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VEHICLE HISTORY
Page 119
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Foden S1 08 8 x 4 Multiwheelers since the test of the Foden S108 with Caterpillar engine as reprinted in the "Old Road Test Collection", a further three examples of the model with different specifications have been put through their paces by CM. Although having many common design features the differences built into the chassis illustrate quite well the strength of Foden in being able to supply vehicles in a variety of specifications exactly as required by the operator, or very close to this.
Looking first at the main common aspects of the test eight wheelers, all had parabolic front springs and Foden FF20 rear bogie rubber suspension, same size wheel brakes, ZF8043 power steering and 273 x89 x 9.5mm high tensile steel frames with light alloy crossmembers and forged gussets.
With regard to differences, these were mainly in respect of major units. For the 5 May 1984 test, the S108 had the Caterpillar 201kW (270hp) charge-cooled engine driving through an Eaton Fuller RTX 11609 nine-speed gearbox to a Rockwell hypoid drive tandem bogie. The 11 May 1985 test was of an 5108 with Gardner 6LXDT 201kW (270hp) turbocharged engine with the same Eaton Fuller RTX 11609 box but an Eaton DS401P rear bogie. Finally the 14 February 1987 test saw the same engine and rear bogie but with an Eaton Twin Splitter 11612, 12speed gearbox. The most recent test on 2 May 1987 was with the uprated Gardner 6LXDT with 216kW (290hp) output driving through an Eaton Fuller RTO 13-speed gearbox to the Eaton bogie. In all cases, the transmissions had overdrive top gears but whilst three of the four chassis had Eaton rear bogies, the drive ratios were different on all four test vehicles.
Because of these variations in specification it is difficult to evaluate test results and make totally
valid comparisons. Results of the tests, however, were in general acceptable. In the case of performance, for example, results of acceleration and hill restart and climb times were commendable, as would be expected with power-to-weight ratios between 9.0 and 9.67hp per ton. Not surprisingly, the Gardner 290hp test produced the best results here including an easy restart on a 33% (1 in 3) gradient. But the other three managed to drive over this gradient and gave easy restarts on 25% (1 in 4).
In the matter of fuel economy the first two tests followed the earlier CM procedure for tippers with 10 circuits of a 12.5 mile route taking in 10 miles of decent roads and 2.5 miles off-road. This was a very severe test and the S108 with Caterpillar engine produced figures comparable to other 8x 4s -53.9 lit/100km (5.24mpg) at 39.63 km/h (24.65mph).
The second test that of the S108 with Gardner 270hp 6LXDT improved on these figures to a point where only one 30 ton eight wheeler had done better than the Foden's 46.01 fit/100km (6,14mpg) at 40.48km/h (25.I6mph). These figures considered on their own do not give good impressions of the standards of economy which the two versions of the S108 are capable of. This was, however, provided on the second test when a check on fuel usage was made when travelling to the Bagshot tipper test ground. Over a distance of 123.5 miles of mixed motorways and dual carriageways, fuel consumption was 35.45 lit/100km (7.97mpg).
This was actually very close to the returns on subsequent tests carried out on the other two S108s. Both were checked over CM's current, less arduous test circuit (including motorways) and with the 270hp Gardner, consumption was 37 .2lit/100km (7.58mpg) which improved to 36.7lit/100km (7.69mpg) with the 290hp unit. Surprisingly, overall average speeds were identical on these two tests at 66.14 km/h (41.11mph).
Although these figures show a strong consistency, they do not break any records as Gardner-engined vehicles used to do. In fact, they do not show up at all well against nine 8x 4s tested since January 1986, 7.69mpg rating sixth place and 7.58mpg eighth.
There was quite a big variation in brake test figures. On the first test (Caterpillar engine) efficiencies were good with 67% overall and individual axles ranging from 58 to 83% (on the second axle). The 11 May 1985 test produced similar results 63% overall and improved on individual axles by being more evenly braked with figures from 62 to 66%.
With exactly the same brake sizes and frictional area as the first two test vehicles there was no reason why brakes on the third S108 should not give similar results. But this was not the case. Measured on a roller brake tester, overall efficiency was only 38.24%. No logical explanation was given for such poor figures which were below legal requirements.
In between the February 1987 and May 1987 tests, brake specifications on the S108 were changed. Drum diameter and shoe width stayed the same but obviously shoe lengths had been increased as frictional area went up from 8790 to 9736cm2 (11%). There is no doubt that whatever had been done to the brakes was sound as extraordinarily good figures (for an eight wheeler) were recorded on roller test 80% overall with 94% over the front steering bogie and 70% over the rear bogie. The S108 cab has also changed to the current 4000 Series with a smoother front end and revised, and improved interior.
When tested in May 1984, the list price of the Foden 5108 with Caterpillar 3306B 270hp engine and Roadranger RTX 11609B nine-speed gearbox was £31,500 net (exluding body and gear). Current price of S108 with the same specification would be £47,350, an increase of 50% as compared to a rise of 28% in the Retail Price Index.