Right Lucy; A true ‘crash box’ was one where the actual gears moved along the mainshaft to engage with the layshaft gears and required expert handilng by the driver to avoid ‘crashing the gears’ and possibly chipping or even breaking the gear teeth. They mostly went out of use by the mid 1950’s. The constant mesh gearbox had/has the gears in permanent mesh with each other and uses sliding ‘dogs’ to move along the shaft to change ratios. The dogs usually have chamfered edges to the teeth to assist with engaging smoothly but double declutching was normally used by the driver to give the two shafts time to match in speed, otherwise you got a ‘crunch’ when changing gears if you tried to rush things. Most heavy vehicle gearboxes were constant mesh until recently, Fuller etc, , although the small 1960’s/early 70’s BMC FG etc models also used it whereas Ford/Bedford and commer etc had changed over to synchromesh by that time.
Synchromesh is just a constant mesh 'box but using tapered cones to engage with tapered sections on the gears, the two cones coming together slow the gears and shaft rotating and ensure a smooth change without double declutching.
Bit like a Sherlock Holmes mystery,Mercs EPS when it first arrived was a whole bundle of laughs and would Mercedes believe it could be knocked out
by radio masts,no way, they claimed EMI…Electro Magnetic Interference could have no effect.Post Office transmitting station the end of Bodmin By Pass
would send the gearbox balistic,up and down it would fly until you had managed to roll far enough away from the signal then it would return to normal
usage strange I knew what it was from Scanias EDC…Electronic diesel control,same area,the throttle would have a mind of it’s own,all good fun when
electronics were first introduced.Those were the day’s.
Personally my top two are in second the 16 speed Volvo with splitter on dash. At first meeting I thought what a ridiculous place to put it but in practice I got along with it famously. With a 240 horse F10 at 38t I got to know my way around it pretty well. Number one for me though is the 13 speed Fuller. Clutchless changes the norm and really satisfying to drive.
switchlogic:
They gave you a £5k + optional extra for free? What dealer is this? I need to get the boss onto the case, I desperately want a dual clutch to call my own
It wasnt an optional extra, it was a no option extra (at additional cost of the long haul version of the i shift) which i paid 6370eur for. However, the total cost of the truck was just over 7K eur less than i would have paid at my local dealer VEINSUR, S.A.U. (Málaga) so in a way i suppose yes, i got the long haul option and dc free…
The dealer i used was BAS trucks BV, veghel, Netherlands
the maoster:
Then earned my wings in this beast. Thorneycroft Antar.
Oldest stuff I’ve driven was a 1977 Dodge on my driving course, and a 1981 Atki Borderer, both old motors at the time of me driving,…but that pic looks like it was taken in a museum.
Then again I aint as old as you Maost.
I’ve changed gears in many different ways with all kinds of gearboxes, constant mesh David Brown 6spd that were like stirring a bucket of porridge with a broom handle and 9spd Fullers with a back to front and round the houses shift pattern and normal H pattern versions which were a much better installation, back to front 12spd splitter and 8spd range changes from ZF, the 12spd being my most hated gearbox ever, it was an awful thing, very unforgiving and if you missed a gear, you pretty much had to come to a stop and start again, the 6spd whatever it was in Leyland Clydesdales, 5spd Turner with a two speed axle. 13spd Fullers, twin splitters and my current truck has an 18spd Fuller that I love.
Synchromesh from Volvo and Scania, the 8/16spd Volvo much better than the 10spd Scania, although the Volvos always had a peculiar rattle, but the 12spd Scania box had the roles reversed being better than the Volvo 12spd. The ZF ecosplit, which was horrible and notchy although not as bad as the B18 from Renault, EPS both the ZF and Merc G4 versions, which I actually liked, although the earlier ZF version was very unreliable.
Autoshifters from the Volvo Geartronic, ZF AStronic, I-shift and I even had a 6spd Allison auto in a Seddon Atkinson, so quite the variety
Best constant mesh. 18spd Fuller.
Best synchromesh. 12spd Scania.
Best gearbox ever. (So far) I-shift.
windrush:
Right Lucy; A true ‘crash box’ was one where the actual gears moved along the mainshaft to engage with the layshaft gears and required expert handilng by the driver to avoid ‘crashing the gears’ and possibly chipping or even breaking the gear teeth. They mostly went out of use by the mid 1950’s. The constant mesh gearbox had/has the gears in permanent mesh with each other and uses sliding ‘dogs’ to move along the shaft to change ratios. The dogs usually have chamfered edges to the teeth to assist with engaging smoothly but double declutching was normally used by the driver to give the two shafts time to match in speed, otherwise you got a ‘crunch’ when changing gears if you tried to rush things. Most heavy vehicle gearboxes were constant mesh until recently, Fuller etc, , although the small 1960’s/early 70’s BMC FG etc models also used it whereas Ford/Bedford and commer etc had changed over to synchromesh by that time.
Synchromesh is just a constant mesh 'box but using tapered cones to engage with tapered sections on the gears, the two cones coming together slow the gears and shaft rotating and ensure a smooth change without double declutching.
Pete.
Some of these lad’s may have hairy ears & drive micra’s, but they certainly know their stuff
Next question, following on…When I was a dodgy new age traveller back in the 90s when such things were fashionable I lived in (:oops:)and learnt to drive - unofficially - in a 1950s BMC FG 350 with a 2.5l taxi engine and a four-speed box. Am I right in thinking that would have been constant mesh? I then went on to pull a very tatty showman’s trailer with a 1957 Fordson Thames 4D, also with a four-speed box but it was much more difficult to use. Would that have been because it was a crash gearbox or just because it had been in the hands of hippies for too long and was knackered?
The BMC 350 FG range with the 2.2 petrol or diesel engine would have been fitted with a four speed box with synchromesh on all except first and reverse. The same set up as the LD van range actually. The larger FG’s fitted with the 3.4/3.8/5.1 or 4 litre petrol were all four speed constant mesh until production ended on the 1970’s, I worked for a BMC dealer!
Regarding the Thames 4D, never drove one but I believe they were constant mesh until the Trader models appeared? Tony (Rastone) would know for certain though.
Lucy:
Cracking stuff guys, thankyou so much - do keep it coming!
I always liked the ZF 16-speed “slap over” I must admit, coming across it in Dafs, Ivecos and, if memory serves me correctly, MANs. The MAN F2000 series I had was one of my favourite lorries of all time in fact, and I’m pretty sure that had a ZF 16-speed in it, though I’m buggered if I can remember whether it was the slapover kind.
The twin splitter definitely needed to be put in the right drive train to show it’s balls. I drove them in both ERFs and Ivecos, and while they were fab in the ERF EC10s with their ■■■■■■■ luggers, the Iveco engine - the predecessor to the Cursor, I’m beggared if I can remember it’s name now - pulled best when you got it spinning, so worked far better teamed with the ZF box, I reckon, having tried both combinations in Eurotechs.
The Spicer box is one I’ve heard of but know nothing about. Can someone expand on that for me please? Also, does anyone know the difference between constant mesh and true “crash” boxes? Could you get a non-synchro box which wasn’t constant mesh? What was the difference mechanically?
Cheers all.
If I remember correctly, it was a 5 speed constant mesh with a splitter.
windrush:
The BMC 350 FG range with the 2.2 petrol or diesel engine would have been fitted with a four speed box with synchromesh on all except first and reverse. The same set up as the LD van range actually. The larger FG’s fitted with the 3.4/3.8/5.1 or 4 litre petrol were all four speed constant mesh until production ended on the 1970’s, I worked for a BMC dealer!
Regarding the Thames 4D, never drove one but I believe they were constant mesh until the Trader models appeared? Tony (Rastone) would know for certain though.
Pete.
That all makes perfect sense - the fact the engine had been replaced in my FG means it’s likely the gearbox was too, although it’s equally possible that it needed double declutching simply because the synchros were shot!
Lucy:
Cracking stuff guys, thankyou so much - do keep it coming!
I always liked the ZF 16-speed “slap over” I must admit, coming across it in Dafs, Ivecos and, if memory serves me correctly, MANs. The MAN F2000 series I had was one of my favourite lorries of all time in fact, and I’m pretty sure that had a ZF 16-speed in it, though I’m buggered if I can remember whether it was the slapover kind.
The twin splitter definitely needed to be put in the right drive train to show it’s balls. I drove them in both ERFs and Ivecos, and while they were fab in the ERF EC10s with their ■■■■■■■ luggers, the Iveco engine - the predecessor to the Cursor, I’m beggared if I can remember it’s name now - pulled best when you got it spinning, so worked far better teamed with the ZF box, I reckon, having tried both combinations in Eurotechs.
The Spicer box is one I’ve heard of but know nothing about. Can someone expand on that for me please? Also, does anyone know the difference between constant mesh and true “crash” boxes? Could you get a non-synchro box which wasn’t constant mesh? What was the difference mechanically?
Cheers all.
If I remember correctly, it was a 5 speed constant mesh with a splitter.
Thanks Pig Pen. Can anyone add to that please? Put a bit more flesh on the bones?
Next question, following on…When I was a dodgy new age traveller back in the 90s when such things were fashionable I lived in ([emoji15])and learnt to drive - unofficially - in a 1950s BMC FG 350 with a 2.5l taxi engine and a four-speed box. Am I right in thinking that would have been constant mesh? I then went on to pull a very tatty showman’s trailer with a 1957 Fordson Thames 4D, also with a four-speed box but it was much more difficult to use. Would that have been because it was a crash gearbox or just because it had been in the hands of hippies for too long and was knackered? [emoji47] [emoji15] [emoji1]
I think Allison Automatic deserves a spot in the Top Ten if only because they have given the disabled the opportunity to drive lorries for a living. They have always offered a full range for all different weights and applications. Most drivers will have never driven one but they are popular with bin-wagons, buses and fire engines. I sometimes driver a 350 bhp sixteen-tonner with a 5 speed Allison and its the easiest lorry I have ever driven.
It’s ok with new vehicles,I liked the old Eton Twin Splitter, but when I started it was in a old 1617 Merc with a 8 speed knock though from left to right. That was fun but it got better when I progressed to a old 1626 Merc 6 speed with split as in one in each corner and some in the middle lol. That was 30 years ago. We have a nice 1728 {I think} with a zf 16 speed in it that went wrong so they have dropped a 6 speed in her which is ok but some ones pinched fifth pot luck if you get it lol.So it’s ok with all the new kit but you could have some fun with the old stuff
Ade
ChrisArbon:
I think Allison Automatic deserves a spot in the Top Ten if only because they have given the disabled the opportunity to drive lorries for a living. They have always offered a full range for all different weights and applications. Most drivers will have never driven one but they are popular with bin-wagons, buses and fire engines. I sometimes driver a 350 bhp sixteen-tonner with a 5 speed Allison and its the easiest lorry I have ever driven.
You’re right there ,salvesen did an auto project and couldn’t get an auto 18t for love nor money.eventually persuded daf to build an LF 220 and we supplied an alison box,they did’nt like it one bit,but it went ahead and it was probably the best rigid i ever drove,nothing would touch it on acceleration and it was brilliant on ,multi drop urban work.mpg suffered but not outragously so.the project was to reduce driver stress and accidents, guess it worked hv02uuz was the reg, how times change, all auto now.got wrote off by a pleb night man ,looking after the kids daytime ,then working all night.
Tony
