robert1952:
…you can effect most upshifts on the flat very quickly by not using the clutch at all. If in doubt you’d always upshift by double-declutching without the throttle blip. But if you are going uphill and want to effect a super fast change without losing vital momentum, the practice described by Pat Kennett is spot-on and it most certainly works once you’re good at it. I suppose it’s just one of those effective, if unorthodox, tricks of the trade; like using the exhaust-brake to effect quick changes. We live in a black, white and grey world in which nothing is ever absolutely right or wrong . Try it with a 14-litre Iveco lump and you’ll have no problems. Robert the Twin-splitter
What’s the ultimate fast upchange method, do you think? No clutch at all and decompression brake? Did I not read somewhere that some Jake brakes can be set/programmed to come on when the the accelerator pedal is released, above a certain engine speed?
Firstly there’s no way that a clutch less upshift can be made as fast as a double de clutched one because time has to be taken to gradually get the engine speed right to get the box into neutral.IE unlike a double de clutched shift any quick reduction in engine speed will create a large torque reversal in the driveline which stops the shift into neutral.Which obviously also counts out any use of engine braking at that point which would just make that situation even worse.Also while the exhaust/jake brake idea might seem good,like using a clutch brake,it seems like a hit or miss method regards engine and road speed matching. Because in that case it can obviously make the engine speed fall too far too fast which then needs to be raised to match it with the road speed which again takes time.The important bit to remember being that fast shifts up or down are all about the fastest way to match engine ‘and’ road speed ‘and’ gearbox input shaft speed.While it’s obvious that just concentrating on one or two of those won’t cut it.Although having said that engine brake and double de clutch seems about as good as it gets ‘if’ it can be released and the engine speed can be ‘caught’ at exactly the right road speed match when the clutch is engaged in neutral to match the input shaft speed.
robert1952:
…you can effect most upshifts on the flat very quickly by not using the clutch at all. If in doubt you’d always upshift by double-declutching without the throttle blip. But if you are going uphill and want to effect a super fast change without losing vital momentum, the practice described by Pat Kennett is spot-on and it most certainly works once you’re good at it. I suppose it’s just one of those effective, if unorthodox, tricks of the trade; like using the exhaust-brake to effect quick changes. We live in a black, white and grey world in which nothing is ever absolutely right or wrong . Try it with a 14-litre Iveco lump and you’ll have no problems. Robert the Twin-splitter
What’s the ultimate fast upchange method, do you think? No clutch at all and decompression brake? Did I not read somewhere that some Jake brakes can be set/programmed to come on when the the accelerator pedal is released, above a certain engine speed?
Firstly there’s no way that a clutch less upshift can be made as fast as a double de clutched one because time has to be taken to gradually get the engine speed right to get the box into neutral.IE unlike a double de clutched shift any quick reduction in engine speed will create a large torque reversal in the driveline which stops the shift into neutral.Which obviously also counts out any use of engine braking at that point which would just make that situation even worse.Also while the exhaust/jake brake idea might seem good,like using a clutch brake,it seems like a hit or miss method regards engine and road speed matching. Because in that case it can obviously make the engine speed fall too far too fast which then needs to be raised to match it with the road speed which again takes time.The important bit to remember being that fast shifts up or down are all about the fastest way to match engine ‘and’ road speed ‘and’ gearbox input shaft speed.While it’s obvious that just concentrating on one or two of those won’t cut it.Although having said that engine brake and double de clutch seems about as good as it gets ‘if’ it can be released and the engine speed can be ‘caught’ at exactly the right road speed match when the clutch is engaged in neutral to match the input shaft speed.
I beg to differ regarding your claim that a clutch less up shift isn’t as quick as a double de clutch upshift
It may be with a cable change as in Foden or SA Strato but with a mechanical linkage whether it’s a Spicer /Eaton/Fuller 9 or 13spd or a Eaton twinsplitter a clutch less upshift wins hands down with the right driver
Plus nearly every lorry I’ve driven for a living has had a constant mesh gearboxes fitted
99% of the time I only used the clutch to stop and start
in 30 years of driving class 1s I’ve never had a clutch fitted in a lorry I’ve had
robert1952:
…you can effect most upshifts on the flat very quickly by not using the clutch at all. If in doubt you’d always upshift by double-declutching without the throttle blip. But if you are going uphill and want to effect a super fast change without losing vital momentum, the practice described by Pat Kennett is spot-on and it most certainly works once you’re good at it. I suppose it’s just one of those effective, if unorthodox, tricks of the trade; like using the exhaust-brake to effect quick changes. We live in a black, white and grey world in which nothing is ever absolutely right or wrong . Try it with a 14-litre Iveco lump and you’ll have no problems. Robert the Twin-splitter
What’s the ultimate fast upchange method, do you think? No clutch at all and decompression brake? Did I not read somewhere that some Jake brakes can be set/programmed to come on when the the accelerator pedal is released, above a certain engine speed?
Firstly there’s no way that a clutch less upshift can be made as fast as a double de clutched one because time has to be taken to gradually get the engine speed right to get the box into neutral.IE unlike a double de clutched shift any quick reduction in engine speed will create a large torque reversal in the driveline which stops the shift into neutral.Which obviously also counts out any use of engine braking at that point which would just make that situation even worse.Also while the exhaust/jake brake idea might seem good,like using a clutch brake,it seems like a hit or miss method regards engine and road speed matching. Because in that case it can obviously make the engine speed fall too far too fast which then needs to be raised to match it with the road speed which again takes time.The important bit to remember being that fast shifts up or down are all about the fastest way to match engine ‘and’ road speed ‘and’ gearbox input shaft speed.While it’s obvious that just concentrating on one or two of those won’t cut it.Although having said that engine brake and double de clutch seems about as good as it gets ‘if’ it can be released and the engine speed can be ‘caught’ at exactly the right road speed match when the clutch is engaged in neutral to match the input shaft speed.
Well, it would seem that Pat Kennett would fundamentally disagree with you as well, going by the article I posted by him yesterday on this thread. As he is no longer with us and cannot answer for himself however, I have found two further pieces by him both of them describing in detail how to use the clutch-brake for upshifts with some backup technical evidence. Here are the scans. Robert
PS. The fastest upshifts I made (dozens of times a day) were the knife-through-butter clutchless changes I could make on my Eurostar’s Twin-splitter making the stick-change between 6th and 7th diagonally across the H-pattern. Strange but true. Executing the same stick manoeuvre from 9th to 10th (down the right hand side of the ‘H’) should have been even easier, but you always had to pause a fraction in neutral before pushing the stick home, if you were not using the clutch. Robert
robert1952:
Firstly there’s no way that a clutch less upshift can be made as fast as a double de clutched one because time has to be taken to gradually get the engine speed right to get the box into neutral.IE unlike a double de clutched shift any quick reduction in engine speed will create a large torque reversal in the driveline which stops the shift into neutral.Which obviously also counts out any use of engine braking at that point which would just make that situation even worse.Also while the exhaust/jake brake idea might seem good,like using a clutch brake,it seems like a hit or miss method regards engine and road speed matching. Because in that case it can obviously make the engine speed fall too far too fast which then needs to be raised to match it with the road speed which again takes time.The important bit to remember being that fast shifts up or down are all about the fastest way to match engine ‘and’ road speed ‘and’ gearbox input shaft speed.While it’s obvious that just concentrating on one or two of those won’t cut it.Although having said that engine brake and double de clutch seems about as good as it gets ‘if’ it can be released and the engine speed can be ‘caught’ at exactly the right road speed match when the clutch is engaged in neutral to match the input shaft speed.
Well, it would seem that Pat Kennett would fundamentally disagree with you as well, going by the article I posted by him yesterday on this thread. As he is no longer with us and cannot answer for himself however, I have found two further pieces by him both of them describing in detail how to use the clutch-brake for upshifts with some backup technical evidence. Here are the scans. Robert
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The idea of either use of the clutch brake or clutchless up shifts being the fastest way is an obvious contradiction in itself.
As I said clutchless shifts run into the problem of having to reduce engine speed more slowly to prevent any torque reversal in the driveline stopping the shift into neutral or at least preventing unnecessary stress on the box.Whereas de clutching it allows the accelerator and therefore engine speed to be reduced instantly/immediately with no chance of any torque reversal issues affecting the shift into neutral.
While then using the crankshaft/flywheel to act as the input shaft brake also obviously synchronises engine speed with input shaft speed and road speed all at the same time unlike using the clutch brake to just slow the input shaft.IE it’s difficult to see how anything can be faster than using by the book double de clutched up shifts especially with a decent gearbox with plenty of close ratio steps.
While if it’s in the realms of an up shift creating the situation of road speed falling much faster than engine speed it’s probably best to leave it in the gear it’s in and wait for better conditions to make the shift.On that note Pat’s own statement of use the clutch brake then use the clutch to drag the engine speed down after the shift says it all.IE the clutch brake doesn’t solve the issue of matching engine speed to input shaft speed with obvious results.
The Turbostar from page 2 was the first lorry I had after passing my test at 21, 190 36 twin splitter, bit daunting at first no one shew me how it worked but once I got the hang of it there was no stopping me piece of cake.
Well it would have been an interesting experience to pick up an Italian-spec Bedford TM with a Fuller 'box and then slide into the passenger seat ready to hammer round the Ardennes Euro-Test route twice: 1st time with CF in the driving seat and 2nd time with Pat Kennett in the driving seat. Pause for thought. Robert
The only time I used a clutch brake was with a Gardner & a David Brown box, mind you a good book between gear changes was always of great use with this combination, Rolls Royce & Fuller no clutch pedal used to get the best gear changes with this combination.
robert1952:
Well it would have been an interesting experience to pick up an Italian-spec Bedford TM with a Fuller 'box and then slide into the passenger seat ready to hammer round the Ardennes Euro-Test route twice: 1st time with CF in the driving seat and 2nd time with Pat Kennett in the driving seat. Pause for thought. Robert
Or if anyone has a youtube account maybe they could ask him whether that’s clutch braked,or floated,or double de clutched up shifts.My money is on the latter.
robert1952:
Well it would have been an interesting experience to pick up an Italian-spec Bedford TM with a Fuller 'box and then slide into the passenger seat ready to hammer round the Ardennes Euro-Test route twice: 1st time with CF in the driving seat and 2nd time with Pat Kennett in the driving seat. Pause for thought. Robert
Or if anyone has a youtube account maybe they could ask him whether that’s clutch braked,or floated,or double de clutched up shifts.My money is on the latter.
robert1952:
Well it would have been an interesting experience to pick up an Italian-spec Bedford TM with a Fuller 'box and then slide into the passenger seat ready to hammer round the Ardennes Euro-Test route twice: 1st time with CF in the driving seat and 2nd time with Pat Kennett in the driving seat. Pause for thought. Robert
Or if anyone has a youtube account maybe they could ask him whether that’s clutch braked,or floated,or double de clutched up shifts.My money is on the latter.
Some of our driver’s used the ‘Bunny Hopping’ method with the old Foden 12 speed boxes, I was far too idle to bother though! I rarely used a clutch brake anyway except at standstill, an article I read by a Fuller rep advised drivers to use the clutch to dissengage the drive and then engage the next gear with the clutch already engaged, he reckoned there was less drag on the dogs doing it that way and that was mostly how I did it. The Foden/Fuller cable change was heavy anyway on some of the ones I had, when new it needed two hands to get it into and out of gear at times but it did bed in after a couple of months. Always a lot of cable drag though unless they were kept well lubricated and they could ‘hang’ in gear at times. The Sed Ak 400 I had (rod linkage) needed to be knocked out of top gear with the palm of my hand, it never got better despite being six years old and getting reverse was a two handed job. No wonder my left shoulder is knackered!
robert1952:
Well it would have been an interesting experience to pick up an Italian-spec Bedford TM with a Fuller 'box and then slide into the passenger seat ready to hammer round the Ardennes Euro-Test route twice: 1st time with CF in the driving seat and 2nd time with Pat Kennett in the driving seat. Pause for thought. Robert
Or if anyone has a youtube account maybe they could ask him whether that’s clutch braked,or floated,or double de clutched up shifts.My money is on the latter.
I didn’t know Bedford offered the twin splitter as an option in the TM !!!
Yes, I know of one but it was a rarity. However the TM did have 9-speed Fullers in the Italian-spec version. CF is right in thinking that we are discussing generic clutch-brakes across the Eaton/Fuller range: ie 9-speeders and Twin-splitters alike - all twin counter-shaft constant-mesh 'boxes along the same principle lines. Robert
windrush:
Some of our driver’s used the ‘Bunny Hopping’ method with the old Foden 12 speed boxes, I was far too idle to bother though! I rarely used a clutch brake anyway except at standstill, an article I read by a Fuller rep advised drivers to use the clutch to dissengage the drive and then engage the next gear with the clutch already engaged, he reckoned there was less drag on the dogs doing it that way and that was mostly how I did it. The Foden/Fuller cable change was heavy anyway on some of the ones I had, when new it needed two hands to get it into and out of gear at times but it did bed in after a couple of months. Always a lot of cable drag though unless they were kept well lubricated and they could ‘hang’ in gear at times. The Sed Ak 400 I had (rod linkage) needed to be knocked out of top gear with the palm of my hand, it never got better despite being six years old and getting reverse was a two handed job. No wonder my left shoulder is knackered!
Pete.
You’re right: the 9-speed Fuller installation in the SA 400 was appalling. I too drove one. And to add insult to injury, it was all arse-about-face and U-shaped (instead of H-shaped) to boot! Notwithstanding all that, I’d have still put up with the LHD Europeanised version called the ‘International’ which had a ■■■■■■■ 335 in it! Not bad for its day . Robert
robert1952:
the TM did have 9-speed Fullers in the Italian-spec version. CF is right in thinking that we are discussing generic clutch-brakes across the Eaton/Fuller range: ie 9-speeders and Twin-splitters alike - all twin counter-shaft constant-mesh 'boxes along the same principle lines. Robert
The question has now been put on the youtube link.If only that wagon could be brought home then converted to rigid drawbar spec and then take it to visit bma where it could be put to work pulling a 45 foot trailer.
robert1952:
Or if anyone has a youtube account maybe they could ask him whether that’s clutch braked,or floated,or double de clutched up shifts.My money is on the latter.
the TM did have 9-speed Fullers in the Italian-spec version. CF is right in thinking that we are discussing generic clutch-brakes across the Eaton/Fuller range: ie 9-speeders and Twin-splitters alike - all twin counter-shaft constant-mesh 'boxes along the same principle lines. Robert
The question has now been put on the youtube link.If only that wagon could be brought home then converted to rigid drawbar spec and then take it to visit bma where it could be put to work pulling a 45 foot trailer.
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Yes, CF the drawbar fantasy would be good fun. However, above you’ve got me saying all that starting with ‘Or if anyone has a youtube…’ etc. I didn’t say any of that so you’ve misquoted me. I know it’s only a sleight of hand and not deliberate, but please take care with your QUOTE button! Thank you, Robert
. Try it with a 14-litre Iveco lump and you’ll have no problems. Robert the Twin-splitter
