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NEW VOLVO ENGINE GIVES 30BHP
Page 81
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• A maximum output of 330 bhp net (DIN) is produced by a new 12-litre six-cylinder in-line turbocharged diesel announced by Volvo of Sweden. This power unit is used in a new range of goods chassis—the 89 Series—which is based on the existing 88 models but has detail changes. There are fourand six-wheel designs for normal haulage, with maximum gross train weights of up to 51.5 tons (as is possible in Sweden) and at least 100 tons for Special Types operation.
Compared with the TD100 9.6-litre (586 eu.in.) engine used in the 88, the new 12-litre (732 cu.in.) TD120 has bigger bore and stroke dimension s-130.75mm (5.125in.) and 150mm (5.91in.) respectively as against 120.65mm (4.125in.) and 140mm (4.5in.). Maximum net torque (DIN) is 927 lb ft at 1300 rpm as against 723 lb ft at 1400 rpm for the TD100 but there is a pronounced "droop" at lower speeds in the case of the TD120 so that at around 1000 rpm the torque values are similar for both engines and in the region of 650 lb ft. Both the 330 bhp of the TD120 and the 260 bhp net (DIN) of the TD100 are produced at 2,200 rpm. Specific fuel consumption at maximum torque with the TD120 is quoted as 0.34 lb/bhp/hr.
In general, the design of the TD120 follows that of the TD100. Notable differences are the use of eight holding-down bolts for each of the six individual cylinder heads instead of four, and an oil cooler with three times the capacity. Lubricating oil capacity and cooling system capacities of vehicles using the new engine are increased by about one-third, to 8gal and 10.3gal respectively.
There are three basic models in the 89 Series, which has certain components made stronger than in the 88 Series to match the higher-power engine. There is a four-wheeler and single-drive and double six-wheelers, all being made as tractive units and as load-carriers for use with drawbar trailers. The TD120 engine drives through a 15in. twin-plate clutch with air /hydraulic offered in all the new models. As an option in the four-wheeler and 6 x 2 there is a double-reduction driving axle, while a pair of single reduction units is optional in the 6 x 4. Differential locks are standard in all axles and the differential between those in the 6 x 4 can also be "locked-out".
Except for the tailing axle on the 6 x 2, lin. wider brake shoes are used for the 89 Series to take care of the extra performance and while the same cab as on the 88 is retained, frontal styling is changed, with a wider grille, and the dashboard is rearranged. Accompanying the F89 models are G89 types which, like the G88s, have their front axle located 12in. farther forward and access steps behind the front wheels. With both F and G models there are sleeper and non-sleeper versions.
It is not expected that there will be demand for the higher-power Volvo for operation in Britain, so only left-hand drive versions will be produced. But British operators requiring the new models for use in operating on the Continent, for example, will be able to make use of the designs.
The potential offered by the new Volvos was sampled by me on short test runs in Gothenburg at the time of the introduction. I drove a 6 x 4 with two-axle trailer at a gross weight of 34 tons and a 6 x 2 with three-axle trailer at 49 tons gross combination weight. Both of them had the SR61 16-speed splitter /range-change gearbox although on the slightly undulating route there was no real need for this number of gears. Having already tested a Volvo 88 over fairly hilly country I am, however, aware that this transmission can give particular advantages in enabling exactly the right ratio to be selected on long gradients. One reason why it was not necessary on the route that I covered was the extremely high torque provided by the TD120 engine. Even at 49 tons there was a very good performance, certainly as good as the F88 running at 38 tons. The 89 has the same character as the 88, being very quiet and easy to drive with first-class power-assisted steering and excellent brakes. Gear changing is by a shorter lever than on the 88, which is a worthwhile improvement; selection and engagement of the ratios was light and positive.
Far left: These graphs show comparisons for output, torque, smoke level and specific fuel consumption of the Volvo TD 120 and the TO 100 diesel.
Left: Latest model from Volvo is the F89 which is suitable for operation on the road at up to 51.5 tons. Left-hand drive versions only are planned at this stage.
Above left: The F88 has a new 12-litre turbocharged diesel—the TD 120—which has a maximum net output {DIN) of 330 bhp at 2200 rpm. Top left: Changes inside the cab for the latest Volvo include revisions to the instrument panel and a shorter lever for control of the synchromesh gearbox.