(34) Working as a Contract Engineer (8/8).

Around 2004, while rushing to a road accident, an ambulance vehicle crashed in a winding road in the hills around Healesville (Black Spur). The crew consisted of two paramedics, both with long years of experience in the field. In one of the sharp bends the vehicle, instead of turning, decided to go straight onto a steep downhill into the woods, and both men died on the spot. A short few weeks after the accident we had a visit from the ambulance regional management in the company I was working for at the time (HoldenSpecialVehicles at Clayton, Vic.); they were looking for help.

Their managing director Stephen Hill outlined to us the problems their vehicles were encountering, the main ones of which were overheating engines, failing batteries, alternators, and failing fuel pump management electronic module. In reply our management suggested that the offending vehicles can be subjected to tests in a wind tunnel under a variety of climatic conditions. When the ambulance management agreed, one of the offending vehicles was delivered to us the next day. I was told by the two drivers who delivered it that the overheating is not much of the problem – the „dying“ batteries were!

Testing was entrusted to a young engineer Steve Henderson, and I was asked to assist with the electrical side of the job. The vehicle spent in the tunnel some 20 hours, and it was confirmed what was obvious to both of us from the very beginning: the vehicle (a GMC Sierra base, fitted with all possible ambulance gear) was overheating because the radiator entry was clogged with all kinds of ambulance paraphernalia: driving lamps, sirens, flashing lights, etc. As soon as these were removed the engine began to work within its normal range of temperatures, regardless of the range of conditions it was exposed to in the wind tunnel. Here is the original front of the vehicle:

In spite of all the abuse we subjected the vehicle in the wind tunnel to, the engine never stopped as consequence of overheating, or due to the failure of fuel pump. I decided to pay some attention to the electrical system.

I started with examination of battery operation. Electrical situation the battery was in became obvious after only a handful of measurements: the maximum output the alternator was capable of was adequate – not vastly excessive, mind! -  for the basic vehicle. Our vehicle had a number of electrical consumers added to it, such as external lamps, beacons, sirens, a computer in the cabin, and a number of medical electrical equipment inside. No wonder the alternator was overloaded, no wonder the battery was not getting charged... The maximum output of alternator when engine was running at cruising speed was 140 Amps. and about 65 Amps. with engine at idle); a minimum output for this vehicle should have been 215 Amps. And preferably with the engine idling at that!!!

Now, for the fuel pump.
For details see

   http://cdpl1.blogspot.com.au/2007/05/gmc-sierra-65l.html)

The pump motor in this vehicle is controlled by an electronic module mounted on the engine. Engine is able to run only when the pump is delivering fuel to the injectors. When the pump stops, the engine stops; with the engine stopped the vehicle loses steering power assistance, and the power brakes, both of which immediately require fairly hard handling on the part of the driver- vehicle thus becomes difficult to handle. Possibility of the fuel pump malfunction could explain the situation the ambulance crew found itself in while negotiating a sharp bend is likely explanation of the cause of the accident mentioned at the top.

Official report, as usual, cites „a mistake on the part of the crew“; of course, a mistake it was, only it was a mistake to refuse to drive a vehicle known for the number of its failures.

The fault was of such nature as to require a lengthy negotiation with the vehicle manufacturer. As the vehicles were nearing the end of their service life it was decided to de-commission and sell all vehicles of this type, some 400 of them, I heard.

Other similar models (such as Ford 350, for instance) were not overheating as much, but their electrical system was suffering from the same problem: too many additional electrical consumers, under-powered alternator and resulting undercharging of the battery.
General hints for correct alternator requirements are shown in the following article  http://cdpl1.blogspot.com.au/2007/05/alternator-in-cars.html

After these two models I was asked to examine, and report on, all vehicles in the Ambulance’s service, some dozen of them all up. Their problems were identical with the first two vehicles, but each of them required slightly different solution.

After my results were delivered to the Ambulance management, I had to field a number of questions from various organisations involved in supplying electrical components: from alternator suppliers, batteries manufacturers, ambulance bodies outfitters, etc. When all this began die out, I decided to retire. I kept working for a while, until well into my seventies, for various electrical companies, but the lure of grandchildren, garden, golf and similar pastime was becoming too big..

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Reading my blogs from (1) Childhood, etc., through Schools, Universities and various jobs, I am quietly satisfied with my life story. I was planning to do more, mostly in vain, more due to my inability and lack of knowledge than due to some external influences, or rulings of Destiny. This is the end, and goodbye to you all who happen to stray onto these pages.