Construction

The Buildings

Overhead Power Supply

The Contact Wire

Busy Tram junction at the intersection of Centuurbaan and Lammer Bridge, City of Momentum.


New Trams for the
City of Momentum:
Siemens Combino's

Construction

The layout is mounted on what we call "Chipboard", a kind of pulp compressed wood (not suitable for damp climates). Fortunately the climate here on the Highveld is of a very dry nature, so the use of Chipboard can be permitted.

The shape of the circuit is a letter 'W' or 'M', depending which way you look at it. The city of Momentum is situated in a loft consisting of 77sq.m.

The length of track utilised was around 36 metres, consisting of 14 Tram routes, servicing the City. The track used has been varied from 70 gauge double track, to 70 gauge single track. The majority of the track is code 100 moulded into a proper 'Girder' Rail', with the exception of the interurban and private right of way sections. Mostly double track. In the street sections, the rail is counter sunk into the street, as in the prototype. This feature is achieved by soldering code 70 rail at right angles to the inside of the code 100 rail. This method is costly, as you virtually double up on your track costs.

The track is completely sectionalised; this was done before DCC control came into being. The layout was started in 1978, so the question of running one tram behind another would be possible on this layout, with the use of the overhead current collection being the 'common' and left or right rail being the positive in the individual trams. Since then, the city has been upgraded with "Digitrax Command Control", allowing this realistic operation, to be even better than was originally planned. The sectional construction did not hinder the change over to DCC.

The Buildings

These consist mainly of the branded variety as supplied by the likes of Kibri, Vollmer, Heljan, etc. There are a few American models on the layout, but they are not to scale and have to be selectively placed, so that they do not detract from the remainder of the buildings.

The drawbridge which is quite a prominent feature in the city, was scratch built by one of our members; the material used consists mainly of 'Summerfeldt' traction poles and solid brass rod. The base is mounted on PC board, with re-enforced rail. The mechanism driving the bridge consists of a 6.3 DC voltage, (old radio mains transformer) driving a 12V DC motor, governed by a limiter switch arrangement. Warning lights are displayed at each end of the bridge, warning drivers of the position of the bridge.

All the buildings are internally illuminated; street lights are evident throughout the city and provide a interesting atmosphere in the evening. Some of the street lights have been purchased, but a large amount have been made by myself with different widths of brass tubing and using a larger type LED as the bulb. The period of the buildings is off course in keeping with the times in which the trams reigned the streets of our cities.

Overhead Power Supply

The traction poles are solid brass rod, 4mm thick and has a thread turned on the baseboard side, by which it is housed on the baseboard. Drilling a 4 mm hole through the board , giving a tight fit. This is secured with two 4mm nuts and washers. 72mm is the height above rail level where the contact wire is to be secured, giving us the trolley wire height. The bracket from which the 'arm' is constructed is a simple carton staple (in everyday use in the commercial world) soldered to the brass rod. At point of contact a small 1mm hole is drilled, together with a similar hole on the other side. Through these holes is soldered the support to which the contact wire is secured, by way of an 'ear'.

Just above you in the picture you will see this bracket to which I refer.

Why solid brass rod is used, would make the conducting of the power much simpler, when the buss bar for the power is fed through the poles from underneath the baseboard.

With the exception of the Inter-Urban section of the layout, all the brass poles, with it's gantry was made by myself on the workbench. Pull-off poles are identical, but without the brackets. A 1mm hole is drilled through the pole for the attachment of the pull-off wires. There are several slight variations with the traction poles, in as much as the bracket arrangements and whether they be single or double poles.

In a situation where three tracks are parallel to one another, I use code 70 rail for the brackets, bent to shape.

The Inter-urban catenary is manufactured by Summerfeldt, together with the lattice poles used for this construction. It is very a realistic overhead, but costly to come by.

The Contact Wire

This is 0.25 mm thick phosphor bronze wire. This wire is very 'springy', so it cannot be used for pull-offs, but is very useful for the manufacture of springs pertaining to the construction of the overhead.

Those who prefer overhead catenary on their traction layout will know that breakages are common. For this reason I use a 5 amp single strand annealed copper fuse wire, for the pull-offs. This is high in lead content, so it stretches to fit, but also acts as a safeguard in breakages for those waving arms.