Australian Railway History 803, September 2004 p 340

John Knowles comments on a small aspect of this article:

Captions to photographs on pages 349 and 350 (top) state that the six wheeled carriages illustrated were radial, meaning that the wheelsets could turn so that they pointed along the radius of the curve towards the centre of the curve.

No radiating systems are visible, and the outside axleboxes are not especially long nor at an angle to the axles. The vehicles illustrated appear to be six wheelers with parallel rigid axles, no doubt with side play allowed to the axle boxes for the centre axles, or thin flanges on the wheels on those centre axles.

The six wheeled tenders visible in other photos illustrating the article also had parallel axles, as did most if not all six wheeled tenders used in Australia.

There were several devices which allowed axles of railway vehicles to lie on a radius of the curve. Single carrying axles of steam locomotives, as on 2-6-2s for example, were almost always radial, usually in a Bissell or radial arm truck. Such a truck moved sideways on a curve; because the truck was pivoted at some distance from the axle, and the sideways movement allowed the axle to become radial. Return of the truck to the normal position for straight track was brought about by a spring (which spring also assisted in controlling the nosing of two cylinder locomotives).

On some locomotives, like the QR A10 0-4-2 and D16 4-6-2T as built, and the SAR F 4-6-2T, the rear carrying axle ran in radial axleboxes with curved sides, which moved sideways in curved horns, the movement initiated by flange and tread pressure, and the return brought about by a spring (but not on the A10, on which the return depended on the same pressures).

More common on six wheeled rolling stock were systems where the radiation on outer axles was brought about by mechanical connections between the outer axles and the inner axle, the relative sideways movement of the inner axle on curves causing the outer to radiate (but not until the vehicle was fully on the curve). Such systems included the Clark and Cleminson.

The QR made extensive use of rolling stock with radial axles, including on four wheeled vehicles. The systems used are described in my article in the ARHS Bulletin for April 1974, p 75.