decibel tester did during the “drive by” test. I cannot think of a finer, more versatile gearbox. All right, I admit I’ve played the odd tune on them, usually the “Eaton Doting Song” — who hasn’t? I’ve had them in ERFs, MANs, Seddon- Atkinsons and Ivecos. I’ve done Europe, Africa and Asia with them on long-haul work. Some drivers swear by them; some shun them as “the box of a thousand neutrals”. And that’s the point; we used to have a choice. Now we have less choice. Yes, I appreciate the need for change, and I wouldn’t want to return to starting handles and “armstrong” steering, but it does seem a shame to discard a beautifully engineered and virtually indestructible lorry transmission. Given mountainous terrain and treacherous roads, I know without hesitation which box I would choose. Now that driver trainers have abandoned teaching the gentle art of double-decrunching, the old Twin Splitter is becoming a useful anti-theft device. If the absence of synchromesh doesn’t get them, the clutch brake undoubtedly will. Fresh-faced crims probably think a Twin Splitter is a surgical implement for separating Siamese twins. Robert
Here’s my last lorry I drove before I packed up driving and took a yard shunting job
It was fitted with the magnificent twin splitter and coupled to a 375 Perkins/Rolls engine it was a cracking motor
Sorry about the photo
And here are a couple of left-■■■■■■ ones for you. Robert
gazsa401:
robert1952:
Here’s my last lorry I drove before I packed up driving and took a yard shunting job
It was fitted with the magnificent twin splitter and coupled to a 375 Perkins/Rolls engine it was a cracking motor
Sorry about the photo
It was clearly an excellent hill-climber, Gaza! Never mind, I’ve straightened it up for you. Robert
