The main chassis is in 2 parts. From the upper fret the w-irons fold down, and in which the bearings can slide up and down. These are linked by cross beams pivotted on a longitudinal wire. This also acts as a torsion spring between the two axles. There is a lower fret which acts as the underside of the chassis framing. Â This carries the spring castings, and locks the assembly together. Between these 2 etchings, whitemetal ballast weights provide some usful low down weight, particularly for plastic open wagons. The wheel bearings are carried in plates behind the w-irons which bear upon the arms of the crossbeams.
Further torsion wires link each crossbeam to the chassis. Thus if one axle rises, it is resisted by the body on one side and by the other axle which is similarly fixed to the body. This means that the body will take up a deflection half way between each axle, and that the relative movement of one axle to the other is independent of the body weight.
The chassis is easily fitted by glueing to the underside of the floor of any plastic or whitemetal kit, as well as to many proprietry models. It has a depth of 3mm (9 inches prototype) so that some packing may be needed for use with 10 and 12 inch types.