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Bulk delivery feeds on bright idea

6th February 1982
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Page 31, 6th February 1982 — Bulk delivery feeds on bright idea
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While this Dutch-designed equipment may not be mind blowing, it offers significant advantages, reports Tim Blakemore

VHOEVER it was who said 'Never believe what you hear, ind believe only half of what ,ou see," it might well have leen a road haulier. Countless rustrated salesmen could testify o this. They are the ones who lave tried and failed to persuade operators that this or that new levice improves efficiency and ayes money — in the long run. Before an operator is onvinced, he will probably first vant to try the equipment in his 'Bet. I am not criticising operators for adopting this ap'roach. Many engineers who lave been persuaded to forsake "softly softly" approach have lad cause to rue that day.

In this conservative industry one of the most conservative ;ectors is that of bulk transport. lim Lamb, of Capper and Lamb Engineering) Ltd, is well aware of this. He should be. For 13 rears he has been running a bulk oad transport company himself vith a fleet that he and his fellow

director, Robert Capper, have built up from one to 27 vehicles.

But still he believes that the advantages of the bulk discharge equipment, for which Capper and Lamb has become sole UK agent, are great enough to persuade significant numbers of British bulk operators to change from the type of equipment in common use.

What is the most popular way of discharging animal feeds and grain from bulk vehicles? Jim Lamb reckons that about 95 per cent of animal feed delivered in the UK currently is discharged pneumatically. In the past, his company-has fitted many lorries with this kind of equipment using Peabody Holmes, Wade or Godfrey blowers.

A rotary valve is fitted at the rear of the body when this system is used to feed the product being discharged into the airstream in the discharge hose. The rotary valve is driven by an hydraulic motor driving through a twin-output gearbox which

also transmits power to the independently controlled auger. Capper and Lamp used Edbro front end tipping gear.

The main disadvantage with this discharge system when it is used with a multi-compartment ! body, as it invariably is, is that the compartments can be unloaded only in one sequence, starting at the back and working forward.

This limitation can present serious problems for an operator, especially if, for whatever reason, the first drop of the day cannot accept its full quota.

The conventional pressurised discharge with non-tipping body provides a solution to this particular problem but it has its own inherent operational difficulties. At the base of each compartment's outlet is fitted an aeration pad through which air is blown to liquidise those products which will not flow freely.

In Jim Lamb's experience these aeration pads are ineffective with some animal feeds such as beef nuts (coated with molasses). But with whichever product they are used, the pads require regular cleaning — sometimes as often as twice a week. Although tank manufacturers have been seeking means of reducing this down-time — for example, Crane Fruehauf has some quick-release aeration pad holders — this remains a timeconsuming task.

The Capper and Lamp system has no aeration pads and virtually no regular maintenance is required.

More correctly, the discharge system should be called the Welgro one because it is manufactured at Dungannon, Northern Ireland, under licence from Welgro BV of Holland. The heart of the system, and the part that is patented by Welgro, is the discharge regulator, one of which is fitted in each of the tank's compartments.

There is nothing complicated about the regulator and inevitably one wonders why such a device has not been thought of long ago.

A cylinder is mounted inside an aluminium funnel which, when fitted in the, tank, feeds into the pipe running underneath the compartments. This pipe joins each compartment with the discharge nozzle fitted at the rear of the tank.

Inside each cylinder is a hollow piston which can be moved up and down. The top of the cylinder is capped by a conicalshaped lid and the joint between the piston and funnel is sealed with a rubber seal.

"These seals are the only parts requiring regular maintenance," claims Jim Lamb, "and replacement of them will probably only be necessary as infrequently as every two years."

Movement of the piston is controlled either mechanically by rods and linkages, or pneumatically, in which case an air chamber (similar to a brake chamber) is fitted inside the cylinder. In either case the piston has to be raised to allow the product to be discharged.

The conical cap has the effect of distributing the product evenly around the funnel and continued overleaf preventing jamming caused by excessive point loading. For shifting the most stubborn, sticky feeds a vibrator may be fitted to the outside of each cylinder.

By comparison with other pressurised discharge systems which generally operate at a pressure of around two atmospheres, the 0.6 atmosphere working pressure of the WeIgro tanker is low. Nevertheless, discharge times compare favourably.

Two forces act on the tank's contents to push it into the discharge nozzle. The air above the product is pressurised by a (conventional) blower. Welgro says that 49 per cent of the air pumped by the blower is directed to the tank. The remaining 51 per cent passes through the 1 02mm (4in) diameter discharge pipe.

The venturi effect, as the air passes the narrow funnel openings from the compartments, drags the product with it — provided that a regulator's piston is raised.

Typical blowing times for the system are quoted as: pig meal, 25.16 kg/hr; beef nuts, 28.45 kg/hr; poultry layers mash, 42.69 kg/hr; and fat spread pellets, 29.43 kg/hr.

"Compared with a pneumatic discharge system the air velocity in the discharge pipe is lower," says Jim Lamb, "and so there is much less chance of feed being broken up — an important point for chicken farmers, for example, who like to have pellets delivered in the same condition in which they were made.

"However, the discharge times with this system are quicker because the percentage of product per cubic foot of air is greater — 95 per cent as against 60 per cent for a typical pneumatic discharge."

Another point in the Welgro system's favour is that it is relati vely quiet in operation. Two silencers are fitted — one on the suction side and one on the delivery side of the blower.

The importance of the quietness of feed discharge was demonstrated to me when I joined Jim Lamb and one of his drivers who was making a delivery of 10 tons of pellets to a chicken farm in Dromore, County Down. The feed silo is within a few feet of one end of the "house" in which there were around 25,000 broilers, which, incidentally, between them consume about 21/2 tons of feed a day towards the end of their 60day life. If the chickens at one end of the hut areJrightened by a loud noise they will stampede towards the other end.

And I am assured that the damage done to their fellows by 25,000 stampeding chickens makes an All Blacks eight-man maul look like chicken feed.

All the discharge controls, including the pressure gauge and individual compartment con trols, are grouped together at the rear of the tank. This makes the driver's job easier and helps to reduce delivery times. Capper and Lamb's driver at the farm had the 10 tons discharged and was on his way within 21 minutes.

The tank compartment covers are also designed for ease of operation. They slide open and this is a one-handed exercise. For safety reasons the covers' seals are designed in such a way that even a slight residual pressure in the tank, as low as 0.1 atmosphere says Jim lamb, prevents the covers from being opened.

A sceptical reader may be saying to himself at this stage that all this sounds too good to be true. What are the disadvantages?

Jim Lamb readily admits that compared with the tipper/blower body the Welgro tanker has backloading limitations. Few farms are equipped with the necessary augers and there is also the problem of a Welgro body being higher mounted than an equivalent pneumatic discharge type.

So without modification some older mills will be too low to accommodate them. The lowest of Capper and Lamb's semi-trailer tanks is 3.48m (lift bin) high. But the backloading of barley, for example, is possible only for one short period each year. Losing this facility seems to be small price to pay for all the advantages of the Welgro system.

The Capper and Lamb bodies are not cheap. Jim Lamb quotes the price of a tank and discharge equipment for a six-wheel rigid as being £3,000 more than an equivalent tipper/blower type. The price of a single-axle tank semi-trailer is £24,000 with a self-steered axle, and £2,300 less with a fixed axle. Both these prices include the cost of air suspension; Capper and Lamb will use no other type with aluminium tanks.

The steered semi-trailer axles used by Capper and Lamb (Haulage) Ltd and offered as an option by Capper and Lamb (En-. gineering) Ltd is another legacy from Holland. When Welgro first approached the Dungannon company and offered it the UK agency Jim Lamb responded in the way he knew his customers would respond. "Yes, I am interested," he said, "but I want to prove the equipment in my own fleet first."

This trial has resulted in the modification of the trailers' steering linkages so that swinging-up trailer legs are not necessary. It has also wholly convinced Jim Lamb of the merits of the Welgro system, especially when used with a semitrailer. This gives the operational flexibility that is vital to so many operators these days.

The steered axle has extended trailer tyre life to a remarkable extent in the Capper and Lamb fleet. One trailer has already covered 180,000km (112,000 miles) on its original tyres and they will not need replacing for a while yet.

Other operators are coming round to Jim Lamb's way of thinking. Wilsons Feeds of Belfast, for example, is said to be averaging 40 tons a week more with a Welgro tank semi-trailer than it was with a conventional tipper/blower body. West Cumberland Farms is taking advantage of the flexibility offered by semi-trailer operation by using a tractive unit to pull a Welgro tank during the day, and for trunking with a flat during the night.


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