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replace with wheels fitted with non-magnetic (brass or plastic) axles.
Uncoupling magnets work well on straight track, but where the track is curved, there are problems in coupler alignment. Coupled vehicles on a curve introduce lateral forces into the couplers that can inhibit uncoupling. The uncoupling ramp needs to be sufficiently clear of the curve that both vehicles being uncoupled are on the straight. The longer the vehicles involved, the further the uncoupler needs to be from the end of the curve.
Uncoupling ramps should also be on level track. If there is a slope and axles are free running, then there can be difficulty in taking tension off the coupler or the uncoupled vehicle may follow the train from which it has just uncoupled. Whilst free-running trucks allow longer trains to operate, they are not necessarily what is wanted for easy coupling and uncoupling.
In HO scale it is the norm that couplers are fitted to the ends of the car bodies, but in N scale, it is more usual to find the couplers truck mounted. There are pros and cons for both practices. Body mounted couplers can be a problem on reverse curves and where long vehicles couple to short vehicles. Truck mounted couplers can introduce side forces to the wheels which could introduce a greater risk of derailment. Intermixing body mounted and truck mounted couplers does not seem to be a good idea.
I have a piece of test track where I can pass a complete train over it. This includes a short length of rail mounted at right angles to the track between the rails. The top of this rail is about 1mm above rail top height and can detect any low coupler pins. There is also a piece of card mounted between the rails with a centre-line drawn on it. Looking downwards will show any couplers that are not self-centring correctly.
Wiring
If a layout is portable, then the wiring is subject to vibration when in transit. This can lead to wire breakage, particularly at terminations. The risk of this happening can be reduced by fixing the wiring to the baseboard so that the connections cannot come under tension and movement is limited.
DCC has led to a couple of changes in wiring. The number of wires tend to be fewer and are often much thicker. This reduces the chance of wire breakage. So whilst the chance of a fault due to wire breakage or disconnection has reduced, the time taken to track down a short circuit may be more time consuming. The ability to make disconnections so as to locate the short can reduce down time, but these disconnection points can, in themselves, be the source of unreliability.
DC tends to involve a lot more wires with at least one to each section. Failure restoration depends on locating the fault. If the layout has a degree of complexity then documenting the wiring can be of great assistance.
The wiring of my DC layout is recorded on a CAD (Computer Aided Design) system which means that fresh diagrams can be printed easily. Changes to the wiring can be carefully planned in advance and drawings produced which show just what needs changing.
Temperature and Environment
For both DC and DCC operation the maintenance of electrical insulations is important. Nickel silver rail changes length with temperature. A one metre length of rail would expand by 0.016mm per degree Celsius. A 3 metre length of rail would
expand by 1 mm with a 20°C temperature rise. This can easily close up an electrical gap.
If temperatures fluctuate, a rail “walk” can occur. When the rail expands, it does so by moving in the easiest direction. When it cools, it will contract but it may do so from the other end so that the whole rail has moved.
Gaps should be filled with insulation to restrain the rail and prevent shorts. This can be an insulated fishplate or some other insulation such as an epoxy resin. This year I had a gap close up in a most inaccessible place. It had been fitted with an insulating fishplate but the force produced by the expansion had moved the rail though the insulating material. I think that the end of the rail had not been filed flat so that there was a sharp point available to drive the rail though the polythene insulation.
Ideally, temperature should be as stable as possible but this can be difficult to manage. Some of the more extreme problems may arise where direct sunlight close to a window can affect track. In theses circumstances the rail temperature can rise significantly above room temperature, particularly if it has been “weathered” with dark matt colours.
Where humidity is high, as the room cools, water can begin to condense from the air and settle on cooler surfaces. This is unlikely to be a major problem with track as the water evaporates again as the temperature rises and will probably leave the rail surface unaffected. It can start any iron based material to start rusting and wood can swell, but serious condensation would be necessary to cause significant problems.
I have encountered problems with dust. When I have sawn insulation board and Sundeala, this can produce a fine dust that seems to head for any rail surface it can find. It is an excellent insulator, and removing it has been quite a job. It is probably worth sawing this sort of material well away from the layout.
Summary
There is no simple “magic bullet” for a reliable layout. I have learned through bitter experience that the following are very important.
The best way to ensure that a layout is reliable is that derailments and other problems are followed up and acted on. If your memory is as good as mine, keep records.
Take note as to whether an incident occurs repeatedly at the same place or whether a particular vehicle can have problems at other sites.
Try to repeat a derailment, and if it can be repeated, work out exactly what is going wrong.
Don’t undertake maintenance for the sake of it. Every bit of maintenance should be aimed at preventing an identified issue but remember that frequent maintenance can lead to unreliability.
Maintenance should take account of the type of layout you have. Portable layouts have different problems to fixed layouts.
If you are keen on operation, then couplers need attention to ensure that they are all installed to standard. It can save a lot of frustration.
If a piece of track is hidden and not easily accessible, it should be installed to the highest standards as going back to fix it later can be a nightmare.
    18 ROUNDHOUSE - April 2019







































































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