Page 8 - September October 2000

BRASS
Sorting out HO Brass.
Part 1. An Introduction
The Editor
The brass steam loco is approached by many owners as though it were a cross between a Swiss watch and an atom bomb. It is certainly complex compared to most of our models, but it has a degree of order in its construction and can be repaired and improved by most modellers, with care and a little patience. The surprising discovery is how similar many of these apparently varied models can be, considering what a wide range of prototypes they cover. The major differences are usually down to when they were produced, between say the late 50’s to the present day.
I thought it might be useful to write a “serialised” column of description and tips, so that the curious owner might feel better able to tackle problems. Perhaps this will build up into a kind of generalised workshop manual of, at least, the simpler aspects of looking after these valuable models. Other brass tinkerers should feel free to send in their own tips and experiences so that I can cadge....er, give them credit for the extra information.
At this stage I’ll limit my scribblings to what we might describe as mainstream, rigid- framed HO brass - e.g. your typical Mikado or Pacific. Later we can add riders applying to articulateds and other oddballs.
Where applicable I’ll try to indicate variations from the norm, but I will certainly overlook some details! For this, Part 1, I’ll finish by briefly describing the typical construction. (I will assume for this purpose that the loco has been stripped down to its components by simply removing every screw in sight, and unsoldering any motor or lighting wiring. I will assume also that you have placed each small item in a safe container, with perhaps some notes as to its location/purpose on the model.)
Tools needed:
(put away that hammer!)
• Set of small “jewellers” screwdrivers
• Small pliers, needle nose
• Assorted small files
• Small drills and metric taps
• Small and large soldering iron (the latter for repairs only).
Useful additions:
• NSWL Quarterer
• Riveting tool, e.g. Bowser
The mainframe usually comprises two frames running from pilot to rear of cab, separated by a series of transverse spacers soldered between them. Occasionally some of the spacers are riveted. The front end might have a non-detachable pilot and deck, with other fittings - more often this
assembly is removable.
The rear end will have
a mounting plate to
secure the chassis
under the cab, and
might also carry some
details and pipery. In
most models the
cylinder block will be
removable, held by a
single hollow screw
(whose bore takes the
long vertical screw holding the front end to the smokebox). Occasionally two small screws secure the cylinder block to a cross bearer in the mainframe. The cylinder block usually has the slidebars connected to it. They are prone to detachment and should be checked for security of fit into the rear cylinder cover.
In most models the mainframe will have a line of dummy driver springs soldered to the top edges of the frames, and some form of bracket to hold the motor. This bracket in turn is often removable.
The mainframe will have cut-outs (hornblocks of sorts) for the driver bearings except in very old models where the axles run directly in the mainframe brass. It might also have threaded holes between each driver cut-out, to take the brake pivot screws, though sometimes the brakes are part of an assembly secured to the keeper plate by solder, or more usually by screws. In the type of loco where there are separate, screwed on brake hangers, you will have a collection of these in brass or plastic. Some brass ones secure to the chassis via plastic bushes to insulate them. (The left hand brakes will cause short circuits if they are uninsulated and can touch their nearest driver tyre.)
You will have an appropriate number of driver sets, each set comprising two wheels and two bearings on an axle, unless this is one of the very old locos with no bearings. One axle will have a wormgear fitted, one or more sets might be “blind”, i.e. have no flange.
Note that in most locos the wheelsets are not interchangeable. The cast-on weights are different, the geared axle must obviously go in the right slot to line up with the gearbox and keeper plate cut-out. Identify the insulated sides, visible as a fine band of plastic or fibre just inside the tyre. (I mark this side with a
fine short scratch on the inside of the weight - I have seen numerous locos with one axle reversed and the owner wondering why it is shorting.)
The other items to note regarding drivers are the coil springs. These fit between the top of the frame cut- outs and the driver bearings. The coil springs are sometimes carried in holes bored in the tops of the
bearings, and often locate over small pegs in the top edges of the frame cut-outs.
A rare alternative to coil springs is the use of a single longitudinal stainless steel wire each side, running along near the top of the frame cut-outs (see above). The top of each driver bearing presses up against this. I’ve only seen this on a couple of Custom Brass locos, and it is pretty poor. Very old locos are without springs and also without brakes! (Sounds likes some old bangers I’ve driven!)
Similarly you will have a truck or trucks unless the loco is a switcher. Some are one- piece, others can be dismantled if necessary. Again it is a good idea to identify any current-collecting wheels and mark them. Some trucks have fine springs to act as a self-centering mechanism, and also to provide a slight downward pressure against the rails. I invariably try to discard these springs. A well-sorted loco, on decent track, has no need of them, and they are actually detrimental to traction. Some trailing trucks (and tender trucks) at the upper end of the market have sprung wheelsets. In HO these are probably almost non-functional.
You will have a pile of short side rod parts, connecting rods, and valve gear parts - unless you are very familiar with prototype steam locos, mark everything clearly as it comes off the model. The same goes for the crankpin screws that released the siderods.
You will next have a motor and gearbox parts (see below). The former will be an open frame type or an enclosed “can”. The gearbox can be open (i.e. gears all visible) and built up from brass plate, or closed, usually two half castings of white metal and a small pressed metal bottom cover to be secured with two screws to the side castings. Variations include Delrin gearbox
8 ROUNDHOUSE
Part 1