Tracklaying is now largely completed on the new fiddle yard on Meacham, and wiring up is beginning. The aim is to have this complete in time to familairise ourself with the new operational practices required, in good time for the Warley MRC show this autumn

Aim

The aim of the redesign of the yard is principally to increase capacity for when exhibiting Meacham, without requiring a change to the baseboards. We considered extending the baseboards in various different ways, but discounted that option as it woudl have too much of an impact on our ability to transport the layout by car.

Previous situation

Previously we had a traditional four track 'ladder style' fiddle yard on each of the inner and upper lines. Each yard took about two baseboards and was bypassed by a single arrivals line leading to the other direction's fiddle yard. Most of the centre board of the layout was wasted space as it was occupied by the points for both yards, which had been laid without working out how to put them close together.

In practice, it meant that each yard line could be used for one or two trains, depending on the length of the train used.

Revised Design

The new yard fits in one more line, giving a total of six lines. The yards though run the full length of the layout, giving two x three-track yards each about four baseboards long. There are now no bypass lines - all the yard can be used for storage, and the wasted space on the centre board has been used as well. Each line has been designed to queue up several trains, which can be shuffled u fromt he arrival end to the departure end, while other trains are operating on the public side of the layout.

The design has been prepared for the additional MPD board,which has not yet been constructed. It will add an additional section to each of the six lines of the fiddle yard, allowing up to a further six full length trains to be stabled in the fiddle yard.

Electrical design

Obviously, to queue trains behind each other can most easily be done with DCC - but the locomotives used on the layout are not DCC fitted, belong to a variety of people, and would be expensive to convert all together. So, a conventional DC solution had to be found.

The route taken was to break the length of each line into standard 'train length' sections, designed to comfortably hold the length of full-length trains used on the layout. One lien in each three was subdivided into half-length sections, allowing shorter trains to be queued ina  half length section, or longer trains to be queued by using three half-length sections.

Rather than switching the power to the entire sections, the decision was made to provide short (20cm) dead sections at the head of each section, and to normally feed the rest of the the length of each section. The arrival section and the departure loco section are normally fed from the regular line controller, the remaining sections from a local fiddle yard controller for each direction.

Each short 'loco length' section is normally dead, but has a power supply feed through a centre-off switch. For normal use the switch is depressed and this feeds power to the section to allow the locomotive to leave, and enter the next section in advance. Once this is done, the switch can be release and it is sprung to return to off, to trap the next locomotive to arrive at the head of its train.

Alternatively the switches can be lifted from their sprung centre-off position to a latched raised position. This feeds the power in exactly the same way as when they are depressed, but will leave the short section live after the locomotive has left. This is intended for club night use, when it is rare that multiple trains are being run, and also for the last part of the day at an exhibition, when one line may be left running as other stock is packed away.

Route selection through each fiddle yard will be by a three-way four-pole rotary switch. The four poles are used thus

1. Non-fiddle yard power supply for arrival and departure sections
2. Flddle yard power for 'internal' sections
3. Point selection, via a small diode matrix, and a push button
4. Indicator lights (on control panel, and the layout itself, to show shich fiddle ayrd line is currently accepted for arriving trains.