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Fig hting

11th May 1973, Page 67
11th May 1973
Page 67
Page 68
Page 69
Page 67, 11th May 1973 — Fig hting
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Which of the following most accurately describes the problem?

the freeze in Finland

by Gibb Grace

ONE of the reasons why cold-starting and cab heating on commercial vehicles have improved so strikingly in recent years is that chassis and equipment manufacturers have undertaken so much research into the needs of really cold countries — and the results rub off to the advantage of operators elsewhere.

Every winter a small fleet of Ford test vehicles and a team of engineers and drivers carry out a cold weather test programme of up to five weeks inside the Arctic Circle, in Finland's Lapland. In February this year (while the Editor was sunning himself in Brazil) I joined the cold team to study their testing procedures.

Finland and Sweden are growing export markets for Ford and it is important for the vehicles built at Langley to be able to cope with the very prolonged cold winters there. Much of the initial engine and component testing is carried out in the controlled conditions of a cold room at the Engineering and Research Centre at Dunton, but Ford engineers know that the only way to make sure the whole vehicle is acceptable under extreme cold conditions is to take it somewhere cold and try it.

The cold weather testing is based on the small town of Rovaniemi, which is just a few kilometres south of the Arctic Circle, and when I arrived complaining of the cold, — 15deg C, I was told that this was relatively

mild for February; the temperature had risen rapidly overnight from —34deg C the day before!

These temperatures are hard to imagine but suffice it to say that unless one is properly dressed with fur boots, long underwear and fur hat, etc, a few minutes in the open is enough to make one feel ill with cold. Such conditions are harder than ever experienced in Britain, but British operators must benefit from the lessons learnt there. Snow ploughs rarely clear the snow away down to the road surface and the roads are typically covered by inches of ice. All vehicles have to run on studded tyres between October and March by law, and in fact the grip they give is so good that it is almost like driving on a normal road.

I met the Ford contingent in the workshop of the local Ford tractor dealer which they had largely taken over as a headquarters. The workshop was well set-up with an inspection pit, welding gear, lathes, drills, etc, for the mechanics and an office with a drawing board and a desk calculator for the engineers.

Some 90 per cent of the test programme had been planned before leaving Dunton so that as much time as possible could be devoted to the job of testing.

Typical test programmes were for cold starting and heater performance. Many of the locals use sump heaters to warm the engine oil through before starting, but Ford makes a point of being able to offer cold-start equipment out of the factory which will suit temperatures as low as —30deg C.

For the cold start tests the vehicles are left to stand out all night so that by the morning they have soaked right down to the low ambient temperature. The tests were run with the seriousness of a lift-off from Cape Kennedy, even to the countdown. Because the recording instruments are delicate, not to mention expensive, they are housed inside the workshop and connected to the vehicle under test by an umbilical cord which plugs into the vehicle just below the front bumper. The driver starting the vehicle is in touch with the instrumentation engineer in the building via an intercom system.

In temperatures down to —10deg C Transits use a 38 Ah battery and for temperatures to —20deg C and below a 55 Ah battery is used and the first job is to measure the voltage available and the coil voltage. Then with full choke and the clutch depressed the engine is cranked by the starter until it fires. On the test I watched at —15deg C this was virtually instantaneous, ITmestimmeresemesimo As the driver reaches zero in this countdown (the point at which he operates the starter), the instrumentation engineer pushes the button on his console which starts a graphical recording of the starting sequence. Cranking speed, current to the starter, battery voltage and coil voltage are recorded simultaneously on a paper trace so that they can be studied later. Once the engine is running, the choke is released to a minimum position.

With diesel engines the procedure is much the same except that the thermostart voltage is also recorded. A thermostart is similar to the pull-out part of a dashboard cigar lighter to look at; it is placed in the inlet manifold and once its coil is heated up a hi-metal strip opens the fuel line and fuel dribbles in and sets light. The engine is then cranked with the excess fuel valve open and the throttle fully depressed. The cylinders which take the flames from the thermostart start to run, and the engine picks up until all cylinders are working. This period, referred to as the run-up time, lasts anything from 10 to 30 seconds and during it clouds of white smoke are produced. The excess fuel valve (which is recommended for use below Odeg C) knocks off automatically once the engine reaches maximum governed

speed. On the 360 turbo-engine, one thermostart is specified down to — 10deg C and two below that figure.

Once the engines have been started, the vehicles go off on a series of tests, some in and around the town, others on long journeys up to 100 miles farther north, depending on the nature of the test. I went out in a D series to watch a typical engine warm-up test. Here the vehicle, having started from cold, drives quickly out of town and just keeps going at a steady speed of about 60 kph (36 mph). A sophisticated temperature recorder automatidally plotted the rise in temperature of 12 points as we drove along. These included the top and bottom hose, cylinder head, sump, air intake manifold, gearbox, rear axle, fuel tank, heater water inlet and heater water outlet. The test was over only when all these temperatures had stabilized.

By plugging a different connection into the recorder, we could have measured the rise in temperature inside the cab; tiny platinum resistance thermometers were everywhere, hanging from the roof lining and dashboard and even poking up through the floor covering.

Such a test tells the engineers whether or not the heater is up to its job; all being well the cab should be up to a comfortable working temperature from — 15deg C within 15 minutes. A crew bus version of the Transit which was undergoing trials with an additional remote heater in the passenger saloon, carried 36 temperature sensors so that the temperature at all points of the interior could be studied.

But as always in the best run programmes, problems crop up and this had appeared in D series truck in the shape of a sticky range-change mechanism on the Ford eight-speed gearbox. Tests done earlier at Dunton had shown it to be ok at — 10deg and slow to react at —15deg C, but in Finland at — 20deg C and below range-changes were proving nearly impossible until the gearbox had warmed up a little. The problem area proved to be the arm which operated the synchromesh cones of the range-change gears. This arm slides on a rod and due to the small clearance and the near solid film of oil it refused to move at very low temperatures. The engineers had already modified the size of the air cylinder and piston which operated the arm and had showed that a larger one pushed too hard and reduced the life of the synchromesh.

Thanks to some clever instrumentation and some on-the-spot changes, the problem was overcome. Brian Holder, the engineer in charge, was in daily telex and telephone contact with engineers at Dunton and while he turned his mind to other things, they were already busy checking his findings. It looks now as if the improvement to the range-change has not only solved the cold weather problem, but also quickened up the change under normal conditions.

Seemingly minor breakthroughs such as this are the raison eetre of practical engineers and part of the never-ending story of improving the breed.


People: Brian Holder
Locations: Rovaniemi

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