Scania 1.1381 H531 tractive unit at 32 tons gm
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by Trevor Longeroftphotographs by Dick Ross IN NOVEMBER Scania replaced its long-serving and popular right-hand-drive LB80 truck model with the LB81, which has a redesigned engine and cab furniture modifications. In other respects the 81 retains the same basic specification as the 80, and it is marketed in the UK with the same vehicle options.
The 7.8-litre (475cuin) turbocharged engine from the 80, further developed for the LB81, in its present form offers reduced emissions and improved specific fuel consumption at slightly increased output. Maximum power is raised from 148kW (199bhp) to 153kW (205bhp) at 2,400rpm, and peak torque is increased from 676Nm (4991bft) at 1,500rpm to 696Nm (5131bft) at 1,400rpm.
Cab improvements include a redesigned instrument and control layout, a reworked ventilating and heating system and improved in-cab noise insulation.
The LB81 tractive unit that we have just tested has an unladen, on the road, weight of 5.5 tonnes—fractionally less than that of the Leyland Buffalo but about 204kg (5cwt) more than the Volvo F86 tractive units already tested by CM. Coupled to the 12.2m (40ft) York Yolloy high-tensile steel frame flat-platform semitrailer weighing 4.4 tonnes, the Scania pulled a payload of nearly 22.3 tonnes (22 tons) excluding the driver and two observers.
In terms of overall fuel con sumption for our operational trial route there is little to choose between the three vehicle marques: the LB81 returned 38.4 lit re s/100km (7.4mpg), equal to the Volvo's figures and just a nose in front of the Buffalo's. For motorway work the Volvo is out in front with an unbelievable 34.5 litres/100km (8.2mpg) with the Buffalo returning 38 litres/ 100km (7.4mpg) and the Scania LB81 38.4 litres/1 0 Okm (7.5mpg).
Although not ideally specified for arduous operation such as the switch-back section of A68, the Scania LB81 can take it in its stride and .return good fuel consumption figures.
Fuel consumption for the in dividual stages of the route were consistent with what is expected on the type of terrain and weather encountered. The good first day's figures were achieved despite heavy rain and strong crosswinds. On the tortuous Rochester to Neville's Cross section an estimated 1 litre (2pts) of fuel were lost when the fuel system had to be bled. A fault in the fuel-measuring device fitted allowed air to enter the fuel system and the meter had to be removed.
Rated to 153kW (205bhp), the redesigned Scania DS8 engine provides a power to weight ratio to 4.7kW/tonne (6.4bhp per ton) at 32.5 tonnes (32 tons) gcw. Though some operators may consider this ratio to be only marginal for this gross weight the engine is a glutton for work and coupled to the 10-speed gearbox the vehicle provides all that is asked of it. The legal motorway speed 69km/h (60mph) is achieved with the engine on the governor though speeds in the midfifties were typical for all but the hillier motorway stretches. Keele gradient on M6 called for 5L, and M6 Shap was climbed in 5L except for 4L for a few brief seconds to build up speed on one stretch. Lowest speed on M6 Shap was around 45km/h (28mph).
At the other extreme, over the grinding climbs of A68 between Rochester and Neville's Cross, the LB81 put up a creditable performance. First gear was required for the short, sharp climbs with gradients approaching 1 in 5 with the steep, top section of Riding Mill, for example, requiring 11.. Operators have the option of a lower 5.67 to 1 axle ratio for vehicles required for continuous service over such routes, though some may opt for more power.
The Scania was unable to restart on the 1 in 5 gradient, which was still damp from a previous rain shower. In dry conditions I have no doubts that with gentle clutch coaxing a restart could be successfully accomplished.
Full-pressure braking stops were completed at MIRA on a track flooded by rain. In these circumstances the stopping distances returned from speeds of up to 64km/h (40mph) are extremely good. I was told by the Scania engineers that the same outfit had, in dry conditions, returned stopping distances of less than 30.5m (100ft) from 64km/h (40mph).
Though the vehicle is fitted with a 10-speed gearbox, 4H and 5L are practically the same ratio—so, in effect, there are only nine gears. Also 4H is a higher ratio than 5L and so the correct up-change sequence at the top end is 4L-4H-5H or 4L-5L-5H.
The air-assisted clutch is matched to the five-speed with splitter synchromesh gearbox in that any driver attempting to double the clutch will find, as I did, that the clutch pedal goes solid if the second declutch follows too closely on the first. Until I became used to the arrangement I occasionally found myself in the middle of a gearchange with the lever in the neutral gate and the clutch pedal immovable.
The correct technique is to press the clutch to the floor just once and shift the gearlever firmly against the required gate-slot until the synchromesh allows the cogs to mesh and the lever to move into the required position.
Changing gear correctly seems to take longer than doubling the clutch with a constant-mesh gearbox, but the change was foolproof and did not have any derogatory effects on optimum performance, say when accelerating away from rest.
The split change was effected in the normal method by preselecting the split on the gear-knob button and then either declutching to make the straightforward split or by shifting the lever in the normal way.
When restarting fully laden and on the flat it was necessary to use 1H to avoid the excessive clutch-slip experienced when using 2L, which is more conveniently located in the gearbox gate.
An excellent feature of the Scania test vehicle was the superb steering : the unit could effortlessly be turned from lock to lock-a strong advantage when reversing into narrow entrances or negotiating tight roundabouts when coupled to a 12,2m (40ft) trailer.
With the tractive unit's front and rear axles loaded to just below their legal maximum vehicle ride was as good as that of any other vehicle 1 have driven. The cab was free from any vibration and the more severe jolts sometimes experienced when passing over potholes in the road were quickly and efficiently damped.
As tested, the Scania LB81 r costs £9,960 with an extra £345 for the optional thermostatic radiator fan, exhaust brake, tachograph and radio/document shelf above the windscreen. Supplying and fitting the fifth-wheel costs £406 (including VAT) and the York trailer is quoted at £3,534. Scania markets its vehicles in the UK on a net price basis with nn discounts.