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Where do we go from here?

TWENTY-FIVE months slipped by before the Home Office amended the Conveyance of Petroleum Spirit (By Road) Regulations, to permit the operation of petrol tankers at the maximum-gross-vehicle weights afforded by the 1964 C and U Regulations changes.

Capacity of a single compartment was raised from 800gal to 1,100gal. Previously the gross maximum capacity was 4,000gal but the regulations now allow for a capacity of 6,600gal of motor spirit—equal to a payload of about 21.8 tons.

Because of the long delay before• this capacity became law, many tanker operators made interim arrangements for the design of vehicles built for them during that time. Guesswork and imagination stood some in good stead, while others could not have been wider off the mark and in September 1966—when the Home Office eventually moved—found that they had acquired expensive equipment that had now become difficult to justify.

Before many months have elapsed new proposals to allow overall lengths of 15 metres (almost 50ft) may bear fruit. This will make a four-axle 32-tonner a distinct possibility, and with it the opportunity to carry an extra ton or so—due to the elimination of the fifth axle.

However, to achieve the full permitted payload of 6,600gal

appears to be a near impossibility, even by using a four-axle configuration. A tractive unit weighing 5.4 tons with a payload of 21.8 tons has only 4.8 tons left for the tank and running gear. And the lightest running gear comes out at 1.9 tons. This means the tank makers will have a big job on indeed to construct a vessel of 3.7 tons dead weight with six compartments affording a minimum axle spread of 38ft.

So even though it was a bit late in the day it looks as though the Home Office made an astute move in setting the figure.

Meanwhile the petrol companies have quietly produced a number of 30-tormers for fuel oil distribution and have recently announced the introduction of some five-axled 32-ton spirit tankers. Shell-Mex and 13P Ltd. is leaning towards three-axle tractive units on the grounds of improved stability. It appears that even if the 15-metre overall length becomes legal—when 32 tons on four axles would be possible—Shell will still stick to the five-axle configuration. Many vehicles used by oil companies to transport fuel oil, aviation fuel and industrial solvents and the like, arc hired from professional hauliers. Among these hired vehicles arc a considerable number of 30and 32-ton types, some in fact constructed to carry spirit. Because of the haulier's varying needs his equipment must provide for the biggest possible payload in

tons and capacity in gallons. Not so the oil company men; their designs must be wrapped up in the economics of retail distribution which gets second consideration only to mechanical efficiency.

The latest additions to the Shell-Mex and BP fleet are the biggest spirit tankers yet constructed by Gloster Saro, of Hucclecote, Gloucestershire. Built for operation at 32 tons the outfits comprise Scammell Trunker tractive units hauling 6,300gal light alloy tanks of six compartments, three of 1,000gal and three of 1,100gal. The tanks are of max-section, tapered at the front to keep the overall height down while at the same time clearing the fifth wheel. Although the outfits are equipped with 200 g.p.m. cargo pumps, 4in. outlet valves and lines they can still legally carry a full payload of 6,300gal of motor spirit.

Because the vessels are so complex and expensive they have been mounted on air suspension running gear to eliminate damage caused by unladen running. The Scammell Trunker employs a close-coupled second steering-axle with load transfer and a single driving axle. It is powered by the Leyland 0.680 diesel engine. One of the units delivered has been equipped with the Leyland semi-automatic 10-speed gearbox.

No problems

Apparently no problems have been experienced regarding access to customers' premises with the bigger vehicles. It seems safe to say that where a 24-ton artic can manoeuvre, then so can the 30 /32-tonner. But Shell has been careful to keep the overall length of these latest vehicles well within the permitted maximum of 42ft 7.5in.; any increase over this becoming available by introduction of the 15 metre is not likely to be taken advantage of on the grounds of decreased manoeuvrability.

One of the newer oil companies now getting quite a large toe in the British market is Atlantic Petroleum Ltd. Recently a fleet of 10 vehicles was placed on hire to it by Trans-Port Terminals Ltd. and it is interesting that even though all the outlets which this organization has are fairly new and therefore presumably modern, only one maximum-capacity vehicle was specified in the contract.

This is a 32-ton 6,000gal spirit tank hauled by an AEC Mammoth Minor tractive unit. The tank is constructed from 10 s.w.g. mild steel throughout and does in fact legally carry the full payload capacity. Full advantage has been taken by this company of the 24 tons on three axles regulation, producing four Ford D1000 4,000gal vehicles which also legally carry full payloads of gas oil and derv. With the introduction of lower priced vehicles of higher g.v.w. by mass-producing companies, it is now a proposition to build vehicles of this size which give excellent returns for a relatively low initial cost. And, of course, the unladen weight of this type of tractive unit can be a bit lower than bespoke types offered by the heavy vehicle manufacturers.

The next step down in the new Atlantic fleet are four 16-ton four-wheelers carrying 2,700gal tanks. Again advantage is taken of the new Ford D1000 range and even though the tanks are of mild steel and the units are equipped with Wayne meters and permanently connected 120ft-long reel hoses, they can still carry full payloads of motor spirit.

It is not only technical know-how that makes bigger vehicles a viable proposition. Of the companies with them in operation, those having staff-productivity agreements are reaping the larger benefits. Bigger vehicles are more complex and naturally more expensive than those they will eventually replace, making standing time and low productivity even more prohibitive.

During the interim period between 1964 and 1966, some farsighted hauliers had tankers built which, while offering the maximum permissible payload of spirit also had the lowest possible unladen weight. And, when the regulations for spirit vehicles were changed their designs allowed quite simple conversions to carry the greater capacities.

This type of conversion proved quite big business for some tank makers. A recent contract for the road tank division of Thermotank Ltd., came from the High Wycombe-based Tyburn Road Tank Services Ltd. Four of this company's 4,100gal (24-ton) semi-trailer tanks had to be converted to carry net payloads of 5,840ga1 and this was done by adding two extra compartments of 870ga1 capacity to the rear end of the existing shell. The vehicles are now suitable for operation at 32 tons g.v.w. being hauled by AEC Mammoth Minor twin-steer tractive units.

Most operators of maximum-capacity tankers have recognized the need to make provision for added stability. A tank carrying a part-load suffers quite badly from a lack of lateral stability. When a cargo starts to wash from side to side it causes stresses right through to the tyres and can result in either the driving axle or trailer bogie breaking into a slide. An accident involving tankers of the sizes which we now have in operation, because of their size and the quantity of materials carried, can be extremely serious. Operators in general recognize this fact. That is evident by the many vehicles now having or being equipped with either load-sensed braking or one or other of the anti-jack-knife devices.

Attractive as the 30 /32-tonners may be, other changes in the C and U Regulations permit some extremely good permutations of design at lower g.v.w. I have already written of the three-axle 24-tonners built for Trans-Port Terminals Ltd. and also its metered 16-ton units. But sometimes something out of the ordinary is needed—small but also exceptionally capacious.

A typical example was Esso's recent request to Scottish haulier William Dobson Ltd. to produce a 3,000gal delivery vehicle capable of negotiating small entrances and back streets. Dobson, together with Atkinson Vehicles Ltd. and Darham Industries Ltd., came up with the following requirements: A four-wheeled chassis with a wheelbase of 15ft and for 16 tons g.v.w. which would weigh less than 4.6 tons unladen, and a five-compartment tank weighing no more than 1.85 tons.

A problem

A closer look at the normal 16-ton four wheeler reveals a problem in the shape of front axle loading. When the machine is fully loaded with its evenly distributed cargo the steering and driving axles are laden to full legal capacity of 6 and 10-tons. respectively. Load transfer caused by the removal of part of the load located behind the rear axle can quite easily cause loading on the front axle to increase beyond the permitted limit. In the event of a roadside check the operator is liable to a heavy fine. So special care is required to ensure the sequence of offloading is such that front compartments are emptied first.

But when the Dobson tank was designed by Darham, its compartment sizes were chosen and situated so that no matter in what order they were unloaded, providing that they were then completely empty, there was no possibility of overloading the front axle. At worst, emptying the 600gal rear compartment cannot raise the front-axle loading above its maximum limit of 6 tons.

In the chassis construction, Atkinson refused to reduce dimensions of frame components on the grounds of reliability. Conventional engines were too heavy and so Atkinson decided to utilize a not very well-known unit in this country, a General Motors 140 bhp four-cylinder two-stroke. It produces power at fairly high rpm and to avoid poor driver-reception an Allison single-stage three-element torque convertor was used with it. Still in search of weight saving, a Centrax single-reduction rear axle, a matrix-type radiator and tubeless tyres were used. As a result the complete chassis scaled a mere 4.25 tons.

The tank is constructed from mild steel of 12 s.w.g. throughout, but to keep the weight down the rear wings.and most of the fittings are aluminium.

My immediate reaction to the specification of the GM engine and Allison transmission is: Very good but very special, Dobson must have been following the technical Press fairly closely, however, for the considerable amount of advertising by GM in recent months seems to herald the introduction of greater numbers of these units to the UK in the not too distant future. And, he must have asked• the stock haulage question: "What about spares?"

The end result of the exercise is a manoeuvrable four-wheeler which can in fact legally carry its stated payload of 3,000gal of motor spirit.

Speedy discharge is necessary before bigger tankers can become a viable proposition in a retail delivery fleet. The answer would be simple if the passage of cargo through pipework and valves on the vehicle was all that had to be catered for. However, many delivery points are old, and filling arrangements rather Heath Robinson. The smallest bottleneck in a pipeline is the one that determines the rate of flow, and as it will take many years before modern equipment can be installed at all receiving points this problem is likely to remain with us for a long time.

What can the planner do to assist the operating department in the meantime? Where products handled fall within the below-74° F flashpoint category, he can only ensure that equipment carried on the vehicle will be more efficient than any it is liable to be coupled to. In this way the best possible advantage can be taken of those installations which are modern or have been modernized. And, he will be no worse off where the installation is a bad one.

Time factor Products that can be pumped give him far greater scope because here there are more factors with which he can juggle. First of all there is the pumping unit and again depending on what it has to do there is plenty of scope. Before dealing with the pump, however, whatever the cargo, it is worthwhile taking a look at the time involved in making ready for the delivery. This can amount to a considerable portion of a vehicle's working day when employed on multi-deliveries and can be substantially pared down with a little thought. Pumps and outlets should be manifolded together and a long delivery line permanently coupled to the pump so that the operative has only one connection to make. Even the clumsiest driver finds it difficult to make a mess or justify 15 minutes for coupling up under these conditions.

Working this system with a rigid vehicle presents no problems at all. But, the same cannot be said for the artic, when the pump must be mounted on the tractive unit, and the cargo must be piped to the pump. A number of abortive efforts have been made to

design pipework that runs through or around the kingpin of the fifth-wheel but because this must swivel, tilt and rock it invariably leaks after a short period of operation and is then extremely difficult to overhaul. The next step was to employ a donkey engine or electric motor to drive a tank-mounted pump. The drawbacks were that the engines were nearly always bad starters, and bigger batteries and electric motors are heavy.

An easy task Recent developments in hydraulic drives and vast improvements in the construction of universal joints have made available power that goes round corners at modest cost and weight. And by using these components pumping units can be mounted anywhere on the vehicle with a minimum of trouble, making manifolding an easy task. Furthermore tractive units with an hydraulic drive or shaft connection can be universally employed on tanks equipped with either pumps or blowers without having to carry an extra unit around all the time as would be the case if both were mounted on the tractor.

Having established the method of driving the discharge equipment, the type to be used must be chosen. In the past numerous types of reversible pumps have been available but of necessity these have been heavy and expensive, and when manifolcled the only way to reverse the flow is to reverse the pump.

Overcoming both the above problems, equipment designed and built by The Drum Engineering Co. Ltd. has come on to the market in the last year. This company has developed an extremely light and efficient hydraulic drive which gets auxiliary power just where it is needed, and a very simple and robust reverse flow valve.

A farsighted development has come from Harold Wood and Sons Ltd. Early in 1966 its managing director, Mr. B. J. Wild, realized that now vehicles were not quite so tight on unladen weight as was the case in the 24-ton days, there might well be a future in road-rail services.

Before August 1964, unladen weights of the equipment needed for this style of operation would have made it uneconomic from the haulier's point of view. But 30/32 tons and, a bit later perhaps, the 15-metre four-axle 32-tonner permit substantial payloads to be handled economically by road rail services. Harold Wood, Darham Industries Ltd. and Peak Trailers Ltd. shared the costs of developing outfits capable of doing the job. The more recent actions of Mrs. Castle make this development even more important to the long-distance haulier. Many of them could take a leaf from Mr. Wild's book. "Why not let British Railways do the donkey-work?" he asks.

To be bigger does not necessarily mean to be better. Much thought must be given to the selection of tank vehicles if they are to tit one's pattern of distribution exactly. Mrs. Castle's new taxes could well destroy the productivity advantage of the bigger vehicles where these are marginal.