Care & Maintenance
Page 68
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These old tricks spell loads of trouble...
LOADINO TRICKS learned in the old davs for dealing with heavy or awkward freight are no longer safe today.
Lorries used to be much slower a few years ago; tbey trundled aroun.d corners, and their brakes hod very little power. In other words, the tricks were safe so long as the drivers took their tinne and kept a woather eye on the load.
Now that loads arid inclividual containers are much bigger, vehicles are faster and can corner quite quickly, while brakes are much more efficient, there is only one answer to securing. loads -fi:x them positively.
In a van or dropside truck, it may appear that so long as the cases are packed to fill part of the load area tightly, they are therefore fixed positively and safely, but this is not necessarily so.
For example, before manhandling some large cases or containers about on the platform, the loader might use one of his tricks of the trade and sprinkle some round gravel' or plastic granules on the platform to ease movement. Since the gravel acts as a number of ball bearings, movement was clear-ly easier, and it may have been assumed that the gravel stayed in the free area of the platform, and was not trapped beneath the container.
Inevitably, though, some of the gravel does get caught, and then the container is likely to move about as the vehicle is accelerated, braked and cornered.
Some time ago, a load of boxed refrigeration units was lost on a bend to the driver's surprise. Some pea-sized plastic granules on the platform, and at first it was assumed that these had been placed there to assist in moving the boxes. In fact, they had been spilled in a previous, load, and there is little doubt that their presence led to the freight being lost.
In another case, a burst sack of rice in a mixed load contri buted to the loss of a one-tonne stack of cased sauce bottles. What had happened was that during loading, the sack had been burst, and had already spilled over the platform before the cases of sauce were loaded.
Although the sack had been sealed again, no one had thought to remove the grains of rice that were on the platform.
As a result, the cases were eventually floating about, and so when the driver took one bend particularly quickly, they just shot over the side.
Another trick that results from a lack of thought is the insertion of a short batten under one end so that slings can subsequently be passed be neath without the need for the use of a crowbar. The insertion of the batten means that the heavy case is in contact with the platform at only two points, only one of which is attached to it.
This is much the same as placing a load on a pair of skids.
Even when a case can be secured rigidly, it is preferable to ensure that it has the maximum area in contact with the platform of the vehicle. If the load is heavy, the contact area will create quite a resistance to motion, owing to . friction, but if only a couple of battens are in contact, there is precious little frictional resistance. Often, the load is pushed around on these two battens, which become very shiny, so that there is virtually no frictional resistance -they become just•like the runners on a sledge': • Heavy chain is a difficult load to transport, and it is often assumed that the weight of the steel is enough to keep it still.
The problem is particularly acute with new chain, which has been painted so that it is smooth and shiny. Some form of lashing is normally used, of course, but in some instances a few runs of soft rope are expected to retain 10-20 tonnes of chain.
• The problem with a chain is that each link can move relative to the others, so with only four lashing points, there are great lengths of chain free to float about -perhaps 2-3 tonnes of metal with only point contact with the platform. A few sharp corners, or an emergency braking situation could soon cause the chain to break free.
Owing to the freedom of movement of the links of a chain, it is necessary to lash the links together as far as possible, to restrict the individual movement. Then, the main lashing wires should be passed through a link in each layer of chain before it is tensioned.
Light loads can also require careful loading, especially when they consist of several slim, flat packages -a load doesn't have to be heavy to cause damage when it comes off the vehicle.
In one case, a load consisting of a number of highly polished laminated panels, about 20mm (0.78in) by 1.2 (4ft) by 2.4m (8ft), was lost in a catastrophic manner on a motorway. The panels were covered in thick paper, and they were then stacked to just below cab height across the flat platform. Because the loader did not want to damage the panels, he sheeted them down and roped them lightly.
Twice during the early stages of the journey, other drivers warned the driver that his load had moved, and with help he repositioned the upper panels, and carried on. Subsequently, however, the load began to move when the vehicle was on the motorway, and the upper panels appeared to float about, and then flew off the platform, which was soon empty.
Now, the vehicle had been travelling at about 100km / h (60mph), and at this speed the air has surprising power, especially when it is turbulent following the disturbance around the cab. When the cal is higher than the load, there iE often a partial vacuum formed behind the cab, and this tends to lift up the load -it is this lifi that the reversed wings or racing cars are designed tc counteract.
. When the load is light, anc has a large surface area, there can be sufficient force tc actually lift the panel. Once thai happens, further wind currents can get beneath the panel. which is then forced off thE vehicle.
If the panels are delicate and you cannot risk ropinc, them down tightly, they shoulc travel in a van. But whatevel the load, secure fixing essential, unless the load totally enclosed.