Volvo Trucks - 5 things that make I-Shift Dual Clutch outstanding

[kscarbel2]

Volvo Trucks Press Release  /  December 5, 2016

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[TeamsterGrrrl]

Still wondering when North America gets Volvo's DCT. My Golf TDI has a DCT, very impressed with it,

[Red Horse]

So this is an automated manual?  How many speeds? Intended primarily for on highway service?

[TeamsterGrrrl]

Been out for a couple years in Europe, not available with the 16 liter engine so I guess it's for on highway at 50 ton or less gross combination weight.

[kscarbel2]

10 hours ago, Red Horse said:

So this is an automated manual?  How many speeds? Intended primarily for on highway service?

Bob, I "know" that I posted news on the I-Shift Dual-Clutch, but I can't located the link. To date, sales remain very low, and to my knowledge are only in Western Europe where Volvo can monitor them closely. Here's some info:

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Volvo I-Shift Dual Clutch: Smooth Operator

Heavy Duty Trucking  /  December 2014

Volvo Truck claims to be first in the world to launch a dual-clutch automated mechanical transmission in heavy trucks, and to this reporter’s knowledge, that is correct. Deliveries of the [12-speed] I-Shift Dual Clutch started in Europe this fall. There's no official word yet if they will be available in the U.S., but it's seen as likely by many in the industry.

As a concept, dual clutch transmissions appeared in the 1980s in auto rallying and racing. Some European cars now offer them, and Eaton recently introduced a dual-clutch transmission for medium-duty trucks.

The current I-Shift automated manual, with a single clutch, goes back to 2002 in Europe and 2005 in the U.S. About 95% of Volvo's sales of heavy trucks in Europe last year included the I-Shift, and in the U.S. it's now in 74% of Volvo heavy trucks.

The two Volvo I-Shifts are similar mechanically, but to the driver they operate much differently.

I-Shift Dual Clutch can basically be described as two parallel connected gearboxes in one housing. One gearbox contains the even gears and the other has the uneven gears. When one gear is active, the next gear is pre-selected in the second unit. When shifting changes from the first gearbox, the other is poked in. This provides ratio changing without any disruption in power or speed.

The I-Shift Dual Clutch has two input shafts, one located inside the other, and the two clutches. This allows two gears to be engaged simultaneously. Which of the gears that is activated is determined by which clutch is engaged.

Volvo’s I-Shift Dual Clutch weighs 222 pounds more and is 4.72 inches longer than the single-clutch I-Shift.

Demanding driving

Volvo showed the I-Shift Dual Clutch to the European press corps recently in south-coastal Spain. We drove almost 300 kilometers (about 180 miles) using 12 vehicles. All were typical European 4x2 tractors with three-axle semi-trailers, loaded to 40 metric tons or 90,000 pounds GCW. Some were equipped with Dual Clutch I-Shifts, while others had the regular single-clutch I-Shift.

  The reason for choosing this part of Europe was the demanding, long and steep ascents and descents of up to 7 and 8 percent. One 65-kilometer (40-mile) leg started at sea level, rising to 916 meters (2,005 feet).

I became especially fond of a FH13-liter with 500-hp engine and 2500 Nm (1844 lb-ft) of torque equipped with the Dual Clutch. It took off almost like a bullet and changed gears fast and without any interruptions. One could only hear, not feel, most gear changes.

Like a regular I-Shift, the new transmission skips some gears whenever possible, and makes only one small pause, during a range shift between 6th and 7th gear. Gear changes were made at low rpms, but revs did not drop during gear shifting. Low engine speed gave an extra comfortable setting in an already quiet cab. Volvo says fuel consumption does not exceed a "normal" I-Shift.

In the long and steep downhills, the transmission shifted down more quickly and more often than otherwise, due to the activated engine brake and retarder. This is controlled by the cruise control, where the desired maximum speed is set. The Volvo cruise control switches are on the left side on the steering wheel, and prompting slower or faster set speeds is done with a superb thumb switch.

It is amazing how quickly one can lose previous frames of reference. After time in a truck with an I-Shift Dual Clutch, an otherwise distinguished and popular long-haul FH 13 with a 460-hp engine and a single-clutch I-Shift felt far weaker with its slower gear changes.

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[Red Horse]

Thx Kevin- I just remember an old timer one time giving me an "additional" reason why the Maxidyne with a five speed was so good-vs say a Cummins with a 10 speed RR.  In essence he talked about parasitic loss because of "all the gears".  granted they all aren't engaged but in a dual clutch as I understand it, you do have a lot of "gears in motion" do you not?  

In any case, videos are convincing in terms of smoothness

[DSCannon]

The dual clutch transmission (DCT) won't power shift during the range 6->7 as stated above in marketing info. You should only have to pay for 10/11th of the price increase. I'd rather have a working Allison 4500 where I can power shift through every gear. DCT transmissions have much more problems than a bullet proof planetary system.

[kscarbel2]

Volvo Dual Clutch: a clutch of class

Steve Brooks, Trade Trucks AU  /  June 26, 2019

If you think automated transmissions don’t come any smarter or smoother than Volvo’s super-slick I-shift, well, you’ll have to think again following the release of a new ‘Dual Clutch’ version. But are quicker, slicker shifts Volvo’s only motivation for adding the significant cost and complexity of dual-clutch technology?

Volvo’s dual clutch system is clever technology. No question. Launched in Sweden in 2014, which suggests any bugs have been well and truly ironed out by now, it remains a world first for heavy-duty trucks. As Volvo declares, "Transmissions with dual clutches are used in cars, but Volvo Trucks is the first and only manufacturer in the world to offer a similar solution for series-produced heavy vehicles."

Built on the remarkably, and deservedly, successful I-shift 12-speed transmission, the dual-clutch assembly makes Volvo’s supremely smooth and responsive automated shifter even smoother and more responsive. Some of the time!

But how much smoother and how much more responsive?

A little or a lot, the answer depends largely on where the truck is and what it’s doing.

Like, there were numerous occasions on a recent drive of a 13-litre FH540 B-double outfit when it was difficult to determine if there was any practical difference between this dual clutch version and the standard I-shift gearbox I’ve come to know and admire over many years in many trucks. Not just Volvo trucks either, but in the same transmission’s other identities as the Mack mDrive or UD’s strangely titled Escot.

Yet at other times during a busy stint that included hauling the 55-tonne combination up the formidable Toowoomba Range and down the unforgiving Cunningham’s Gap, the spontaneity of shifts through the dual clutch system was nothing short of outstanding.

Put simply, in the fluctuating flows of suburban traffic, where any modern automated shifter will routinely deliver multiple skip-shifts as traffic teeters between stop, go, fast and slow, the dual-clutch system showed little, if any, advantage over a standard I-shift.

Out in rolling country, though, and particularly where the grades came long and sharp both uphill and down, single-step shifts through the dual clutch system were breathtakingly quick and smooth. Sensationally seamless and, yes, appreciably more responsive than the standard I-shift.

Volvo refers to these single-step swaps as ‘power shifting’ – meaning no interruption to power and torque delivery during gear changes – and overall performance of the dual clutch system was effectively just as the press blurb said it would be.

Like, "When driving in conditions where it is optimal for the transmission to skip a few gears, the transmission changes gear just like a regular I-shift unit," Volvo’s press statement reads.

Conversely, as Volvo Trucks vice-president Tony O’Connell says in the same statement, "I-shift dual clutch … delivers seamless gear changes and uninterrupted engine power to the road when accelerating and climbing or descending tough grades."

And again, that’s just how it panned out on a run that started early on a weekday morning from Volvo’s Brisbane North dealership and ended 350km later at Volvo Group’s new headquarters at Wacol on the city’s western edge.

Riding shotgun was Volvo Group fuel efficiency manager Matt Wood (yes, the same Woody I’ve shared many travels with in his former life as a truck scribe) who had the 13-litre FH540 perfectly prepared, hooked to a B-double trailer set mounted on wide profile single tyres.

DEFINING THE DETAIL

With just 1,600km on the clock, peak performance was probably still a few thousand kilometres away but that said, Volvo’s top 13-litre rating was typically lively and certainly not shy when required to dig deep.

Even so, this was an exercise primarily designed to showcase the merits of the dual clutch system over a relatively short but demanding route, and ideally, how this form of transmission technology can aid the efficiency and performance of Volvo 13-litre models at 500 and 540hp (373 and 403kW) in either FM or FH forms.

At this point it’s worth noting the dual clutch system is not available behind Volvo’s flagship 16-litre models.

So what exactly is ‘Dual Clutch’ and how does it work?

Its technical name is the SPO2812 transmission, meaning it’s a 12-speed box with input torque capacity of 2,800Nm. Most importantly, though, the ‘O’ signifies an overdrive gearbox whereas the standard I-shift behind the 13-litre engine in linehaul B-double applications is a direct-drive unit.

As Volvo puts it, the broad ratio coverage of the overdrive shifter – from a first gear of 11.73:1 to a relatively tall 0.78:1 top slot – provides good lift-off capability and critically at the other end of the spread, fuel efficient engine revs at cruising speed.

However, it needs to be also pointed out that this dual-clutch version of I-shift drove into a 3.4:1 rear axle ratio instead of the 3.09:1 final drive typically used behind the direct-drive box in 13-litre linehaul B-double combinations. That means the 13-litre dual clutch derivative uses the same gearbox and diff combination fitted in the vast majority of Volvo 16-litre B-double outfits.

Consequently, as our test run revealed, engine speed at 100km/h with the dual-clutch overdrive box is around 1,400rpm. By comparison, the standard direct-drive version of I-shift running through the 3.09:1 diff ratio notches 100km/h at a twitch off 1,600rpm.

Therefore, it shouldn’t surprise anyone that a prime goal for the dual clutch layout is to improve the fuel efficiency of 13-litre models in linehaul B-double roles.

Anyway, as for the details and actual workings of the I-shift dual clutch system, Volvo says, "I-shift dual clutch can be described as two gearboxes with two clutches, integrated into one unit.

"The two [dry type] clutches are connected to two different input shafts, operating independently of each other. Since the gearbox has 12 [forward] gears, one shaft holds the six odd numbered gears while the other holds the six even numbered gears.

"During gear changing, the first gearbox is disconnected at the same instant as the second gearbox is connected, so gear changes take place without any interruption in power delivery."

POWER SHIFTING!

There is, however, a significant exception in ‘power shifting’ availability. It does not operate on the range-change between 6th and 7th gears, which, as most drivers will confirm, is where fast shift speed is generally most beneficial.

What’s more, there are significant control components which operate the dual clutch arrangement and in addition to more mechanical parts, add substantially to I-shift’s complexity. As Volvo explains, "The clutches are controlled by the DCCA (Dual Concentric Clutch Actuator), which in turn is pneumatically controlled via the DCVU (Dual Clutch Valve Unit) while another device, the GCU (Gearbox Control Unit) controls gear changing."

Predictably, with complexity comes cost but unlike complexity, cost isn’t so easily uncovered in the corporate context.

In fact, Volvo’s official response when asked about the price premium for the dual clutch version of I-shift were a couple of rather lame lines about not speaking specifically about price and suggesting, "anyone interested in this unique offering … should contact their nearest Volvo dealer".

Following that advice, it seems there’s some ‘wriggle room’ when it comes to price but nonetheless, the dual clutch system won’t come cheap at between $10,000 and $12,000 over the cost of a standard direct-drive I-shift in the 13-litre Volvo.

For the driver, however, nothing much has changed in operational terms. There’s a shift lever integrated on the left side of the seat, which has no mechanical contact to the actual transmission, and selecting auto, manual or reverse modes is as easy as pushing the short stick forward or back, with buttons on the side of the lever for fingertip shifts up or down when required.

There’s also a button for ‘Economy’ and ‘Performance’ modes, which give the driver the option of engine speeds tailored for fuel economy or, as Volvo states, "when extra engine power is needed". In reality, all ‘Performance’ mode does is increase the engine speed for upshifts made under full throttle.

Used correctly, the ‘economy’ and ‘performance’ functions of I-shift can be beneficial but it’s no secret that ‘performance’ mode has become something of a bane for Volvo and some of its customers. There are drivers who simply over-use ‘Performance’ in the mistaken belief of extracting more muscle from the engine – particularly the 13-litre engine – when, in fact, all they’re doing is using more fuel to gain marginally higher engine speeds.

In response, and obviously striving to improve fuel returns, Volvo some time ago introduced the option of dash-mounted transmission controls in place of the shift lever, a move which not only deleted ‘economy’ and ‘performance’ modes but also removed the ability to make manual shifts.

It’s easy to understand why Volvo developed the lever-less option but in practice, it also negates many of I-shift’s inherent attributes.

Fortunately, the ‘Dual Clutch’ test truck had the standard lever arrangement and as the exercise moved into the hard haul up Toowoomba Range before dropping down Cunningham’s, it was in manual mode that the dual clutch system showed its most impressive traits.

Before then, of course, came the dawdle out of Brisbane’s northern ’burbs, where it was difficult to recognise the difference between a standard I-shift and its dual clutch counterpart.

Sure, there were occasional moments, such as the drag over the Gateway Bridge, when an almost imperceptibly fast single shift suggested what was to come, but for the most part, the run west through morning traffic was just another quiet stroll in another smooth Swede.

Likewise, the 13-litre engine was making relatively easy work of its 55-tonne gross weight, cantering comfortably in auto mode. Then again, the I-shift dual clutch transmission is rated to gross weights up to 80 tonnes, so if you’re out to showcase a transmission to its peak ability, why limit the combination to 55 tonnes instead of a B-double’s maximum of 62 tonnes and more?

The answer, apparently, is that the majority of linehaul B-double combinations hauling general freight rarely run at peak B-double weights anyway. So, given that a multitude of Volvo 13-litre B-double combinations haul general, 55 tonnes is probably an accurate indicator of real world operation.

FLASHBACK

In fact, a quick stroll into the recent archives revealed that Volvo’s thinking on its 13-litre model’s preferred place in the B-double business hasn’t changed at all over the past five years or so.

For instance, a road test on a 13-litre FH540 B-double in late 2013 – just months after the Australian launch of the new generation FH range – was run at a pinch over 55 tonnes, with Volvo even then making the point that it’s perhaps a typical gross weight for a B-double on general freight.

What’s more, the trucks then and now were run over much the same route, except the dual clutch version had a longer stint in the ‘burbs than the previous combination. Either way, the similarities were remarkable except, of course, for the dual clutch system with its different drivetrain and the fact that the earlier outfit at least had a few thousand more kilometres under its belt.

Like the previous test unit, the dual clutch Volvo was equipped with a swag of safety and efficiency features including the I-roll function, which under certain conditions puts the transmission into neutral, allowing the engine to coast at idle. The aim, of course, is to save fuel and in the undulations between Brisbane and the foot of the Toowoomba Range, I-roll certainly delivered many bouts of idle time … pardon the pun!

On a number of occasions, however, there was a slight ‘bump’ as the transmission re-engaged when the foot went back on the ‘go’ pedal. It wasn’t severe but it was definitely noticeable, at least to this nut behind the wheel, and certainly the first time I can recall anything of this nature in I-shift.

Anyway, through the village of Withcott as the range rears up, with ‘Woody’ asserting the benefits of engaging cruise control at 80km/h and leaving the transmission in auto for at least the first half of the climb, the dual clutch system was soon strutting its stuff.

Suddenly, it was obvious what all the dual clutch hype was about, with ‘power shifts’ kicking in and each step down the box coming quicker and slicker than anything I’ve ever experienced in an automated box of any kind.

Still, as Volvo had already explained, the only exception in power shifting was in the range-change swap from 7th back to 6th. But seriously, the difference was negligible; such is the responsiveness of I-shift generally.

Halfway up and onto the saddle between the two climbs, experience determined a move to manual mode to hold the transmission in 6th gear and avoid an untimely and short-lived upshift before the tougher second stage of the ascent.

Beyond the saddle and with revs slowly peeling off as the grade grew, a manual swap to 5th went through in another silky smooth instant. Meantime, with engine speed dropping no lower than 1,550rpm on the sharpest pinch, it wasn’t long before an upshift to 6th went through with similarly spectacular speed while near the top, a manual move across the range-change to 7th might have been marginally less instant, but was nonetheless effortless.

From here on it was back to auto mode, through Toowoomba’s busy main artery and across the undulating tableland to the top of Cunningham’s Gap before a move down to 5th gear in manual mode for the drop over the lip.

Here again, the dual clutch system was every bit as impressive as it had been hauling up the range, delivering spectacularly fast, smooth single shifts, working in concert with flicks through the various stages of engine retardation to provide a safe, effortless descent of an historically difficult and dangerous grade. It just doesn’t get any easier.

Then on the run-off, a move back to auto and let I-shift just do its thing for the last leg to Volvo headquarters in Wacol. Simple!

CONCLUSION

As stated at the start, "Volvo’s dual clutch system is clever technology. No question."

In fact, if Volvo’s only goal with the system is to deliver the fastest, smoothest automated gear shifting transmission in the heavy-duty truck business, it has unequivocally succeeded.

There is, however, more to it than that and with the move to the same drivetrain – overdrive transmission and 3.4:1 final drive ratio – used in the great majority of its 16-litre B-double combinations, Volvo is obviously aiming to enhance fuel efficiency of its 540hp 13-litre outfit in linehaul B-double duties.

Similarly, perhaps, the characteristics of the dual clutch version of I-shift have the potential to at least partially reduce stress on the 13-litre engine in B-double combinations.

Still, if enhanced fuel efficiency is indeed a prime goal, does the dual clutch system achieve a gain worthy of the increased cost and complexity? Probably not!

Back in late 2013, our FH540 test unit running the standard direct-drive I-shift through a 3.09:1 rear axle ratio, at much the same weight over much the same highly demanding route, returned a fuel figure of 1.72km/litre, or 4.85mpg. By comparison, the overdrive dual clutch unit in this exercise returned a fuel figure of 1.64km/litre (4.63mpg), but given the severity of the route, neither figure is unacceptable.

Yet even though the dual clutch truck had a couple of thousand fewer kilometres on the clock and travelled through marginally more traffic, it’s difficult to substantiate any fuel gain with the dual clutch transmission.

Most perplexing of all, though, is Volvo’s promotion of the dual clutch option when it has a perfectly good alternative to its 540hp 13-litre model for linehaul B-double work.

That option is a 540hp version of its 16-litre engine, which already runs an overdrive I-shift and 3.4:1 rear axle but, for whatever reason, remains a largely understated option in Volvo’s model menu.

From the outside looking in, the bigger cubes will almost certainly enhance long-term durability, and doing the job with considerably less stress than its smaller sibling, it’s entirely possible the 16-litre 540 will be better on fuel.

Finally, any consideration of the dual clutch option for B-double work should perhaps start with the simple fact that Volvo’s I-shift is still as good as it gets; a supremely successful and immensely intuitive automated shifter which from the moment of its release set a new standard in transmission technology.

As for the operational and economic value of ‘Dual Clutch’ … well, maybe it should be contemplated alongside a thought which jumped into the brain as the test truck ran up on a struggling, slower vehicle on the first long pinch up Toowoomba Range: If circumstance decreed a stop on such a severe grade, what would be the better addition to I-shift for a heavily loaded B-double – the dual clutch system or the crawler gear option released late last year?

For me, it’d be the crawler gear. Every time!

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[kscarbel2]

How Many Clutches Do You Need?

Diesel News Australia  /  July 2019

The obvious answer to the question, ‘how many clutches do you need?’ would be one, but Volvo reckon there are advantages, in some cases, to using two clutches to improve driveline efficiency. The Volvo dual clutch technology has been available for some time in Europe, but has finally made its way here, after prolonged testing in Australian conditions. 

There are now examples of the new gearbox option on the road and Diesel News took the opportunity to drive a B-double out of Brisbane, up the Toowoomba Range and along to Cunningham Gap, before returning down from the Dividing Range to Brisbane.

There have been dual clutch vehicles in Australia before. They are an option in Volkswagen cars and available as the Duonic option on the Fuso Canter model. Volvo’s introduction of the concept is a first for the heavy end of the market. 

Volvo claim that by having two clutches in the gearbox most gear changes made can be power-shifts and there is no interruption of power as the change is made. Essentially this should make the driveline more efficient, but it can also reduce the number of times the driveline is interrupted during ratio changes.

The I-Shift Dual Clutch transmission consists of two input shafts and a dual clutch, which means that two gears can be selected at the same time. It is the clutch that determines which of the gears is currently active. I-Shift Dual Clutch is based on I-Shift, but the front half of the gearbox has been redesigned with entirely new components.

Essentially, the I-Shift Dual Clutch is two gearboxes linked together. During gear changing, the first gearbox is disconnected at the same instant as the second gearbox is connected, so gear changes take place without any interruption in power delivery. 

The two clutches are connected to two different input shafts, operating independently of each other. Since the gearbox has 12 gears, one shaft holds the six odd numbered gears, while the other holds the six even numbered gears. The gear changes using the two clutches can be used for all single step gear changes apart from the one between sixth and seventh gear, as this involves a range change –from low to high, or vice versa.

When the transmission control unit decides it is a good idea to skip ratios, when the load is light and the going easy, either going up or down the box, the I-shift will change gears as it would normally without a second clutch. 

According to Volvo, the I-Shift Dual Clutch makes a big difference when transporting moving or liquid cargo, such as livestock and tanker operations. The smoother uninterrupted gear changes create less movement in the cargo itself. The power-shifting on offer also means there is less risk of getting stuck on slippery or uneven roads, for instance when hauling timber in the forest. 

The dual clutch does introduce a number of new components into the gearbox and, as a result, the transmission is 120mm longer than its single clutch equivalent. The extra componentry also adds 100kg to the weight of the gearbox.

When Ove Wikström, Volvo Global Heavy Duty Transmission and Rear Axle Manager came to Australia last year he spoke about the intended release of the dual clutch technology and gave examples of how it is working in Europe.

“We have some information from some of our customers that there is a fuel consumption saving with the dual clutch,” said Ove. “If you go on a flat road, you don’t save any fuel, but if the road is up and down you can save three or four per cent, and we had one customer saving five per cent on fuel. You also have some time saving and the smooth gear shifting is good for the driver and the load.

“We ran a trial in Sweden to see how much time could be saved. We went from Gothenburg in the east of Sweden to the west coast. This is a distance of 645km and we had an average speed of 70 km/h and it took 9.5 hours. The road was up and down, but not extreme, the normal landscape in Sweden, and the result was we saved them 15 minutes, which corresponds to a three per cent improvement.”

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