Heljan Class 52: Preparing the Locomotive

Following the manufacturers' recommendations for running-in, ensure that the locomotive is performing smoothly and to your satisfaction generally. Deal with any issues now, especially those covered by warranty or your basic statutory rights as customer, before making any modifications.

Separate the body moulding from the chassis block of the locomotive according to the manufacturer's instructions.

Gently slide four cocktail sticks between the body and chassis block, one to the side of each body retaining clip, just far enough to hold the clips clear of the chassis block so that the body may be slipped easily off the block.

Make a note of the identification of the sockets on the circuit board to which the two wire power feeds from each bogie are connected. Note also to which side of each bogie the wires go. Unplug the power feeds from the circuit board.

Identify the 'A' and 'B' ends of the chassis. Look at the underslung 'gondola' between the bogies: there is a rectangular opening on one side at the 'B' end. Scratch a triangular mark on the 'B' end of the chassis. Assign the bolster and subframe with triangular marks to that end of the loco.

Kestrel Bogie Fixing Remove one of the bogies from the chassis block.

(These photos use a different type of loco to illustrate the procedure).

Unclipping Bogie To dismantle the Heljan bogie retaining assembly, unclip the top cover of the drive train as shown. This will allow the two halves of the drive unit to be separated slightly, allowing the worm gear and bearings to move a little, which in turn allows the bottom of the circular part of the 'yoke' to be unclipped from the drive unit.

Removing plastic yoke Remove the plastic yoke.

Strong finger pressure, to lift the edge of the moulded ring over the edges of the chassis block, will allow the yoke to be slid sideways as shown, at which point one end of the moulding becomes free of the block. The moulding is then easily removed.

Similarly remove the other bogie. Mark the bogie drive from the 'B' end with a triangular mark.

Pivot Frame Assembly

Heljan Pivot Fret

P2, Pivot Frame.

P3, Pivot Rib.

P1, Pivot Flange.

*1: Body of nylon insulator to fit through this hole.

Pivot Frame in position Test fit the pivot frame assemblies in place in the chassis block, with the holes in the sides of the frames lined up with the holes in the chassis block which retained the plastic yokes. It may be necessary to file the outside faces of the frames a little to fit the tapering casting.

This photo is from an earlier test build and shows a slightly different design of pivot frame.

Note that the Pivot Frames shift the bogie pivot centres to their correct position.

Secure the pivot frames in place. They may be secured by lengths of 3mm plastic rod inserted through the holes in the sides of the chassis casting and engaging between the Pivot Flanges and the half-etched housings in the Pivot Frame. You may need to file flats on the rods to get them to fit the etch. The plastic cylindrical shafts of the original yokes, cut off, make suitable rods for this purpose if you are prepared to sacrifice them.

Ultimately the Pivot Frames can be bedded on epoxy resin for additional security.