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25th December 1982
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Which of the following most accurately describes the problem?

)M' 0 / BD rr

by Graham Montgomeri After the spy in the cab, the voice in the cat Econocruise, always striving to improve fuel economy, has come up with a machino that tells the driver when to change gear. Ten mpg is possible if its instructions are religiously obeyed

THE GROWING USE of aerodynamic devices has bought in its wake an increase in road-speed limiter sales. Such limiters are extremely effective but in the main they operate only in top gear and a large proportion of commercial vehicles spend a lot of time in the middle gears.

Rugby-based Econocruise is part of the Associated Engineering group and has marketed a very sophisticated road-speed governer for some time now. Conscious of the latent potential for fuel saving in the intermediate gears, the company is developing a "talking gear shift" which actually tells the driver when to change up or change down to keep the engine operating in its region of maximum economy.

Econocruise has been highly delighted with the performance of the speed limiter, both on the road and in the market place. Managing director Tim Blee claims that it is the number one seller in spite of the fact that at £600-plus it costs about twice as much as the opposition.

However, although the benefits of the limiter were demonstrated very effectively in terms of a fuel economy bonus, as more and more operators fitted the device the odd disappointing result showed up. This was analysed as being entirely due to driver variance with Tim Blee suggesting 30 per cent in some cases.

In many cases the disappointing results were found to be the result, not of over-speeding but incorrect gearchanging — especially in the middle gears. The current generation of heavy diesel engines are often very sensitive to driving technique, especially as far as the working range is concerned.

The E290 Cummins is a typical example of this and I remember proving this to myself when the engine was launched back in early 1 97 8. The Cummins recommendation for the E290 is to change up at 1,600rpm and to "let it lug" down to 1,000rpm dare the downchange. It is isy, however, to take the enne up to 2,100rpm with no echanical problems hatsoever. The only problem is at the fuel economy suffers. When I first tried the E290 in a Bddon Atkinson chassis, I eve it around a 125km (78 iles) test route using the full 100rpm before changing up ith the result being a fuel conmotion of 44.1 lit/100km .4mpg). Going around the ime route but using the Cumins recommended change Ants improved this to 38.7 / 00km (7,3mpg) with the difrence in driving time being agligible — about five minutes two hours.

Thus there is a great deal to be lined by having the driver folw the manufacturer's recome dations. The problem is )W to get him to do it. Many r vers are engine-speed scious and keep an eye on rev-counter but it has to be irfr'iitted that there are a lot who ) ot.

o try to improve the situaon Econocruise started by king at what Tim Blee desi ed as "buzzers, bleepers and hing lights." One such early ign was a moving arc rev ) nter with two bands of lights ne red and one yellow. A inner (red) band moves with road speed to indicate which speed range the engine should be operating in. The yellow outer sector indicates the speed the engine is doing. The idea is to get the two to coincide, with a bleep warning the driver if he strays out of the correct range.

Eventually, however, it was proved that the success of such a device still depended upon the driver actually looking at the instrument and if he would not look at the conventional colour coded rev-counter why should it be assumed that a flashing light moving arc instrument should make any difference? As Tim Blee explained: "We just had to admit that we couldn't reach the driver visually." And this is where the voice comes in.

Texas Instruments manufactures a great many electronic components, one of these being the voice synthesising chip used in television video games. It can be programmed from its Orator master vocabulary to "speak" a number of words or phrases and as this vocabulary includes the words "up", "down" and "change" it was a simple matter, to come up with a gear-changing recommendation.

The main aim when going for maximum fuel economy is to drive around the loop of minimum specific fuel consumption for as much as possible. With the Econocruise talking gear shift, the system is programmed so that when the engine speed passes out of this economy area, the voice says "change up" or "change down" as the case may be. It is not just engine speed sensitive, however. The circuiting takes into account the road speed, engine load and gear ratio in use and computes the optimum conditions.

The chip will hold 30 seconds of speech in total so the two commands (or should it be suggestions?) hardly scratch the surface. The Orator vocabulary is still very limited, and, as yet, it is not possible to programme in such comments as: "Sort 'em out. They're all in the're somewhere!"

The system operates via the normal radio speaker with the voice overriding the radio programme when necessary.

I must admit that I was a trifle apprehensive when I tried the talking shift fitted to the Econocruise Transconti demonstrator. I was not sure if I could live with an electronic voice repeating itself over and over again nor was I keen on having any driving idiosyncrasies exposed.

As it turned out, my idea of when I needed to change gear coincided with that of "The Voice" (for about 90 per cent of the time) but about the former worry I was not quite so happy.

The system cuts off below about 15mph which is a sensible idea as the voice would never shut up in heavy traffic conditions. When on the open road however, it was a different story. Going up through the box the voice would say 'change up" at the appropriate moment which had the tremendous advantage that I did not need to take my eyes off the road to look at the rev-counter.

Coming into roundabouts, the system was superb as I could concentrate completely on the mirrors and positioning the vehicle.

As I mentioned earlier, I am not yet convinced about the effect on the driver of spending the whole working day listening to the voice. Tim Blee argues that the effect will be subliminal and after a while the driver will not consciously be aware of it. My relatively brief drive did not prove or disprove this idea; it may be so.

The talking gear shift is due to go out on trial with selected fleets for evaluation at the end of the year. Not surprisingly there is no definite price set yet but it is expected that it will be in the region of £800 to £900. For this the operator will get a programmable road speed limiter complete with the talking gear shift. As Tim Blee put it "we are selling 10mpg for £900."

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