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Volvo smooths out heavy vehicle gear changes with I-Shift Dual Clutch

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July 9, 2014

Volvo's I-Shift dual-clutch gearbox is the first of its kind for heavy vehicles

Volvo's I-Shift dual-clutch gearbox is the first of its kind for heavy vehicles

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Dual-clutch gearboxes are not all that new in the car world where they feature on light hatchbacks through to the venerable Bugatti Veyron. But when it comes to trucks, dual clutch gearboxes are yet to make an impact. Volvo is hoping to change that with its I-Shift Dual Clutch gearbox, which it claims is the first of its kind for heavy vehicles.

Dual-clutch set ups allow lightning quick shifts by always having another gear at the ready. Volvo's transmission features two input shafts and a dual-clutch, essentially meaning that two gears can be selected at the same time. The clutch dictates which of the two selected gears is engaged.

Volvo's I-Shift dual-clutch gearbox is the first of its kind for heavy vehicles

"When driving it feels like you have access to two gearboxes. When one gear is selected in one gearbox, the next gear is already prepared in the other," says Astrid Drewsen, product manager for drivelines at Volvo Trucks. "With dual clutches, gear changes take place without any interruption in power delivery. As a result, engine torque is maintained and driving comfort is significantly improved."

Volvo argues that these benefits are even more relevant to trucks because of their size, and because they regularly cover terrain where a lot of gear changes are required. This means that those hauling sensitive cargo are set to benefit most from the dual-clutch set up, along with drivers who travel in wet or uneven conditions, like logging truckers who travel through forests to collect their cargo.

How Volvo's I-Shift Dual-Clutch gearbox works

Volvo says that the smoother shifts the dual-clutch provides should also lessen wear on other driveline components, meaning lower maintenance costs, while fuel consumption remains the same as the standard I-Shift transmission.

When it is best to skip gears, the I-Shift Dual Clutch system can act in the same way as Volvo's standard I-Shift setup.

The I-Shift dual-clutch will be available on Volvo's FH, and can be coupled with D13 engines that make 460, 500 or 540 hp (343, 372 and 403 kW, respectively).

Volvo's video below details how the I-Shift Dual Clutch system works.

Source: Volvo Trucks

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8 Comments

Combine this unit with a sat-nav that not only knows where it is, but also its elevation so that it knows how steep the ascents and descents are, and the whole shebang can be automated. Programme it properly and optimum fuel consumption should be obtainable, which is more important to operators than driver comfort.

Mel Tisdale
9th July, 2014 @ 05:25 am PDT

Given the very slow rate of change of RPM on big diesel engines compared to modern sports and racing car engines, I can't see how this can help.

A long time ago I drove trucks with Gardner engines (lovely things!) where, when you came to change gear, you could literally take out and light a cigarette between taking it out of gear, waiting for the revs to change, and putting it into the next gear - all clutchless, naturally.

So I would have expected that just slamming the thing into the next gear without waiting for the revs to drop would stress the drive train.

Catweazle
9th July, 2014 @ 05:33 am PDT

@catweazle

I'm glad you said that. I have never driven a HGV, but it did occur to me that there has to be some time for the engine revs to change to match the next gear, otherwise, depending on whether one is changing down or up, there will be either a jolt in the back or a tug on the seatbelt, assuming the transmission can take it, of course. (I assume a fly-by-wire throttle takes care of down changes.)

Perhaps gizmag can contact Volvo and put catweazle's concern to them. They must have considered it.

Mel Tisdale
9th July, 2014 @ 06:59 am PDT

The diesel engine technology has seen tremendous advances since the times of Gardiner diesels. One had to use the clutch to first disengage the gear and then use it again for shifting into the next higher or lower gear.

Unless one is using the engine to drastically slow down the vehicle , without using the brakes, by downshifting you would definitely not feel the jerks. The transmission train is much more robust and can take the load. The smoothing of the vehicular speed change is taken care of by the integrated springs in the clutch plate and the slight slippage between the clutch and pressure plate. But all this would not be known to the spoiled drives who have never driven a stick shift.

BTW, and this is especially true of smaller engines, there are medium sized diesel engines around with kind of acceleration that would put fancy high priced cars to shame.

pmshah
9th July, 2014 @ 09:14 am PDT

When are they going to eliminate the transmissions and replace it with a diesel generator/electric traction motors? Two Tesla motors geared down for the transaxles with an 85kw powerpack for power spikes and a downsized diesel engine designed for two speed ranges: to recharge the battery and power the drives during accel or uphills. It has to cost less in the long run.

dugnology
9th July, 2014 @ 09:30 am PDT

@ dugnology

When the improvement in performance is worth the expense.

Slowburn
9th July, 2014 @ 11:23 am PDT

Big diesels can drop revs quickly, maybe not like a small unit of course. The problem that Volvo is addressing is the lack of power being put to the wheels when shifting from gear to gear, especially on hills. As long as the transmission is robust, and not too expensive, it will be an excellent feature.

While a hybrid system may work for local runs, it is of less benefit for long-haul drivers. And if there is extra weight because of the engine/generator/motor/battery setup, that means less freight a driver can haul, which is not going to win many people over.

Bruce H. Anderson
9th July, 2014 @ 12:28 pm PDT

The dual clutch tranny in my Jetta is computer controlled & I'm sure this Volvo is as well. 1 of the upsides of a diesel-electric drive is that it can make use of regenerative braking. That could be a factor depending on the application - buses, for example.

theotherwill
9th July, 2014 @ 05:14 pm PDT
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