Heljan Class 52: Powered Test

Remove the wheelsets from one of the subframes. To start, support the subframe on a narrow block as for fitting. Use a screwdriver to press the primary springs downwards and inwards out of their seats, allowing them to spring back up to rest on the insides of the seats. Now move the bogie to a flat surface and lightly press the subframe downwards so that the wheelsets move upwards in their slots, at the same time sliding and guiding the primary springs up over the insides of the primary and secondary spring seats.

Working on the drive unit that goes with that subframe, ensure that the interior of the drive unit is free of any foreign bodies. Lubricate the teeth of all gears in the drive train using a suitable grease. Lubricate the worm shaft bearings with a light oil.

Fit the wheelsets to the drive unit, ensuring that they are fitted in the correct locations and the correct way round, as indicated by the id marks on the bearing carriers. While doing this, adjust any pickups to give a light preload onto the wheel flanges. Clip the lower cover of the drive unit into place.

Inserting springs Using a pair of tweezers to handle the springs, and a small screwdriver to manipulate the bearing carriers, thread one of the primary springs through the hole in the ear of the central bearing carrier facing the outer axle.

Thread the spring through the slots in the ears of the bearing carrier of the outer axle.

Thread a second spring through the hole in the other ear of the central bearing carrier.

Thread that spring through the slots in the ears of the bearing carrier of the inner axle.

Springs in drive unit Similarly fit the two springs on the other side of the bogie.

Note that these photos show a similar bogie in which the bearing carriers face outwards rather than inwards.

Place the subframe on the narrow block for wheeling.

Slot the drive unit into the subframe with the primary springs resting on the tops of their spring seats - you will have to guide the springs over the secondary spring seats on the way. Ensure that the bearing carriers are correctly engaged in the slots in the subframe, and that the drive unit is facing the right way.

Use a screwdriver to spring the springs inwards and downwards on to the inner faces of their seats.

Push the springs downwards so that they slide over the seats, until they spring back out and up into place under the seats.

Now take the bolster for that subframe, make sure it is facing the right way, and slide it into place in the subframe, until the secondary spring wires are resting on the tops of the secondary spring seats.

Pushing down gently on the bolster, use a small screwdriver to bend each spring slightly inwards so that it slides down the inner face of its spring seat and snaps into the slot in the seat (you may find that simply rocking the bolster from side to side is sufficient to seat the springs).

Unclip the circuit board from its rubber retaining lugs in the centre of the loco. This will make it easier to see the fit of the cardan shafts into the sockets at the ends of the motor shaft.

Find the cardan shaft and clip the correct end into the drive socket of the bogie.

Offer up the bogie into the aperture at its end of the loco. Engage the free end of the cardan shaft into the loco's flywheel drive socket and line up the holes in the pivot frame and the bolster top. Fit the bogie retaining screw, sleeve and washer (the latter will have one of the pickup wires soldered to it if using 'American' current collection).

Repeat all of the above for the other bogie.

Plug the pickup wires into the correct sockets of the circuit board.

Place the locomotive on some track and give it a test run under power.

Run the locomotive in gently at first. If the loco does not run freely or begins to bind up at any point, pay particular attention to lubrication of the axle bearings. You can feel for any binding by rotating the wheel rims with the fingers - there is enough slack in the drive train gears that you should be able to distinguish between a binding and a free wheelset.

Keep testing and making any adjustments until you are satisfied that the loco is running OK.

If you are not going on to fit any further detail to the bogies, you're nearly done, and you can proceed directly to the "Final Assembly" section.

Remove the bogies from the loco once more, and separate the drive units, wheelsets, bolsters and subframes.

IMPORTANT NOTE: If you need to remove the body, please DO NOT at any stage attempt to pull the chassis from the body by pulling on the bogies, as this may damage the spring mountings.