Bachmann LMS 10000/1: Springs, Bogie Assembly and Rolling Test

Primary Spring Wires Cut eight lengths of the primary spring wire, each 35mm long.

Degrease the wires and apply, to one end of each wire, a bead of fast setting epoxy resin about 1mm diameter, i.e. just large enough to prevent the springs being pulled through the holes in the ears of the central bearing carriers. Put the springs to one side while the resin sets.

Secondary springs Cut eight lengths of the secondary spring wire, each 20mm long. Make a 90° bend in each wire, 2.5mm from one end.

Inserting secondary spring Take the two bogie Bolsters and fit four secondary springs to each: pass the longer arms of the wires through the holes in the secondary spring seats...

Secondary spring retention ...and clip the shorter arms into the spring retaining ears. You might need to adjust the angles of the bends so that they are retained securely but do not impose any bending on the spring.

Centre pivot moulding Taking each bolster in turn, fit the plastic pivot mouldings (previously removed from the top of the Drive Unit) into the space between the two Bolster Ribs (4)…

Pivot moulding fitted …with their bases sitting down on the Pivot Lands (3). The mouldings should be a tightish push fit between the Ribs.

Checking fit in chassis block Offer the bolster up into place in the chassis block, with the central spigot of the pivot moulding engaged in the pivot hole of the chassis block. Push the bolster up in to the block, and check that this force is resisted by the shoulders of the bolster against the lower face of the base moulding of the chassis, without any rocking about the top pivot. If rocking does occur, try taking a little off the outside top ridges of the pivot moulding, which come into contact with the transverse ribs in the chassis block, either side of the pivot hole. Smooth / chamfer the edges of the bolster shoulders if they catch on the edges of the base moulding.

Shaping pivot moulding Mark the profile of the arched tops of the Bolster Ribs (3) against the pivot moulding. Remove the moulding from the bolster, and file away material from its underside to match the profile.

Cut-off pickup strips Take the brass pickup strips, previously removed from the Drive Units, and cut away the vertical parts of the strips, about 2/3rd of the way down their fixing holes, as shown.

Pickup strips fitted to bolster Solder the vertical parts of the pickup strips to the outside faces of the Bolster Sides (5), between the Bolster Ribs (4), projecting upwards through the slots in the Pivot Lands (3) and extending about 5mm above the tops of the ribs. Retain the cranked shape of the strip, and solder just the bottom couple of mm.

If you are using 'American' or conventional pickup, you'd fit only one of the conductor strips on each bogie. You might also prefer to use conductor wires instead, to by-pass the sliding contacts, though they haven't given us any trouble in extensive testing.

Pivot moulding and pickup strips Refit the plastic pivot moulding to the Bolster top, with the pickup strips passing through it. Screw the pivot screw fully home, and then unscrew it, two or three times, until the screw becomes relatively easy to insert and remove.

Checking pivot strip upstand Test fit the bolster in the chassis block once more. With the bolster shoulders held up against the base of the chassis, the pickup strips should compress the spring pickups, hanging from the underside of the circuit board, to approximately horizontal. Trim their lengths or adjust their fixings until this is achieved.

Primary springs in centre wheelset Return to the primary suspension wires and check that the epoxy resin beads have set hard.

Take four of the primary springs, one of the central wheelsets, and insert one spring through each of the four holes in the ears of the bearing carriers, feeding them through until retained by the epoxy beads.

Check that the epoxy beads do not restrict the movement of the springs in the carrier. Reduce their length and/or diameter if necessary (having only recently hardened, they will respond quite well to paring with a sharp knife).

Inner and outer wheelsets on primary springs Take the inner and outer wheelsets, check their correct orientation to the central wheelset, and slide their bearing carriers on to the primary springs.

Bogie wheeling jig Find a block of material long enough to support the bogie subframe, deep and narrow enough to allow the wheelsets to drop all the way down in their slots.

We use this tufnol jig for wheeling up and other assembly work. It allows the whole bogie to be turned round without disturbing any of the parts.

Wheelsets on subframe Place the bogie subframe on the jig. Pick up the three wheelsets together and rest them on top of the subframe, with the bearing carriers of the central axle aligned over their slots.

Wheelsets in slots Pull the primary springs outwards so that their inner ends are sitting properly in the tops of the central bearing carriers.

Move the inner and outer wheelsets towards the ends of the bogie, until their bearing carriers are engaged in their slots. Adjust the assembly so that the primary springs are sitting on top of the secondary spring seats.

Primary springs over secondary seats Using a small screwdriver to manipulate the springs, bend them outwards to slide over the secondary spring seats…

Primary springs over primary seats …and then part way down the outsides of the primary spring seats.

Pushing primary spring under its seat Finally push each spring downwards…

Primary springs seated … until it snaps inwards and back up into its primary spring seat.

Turn the bogie round and repeat for the axle at the other end.

Assembled primary suspension You now have a rolling bogie with fully functioning equalized primary suspension. Do a hand-powered rolling test to check for any tight bearings, wobbly wheels etc. It is easiest to correct such things at this stage.

Fitting bolster Now take the bolster, make sure it is the right way round, and slide it into place over the subframe. As you do so, push it to one side and you should find that the secondary springs on that side will snap in to place in their spring seats. On the other side, working through the slots in the tops of the traction ears with a small flat bladed screwdriver, push the secondary springs outwards and slide them down over their spring seats until they also snap into place.

Assembled sprung bogie Repeat the above operations for the other bogie so that you now have two rolling bogies.

Fit the bogies into the chassis block, using the original pivot screws to retain them.

You can now do static and rolling tests, with and without the body fitted, to check ride height, body clearances, ability to handle curves, and suspension characteristics. It's helpful to clear any gremlins now, before the mechanical drives and detail are fitted. It is also extremely satisfying to feel how the locomotive moves with its sprung suspension.

The kit has been designed to give a ride-height which places the top of the loco at the correct distance above the railhead. Variations in manufacture and construction may cause the ride height of your model to be slightly different. As manufactured, our loco was just a fraction high over roof panels, with buffer height just a fraction low. Half- and full-thickness Spacers (14) have been included on the fret: you can stick these to the underside of the loco's baseplate where it sits on the Bolster shoulders, to raise the ride-height, if required.

Ride height is normally set to give a nominal buffer height of around 13.8mm above rail level. You may well find that there is a variation in the order of 0.5mm over the four buffers, just in the way that they've been fitted to the loco. You might also wish to check for maximum height overall, and then reflect on whether the manufacturer has got the buffers in the right place. Ultimately, working to tenths of millimetres, it will be a judgement call as to exactly where the correct ride height lies.

Remove the bogies from the loco and dismantle them ready for the next stage.

To remove the Bolsters from the Subframes, gently lift each end of the bolster in turn, and use a small screwdriver through the slots in the bolster shoulders to push the secondary springs outwards and out of their seats in the Subframe.

To remove the wheelsets from the Subframe, support the frame on the tufnol block and use the screwdriver to press down the primary springs and pop them out to rest on the outsides of their spring seats, at the same time lifting the adjacent wheelset, then slide the primary springs up over the outsides of the primary and secondary spring seats, bringing the wheelsets together as at the start of assembly.