Heljan Class 47/Kestrel: Subframes

This section describes the construction of the bogie subframes.

Annotated view of bogie subframe

Subframe mainframes On the Mainframe etches (10), check that the slots in the sides are clear to take the etch thickness.

Make the two main longitudinal folds, each of which is in three parts carried over the transom sections under each axle slot. Ensure the folds are at a true right angle.

Subframe Seat-Ear etches Remove the spring Seat-Ear etches (9) from the fret. There are two of each hand for each bogie.

Check that the small etched holes are clear to pass a 0.5mm drill.

Four tags folded Fold over the small tags at each of the corners of each Seat-Ear etch.

180 Seat/Ear fold Make the 180° fold, with the fold slot to the outside of the fold, at the centre of each Seat-Ear, to fold the two layers of the ear back on themselves.

Lateral ear Fold out the lateral restraint ear…

Outrigger fold … and the longitudinal restraint / outrigger from each Seat-Ear. DO NOT make the fold at the end of the outrigger just yet.

Seat/Ear Fold up Completed Seat/Ear fold-up.

Fitting Seat/Ear to Mainframe From inside the Mainframe, fit each Seat-Ear through the slots in the side of the Mainframe between the centre and outer axle slots.

Soldering Seat-Ears Apply flux to the three laminations - etched holes are provided to facilitate this - and support them firmly together before soldering them in. Ensure that the slots and holes for the springs remain free of solder: use a 0.5mm drill to clear them if required.

Fitted seats Ensure each of the fold over tags along the top edges of the Seat-Ears is reinforced with a small fillet of solder.

Check against a flat surface that the eight secondary suspension seats are square and level.

The end stretchers are on Fret F003. The card insert in the F003 Pack shows which the three different stretcher types are: Outer, Outer for use with coupler pocket, and Inner.

Stretchers for etched brake detail

Remove the stretcher etches from the fret and clean up. Choose the correct types of stretcher depending on whether or not you wish to retain the original coupling pocket.

Fold up the stretchers as shown above.

Fitting Stretchers The frames are reversible until the stretchers are fitted. For consistency, our convention is to fix the outer stretcher to the 'two-spot axle' end of each frame.

Solder the stretchers in place, locating their slots over the tabs in the ends of the subframes.

When fixing the stretchers to the Mainframes, it's convenient to invert the components and support the stretchers on blocks.

Completed subframes Check that the whole assembly is square and true.

Reinforce each of the Mainframe folds with a fillet of solder. Take care to ensure that the region immediately around the axle bearing slots, for at least about 1mm around the edges of the slots, is kept free of solder.