ting changes
Page 24
If you've noticed an error in this article please click here to report it so we can fix it.
IERCEDES-Benz have made significant changes to their New Genration of heavy duty vehicles first introduced in 1973, reports TIM LAKEMORE.
The same basic cab is being sed, but there is a new extra rge cab variant and new model umbers for all the vehicles — .emming from the use of the aw 14.6-litre (891cuin) V8 enine throughout the range.
Naturally aspirated versions of is engine, 0M422 and 0M422 , were displayed at the Birlingham Motor Show in Octo?,r (CM, October 18). The turbolarged versions are designated M422A and 01V1422LA respectifly. These are the engines for e 1633 and 1638 models resectively, rated at 243 kW 126bhp) DIN and 276 kW 70bhp) DIN.
All four engines have a rated )eed of 2,300rpm and all four :velop maximum torque at 200rpm, but the torque curves the turbocharged versions are :ry different from the naturally ;pirated ones.
There are mechanical difrences too — an 0M422A is A simply an 0M422 with twin rbochargers bolted to it. For :ample, the sump capacities of e A and LA variants are greater an those of the unblown verons.
Each turbocharged engine has double oil cooler (single on the Aurally aspirated engine) and e camshaft of the blown enne is also different.
On the turbo engines only, ird sintered metal-coated tapAs are used. Carbide plates are :ed to the tappet bases by a imputer-controlled soldering lit, and Daimler-Benz claim to be the first European commercial vehicle manufacturer to use this process.
Fuel consumption remains low on the two turbocharged engines between the speeds of 800 and 1,900rpm; but if the engines are taken up to their governed speed of 2,300rpm, the fuel consumption curve rises.
To encourage drivers to keep to the most fuel-efficient engine speed range, Mercedes now fit as standard on the 1633 and 1638 an electronic control for the injection pump governor that limits engine speed to 1,900rpm.
Standard gearbox on the 1628, 1633 and 1638 is the ZF 16-speed Ecosplit unit, whereas the 1628 has the eight-speed rangechange gearbox, without splitter. Mercedes say that Fuller gearboxes will be offered as an option in the future.
All the gearboxes have direct top gear ratios, but unlike the 1617 rigid model, which now has a single reduction hypoid rear axle, hub reduction rear axles are retained for the NG80 38tonne range.
Mercedes argue that the greater efficiency of a single reduction axle is almost too small to measure, and perhaps even more importantly, the reliability of its planetary gear hub reduction axle probably could not be equalled by a single 'reduction model.
Daimler-Benz claim that of 450,000 planetary axles supplied, less than 50 have broken down. Until now Mercedes-Benz used the same type of chassis frame for both tractive units and rigid vehicles but, in order to reduce the frame height, the company now use a different doubleU section frame for tractive units.
This has the same strength as the earlier design, but its reduced depth means that the upper frame edge is 120mm (4.7in) closer to the road surface and on 12 R 22.5 tyres it is now possible to carry a standard 8.5ft high container and be within the four metre maximum height limit.
Another advantage of the new chassis frame design is that a subframe for the fifth-wheel coupling is no longer necessary.
Parabolic springs on the new tractive units also help to keep the frame height low.
For 1625, 1628 and 1633 models three cab versions are available (in the same way as with 1626 and 1632 models) — the standard day cab (S), a 37cm (14.6in) longer version (M), with a bunk and an optional second, folding bunk; and the L-type double bunk sleeper cab which is 23cm (9.1in) longer than the M-version.
Mercedes say they have no plans to offer the GR cab in the UK as yet, but if demand were sufficient it would be made available.
Current retail price of a three metre wheelbase standard cab 1628 tractive unit is £27,940 and a similar specification 1625 will cost £25,440.
When the 1633 becomes available here it is likely that spec for spec, its cost will be about 15 per cent more than the 1628, since this was the difference between the 1626 and V10 1632.