AT THE HEART OF THE ROAD TRANSPORT INDUSTRY.

Call our Sales Team on 0208 912 2120

Road test intpressions of the Fiat 684 model

21th July 1972, Page 28
21th July 1972
Page 28
Page 30
Page 28, 21th July 1972 — Road test intpressions of the Fiat 684 model
Close
Noticed an error?
If you've noticed an error in this article please click here to report it so we can fix it.

Which of the following most accurately describes the problem?

by Gibb Grace DAuE, CEng, MIMechE

FOUR TRUCKS in the Fiat range will be available in the UK from early next year and the 32 tons gcw 684 model is the most interesting; it is certainly the one which operators will be studying. I was able to test drive a 4 x 2 drawbar version of the 684 in Turin last week and though not in artic form the specification for the power unit is exactly the same and provides a good indication of how the tractive unit version will compare with the average British artic outfit.

The cab is about as high as those of many British trucks and entry by use of two grab handles and step very easy. The engine cover makes the cab a two-seater but is low enough to allow a full-width dash. A good selection of instruments including a tachometer are positioned flush with the dash immediately ahead of the driver and all are clearly visible. Wheel and pedals are well positioned in relation to the driver's seat which is fully adjustable. Headroom and kneeroom are ample even for a six-footer and visibility through the curved sdreen excellent. Three two-speed wipers clean almost the whole of the screen aided by a foot-controlled windscreen washer. The cab is well trimmed, the roof has a perforated leather-cloth lining, the doors are fully trimmed and the floor is rubber covered.

The 684 and 619 cabs do not tilt, although the same style of cab built by the French subsidiary Unic does. Arguments for and against tilting cabs are many and varied but provided one can be offered at an acceptable price is generally preferred. The weight and quality of the Fiat chassis will make it more a match for those British quality manufacturers' products which do not have tilting cabs, so this point should not be a deterrent. Ample access to the engine is provided through a large remov

able cover and routine water and oil chi are made easy by the upward hing radiator grille Being a two-axle rigid the ride was good and obviously better than would possible with a shorter wheelbase ai there was no noticeable pitch from vehicle, absolutely no push and shove fi the drawbar trailer, and the two units fel one throughout the test. The stee although power assisted had some "feel it and required just over four turns fi lock to lock.

The mirrors were small but vibrationf and well positioned giving a good rear vi It Was difficult to assess noise level . had the windows down most of the tirn provide ventilation in the very hot sti atmosphere. A full flow cab heating ventilation system is standard, but ti very hot, humid, midsummer condition Italy were too much for the ventila system alone. A roof vent is available reasonably priced optional extra; and fi good deal more a Fiat-built cab conditioning system is available. The I also underlined for me the need to breathable seat-cover material. Pvc lo smart and is obviously serviceable, bu very uncomfortable in high temperatures Acceleration and braking With an engine giving only 200 (DIN) and 506 lbft, acceleration at 32 gcw can only be average and this prove be the case — 0 to 40 mph took 77se

good lOsec slower than some 32-tonners tested. Braking proved to be a little better than that normally expected, being 0.46g average retardation at 20 and 40 mph and 0.52g at 30 mph.

All Fiat "heavies" are fitted with exhaust brakes as standard. The exhaust brake was easy to use.

Payload for this drawbar combination was 21.5 tons which is about as good as one can expect at 32 tons gcw. The truck with driver and observer weighed 6.2 tons and the Viberti trailer 4.3 tons, In tractive unit form the weight in the specification tables is given as 5.6 tons, This is a little on the heavy side especially as it does not include a fifth-wheel, but it does compare favourably with quality British vehicles and a payload of 21 tons could be carried with the correct semi-trailer.

The engine drives through a 15in.-diameter single-plate clutch to a five-speed gearbox with a splitter giving 10 speeds. The splitter was easy and reliable in use and could be changed simultaneously with the gear. Synchromesh is provided on second, third and fourth gears and worked well. Gear range in the box is from first low, 1: 7.01 to fifth high 1: 0.80, ie 8.75, insufficient I feel to give a high enough motorway cruising speed if a good bottom gear gradientability is needed. Geared as it was for the test with lowest rear axle ratio of 8.37 to 1 top speed was only 47 mph with a bottom gear gradientability of 1 in 5.

To sum up

The Fiat 684 is not directly comparable to any British-built truck as it has a combination of features not found in Britain at the moment. The cab is modern, tastefully finished and better in these respects than any existing British cab but it does not tilt, a feature which most operators have got into the habit of taking for granted. The chassis is a deep section sturdy design with fully riveted construction and as heavy as quality British vehicles. On the other hand the suspension, ride and steering are better than British quality manufacturers provide at the moment. All these good points about the 684 are, however, almost cancelled out by the engine and gearbox which are not up to the same standard as our home products. The 9.8 litre engine produces 200 bhp (DIN) but this will only just make the 192 bhp net installed to BS AU 141a: 1971, required for 32 tons. This output together with a torque

of just over 500 lbft gives the Fiat only 2 moderate performance. A further restrictior to performance is the gearbox which has z smaller overall range than most comparabk British boxes fitted to vehicles of this weight

Fiat is not stating prices until nearer du Commercial Motor Show, but if they art competitive with the quality British manufacturers I am sure the 684 will find a niche in the market. For those operators who require more power the 619, with it 260 bhp (DIN) engine, will provide it. Roac impressions of a 619 tractive unit running al 38 tons gross will appear in a future issue ol CM.

Tags

Locations: Turin

comments powered by Disqus