On The Road
Hauling 44 tonnes up the tortuous Edge Hill on the A422 outside Banbury isn’t for the faint-hearted, nor is it a time to be mucking about looking for the best gear for economy. The drill here is simply to get the damned thing up without missing a cog. The Kerax certainly wasn’t short of guts – keeping the engine spinning at 1,500rpm we completed the climb in a few seconds under three minutes, dropping to a lowly 13km/h at the steepest point.
That’s well behind the two-and-a-half minutes we’d expect from a typical eight-wheeler, but when you consider the Kerax had an extra 12 tonnes to carry it’s a decent effort.
Under the cab sits Renault’s own 11.1-litre straight-six turbo-diesel , offered here at its top rating of 412hp. Using a touch of marketing licence, Renault insists on designating this engine a 420. In a market where every horse counts clearly a 420 will attract more buyers than a 410 will!
Quite how long this engine will remain in the line-up is debatable: by the advent of Euro-4 in 2006 it will be replaced by a new motor developed with sister company Volvo.
Hillclimbing aside, the ‘420’ Kerax offered a good enough mix of power and torque to maintain a decent road speed. Top power is up at 1,900rpm, though for general on-highway driving full upshifts were made at 1,600rpm, just out of the economy green band, while half splits were taken at 1,400rpm.
In both cases this dropped the revs back in about 1,100rpm, slap bang in the middle of the peak torque zone with plenty of power available to give good acceleration through the rev range.
Flat-out acceleration is down considerably against the eight-wheelers we’ve compared it to here – which was only to be expected – but this big tipper is also beaten by the long-haul 44-tonners we’ve tested, particularly from 0-80km/h.
There are two possible explanations for this: either the Kerax is gutless or it was hampered by enjoying the aerodynamics of a brick. We’d opt for the latter, because out on the road it certainly doesn’t give the impression of being short on muscle.
Renault is a recent convert to ZF transmissions and our test truck was equipped with the 16-speed version of the Ecosplit box. Thankfully, in shifting to ZF Renault has dumped the double-H gear pattern in favour of the near industry standard single-H with a button on the front of the stick for the range-change and one on the side for the splitter. The shift, though not the smoothest, is well spaced and the throw of the stick is short enough for the fast changes that are essential when the going gets tough.
Cab Comfort
If it’s long-haul luxury you’re after from your 6x4 tipper then the Kerax isn’t likely to be at the races. However, for a tough, straight-forward driving proposition the new Renault does everything that’s required, in a fashion.
The cab design may be getting a trifle antiquated but it’s still clear and uncluttered; the new-look dash freshens the display and on the face of it the interior looks easy to keep clean.
With such exceptional front ground clearance clambering into the cab is bound to be a bit of a chore, but once aboard the driver is presented with a good view of the road from the Premium-derived cab. We’ve always liked the in-cab layout of the Premium/Kerax; the pedal position is good and there’s plenty of room to stretch out.
Although the ride verged on the uncomfortable the seat offered enough support to ensure we didn’t suffer any lasting damage.
Storage is adequate for the odd night away – remember this model isn’t built for long-haul luxury – and there’s room enough in the fascia’s central cubby box for pens, fags and other bits and bobs, with some overhead storage spaces for delivery notes.
Our test truck came with a single bunk and the engine hump had been left clear to ensure easy access to the sleeping quarters, but a storage box can be fitted there.
Despite the upright exhaust and the very short overall driveline ratio we were pleasantly surprised by the in-cab noise, or rather the lack of it. With the engine spinning at 1,600rpm in top on the motorway we were expecting high decibel levels; in fact the most noise came from the strong gusting wind around the mirrors’ arms.
