Swing shift
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Renault's automated clutch could take the leg work out of multi-drop routes. CM has been getting to grips with Renault's ACS.
special option on the G230, the G220 17-tonner and the G220.25D 24-tonner, Both the six-speed G406 and the ninespeed B9 are catered for. ACS is also available on the B9 in the 6x4 Maxter G300.26D and the G310.32 eight-wheeler.
Climb into the cab on any of these trucks and you'll find no more than an odd-looking gear lever. You won't find a clutch pedal. On the top of the conventional gear stick is a three-inch high knob connected to the lever by a ball and socket joint. This multi-way joint allows the knob to begin moving before the main lever. The ball and socket is fitted with a micro-switch which activates the clutch mechanism. It is so sensitive that the bad habit of resting the left hand on the gear lever could result in very rapid clutch wear.
ACS works through the ubiquitous microprocessor. It monitors driver demand through the gear lever, the throttle pedal and the changing loads and speed of the engine. It knows, for example, that full throttle precedes a series of upshifts, most likely as the truck is accelerating. It also knows that a stationary truck at idle could engage a gear at any time.
With a low gear engaged and the park brake released, the computer knows to start feeding in the clutch just as soon as throttle demand and engine speed begin to rise.
ACS will not pre-empt the driver's actions, however. The driver retains full control at all times.
We began our drive from Renault's Dunstable base, heading out through the traffic and over the Dunstable Downs on a route guaranteed to provide plenty of clutch pumping in any other truck.
With the engine running, all the driver need do is select first gear. Simply pushing the lever head in the direction indicated on the conventional pattern opens the clutch. Drop the park brake and depress the throttle and, after a pause while the engine rises to clutch engagement speed, the truck starts to move.
Second gear is just as simple, if not a little peculiar to obtain at first. With the revs high enough we backed off the throttle and pulled the lever from first, slotting it into second with a clunk.
Things got easier and smoother as the synchromesh gearbox warmed up, but otherwise the truck drove quite normally. We proceeded to punch the lever up and down the box for two hours without missing a single gear.
Stopping on hills requires some care, This is no automatic transmission. All drive is lost when the truck slows to a halt, with or without brakes. Co-ordinating the throttle and park brake demands practice. Without a pedal to feel for clutch bite there is a danger of rolling back.
Caution
The trick of ACS is not to be afraid of it. It can feel downright wrong to shove a gear lever about without the left leg taking part. Too much caution can't do any harm, it just causes a minor traffic jam while the driver gets the feel of things.
AS costs £2,200. RVI claims it can improve clutch life by as much as three times. It expects orders to come mainly from municipal and distribution operators, though it emphasises ACS is suited to most other operations including long haul.
It is not entirely suited to off-road applications, however. Here even a computer cannot replace the experienced left leg.
Renault believes ACS is cheaper and more fuel efficient than any automatic transmission. And the operator gains by retaining engine braking, thereby avoiding the higher brake wear associated with torque converters, it says. Our impression is that, given the choice, drivers will still opt for the automatic while the transport manager, fleet engineer and accountant will favour ACS.