n Your Opinion

16th September 1966, Page 129

16th September 1966

Page 129

Page 129, 16th September 1966 — n Your Opinion

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Keywords : Sports Cars, Södertälje Municipality, Hatchbacks, Scania Ab, Scania-vabis, Scania, Turbocharger

Turbo-charged engines

I WAS interested to read the report by Mr. Cater of his testing of the Scania-Vabis articulated tractor unit coupled to a York 3 axle trailer (August 26 issue). So far as I can remember, this is the first turbocharged vehicle tested by your journal (was the "King of the road" vehicle pressure-charged?), and confirms my surprise at the unwillingness of the British road haulage industry (and possibly manufacturers) to accept the turbo-charged engine.

Why is this? Road haulage in the Americas and Continent, I know, regularly use such units. Power plants for industrial use in the larger horsepower range are frequently pressure-charged, and in the construction industry, with which I am chiefly concerned, turbo-charged engines are used by all the leading makes of earthmoving machinery. In an industry where prices have fallen by 100 per cent in the last 20 years, not taking into account the fall in money values, this has almost entirely been possible with the greater production of modern units.

Could it be that operators are afraid of turbo-chargers—maintenance wise? Admittedly, they are expensive items to replace but provided end float of the turbine and air filters are regularly checked, there is not much risk of failure. Another point is that frequently turbo-chargers are added to an existing power unit (viz: ScaniaVabis) giving a significant increase in horsepower and torque and cutting down re-tooling costs for the manufacturer. Granted the engine must be solid enough before this grafting operation takes place, but I should have thought Gardners would have considered this. Even cheap high-production units such as Ford 6D and Perkins 6-354 have been turbo-charged with modifications, but their use in vehicles is presumably not,considered necessary.

Returning to your test, Mr. Cater commented on the low level of noise in the cab. He attributes this to the lack of "any metal connections to the chassis". Could it be that this quietness is very largely due to the smooth torque characteristics of the engine and the reduction of exhaust noise, in that the expansion of the gases takes place in the turbo-charger unit and no silencer is usually necessary?

If readers will refer to the review of the Scania-Vabis model on Page 49 of the same issue, they will see that it has a device to reduce fuel input at low engine speeds. This effectively cuts down smoke at this stage, although I admit that sudden bursts of throttle can cause emission of unburnt fuel before the turbo-charger impeller has caught up speed sufficiently to force in sufficient air to ensure complete combustion. This feature is also used in tractors.

So far as Jean see, the only item on the debit side is the increased fuel consumption. Admittedly, in the construction industry this is of lesser importance, because our diesel fuel only carries 23d. tax. However, I would have thought that the aforementioned advantages outweigh this.

Perhaps it would be a sound idea if your technical staff discussed the pros and cons of turbo-charging in a future article.

JOHN R. BILLOWS Managing Director, John R. Billows Ltd.

Braking lights, please

AS A private motorist covering some 10,000 miles per annu I have recently become appalled at the absence of braking hg on many commercial vehicles—particularly on very heavy lorri Whilst braking lights are not a legal necessity they have come be relied upon by a majority of motorists as a warning of impend traffic conditions, and as such have become almost indispensal This is particularly true when one is following a heavy lot when forward visibility is reduced to a minimum and the f that the driver has applied his air brakes is not realised u one's bonnet is neatly slotted beneath his tailboard.

On the lighter vehicles (up to 7 tons U.L.W. say) I understE that vacuum-assisted hydraulic brakes are fitted, in which cas is a simple matter to incorporate a pressure switch. This metl. is both foolproof and reliable.

Larger vehicles, fitted with compressed air brakes, are fit with mechanically-operated switches connected to the pe mechanism. I cannot envisage this system proving reliable with( meticulous maintenance and this probably accounts for estimated 60 per cent of heavy lorries with non-functional brak lights.

Another cause of non-existent braking lights is of course inadequate protection of the lamps themselves, situated in v4 vulnerable positions at the rear of the vehicles.

Surely it is time more attention was paid by manufacturers developing and producing a reliable air-pressure-operated swii for lorry braking lights? More attention should also be devotec rear lighting clusters in order to protect them from carel, reversing etc.

These would seem to me to be very obvious steps towai greater road safety, which could be carried out very economical JOHN A. B. FORTUNE, Nottingh;

LDOY success

I WOULD like to thank you for a very enjoyable day at Brame° A most pleasant impression I had of the day's activities was oft emphasis on road safety which prevailed during the competiti( and I am very happy to say that the Police welcome this approa to safe lorry driving.

F. A. CUTTING, Assistant Chief Constat Warwickshi

Clockwork organization

MAY I express my appreciation of the organizing of the Loi Driver of the Year competition. There is no doubt that the co petition proceeded like clockwork and everyone concerned is be congratulated.

G. A. MORGA The Midland Counties Dairy Ltd., Birmingha

n Your Opinion

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