Forward Step in Tank Construction
Page 56
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ANOV-EL method of mounting tanks on vehicle chassis has been evolved by Thompson Bros. (Bilston), Ltd., Bilston, Staffs. It involves a fresh approach to the construction of the tank itself, and a useful saving of weight is achieved. Chief advantage of the new arrangement. however, is likely to be longer tank life.
Instead of having a series of bolsters placed along the chassis to support the tank, the tank is fabricated to be suitable for three-point mounting. Attached to the chassis by such means, it is relieved of many of the twisting stresses which would otherwise be imposed.
Tanks are made in sections in the usual manner. The bottom piece of each section is a simple curved sheet, but the crosssection of the side pieces resembles the shape of a sickle, with the handle uppermost. These pieces are welded together by the Argonarc process, and a number of sections is then joined to form a barrel.
Rows of Pillars
With the barrel strapped by steel bands, the interior partitions are welded in, and two Z-section uprights are attached to each baffle, continuing the lines of the vertical flanges of each side piece (the handles of the sickle) to the bottom of the tank. These Z sections thus form two rows of pillars.
Two lengths of inverted L sections are welded along the top of the tank to form full-length boxes with the upright flanges of the side pieces and a short part of their curved section., and a dished piece, with loading ports suitably spaced, bridges the flanges.
At the bottom of the tank, two lengths of aluminium of deep top-hat cross section are attached lengthwise in line with the rows of internal pillars. With the domed ends welded on, the tank is an integral. structure of great strength, and no steel supporting members are necessary-for mounting.
The tank is made in light-alloy sheet in. thick, the various components being pressed to the required shape. Of 2,400gal. capacity, it weighs 13 cwt. and is claimed to be 5 cwt. lighter than a normal aluminium tank structure of similar size. This difference is largely because of the absence of steel supports. It may also represent an increase of 150 gal, in capacity.
4,400-gal. Capacity
The first four of these new tanks have been built for Shell Chemicals, Ltd., on A.E.C. Mercury four-wheeled chassis. Applying the same method, 4,400-gal. tanks could be built for eight-wheeled chassis.
With integral construction to allow three-point mounting. the tank is supported on two metal-to-rubber bushes above the rear axle, and on another bush midway between the chassis members near the nodal point where twisting movements are smallest. This means for mounting allows a slight diminution in the height of the tank relative to the chassis.
The tank rests on two shallow-V cradles with trunnion mountings. Axes of the rear bushes are lateral, whereas the front bush is longitudinally disposed in the centre of a beam, the ends of which are rubber-mounted on the chassis members. To demount the tank, a pair of U-bolts on the four plates attached to the chassis is unfastened.
The Shen tankers are of elliptical pattern, but the method of construction is equally applicable to cylindrical tanks.
Further progress has been made in combating water contamination of aircraft fuel carried in tankers. The root of the problem is the condensation which forms on the inside of the tanks when running empty. Research, is being conducted to find which kind of lining has the best water repellency, for if the lining is highly repellent, much of the condensed water can easily be drained out. Polished aluminium, unlined, has been found to have good characteristics in this respect.
A necessary refinement is a positive means for separating the water content from the fuel, and until now this has been done by passing the liquid through such media as wood wool. This causes the suspended globules of water to coagulate, after which they fall and may be drained off.
Thompson Bros., however, have evolved and patented a centrifugal separator after several years' study, and the device is showing good results in its initial tests.