Part Load Hazard

23rd September 1966, Page 88

23rd September 1966

Page 88

Page 88, 23rd September 1966 — Part Load Hazard

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BY HANDYMAN

QUITE a lot has been said and written on the subject of jack-knifing. Everyone should be aware that lack of adhesion at the driving wheels is the main cause of a breakaway. Therefore it can be something of a surprise to had that a perfectly sound articulated vehicle can be placed in a most unsafe position, due to a factor quite apart from high speed, and/or emergency braking, so often the cause of jack-knifing.

I refer now to the vehicle load and the changes that can be brought about in weight distribution during a series of deliveries.

In the normal way, prior to loading, the knowledgeable traffic operative will study the collections and their destinations, and will see to it that the driver understands quite clearly the order in which the vehicle is to be loaded. This does not mean that the main concern is just to speed up collection, it is to facilitate delivery and at the same time keep the platform trimmed for safe running between deliveries.

This is not an easy matter, especially when 12 or more tons is to be split into no more than four parts. But it can be done, because if things do not balance out quite as desired, the skilled driver will adjust matters while still under the crane at delivery point. With a well-trained traffic man and an experienced driver, little will get out of hand.

However, everyone has to learn, and the danger arises when the less-skilled driver finds the unloading plan just cannot be worked, due to such features as a closed factory, crane breakdown, staff at lunch, etc. This means that the correct section of load cannot come off, and the driver must go on to the next delivery and take off another section elsewhere on the platform. In order to complete his unloading duties on time, he may take off a section that will completely upset the trim of the vehicle, but since the distance is. short he may well be tempted to proceed.

An incident in 1965 made it very clear that goods driver instruction does not end with a pass out on all vehicles, but must include loading and unloading know-how. A single axle artic carried three cases of machinery making up 10 turas for three customers, with distances of three and 11 miles between them. The unloading plan was the rearmost case first followed by the centre and forward cases. But the first call found the warehouse sliding doors in trouble, and the driver was told to return in two hours. He followed the drill from thereon and in turn took off the centre and then the front cases, and set off to the first .call again.

He did not reach his destination, as on his first descent under light braking his vehicle jack-knifed helplessly and he brought down a lamp standard.

On examination, it was found that his motive unit driving wheels had bare contact with the ground due to the tail load, and the wheels could be turned by a crowbar with ease.