On the road with Opticruise
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by Toby Clark • Commercial Motor has driven Scania's Opticruise automatic gearchange system (CM 8-14 December). Opticruise automates the pneumatic shift components first used in Scania's CAG semi-automatic system and mates them to electronic control of the engine, retarder and exhaust brake.
The integrated engine and gearbox control means that the system can only be used with EDC-equipped engines —currently any 11-litre variant except the 420hp. The gearbox itself is based on Scania's GRS900 14-speed synchromesh unit.
The system is not yet on sale, but Scania has around 100 units on trial with fleets throughout Europe; we drove an Opticruise-equipped R113 380; one of 15 destined for a large French operator.
The "gearshift" is simply a lever with a fore-and-aft move ment: Reverse-NeutralAutomatic-Manual. The only other new control is a rocker switch next to the lever for "Hill" mode, which programmes the system for faster changes.
Depress the clutch, put the lever into "A" and lift the clutch as normal: the truck pulls away in second gear (a default setting which can be reset at will). Once speed has built up sufficiently Opticruise changes up a gear, and from then on the driver can forget about the clutch until the truck comes to rest again. The system does not need the gearbox's synchromesh—it synchronises engine and gearbox speeds electronically—but changes are smooth and reasonably fast. If a faster upchange is required (in Hill mode, or in kickdown) the exhaust brake is engaged briefly in neutral. The chuffing noise that results is a little disconcerting but otherwise the system works very quietly; the lack of a mechanical linkage to the gear lever reduces cab noise.
With the truck laden to 38 tonnes gearchange points seemed logical and it's easy to believe Scania's claim that drivers testing the system stick to its settings for 95% of the time. To move down or up a speed the driver can simply tap the gear lever to the left or right and the change is made automatically; for block changes he makes several taps and to lock the box in a gear the lever is moved to Manual. In this mode gear changes are made by pushing the lever to the left or right.
The system is integrated with ABS, ASR, the exhaust brake and retarder. A number of manual and automatic retardation and cruise modes are available. Opticruise works well: it is easy to learn, and should be a match for rivals such as Volvo's Geartronic and Eaton's SAMT. It uses proven mechanical components and the electronic systems work well, though its obvious applications in distribution vehicles and in buses have yet to be pursued.